2010 September 20 Monday
Low Stress Men More Attractive To Women

The ladies find more stressed guys less attractive.

Men with low stress levels are significantly more attractive to women than highly stressed rivals, according to new research conducted at the University of Abertay Dundee.

Dr Fhionna Moore, a Psychology Lecturer at Abertay University, led a research team investigating links between hormones and attractiveness. By analysing hormone levels in young men and developing ‘composite’ images of typical faces, they could judge how attractive a group of women found facial cues to different hormone levels.

The study – which is published (Wednesday 15 September) in the Proceedings of the Royal Society B journal – found a strong link between low levels of the stress hormone cortisol in men and how attractive they were to women. It also found no clear link between attractiveness and high levels of the sex hormone testosterone, as has been previously claimed.

Since low cortisol is also good for your long term health Swedish massage and chocolate can help you live longer and have a better love life. Can I trouble a reader to find out whether beer drinking also lowers cortisol? That'd be ideal.

When women are most fertile they find low stress levels more attractive. This has an obvious evolutionary explanation:

The study also showed that female attraction to men with low stress levels was at its highest during the fertile phase of the female menstrual cycle.

She added: “We believe that the link between low stress levels and high attractiveness to women is because an ability to handle stressful situations suggests a strong genetic make-up, the future suitability of a partner, and their ability to pass on ‘good genes’ to their children.

Similar cortisol and testosterone levels predicted greater attractiveness.

“Interestingly, our research also showed increased attractiveness for men with consistent hormone levels. So low cortisol and low testosterone, or high cortisol and high testosterone, were both found to be more attractive than one level being high and the other low.”

The high testosterone, high cortisol result is interesting. Such men probably burn brighter but burn out sooner.

By Randall Parker    2010 September 20 10:48 PM   Entry Permalink | Comments (8)
2010 August 24 Tuesday
Ovulating Women Sexually Compete

It is possible to evoke in women an instinctual desire to sexually compete against other women. Okay, you already knew that. But here's an interesting way to measure this effect.

In an unconscious attempt to outdo female rivals, ovulating women buy sexier clothing, according to a new study in the Journal of Consumer Research.

"Not unlike the chimps featured on the Discovery Channel, women become more competitive with other females during the handful of days each month when they are ovulating. The desire for women at peak fertility to unconsciously choose products that enhance appearance is driven by a desire to outdo attractive rival women," write authors Kristina M. Durante, Vladas Griskevicius (both University of Minnesota), Sarah E. Hill (Texas Christian University), Carin Perilloux (University of Texas at Austin) and Norman Li (Singapore Management University).

Ovulating women were shown photos of either attractive or not so attractive women. Then they were asked to choose clothing to purchase. The women who had looked at more attractive women chose sexier clothing. Non-ovulating women were not similarly affected.

In the study, researchers had ovulating women view a series of photographs of attractive local women and then asked them to choose clothing and accessories to purchase. The majority of participants chose sexier products than those who were shown photos of less attractive local women or women who lived more than 100 miles away. The authors found that women were not conscious of their choices and the researchers did not find the same effect in non-ovulating women.

The study's findings have practical implications for marketers. "For about five to six days each month, normally ovulating women—constituting over a billion consumers—may be especially likely to purchase products and services that enhance physical appearance," the authors conclude.

Since non-ovulating women do not see the same effect does that mean that ovulating women are also easier to make jealous? Also, do women on the birth control pill act like ovulating or non-ovulating women? Also, what physical features in the appearance of attractive women do most to elicit sexy clothes buying behavior? Do women share men's appreciation of big breasts? Red make-up?

By Randall Parker    2010 August 24 07:26 AM   Entry Permalink | Comments (5)
2010 July 08 Thursday
Declining Fertility Boosts Female Sex Drive

If you get attacked by a cougar blame it on her declining fertility.

AUSTIN, Texas—As more women wait until their 30s and 40s to have children, they are more willing to engage in a variety of sexual activities to capitalize on their remaining childbearing years, according to new research by psychologists at The University of Texas at Austin.

Such "reproduction expediting" includes one-night stands and adventurous bedroom behavior, the research shows.

In a paper published in the July edition of Personality and Individual Differences, psychology graduate students Judith Easton, Jaime Confer and Cari Goetz, and David Buss, professor of psychology, found that women age 27-45 have a heightened sex drive in response to their dwindling fertility.

Is the heightened sex drive a consciously arrived at choice? I doubt it. Makes more sense for Mother Nature (a.k.a. Darwinian natural selection) to select for a strong desire to take one last shot at making babies before the reproductive machinery totally conks out.

What I'd like to know: Does the hormone that predicts earlier menopause also predict an earlier peaking of sexual desire in women who are going to have earlier menopause?

By Randall Parker    2010 July 08 09:23 PM   Entry Permalink | Comments (8)
2010 March 21 Sunday
Presence Of Women Makes Men Risk Takers

Young male skateboarders take bigger risks and experience higher testosterone in the presence of attractive women.

Los Angeles, CA (March 18. 2010) The presence of an attractive woman elevates testosterone levels and physical risk taking in young men, according to a recent study in the inaugural issue of Social Psychological and Personality Science (published by SAGE).

Researchers asked young adult men to perform both easy and difficult tricks on skateboards, first in front of another male and then in front of a young, attractive female. The skateboarder's testosterone levels were measured after each trick.

When skateboarders attempt tricks, they make a split-second decision about whether to abort the trick or try to land it, based on a mid-air evaluation of the likelihood of success and on the physical costs that failure might bring. It was that moment the researchers sought to examine because it resembles the type of risky decisions that young men make when behind the steering wheel of a car or when in physical confrontations with each other.

Consistent with predictions, the young men took greater risks in the presence of the attractive female even when they knew there was a greater chance that they would crash. Testosterone levels were significantly higher in these men than in the men who were in the presence of another male.

I wonder whether the presence of attractive women would cause male stock and bond traders to make better or worse investment decisions. Should a trading firm isolate their male traders from attractive women? Or hire attractive models to deliver coffee?

Science proves the truths of ancient mythology once again.

"This experiment provides evidence for an effect that has existed in art, mythology, and literature for thousands of years: Beautiful women lead men to throw caution to the wind," write authors Richard Ronay and William von Hippel. "These findings suggest that, for men, the adaptive benefits gained by enticing mates and intimidating rivals may have resulted in evolved hormonal and neurological mechanisms that facilitated greater risk taking in the presence of attractive women."

Some day, with some help from South Park, we might even be allowed to understand male infidelity. Perhaps the CDC can help us understand.

By Randall Parker    2010 March 21 11:04 AM   Entry Permalink | Comments (5)
2010 January 13 Wednesday
Men Like Smell Of Ovulating Women

The hormones released during ovulation would probably make a powerful perfume.

Results revealed that men who smelled tee shirts of ovulating women subsequently had higher levels of testosterone than men who smelled tee shirts worn by non-ovulating women or men who smelled the control shirts. In addition, after smelling the shirts, the men rated the odors on pleasantness and rated the shirts worn by ovulating women as the most pleasant smelling.

The authors note that "the present research is the first to provide direct evidence that olfactory cues to female ovulation influence biological responses in men." In other words, this study suggests that testosterone levels may be responsive to smells indicating when a woman is fertile. The authors conclude that this biological response may promote mating-related behavior by males.

Men are genetically programmed to go for fertile women. No surprise here.

By Randall Parker    2010 January 13 11:22 PM   Entry Permalink | Comments (32)
2009 August 27 Thursday
More Testosterone Cuts Attention To Family

A study of villagers in Senegal finds that men with more blood testosterone pay less attention to their wives and children.

No matter how many wives they had, fathers had lower testosterone levels than single men, on average, Alvergne and her colleagues found. Among fathers, those with more testosterone tended to invest less time in their wives and children. And polygynous men under the age of 50 produced more testosterone than monogamous men, on average.

Older men with more than one wife made less of the sex hormone than other men. While older men may make less testosterone, they typically enjoy more prestige in their villages, which could make it easier to find multiple wives, Alvergne suggests.

Makes sense. More masculine brains will be less interested in child-raising and more interested in spreading their seed.

Men looking for more wives (or illicit affairs in all likelihood) have higher testosterone.

In cultures where men aren't expected to be outstanding fathers and are constantly on the lookout for potential mates, testosterone levels tend to stay high, Ellison says

That is an interesting comment because getting married and having kids lowers male testosterone. The arrow of causation between testosterone and family life probably runs both ways. Family responsibilities lower testosterone. Cultures that do not demand as much family responsibilities from men probably do not cause as much of a testosterone drop in marriage. At the same time, higher testosterone probably makes men less likely to attend to family responsibilities.

While marriage lowers testosterone ovulating women are more attracted to dominant guys. Marriage turns a guy into less of what attracted his wife to him in the first place?

By Randall Parker    2009 August 27 10:21 PM   Entry Permalink | Comments (1)
2009 August 26 Wednesday
Marijuana Cuts Sexual Pleasure

But if you can't get any I guess this doesn't matter.

Stoners may be trading sexual highs for the chemical kind. Males who smoke marijuana daily are four times more likely to have trouble reaching orgasm than men who don't inhale, finds a new study of 8,656 Aussies.

Observing the mental performance of stoner college roommates convinced me that regular marijuana usage is a bad idea. "Oh wow, I forgot to go to class" and "Oh wow, I forgot I was supposed to meet [name-of-some-hot-babe]". Heavy pot smoking is the road to loserdom.

By Randall Parker    2009 August 26 08:26 PM   Entry Permalink | Comments (27)
2009 August 05 Wednesday
Women Eat Lower Calorie Food With Men Present

Women in heat eat less food with guys around. I bet this doesn't hold true for married women eating with their husbands.

Hamilton, ON. August 5, 2009 – If you are a woman who dines with a man, chances are you choose food with fewer calories than if you dine with a woman. That is one of the findings in a study conducted by researchers at McMaster University.

The results appear in the online version of the international journal Appetite.

Meredith Young, PhD candidate in the Department of Psychology, Neuroscience & Behaviour, found that what a person chooses to eat at lunch or dinner is influenced by who they eat with and the gender make-up of the group.

You can probably measure the decline of a woman's romantic attraction for her mate by how much she eats with him around. At least in college settings (mostly single women) the presence of men restrains female wolfing of food.

By observing students in naturalistic settings in three large university cafeterias with a wide choice of food options and dining companions, Young found that women who ate with a male companion chose foods of significantly lower caloric value than did women who were observed eating with another woman.

The more men the less the women eat.

What's more, when women ate in mixed-gender groups their food choices were at the lower end of the caloric scale; the more men in the group the fewer the calories. When women ate in all-female groups, their food was significantly higher in calories.

I wonder how women eating alone compare.

By Randall Parker    2009 August 05 10:41 PM   Entry Permalink | Comments (20)
2009 June 09 Tuesday
Mating Patterns When Men Are Scarce

In cities were men are scarce the get married later but get married at higher rates in their 30s.

There are about nine unmarried men for every 10 unmarried women in Birmingham, Memphis, New Orleans, and Richmond-Petersburg, Virginia, Kruger says. Philadelphia, Washington, DC, Baltimore, and New York metropolitan areas are tied for the next region where women are relatively most plentiful. In these areas, about 84 percent of the men aged 20-24 are unmarried. In Las Vegas, San Diego, Salt Lake City, Austin, and Phoenix, there are about nine unmarried women for every 10 unmarried men. In these areas, about 77 percent of the men aged 20-24 are unmarried.

Once those young men hit their 30s, they tend to shift from seeking short-term relationships to entering into committed relationships. That's because when women evaluate partners for short-term relationships they value physical features signaling the kind of genes that would be passed on to potential offspring, which may be the only legacy of men who don't stick around for child rearing. These physical features decline as men age, making it more difficult to lure women into uncommitted relationships.

"You see a complete reversal in the pattern," Kruger said, and thus, proportionately more older men are married when women outnumber men.

The first result, men delaying marriage in order to play the field, is not surprising. But the second result is more interesting. It could have broken either way. Guys could have kept playing the field since their odds would stay favorable for finding women for one night stands and short term relationships. But the guys instead use their favorable ratio with women to find women they find suitable to marry.

I'd like to see a more detailed study where men and women are rated in attractiveness and then their mating patterns followed through time. Are the best looking more or less likely to delay marriage? Also, is the divorce rate higher in cities with more men than women or vice versa?

Also, who is more mobile? The most attractive or people with lower levels of beauty?

Update: Maybe the results make sense because as a guy gets older his sex drive diminishes and his desire to bed lots of women goes down. So maybe the higher marriage rate after 30 is a reflection of a weaker desire to spread genes.

Update II: At least one commenter misses the point here: In a city with fewer men and more women a lower status and less attractive male probably has better odds of finding a woman who will marry him. Yet in just such a city either men delay getting married or women decide to become far less inclined to get married. Why do men become less likely to get married when they have more choices? Due to decisions by the men or due to decisions by the women? I figure the men make different decisions and decide to play the field more since they see more opportunities. It would make sense for men to respond this way because evolution has selected men to want to seduce more women since women invest more in reproduction for each child than men do.

By Randall Parker    2009 June 09 08:29 PM   Entry Permalink | Comments (18)
2009 May 29 Friday
Relationships, Women, Rating Male Attractiveness

Women in relationships rate male attractiveness the same as women not in relationships. But the latter look longer. Whereas men in and out of relationships look the same amount.

A study by Indiana University neuroscientist Heather Rupp found that a woman's partner status influenced her interest in the opposite sex. In the study, women both with and without sexual partners showed little difference in their subjective ratings of photos of men when considering such measures as masculinity and attractiveness. However, the women who did not have sexual partners spent more time evaluating photos of men, demonstrating a greater interest in the photos. No such difference was found between men who had sexual partners and those who did not. "These findings may reflect sex differences in reproductive strategies that may act early in the cognitive processing of potential partners and contribute to sex differences in sexual attraction and behavior," said Rupp, assistant scientist at The Kinsey Institute for Research in Sex, Gender and Reproduction. The study was published in the March issue of Human Nature.

What I'd like to see as a follow-up study: Measure time married women spend looking at photos of men and then follow them for several years to see if the divorce rate is higher for women who look longer.

Similarly, is marital infidelity higher in women who look longer? Also, is testosterone higher in women in relationships who look longer?

Also, about the men: have any longitudinal studies been done on male testosterone levels and relationships? Married men have lower testosterone. Do men who become more dissatisfied with their marriages experience testosterone increases in a run-up to a divorce?

By Randall Parker    2009 May 29 04:03 PM   Entry Permalink | Comments (6)
2009 March 31 Tuesday
Genetic Influence On Loss Of Virginity Seen

My genes made me do it.

"It's not like there's a gene for having a sex at a certain date," says Nancy Segal, a psychologist at California State University in Fullerton who led the new study. Instead, heritable behavioural traits such as impulsivity could help determine when people first have sex, she says.

As genetic determinism goes, the new findings are modest. Segal's team found that genes explain a third of the differences in participants' age at first intercourse – which was, on average, a little over 19 years old. By comparison, roughly 80% of variations in height across a population can be explained by genes alone.

The team found a weaker effect from genes with people born before 1948. This supports an argument I've made here previously: the breakdown of old cultural constraints on behavior frees up people to follow genetically driven desires and impulses. We become more genetically driven as external constraints weaken.

Keep in mind that we are not all equally driven by our genes to start having sex earlier or later. Some people probably have genes that make them extremely likely to lose their virginity at a young age. Some others probably have genes that make them delay sexual activity for many years. Still others have genes that leave them more malleable to the environment. We are not all equally genetically driven on each type of behavior we engage in.

By Randall Parker    2009 March 31 11:33 PM   Entry Permalink | Comments (15)
2009 February 08 Sunday
Guys Get Hooked By Oxytocin When They Kiss

Kissing cuts down stress hormone levels in men and women. Think about that after a stressful day or week.

Hill wanted to find out just what happens to evoke such a powerful emotional response from simply rubbing lips. Her research looked at the impact of kissing on levels of two hormones, oxytocin and cortisol, in 15 male-female couples before and after holding hands and before and after kissing.

Oxytocin is known to be involved in social bonding so the researchers predicted that its levels would rise, while cortisol, a stress hormone, would fall. The results showed cortisol levels fell in both sexes, although oxytocin levels rose in men but fell in women.

But at least in the original non-romantic environment of a university health center only the men experienced a bond-forming boost of the hormone oxytocin. Does this mean that men get hooked by kisses but women dont? Maybe not. These sicentists are about to announce whether women too get an oxytocin boost from kissing in more romantic settings.

The scientists have since replicated the tests in more intimate settings, to see if the less-than-alluring environment of the university health centres where the original research was carried out hampered women's hormonal surge.

The final results will be presented at the annual conference of the American Association for the Advancement of Science in Chicago this week.

So guys, you might need to be careful where you kiss a woman if you don't want her getting the upper hand. Before you know it you'll be wrapped around her finger and she won't feel the same.

Update: Oxytocin boosts memories of faces.

Oxytocin, a hormone involved in child-birth and breast-feeding, helps people recognize familiar faces, according to new research in the January 7 issue of The Journal of Neuroscience. Study participants who had one dose of an oxytocin nasal spray showed improved recognition memory for faces, but not for inanimate objects.

"This is the first paper showing that a single dose of oxytocin specifically improves recognition memory for social, but not for nonsocial, stimuli," said Ernst Fehr, PhD, an economist at the University of Zurich who has studied oxytocin's effect on trust and is unaffiliated with the new study. "The results suggest an immediate, selective effect of the hormone: strengthening neuronal systems of social memory," Fehr said.

By Randall Parker    2009 February 08 10:28 PM   Entry Permalink | Comments (4)
2009 February 06 Friday
Mate Preference Trends

Mate preferences studies show big changes in preferences since the 1930s. Men measure women more by their esthetics and income while women care less about whether a guy is nice.

This Valentine's Day, researchers at the University of Iowa have some new answers to the perennial question of what men and women want in a partner.

Men are increasingly interested in an educated woman who is a good financial prospect and less interested in chastity. Women are increasingly interested in a man who wants a family and less picky about whether he's always Mr. Nice Guy.

That's according to a study by University of Iowa sociologists Christine Whelan and Christie Boxer. They analyzed results of a 2008 survey of more than 1,100 undergraduates at the UI, the University of Washington, the University of Virginia and Penn State University, comparing the results to past mate-preference studies.

Since the 1930s, researchers have been asking college students to rank a list of 18 characteristics they'd prefer in a mate from "irrelevant" (0) to "essential" (3), allowing for a comparison of mate preferences dating back three generations. And my, how times have changed: Today's young adults rank love and attraction as most important; a few generations ago it didn't even make the top three.

While the researchers do not capture this in their survey, men are most interested in young and fertile women.

Note that love is not an attribute of the woman who a guy loves. Rather, love is a feeling within the guy's brain. By contrast, brains, beauty, money, and income are all attributes of the woman who the guy loves. These attributes play a big role in making that love feeling happen in the first place.

In the 1930s male respondents were seeking a dependable, kind lady who had skills in the kitchen. Chastity was more important than intelligence.

Now, guys look for love, brains and beauty -- and a sizable salary certainly sweetens the deal. Men ranked "good financial prospect" No. 12 in 2008, a significant climb from No. 17 in 1939 and No. 18 in 1967.

"These results are consistent with the rise in educational and career opportunities for women, and men's increasing desire to share the financial burdens with a future spouse," Whelan said.

Chastity -- which men ranked at No. 10 in 1939 -- fell to dead last in 2008.

Chastity was only No. 10 in 1939. I would have expected higher.

The emotional stability that women want is linked to the ambition that they also desire. Gotta be stable to follow through and achieve one's ambitions. Pleasing disposition? Nice guys finish last.

"When we administered the survey, several female students snickered at the idea that we even included the chastity item," Whelan said. "This is consistent with the widespread hook-up culture on college campuses."

For women of the 1930s, emotional stability, dependable character and ambition ranked as the top three characteristics they wanted in a man. Attraction and love didn't come in until No. 5. Today, women, like men, put love at the top of the list, with dependability and emotional stability rounding out the top three characteristics in Mr. Right.

Women rate desire for home and children much higher in importance than men do. In 2008, women rated desire for home and children fourth men ranked it ninth.

Women ranked "pleasing disposition" as significantly less important in 2008 than they have ever before. Pleasing disposition -- presumably interpreted to mean being a nice guy -- fell from a steady ranking of No. 4 throughout the second half of the 20th Century to a significantly lower rank of No. 7 in 2008.

Strip away tradition. Strip away religious beliefs. What happens? Men and women are looking at each other in ways that seem even more influenced by their evolutionary heritage. The mating market looks like it is becoming more competitive.

Update: See the comments where Jason Malloy thoughtfully takes issue with my analysis. However, Razib's analysis is closer to my own.

If we take these data at face value I think that in some ways evolutionary psychology is becoming more, not less, salient in terms of our life choices. In many "traditional" societies mate choice is highly constrained by the preferences & interests of individuals who are not the principals. Though this is certainly operative in many hunter-gatherer societies (e.g., the bizarre incest taboos among some Australian Aboriginals), I suspect that freedom of choice is more constricted among sedentary agricultural populations because it is in this group that institutionally derived norms loom the largest. As humans subsisted on the Malthusian margins in such relatively complex societies there was little "wiggle" room for lifestyle experimentation. Interesting many Blank Slate theorists who advocate lifestyle experimentation presume that an ideological revolution was necessary for an exploration of the behavior space, but perhaps deviation was always latent which cultural norms strongly constrained.

But Razib makes his point in a much more learned fashion.

By Randall Parker    2009 February 06 11:22 PM   Entry Permalink | Comments (39)
2009 January 18 Sunday
High Hormone Level Causes Serial Monogamy In Women

Women are more motivated to trade up if they have a lot of oestradiol in their blood.

AUSTIN, Texas — Women with high levels of the sex hormone oestradiol may engage in opportunistic mating, according to a new study by psychology researchers at The University of Texas at Austin.

Doctoral candidate Kristina Durante and Assistant Professor of Psychology Norm Li published their findings in the article "Oestradiol Level and Opportunistic Mating in Women" in the Jan. 13 issue of Proceedings of the Royal Society of London: Biology Letters.

"The study offers further evidence that physiological mechanisms continue to play a major role in guiding women's sexual motivations and behavior," Durante said.

Durante and Li investigated the relationship between oestradiol, an ovarian hormone linked to fertility, and sexual motivation in a study of 52 female undergraduates not using contraception. Participants' ages ranged from 17 to 30 years old.

The researchers measured the participants' hormone levels at two points during each woman's ovulatory cycle and then asked them to rate their own physical attractiveness. Independent observers also rated the participants' physical attractiveness.

Participants also answered survey questions that measured their propensity to cheat on a partner.

The researchers found that a woman's oestradiol level was positively associated with self-perceived physical attractiveness. Women with a higher oestradiol level also reported a greater likelihood of flirting, kissing and having a serious affair (but not a one-night stand) with a new partner.

Oestradiol levels were negatively associated with a woman's satisfaction with her primary partner.

"Our findings show that highly fertile women are not easily satisfied by their long-term partners and are motivated to seek out more desirable partners," Durante explained. "However, that doesn't mean they're more likely to engage in casual sex. Instead, they adopt a strategy of serial monogamy."

I wonder how much of the serial monogamy is due to finding a better partner versus just feeling the need to find a different partner. Do the guys these women move on to score better in objective measures of physical attractiveness, wealth, or other factors?

How many of those dissatisfied women torment their partners before dumping them? Maybe a guy needs to know his girlfriend's hormone levels and an objective comparison of his and her level of attractiveness so that he can assess the odds of the relationship lasting.

Are you going to get traded in for a different model? Blame it on a hormone.

"These women are willing to trade up when the opportunity arises and continue to extract these lucrative resources from men when they can," says Kristina Durante, an evolutionary psychologist at the University of Texas in Austin, who led the study. She thinks the behaviour could be an adaptation to the high costs of giving birth.

"For women it's all about the resources that we need. If you're going to be getting knocked up there's a significant cost," she says.

So then did Angelina Jolie finally decide that Brad Pitt was as attractive as she could find? Or will her hormones eventually cause her to move on? She's aging so if she moves on she's probably making a mistake.

The desire does not appear to be for more casual sex.

She said her results are consistent with the possibility highly fertile women are not easily satisfied by their long-term partners and are especially motivated to become acquainted with other, presumably more desirable, men.

However, such motivations do not seem to stem from a greater interest in casual sex, she added.

Prettier girls are more fertile.

"The prettier you are, the more fertile you are," said lead author Kristina Durante, a doctoral candidate at the University of Texas. And the more fertile, the more options — and urges — for mates, she said.

Don't believe her? See my posts Women With Hourglass Bodies Have More Reproductive Hormones and Women With Higher Estrogen Seen As More Attractive.

Update: Anyone have access to the full paper? My question: Adjusted for attractiveness do women with higher hormone level have more relationships? To put it another way: Is it the higher attractiveness's enabling of more relationships or greater motivation to have more relationships that causes this difference in outcome? I see from one news report that the researchers used observers to rate the attractiveness of their subjects and so the researchers should have been able to puzzle out whether motive or opportunity played a bigger role in causing the serial monogamy.

By Randall Parker    2009 January 18 06:51 PM   Entry Permalink | Comments (10)
Women Orgasm More For Wealthy Men

A British researcher finds that women come more often in the arms of wealthy men.

“Women’s orgasm frequency increases with the income of their partner,” said Dr Thomas Pollet, the Newcastle University psychologist behind the research.

He believes the phenomenon is an “evolutionary adaptation” that is hard-wired into women, driving them to select men on the basis of their perceived quality.

The study is certain to prove controversial, suggesting that women are inherently programmed to be gold-diggers.

Women are turned on by wealthy men. It really is true. But the idea that stereotypes are true of course is evil crimethink. We are encouraged to respond to such thoughts by engaging in what Orwell called CrimeStop. But the mental technique of CrimeStop is protective stupidity. I do not feel more safe as a result of the promotion of this mental technique.

The desire of women for a wealthy man seems an obvious product of evolution. That people behave in ways that are a product of our evolutionary history seems obvious to me. Of course ignorant people come up with all sorts of alternative explanations for why we behave as well do.

Cassie is unrepentant about dating rich men. “Of course it is much better to sleep with men with lots of money,” said the 27-year-old lawyer from London.

“Any girl who tells you different is lying. Rich men are powerful and successful and confident and charismatic. They know what they want, and they go out and get it. That translates to being fantastic in bed.”

Women do pick up on the confidence of a successful alpha male and most are attracted to it. So pick-up artists like Roissy advocate a strategy of adopting alpha male behaviors as pick-up techniques. While some (though not all) of his female readers object to the efficacy of these techniques I think he's right overall. But if you can create wealth then you'll do even better. Alpha behavior techniques plus wealth work better than just wealth or just the techniques. So it still helps to get rich.

We are the products of our evolutionary history Denying this does not change us. The denial just leads us into rationalizations to explain why we engage in behaviors that are evolutionary strategies.

By Randall Parker    2009 January 18 10:36 AM   Entry Permalink | Comments (8)
2008 December 21 Sunday
Regular Drinking Women See Male Faces As More Symmetric

Even when sober women who drink more are less able to detect male facial asymmetry. So crooked-faced guys should look for female regular drinkers.

Researchers found that women who drink even moderately develop a reduced ability to rate attractiveness in male faces, even when they are sober.

Those who drank were less able to detect male facial symmetry, a marker of attractiveness and good genes which is thought to play an important role in the choice of a partner.

Even 5 drinks per month diminished ability to score facial symmetry. Researcher Kirsten Oinonen at Lakehead University in Thunderbay Ontario expects that women whose minds are altered in this way will find less attractive guys more attractive when their decreased attractiveness is caused by facial asymmetry.

If a woman stops drinking entirely does her ability to measure facial symmetry gradually return? I am reminded of my previous post Sexual Attraction By Odor Changed By Contraceptive Pill. The Pill is probably causing women to hook up with men who they will eventually find to smell bad once they stop taking the Pill. Marriages probably dissolve as a result. Does the same thing happen in relationships because one member of the couple stops drinking? Or does the alcohol cause a permanent alteration in brain function in an area that processes facial images?

By Randall Parker    2008 December 21 09:52 AM   Entry Permalink | Comments (8)
2008 December 09 Tuesday
Male Faces More Red, Female Faces More Green

Guys, don't go getting green with envy. If you do that you might undermine your masculine appearance. Women have more green coloring in their faces whereas men have more red.

PROVIDENCE, R.I. [Brown University] — Men are red. Women are green.

Michael J. Tarr, a Brown University scientist, and graduate student Adrian Nestor have discovered this color difference in an analysis of dozens of faces. They determined that men tend to have more reddish skin and greenish skin is more common for women.

The finding has important implications in cognitive science research, such as the study of face perception.  But the information also has a number of potential industry or consumer applications in areas such as facial recognition technology, advertising, and studies of how and why women apply makeup.

Digitized pictures of male and female faces showed different ratios of colors.

To conduct the study, Tarr needed plenty of faces. His lab analyzed about 200 images of Caucasian male and female faces (100 of each gender) compiled in a data bank at the Max Planck Institute in Tübingen, Germany, photographed using a 3-D scanner under the same lighting conditions and with no makeup. He then used a MatLab program to analyze the amount of red and green pigment in the faces.

Additionally, Tarr and his lab relied on a large number of other faces photographed under similar controlled conditions. (Tarr has made them available on his web site, www.tarrlab.org.)

What he found: Men proved to have more red in their faces and women have more green, contrary to prior assumptions.

The scientists also created androgynous faces but then altered them with more green or red coloring. Then a few students were asked to sort thousands of these faces into piles for male and female appearances. Well, the greener faces ended up more in the female pile while the redder faces ended up more in the male pile. So people use coloring of faces to categorize faces as male or female.

Next we need studies on the attractiveness of male and female faces with more green or red in them. Do women prefer more red in male faces and do men prefer more green in female faces? Also, how do heterosexual and homosexual preferences differ?

By Randall Parker    2008 December 09 11:08 PM   Entry Permalink | Comments (2)
2008 December 04 Thursday
Nursing Women More Attracted To Higher Pitch Male Voices

Harvard University anthropologist Coren Apicella finds that nursing women prefer men whose voices have higher pitched tones. The non-nursing women looking for mating material prefer deeper voices.

When she started analysing the data, Apicella realized that about half the women she tested had been nursing children. When she divided women by this characteristic, a trend emerged. Nursing women favoured higher-pitched tones, while fertile women showed a slight preference for the deeper voices.

When Hadza women start breast-feeding, their foraging falls off. "They rely on men a lot more to bring in food and resources," says Apicalla. "Maybe a higher-pitched voice is signalling pro-social behaviour."

This makes sense from an evolutionary standpoint. The men with deeper voices are probably more masculine and less likely to help raise the kids. Women seek to mate with men who are more masculine. But then to raise the kids they look for men who have a stronger feminine side. I bet that men who help women raise children of other men are less masculine on average than the men who got the women pregnant.

Previous research would lead one to expect this result. Women who ovulate are most attracted to men outside their relationship at the time when they are ovulating.

Normally ovulating women have been found to report greater sexual attraction to men other than their own partners when near ovulation relative to the luteal phase. One interpretation is that women possess adaptations to be attracted to men possessing (ancestral) markers of genetic fitness when near ovulation, which implies that women's interests should depend on qualities of her partner. In a sample of 54 couples, we found that women whose partners had high developmental instability (high fluctuating asymmetry) had greater attraction to men other than their partners, and less attraction to their own partners, when fertile.

At the same time men are attracted to the voices of women who are most fertile.

A woman's voice becomes more attractive when she is most fertile. That's according to Nathan Pipitone and Gordon Gallup of the State University of New York at Albany.

The pair recorded women counting from 1 to 10 at four occasions during their menstrual cycle. They then replayed the recordings at random to male and female students and asked them to rate the attractiveness of the voices. Both males and females judged the women's voices to be most attractive if they were recorded during the peak fertility period of the menstrual cycle, and less attractive if they were recorded during non-fertile periods (Evolution and Human Behavior, DOI: 10.1016/j.evolhumbehav.2008.02.001).

We are wired up by our evolutionary history to follow genetic programs for mating.

By Randall Parker    2008 December 04 12:27 AM   Entry Permalink | Comments (1)
2008 November 18 Tuesday
Scars Make Men More Attractive To Women

Only for short term relationships women prefer scarred men.

Men with facial scars are more attractive to women seeking short-term relationships, scientists at the University of Liverpool have found.

It was previously assumed that in Western cultures scarring was an unattractive facial feature and in non-Western cultures they were perceived as a sign of maturity and strength. Scientists at Liverpool and Stirling University, however, have found that Western women find scarring on men attractive and may associate it with health and bravery.

What I wonder: Do the scars really increase attraction? Or are more masculine men more likely to get into fights and other dangerous behavior and have facial scars as result?

Researchers investigated how scarring might impact on mate choice for men and women seeking both long-term and short-term relationships. They found that women preferred men with facial scars for short-term relationships and equally preferred scarred and un-scarred faces for long-term relationships. Men, however, regarded women with and without facial scars as equally attractive for both types of relationship.

Dr Rob Burriss, from the University's School of Biological Sciences, explains: "Male and female participants were shown images of faces that displayed scarring from injury or illness, and were asked to rate how attractive they found the person for long-term and short-term relationships.

"Women may have rated scarring as an attractive quality for short-term relationships because they found it be a symbol of masculinity, a feature that is linked to high testosterone levels and an indicator of good genetic qualities that can be passed on to offspring. Men without scars, however, could be seen as more caring and therefore more suitable for long-term relationships.

What I'd like to know: Do more feminine or more masculine women have a greater attraction to men who have facial scars? I'm expecting the most feminine women to feel the most attraction to scarred men.

Roissy's Love In The Time Of Game has me thinking Darwinian thoughts about the attraction between the sexes. Were scarred men in the past seen as proven fighters? How was this female pattern of attraction selected for?

By Randall Parker    2008 November 18 11:16 PM   Entry Permalink | Comments (5)
2008 October 29 Wednesday
Men Detect Infidelities Better Than Women

He's going to figure out your cheating heart.

UNFAITHFUL women beware. Chances are your male partner is on your case. In fact, he is likely to suspect infidelities even when you have kept to the straight and narrow. The flip side is that to counter this constant vigilance, women may be better than men at concealing illicit liaisons.

Paul Andrews at Virginia Commonwealth University in Richmond and colleagues gave 203 young heterosexual couples confidential questionnaires asking them whether they had ever strayed, and whether they suspected or knew their partner had strayed. In this, 29 per cent of men said they had cheated, compared with 18.5 per cent of women.

The men were better than women at judging fidelity. "Eighty per cent of women's inferences about fidelity or infidelity were correct, but men were even better, accurate 94 per cent of the time," says Andrews. They were also more likely to catch out a cheating partner, detecting 75 per cent of the reported infidelities compared with 41 per cent discovered by women (Human Nature, vol 19, p 347). However, men were also more likely to suspect infidelity when there was none.

Andrews says this makes evolutionary sense because unlike women, men can never be certain a baby is theirs. "Men have far more at stake," he says. "When a female partner is unfaithful, a man may himself lose the opportunity to reproduce, and find himself investing his resources in raising the offspring of another man."

The next step in this evolutionary arms race? People will genetically test their prospective partners in order to avoid those who have genes that make them more likely to stray. Though men with high status yet with genetic variants that cause a cheating heart will still be able to get women who would rather have a high status cheating mate than a low status faithful mate.

Also, cheaters will look for genetic profiles of prospective mates who either have genetically caused weaknesses in ability to detect cheating or who have genetic profiles that suggest a willingness to look the other way. So maybe the net result will be more happiness and more cheating.

By Randall Parker    2008 October 29 09:13 PM   Entry Permalink | Comments (7)
2008 October 27 Monday
Color Red Makes Men Hot For Women

Hi puppets. How are you all doing today? Geppetto says the color red makes men hot for women. When the men see red they charge for the flag.

A groundbreaking study by two University of Rochester psychologists to be published online Oct. 28 by the Journal of Personality and Social Psychology adds color—literally and figuratively—to the age-old question of what attracts men to women.

Through five psychological experiments, Andrew Elliot, professor of psychology, and Daniela Niesta, post-doctoral researcher, demonstrate that the color red makes men feel more amorous toward women. And men are unaware of the role the color plays in their attraction.

The research provides the first empirical support for society's enduring love affair with red. From the red ochre used in ancient rituals to today's red-light districts and red hearts on Valentine's Day, the rosy hue has been tied to carnal passions and romantic love across cultures and millennia. But this study, said Elliot, is the only work to scientifically document the effects of color on behavior in the context of relationships.

Did red hair get selected for because it made women look more hot to men?

Men who think they respond to women in a thoughtful and sophisticated manner are deluding themselves.

Although this aphrodisiacal effect of red may be a product of societal conditioning alone, the authors argue that men's response to red more likely stems from deeper biological roots. Research has shown that nonhuman male primates are particularly attracted to females displaying red. Female baboons and chimpanzees, for example, redden conspicuously when nearing ovulation, sending a clear sexual signal designed to attract males.

"Our research demonstrates a parallel in the way that human and nonhuman male primates respond to red," concluded the authors. "In doing so, our findings confirm what many women have long suspected and claimed – that men act like animals in the sexual realm. As much as men might like to think that they respond to women in a thoughtful, sophisticated manner, it appears that at least to some degree, their preferences and predilections are, in a word, primitive."

We are just smart monkeys.

Women don't get turned on by red in men. Red didn't make women seem any more intelligent or kind.

In the final study, the shirt of the woman in the photograph, instead of the background, was digitally colored red or blue. In this experiment, men were queried not only about their attraction to the woman, but their intentions regarding dating. One question asked: "Imagine that you are going on a date with this person and have $100 in your wallet. How much money would you be willing to spend on your date?"

Under all of the conditions, the women shown framed by or wearing red were rated significantly more attractive and sexually desirable by men than the exact same women shown with other colors. When wearing red, the woman was also more likely to score an invitation to the prom and to be treated to a more expensive outing.

The red effect extends only to males and only to perceptions of attractiveness. Red did not increase attractiveness ratings for females rating other females and red did not change how men rated the women in the photographs in terms of likability, intelligence or kindness.

What color makes men more attractive?

By Randall Parker    2008 October 27 11:03 PM   Entry Permalink | Comments (29)
2008 October 19 Sunday
Ovulation Raises Pitch Of Women's Voices

Women have higher pitched voices around ovulation.

A woman's voice tends to rise in pitch the closer she is to ovulation according to research published today in the Royal Society Journal Biology Letters. Researchers believe this is because a higher pitch is more attractive and more feminine, thus signalling fertility to potential partners.

Scientists at the University of California recorded the voices of 69 women to examine whether they raise their voice pitch during ovulation. Using hormone tests the women were recorded at two phases of their ovulatory cycle, once when fertility was low and once near ovulation. Results showed that the closer women were to ovulation, the more they raised their pitch.

Interestingly, this difference was apparent only when women spoke a simple introductory sentence such as 'hi, I'm a student at UCLA' - and not for simple vowel sounds. According to the researchers this shows that women change their voice in relation to fertility and possibly only in social communication contexts.

The findings follow other recent studies which have documented several detectable ovulatory cues in humans, including midcycle increases in body scent attractiveness, flirtation and attention to style of dress.

A 2006 report also finds that women are slaves to their hormones. Just like men.

Thirty-eight normally cycling women provided daily reports of sexual interests and feelings for 35 days. Near ovulation, both pair-bonded and single women reported feeling more physically attractive and having greater interest in attending social gatherings where they might meet men. Pair-bonded women who were near ovulation reported greater extra-pair flirtation and greater mate guarding by their primary partner. As predicted, however, these effects were exhibited primarily by women who perceived their partners to be low on hypothesized good genes indicators (low in sexual attractiveness relative to investment attractiveness). Ovulation-contingent increases in partner mate guarding were also moderated by female physical attractiveness; midcycle increases in mate guarding were experienced primarily by less attractive women, whereas more attractive women experienced relatively high levels of mate guarding throughout their cycle. These findings demonstrate ovulation-contingent shifts in desires and behaviors that are sensitive to varying fitness payoffs, and they provide support for the good genes hypothesis of human female extra-pair mating.

So guys, if you want a girlfriend who gets jealous over you then go for a less attractive woman.

What I want to know: Since the birth control pill prevents ovulation does it reduce the desire of women to dress up? Also, does it lower the average pitch of women's voices?

Once we gain the ability to manipulate the mental switches that cause mating behavior will women choose to put themselves perpetually in the mental state they normally feel just around ovulation? Or will they put themselves in other mental states less oriented toward mating? I'm wondering whether we'll still have lots of sexy dressing women 50 years from now.

By Randall Parker    2008 October 19 02:52 PM   Entry Permalink | Comments (4)
2008 September 04 Thursday
Orgasmic Women Walk Differently

A woman's ability to enjoy sex shows up in her gait.

Paisley, Scotland – September 04, 2008 - A new study found that trained sexologists could infer a woman's history of vaginal orgasm by observing the way she walks. The study is published in the September 2008 issue of The Journal of Sexual Medicine, the official journal of the International Society for Sexual Medicine and the International Society for the Study of Women's Sexual Health.

Led by Stuart Brody of the University of the West of Scotland in collaboration with colleagues in Belgium, the study involved 16 female Belgian university students. Subjects completed a questionnaire on their sexual behavior and were then videotaped from a distance while walking in a public place. The videotapes were rated by two professors of sexology and two research assistants trained in the functional-sexological approach to sexology, who were not aware of the women's orgasmic history.

The results showed that the appropriately trained sexologists were able to correctly infer vaginal orgasm through watching the way the women walked over 80 percent of the time. Further analysis revealed that the sum of stride length and vertebral rotation was greater for the vaginally orgasmic women. "This could reflect the free, unblocked energetic flow from the legs through the pelvis to the spine," the authors note.

There are several plausible explanations for the results shown by this study. One possibility is that a woman's anatomical features may predispose her to greater or lesser tendency to experience vaginal orgasm. According to Brody, "Blocked pelvic muscles, which might be associated with psychosexual impairments, could both impair vaginal orgasmic response and gait." In addition, vaginally orgasmic women may feel more confident about their sexuality, which might be reflected in their gait. "Such confidence might also be related to the relationship(s) that a woman has had, given the finding that specifically penile-vaginal orgasm is associated with indices of better relationship quality," the authors state. Research has linked vaginal orgasm to better mental health.

The study provides some support for assumptions of a link between muscle blocks and sexual function, according to the authors. They conclude that it may lend credibility to the idea of incorporating training in movement, breathing and muscle patterns into the treatment of sexual dysfunction.

Will training a woman in how to walk increase her sexual pleasure? Or does the different walk flow from differences in muscle and bone structure or perhaps differences in their nervous system that sexual responses? I'm going to guess that there's a big genetic component to how men and women walk.

Update: Razib uses this story to show a picture of Israeli model Bar Rafaeli. (but I'm totally turned off because she smokes - what a waste). His commenters bring up the question of the direction of flow of causality. Does having a vaginal orgasm cause a woman to walk differently? Or does the same underlying neuro-muscular system cause both the different walk and the greater ease of having vaginal orgasms? I'm guessing the latter and I'm guessing an underlying genetic cause. Ease of orgasm is probably genetically inherited.

By Randall Parker    2008 September 04 10:29 PM   Entry Permalink | Comments (16)
2008 August 12 Tuesday
Sexual Attraction By Odor Changed By Contraceptive Pill

Men who have immune system genes dissimilar to women have odors which are more attractive to women. This is probably an evolutionary consequence of the advantage of giving one's children genetically diverse immune systems. But the hormones in the contraceptive pill alter sense of smell of women so they are more attracted to men who are immunologically more similar.

The contraceptive pill may disrupt women's natural ability to choose a partner genetically dissimilar to themselves, research at the University of Liverpool has found.

The Pill leads a woman's attraction machinery astray.

Disturbing a woman's instinctive attraction to genetically different men could result in difficulties when trying to conceive, an increased risk of miscarriage and long intervals between pregnancies. Passing on a lack of diverse genes to a child could also weaken their immune system.

So the Pill causes a mismatch in mate selection.

Humans choose partners through their body odour and tend to be attracted to those with a dissimilar genetic make-up to themselves, maintaining genetic diversity. Genes in the Major Histocompatibility Complex (MHC), which helps build the proteins involved in the body's immune response, also play a prominent role in odour through interaction with skin bacteria. In this way these genes also help determine which individuals find us attractive.

The research team analysed how the contraceptive pill affects odour preferences. One hundred women were asked to indicate their preferences on six male body odour samples, drawn from 97 volunteer samples, before and after initiating contraceptive pill use.

Craig Roberts, a Lecturer in Evolutionary Psychology who carried out the work in collaboration with the University of Newcastle, said: "The results showed that the preferences of women who began using the contraceptive pill shifted towards men with genetically similar odours.

There's an even bigger problem: If a woman on the Pill meets a guy, finds him pheromonally attractive, gets married, and then stops using the Pill she can suddenly find her husband's smell very much not to her liking.

"Not only could MHC-similarity in couples lead to fertility problems but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odour perception plays a significant role in maintaining attraction to partners."

How many marriages and relationships has the Pill brought together which fell apart when the woman stopped taking the Pill?

What could be done about it: Once genetic testing becomes cheap and widely available online dating services could match men and women by comparing Major Histocompatibility Complex (MHC) genes. Avoid dating someone who might seem attractive because you are on the Pill.

But doesn't the MHC attraction mechanism work for men as well? They won't be on the Pill. Are men finding that funny-smelling women who are on the Pill are hitting on them? Someone should do a study on this.

The discovery reported in this post is yet another example of how we are genetically programmed to do and feel as we do.

By Randall Parker    2008 August 12 09:19 PM   Entry Permalink | Comments (4)
2008 July 15 Tuesday
How Flirtation Affects Steady Relationships

Some social science research provides evidence for expected truths. Other times it comes up with unintuitive results. Here's a piece of research that does both at the same time. If a good-looking guy has just flirted with your girlfriend she is more likely to forgive you for a bad thing you did?

Temptation may be everywhere, but it's how the different sexes react to flirtation that determines the effect it will have on their relationships. In a new study, psychologists determined men tend to look at their partners in a more negative light after meeting a single, attractive woman. On the other hand, women are likelier to work to strengthen their current relationships after meeting an available, attractive man.

I can understand the evolutionary origin of the male reaction. When he thinks he's got other options he's more likely to be less tolerant of perceived short-comings of his mate. But the female reaction is more puzzling. Anyone got a good evolutionary explanation for the origin of this behavior?

Men may not see their flirtations with an attractive woman as threatening to the relationship while women do, according to findings from a study in the July issue of the Journal of Personality and Social Psychology, published by the American Psychological Association. Researchers found that women protect their relationship more when an attractive man enters the picture but men look more negatively at their partner after they've met an available, attractive woman. Men can learn to resist temptation when trained to think that flirting with an attractive woman could destroy their relationship, said lead author John E. Lydon, PhD, of McGill University in Montreal.

Researchers conducted seven laboratory experiments using 724 heterosexual men and women to see how college-aged men and women in serious relationships react when another attractive person enters the mix.

Maybe the woman is more afraid of getting dumped by her guy if she flirts and therefore she tries harder to strengthen the relationship to compensate for the potential damage done?

In one study, 71 unsuspecting male participants were individually introduced to an attractive woman. Roughly half the men met a "single" woman who flirted with them. The other half met an "unavailable" woman, who simply ignored them.

Immediately after this interaction, the men filled out a questionnaire in which they were asked how they would react if their "romantic partner" had done something that irritated them, such as lying about the reason for canceling a date or revealing an embarrassing tidbit about them. Men who met the attractive "available" woman were 12 percent less likely to forgive their significant others. In contrast, 58 women were put in a similar situation. These women, who met an "available" good-looking man, were 17.5 percent more likely to forgive their partners' bad behavior.

Do these results make sense to you?

By Randall Parker    2008 July 15 11:03 PM   Entry Permalink | Comments (34)
2008 June 18 Wednesday
Male Narcissistic Psychopaths Get More Sex

Why do psychopaths exist? The ladies help the psychopaths reproduce by going to bed with them. Men who are narcissistic, self-obsessed, liars, psychopaths, Machiavellian, and thrill-seekers get laid more.

Bad boys, it seems, really do get all the girls. Women might claim they want caring, thoughtful types but scientists have discovered what they really want – self-obsessed, lying psychopaths.

A study has found that men with the "dark triad" of traits – narcissism, thrill- seeking and deceitfulness – are likely to have a larger number of sexual affairs.

To be fair, not all ladies want these guys. But the genes that cause these personality characteristics wouldn't exist if men and women didn't get together to pass the genes along.

Are all these traits caused by the same genetic variations? Or are there different traits causing different subsets of these traits and each subset of traits has been separately selected for? The study was done on college students.

But being just slightly evil could have an upside: a prolific sex life, says Peter Jonason at New Mexico State University in Las Cruces. "We have some evidence that the three traits are really the same thing and may represent a successful evolutionary strategy."

Jonason and his colleagues subjected 200 college students to personality tests designed to rank them for each of the dark triad traits. They also asked about their attitudes to sexual relationships and about their sex lives, including how many partners they'd had and whether they were seeking brief affairs.

The study found that those who scored higher on the dark triad personality traits tended to have more partners and more desire for short-term relationships, Jonason reported at the Human Behavior and Evolution Society meeting in Kyoto, Japan, earlier this month. But the correlation only held in males.

Once the genetic causes of these behaviors are known will women choose to have offspring with these traits? Will the frequency of these traits rise or fall once it becomes possible to intentionally pass on or avoid passing on these traits?

Some women might reason that they want their kids to be Machiavellian, extremely charming, obsessed with looking out for number 1, and extroverted in order to better succeed.

To men who do not have and not like these traits: Fake them for the sake of the human race. If you can attract women by pretending to have these traits and then make babies you will displace the genes of psychopaths and narcissists from the human race. Roissy thinks a "beta" male can learn to act like an "alpha" and project traits that attract women. Use Roissy's techniques to outcompete those who have the James Bond personality.

By Randall Parker    2008 June 18 11:19 PM   Entry Permalink | Comments (42)
2008 February 04 Monday
Males Get Greater Pleasure In Territory Capture Video Games

The ladies just don't get as much of a thrill out of capturing territory in a video game. File under "no surprise here".

STANFORD, Calif. - Allan Reiss, MD, and his colleagues have a pretty good idea why your husband or boyfriend can't put down the Halo 3. In a first-of-its-kind imaging study, the Stanford University School of Medicine researchers have shown that the part of the brain that generates rewarding feelings is more activated in men than women during video-game play.

"These gender differences may help explain why males are more attracted to, and more likely to become 'hooked' on video games than females," the researchers wrote in their paper, which was recently published online in the Journal of Psychiatric Research.

More than 230 million video and computer games were sold in 2005, and polls show that 40 percent of Americans play games on a computer or a console. According to a 2007 Harris Interactive survey, young males are two to three times more likely than females to feel addicted to video games, such as the Halo series so popular in recent years.

The ladies can capture the territory. Doing that just doesn't turn up the mesocorticolimbic center of their brains as much as it does for guys.

"The females 'got' the game, and they moved the wall in the direction you would expect," said Reiss, who is director of the Center for Interdisciplinary Brain Sciences Research. "They appeared motivated to succeed at the game. The males were just a lot more motivated to succeed."

After analyzing the imaging data for the entire group, the researchers found that the participants showed activation in the brain's mesocorticolimbic center, the region typically associated with reward and addiction. Male brains, however, showed much greater activation, and the amount of activation was correlated with how much territory they gained. (This wasn't the case with women.) Three structures within the reward circuit - the nucleus accumbens, amygdala and orbitofrontal cortex - were also shown to influence each other much more in men than in women. And the better connected this circuit was, the better males performed in the game.

The findings indicate, the researchers said, that successfully acquiring territory in a computer game format is more rewarding for men than for women. And Reiss, for one, isn't surprised. "I think it's fair to say that males tend to be more intrinsically territorial," he said. "It doesn't take a genius to figure out who historically are the conquerors and tyrants of our species-they're the males."

So then when offspring genetic engineering becomes possible will prospective parents choose to give their sons or daughters brains that get more or less thrill out of territory capture than the average boy or girl born today? Will genetically engineered boys be more or less territorial than they are today? What about for the girls? Parents might choose to give girls some of the cognitive characteristics that make them more likely to strive to succeed and rise above in competitions at work. Think that likely?

By Randall Parker    2008 February 04 10:10 PM   Entry Permalink | Comments (1)
2008 January 09 Wednesday
Testosterone Causes Aggressive Humor?

Does humor flow from the desire of males to demonstrate their virility?

Humour appears to develop from aggression caused by male hormones, according to a study published in this week’s Christmas issue of the BMJ.

Professor Sam Shuster conducted a year long study observing how people reacted to him as he unicycled through the streets of Newcastle upon Tyne. What began as a hobby turned into an observational study after he realized that the huge number of stereotypical and predictable responses he received must be indicative of an underlying biological phenomenon.

The study was an observation of people’s reactions to a sudden unexpected exposure to a new phenomenon - in this case unicycling, which at the time few had seen. He documented the responses of over 400 individuals, and observed the responses of many others.

Over 90% of people responded physically, for example with an exaggerated stare or a wave. Almost half responded verbally – more men than women. Here, says Professor Shuster, the sex difference was striking. 95% of adult women were praising, encouraging or showed concern. There were very few comic or snide remarks. In contrast, only 25% of adult men responded as did the women, for example, by praise or encouragement; instead 75% attempted comedy, often snide or combative as an intended put-down.

Equally striking, he says, was the repetitive and predictable nature of the comments from men; two thirds of their ‘comic’ responses referred to the number of wheels - “Lost your wheel?”, for example.

Professor Shuster also noticed the male response differed markedly with age, moving from curiosity in childhood (years 5-12) – the same reaction as young girls, - to physical and verbal aggression in boys aged 11-13 who often tried to get him to fall off the unicycle.

Responses became more verbal during the later teens, turning into disparaging ‘jokes’ or mocking songs. This then evolved into adult male humour – characterized by repetitive, humorous verbal put-downs concealing a latent aggression. Young men in cars were particularly aggressive. Professor Shuster notes that this is the age when men are at the peak of their virility. The ‘jokes’ were lost with age as older men responded more neutrally and amicably with few attempts at a jovial put-down.

The female response by contrast, was subdued during puberty and late teens – normally either apparent indifference or minimal approval. It then evolved into the laudatory and concerned adult female response.

What I'd like to see: A study of female comics where their blood testosterone levels are compared to the average testosterone levels of women of similar age, socio-economic background, and so on. My guess is that female comics have more testosterone than the average woman.

What is the evolutionary purpose or intent of male humor? To demonstrate reproductive fitness to women by showing wit and cleverness? Or to make other men feel inferior and less likely to compete for women? Or some other purpose?

By Randall Parker    2008 January 09 11:42 PM   Entry Permalink | Comments (6)
2007 September 24 Monday
Deep Voiced Men Have More Babies

No surprise here folks.

Hamilton, ON. Sept. 24, 2007 – Men who have lower-pitched voices have more children than do men with high-pitched voices, researchers have found. And their study suggests that for reproductive-minded women, mate selection favours men with low-pitched voices.

The study, published in Biology Letters, offers insight into the evolution of the human voice as well as how we choose our mates.

In previous studies, David Feinberg, assistant professor in the Department of Psychology, Neuroscience and Behaviour at McMaster University, and his colleagues have shown that women find deeper male voices to be more attractive, judging them to be more dominant, older, healthier and more masculine sounding. Men, on the other hand, find higher-pitch voices in women more attractive, subordinate, feminine, healthier and younger sounding.

“While we find in this new study that voice pitch is not related to offspring mortality rates,” says Feinberg,” we find that men with low voice pitch have higher reproductive success and more children born to them.”

What I really want to know: If deep voiced men and high pitched voiced women make babies then are the male babies not as deeped voiced as their dads and are the female babies not as high pitched voiced as their moms? To put it another way: Do more masculine mothers give birth to more masculine sons and do more feminine fathers sire more feminine daughters?

Some day prospective parents will genetically engineer their male offspring to have deeper voices and female offspring to have higher pitched voices. How many parents will give their daughters deeper voices to perhaps help them do better in work careers?

Also, once plastic surgery for voice tone modification becomes safe and effective how many people will change their voice pitch and in which direction?

Of course, if you want to increase your satisfaction with romantic relationships some day there'll be another option besides body alterations that enhance your appeal to others: modify your brain so that you find more kinds of human body shapes appealing. Then you could find easy pickings and satisfaction with those who are less attractive to the majority. Though that approach will become less valuable once most people get their appearances enhanced. You won't be able to find as many lonely people who others find unattractive. Jack Black's distorted view of a fat Gwyneth Paltrow will some day become achievable in real life. But before that happens obesity will become easily curable.

By Randall Parker    2007 September 24 11:08 PM   Entry Permalink | Comments (4)
2007 September 18 Tuesday
Gene Affects Sweetness Of Smells Of Others

If you think someone smells sweet it might be down to genes.

To many, urine smells like urine and vanilla smells like vanilla. But androstenone, a derivative of testosterone that is a potent ingredient in male body odor, can smell like either - depending on your genes. While many people perceive a foul odor from androstenone, usually that of stale urine or strong sweat, others find the scent sweet and pleasant. Still others cannot smell it at all.

New research from Rockefeller University, performed in collaboration with scientists at Duke University in North Carolina, reveals for the first time that this extreme variability in people's perception of androstenone is due in large part to genetic variations in a single odorant receptor called OR7D4. The research is reported September 16 as an advance online publication of the journal Nature.

Combine bind genetic tests for OR7D4 with genetic tests for genes that regulate Androstenone secretion and you have the beginnings of a genetic compatibility test. Online match-making services will some day include genetic profile matching. Why go to the trouble of meeting someone you get matched with online if one of you is going to think the other one has a really disgusting smell?

So now we need scientists to discover genetic variations that regulate androstenone production and secretion.

Androstenone, found in higher concentrations in the urine and sweat of men than of women, is used by some mammals to convey social and sexual information, and the ability to perceive androstenone's scent may have far-reaching behavioral implications for humans.

In the largest study ever conducted of its kind, researchers at Rockefeller University presented nearly 400 participants with 66 odors at two different concentrations and asked them to rate the pleasantness and intensity of each odor. When scientists at Duke University identified OR7D4 as a receptor that androstenone selectively activates, Leslie Vosshall, Chemers Family Associate Professor and head of the Laboratory of Neurogenetics and Behavior at Rockefeller University and Andreas Keller, a postdoc in her lab, formed a collaboration with them, and began collecting blood samples from participants and isolated their DNA. The Duke team, led by Hiroaki Matsunami, used DNA from each participant to sequence the gene that encodes the OR7D4 receptor.

You can bet that many more genetic variations that influence physical attraction will be found.

By Randall Parker    2007 September 18 12:15 AM   Entry Permalink | Comments (0)
2007 September 17 Monday
People Pay More Attention To Good Looking People

More fun with human sexuality and attraction.

Whether we are seeking a mate or sizing up a potential rival, good-looking people capture our attention nearly instantaneously and render us temporarily helpless to turn our eyes away from them, according to a new Florida State University study.

“It’s like magnetism at the level of visual attention,” said Jon Maner, an assistant professor of psychology at FSU, who studied the role mating-related motives can play in a psychological phenomenon called attentional adhesion. His findings are published in the September issue of the Journal of Personality and Social Psychology.

The paper, “Can’t Take My Eyes Off You: Attentional Adhesion to Mates and Rivals,” is one of the first to show how strongly, quickly and automatically we are attuned to attractive people, he said. FSU graduate students Matthew Gailliot, D. Aaron Rouby and Saul Miller co-authored the study.

In a series of three experiments, Maner and his colleagues found that the study participants, all heterosexual men and women, fixated on highly attractive people within the first half of a second of seeing them. Single folks ogled the opposite sex, of course, but those in committed relationships also checked people out, with one major difference: They were more interested in beautiful people of the same sex.

Why the attention paid to same sex attractive people? Jealousy.

In the experiments, study participants -- 120 people in the first study and 160 and 162 in the second and third studies, respectively -- completed questionnaires to determine the extent to which they were motivated to seek out members of the opposite sex. They then took part in a series of “priming” activities before they were shown photos of highly attractive men, highly attractive women, average-looking men and average-looking women.

After a photo of one of the faces flashed in one quadrant of a computer screen, the participants were required to shift their attention away from that face to somewhere else on the screen. Using a precise measure of reaction time, Maner found that it took the participants longer to shift their attention away from the photos of the highly attractive people.

Maner said he was surprised that his studies showed little differences between the sexes when it came to fixating on eye-catching people.

“Women paid just as much attention to men as men did to women,” he said. “I was also surprised that jealous men paid so much attention to attractive men. Men tend to worry more about other men being more dominant, funny or charismatic than they are. But when it comes to concerns about infidelity, men are very attentive to highly attractive guys because presumably their wives or girlfriends may be too.”

So then can one measure loss of attraction to one's own mate by measuring how much people pay attention to same sex attractive people? Do people who are ready to file for divorce pay less attention to same sex attractive people?

Also, when people become involved in a relationship do they become more averse to spending time with their more attractive friends?

I'd also like to see this phenomenon measured as a function of blood sexual hormone levels. Do people with more testosterone pay more attention to same and opposite sex attractive pictures?

By Randall Parker    2007 September 17 11:47 PM   Entry Permalink | Comments (2)
2007 August 21 Tuesday
Women Have Excellent Navigational Abilities To High Calorie Foods

Really, I'm not joking. Max Krasnow and a team at Yale and UC Santa Barbara have found that women can navigate as well as men but their skills only show up when shopping.

The team asked the men and women to show the direction of a stall where they had bought a certain food, such as strawberries or tomatoes, using a compass.

A zero degree error meant the subjects were bang on target, while 90 degrees meant they were hopeless.

“Men were making 33 degree pointing error, when women were around 25 degree, which is a 27 per cent improvement,” said Mr Krasnow.

Women also did better with a high-calorie food, such as a doughnut, compared with a stick of celery.

Women had much better accuracy for where to reach higher calorie foods as compared to vegetables and other lower calorie foods. Is it any wonder that we don't eat enough vegetables? Women have a hard time finding the produce section. Suddenly they find themselves in the pastry aisle.

Calorie malnutrition has been the biggest killer in human history. Women were the gatherers. They know how to get back to the places with the best food gathering potential. Whereas men had to know how to track prey over a larger range of areas.

How to make use of this knowledge? Depends on your motives. How about putting a women's clothing store next to Dunkin Donuts or International House of Pancakes?

So how to enhance the cognitive performance of both boys and girls? Put them in school together.

By Randall Parker    2007 August 21 08:34 PM   Entry Permalink | Comments (0)
2007 August 20 Monday
Women Prefer Pink More Than Men

Yes, women prefer pinker colors yet we all like blue.

A study in the August 21st issue of Current Biology, a publication of Cell Press, reports some of the first conclusive evidence in support of the long-held notion that men and women differ when it comes to their favorite colors. Indeed, the researchers found that women really do prefer pink—or at least a redder shade of blue—than men do.

"Although we expected to find sex differences, we were surprised at how robust they were, given the simplicity of our test," said Anya Hurlbert of Newcastle University, UK. In the test, young adult men and women were asked to select, as rapidly as possible, their preferred color from each of a series of paired, colored rectangles.

Blue Man Group embody our basic human preference for blue.

The universal favorite color for all people appears to be blue, they found. "On top of that, females have a preference for the red end of the red-green axis, and this shifts their color preference slightly away from blue towards red, which tends to make pinks and lilacs the most preferred colors in comparison with others," she said.

So then when genetically engineered skin color becomes possible will anyone opt for blue skin or blue hair? Look at how popular blue eyes are.

Does it make more sense for women to die their hair blue to attract men and for men to go for a more reddish color to attract women? Or does the color preference not extend to preferences for mates? After all, blond hair is most desired in women. Yet blue eyes are too.

What I want to know: Does color preference vary at all according to sexual orientation? For example, do homosexual men lean more toward lilacs than hetero guys? Or do homosexual females lean more toward blue preference than hetero females? Also, does blood testosterone level influence color preference?

Overall, the differences between men and women were clear enough that the seasoned researchers can now usually predict the sex of a participant based on their favorite-color profile.

The color preference seems to track across at least 2 races.

To begin to address whether sex differences in color preference depend more on biology or culture, the researchers tested a small group of Chinese people amongst the other 171 British Caucasian study participants. The results among the Chinese were similar, Hurlbert said, strengthening the idea that the sex differences might be biological.

The question arises: Where does this color preference come from?

The explanation might go back to humans' hunter-gatherer days, when women—the primary gatherers--would have benefited from an ability to key in on ripe, red fruits.

"Evolution may have driven females to prefer reddish colors--reddish fruits, healthy, reddish faces," Hurlbert said. "Culture may exploit and compound this natural female preference."

Reddish faces as indicators of good nutrition and lots of red blood cells seems plausible. But reddish fruits? Seems like many more plant foods are green. Why would food gathering favor reddish foods? Are reddish plants more likely to be digestible for calories than, for example, green leaves?

Hurlbert suspects the preference for blue might be due to the desirability of blue skies for hunting or perhaps blue water for greater purity and safety. Can you think of another reason for the blue preference?

By Randall Parker    2007 August 20 08:20 PM   Entry Permalink | Comments (4)
2007 July 11 Wednesday
Muscular Men Get More Sex

Here's one big reason why I expect men will eagerly embrace the use of biotechnology to alter body shape.

Frederick and Haselton lead a team that photographed 99 male undergraduates. A panel of independent judges rated the young men on a nine-point scale, with "1" being much less muscular than average and "9" being much more muscular than average. The researchers then asked the men about their sexual histories.

When compared with their less-muscular peers, young men who were more muscular than average were twice as likely to have had more than three sex partners in their lives.

In another study, Frederick and Haselton asked 120 undergraduate males to rate their own physiques on the same scale and then asked them about their sexual histories.

The self-identified muscular men had not only had more sexual partners than their less burly peers, but they were twice as likely to have had brief flings or one-night stands with women. The difference in the number of sexual partners reported by the men who were more muscular than average was also notable: They reported having had an average of four partners, compared with an average of 1.5 partners for men who reported average or below-average muscularity.

In a similar study, Frederick and Haselton asked 60 undergraduate males an additional question: How many affairs had they had with women who already had a boyfriend at the time of the affair? Muscularity mattered here as well. The more muscular individuals were twice as likely as their less well-built peers to have hooked up with someone else's sweetheart.

Women know the muscular men have different personalities and behaviors as compared to the skinnier guys.

Interestingly, women in the study seemed to be on to muscular men. When presented with six standardized silhouettes of men ranging from brawny to slender, 141 undergraduate women consistently identified the most muscular ones as not only less likely to commit but also more volatile and domineering. In the study, the women rated "toned" guys - the physical type two notches down from "brawny" - as the most sexually attractive.

"Moderate muscularity demonstrates that men are in good condition, but they're not so overloaded with testosterone that they are volatile, aggressive and dominant," Frederick said. "Just based on their experiences, women seem to be able to weigh good and bad male traits."

Still, in a study by Frederick and Haselton of 82 college coeds, most women reported that their short-term partners were more muscular than their long-term ones. They characterized their long-term - and presumably less muscular - partners as more trustworthy and romantic than their one-night stands or brief affairs.

I vaguely recall earlier studies that purported to show that upper class women prefer men with less muscles than lower class women.

Will men adjust their body shapes when they change their minds about how long term they want their relationships to be? Time to get married and therefore time to slim down the muscles somewhat in order to appear more caring?

We can expect by using biotechnology future males will have more muscles, less body fat, less gray hair, and less receding hairlines.

By Randall Parker    2007 July 11 12:03 AM   Entry Permalink | Comments (11)
2007 February 03 Saturday
Estrogen Enhances Rewards For Women

When women win they get a bigger mental reward before ovulation than after.

Fluctuations in sex hormone levels during women's menstrual cycles affect the responsiveness of their brains' reward circuitry, an imaging study at the National Institute of Mental Health (NIMH), a component of the National Institutes of Health (NIH), has revealed. While women were winning rewards, their circuitry was more active if they were in a menstrual phase preceding ovulation and dominated by estrogen, compared to a phase when estrogen and progesterone are present.

My guess is that it is more rewarding to be around women who are in their pre-ovulatory phase.

What is the purpose of this effect of neurons on reward centers? Is it to make women get greater enjoyment from sex when they are more likely to get pregnant?

Reward system circuitry includes: the prefrontal cortex, seat of thinking and planning; the amygdala, a fear center; the hippocampus, a learning and memory hub; and the striatum, which relays signals from these areas to the cortex. Reward circuit neurons harbor receptors for estrogen and progesterone. However, how these hormones influence reward circuit activity in humans has remained unclear.

To pinpoint hormone effects on the reward circuit, Berman and colleagues scanned the brain activity of 13 women and 13 men while they performed a task involving simulated slot machines. The women were scanned before and after ovulation.

The fMRI pictures showed that when the women were anticipating a reward, they activated the amygdala and a cortex area behind the eyes that regulates emotion and reward-related planning behavior more during the pre-ovulation phase (four to eight days after their period began) than in the post-ovulatory phase.

When they hit the jackpot and actually won a reward, women in the pre-ovulatory phase activated the striatum and circuit areas linked to pleasure and reward more than when in the post-ovulatory phase.

Both reward anticipation and reward reception were enhanced by estrogen.

The researchers also confirmed that the reward-related brain activity was directly linked to levels of sex hormones. Activity in the amygdala and hippocampus was in lockstep with estrogen levels regardless of cycle phase; activity in these areas was also triggered by progesterone levels while women were anticipating rewards during the post-ovulatory phase. Activity patterns that emerged when rewards were delivered during the post-ovulatory phase suggested that estrogen's effect on the reward circuit might be altered by the presence of progesterone during that period.

So then do women enjoy life less after they've ovulated? Also, do women on birh control pills get more or less pleasure from rewards? Same question for post-menopausal women who have less estrogen in their bodies? Do they get less of a thrill from rewards?

What is going to happen with this information in the long run? Imagine drugs that cause or block the effects of estrogen on reward centers and pleasure-related neurons. Will women choose to have their minds always in the pre-ovulatory state and feel more reward from wins and gains? Or will they choose to block the effects of higher estrogen on their brains?

By Randall Parker    2007 February 03 02:51 PM   Entry Permalink | Comments (5)
2006 October 29 Sunday
Men Subconsciously Prefer Blue Eyed Women As Paternity Test

Natural selection gave blue eyed men a preference for blue eyed women. Natural selection for women whose babies will be more obviously testable for paternity gave many men a preference for blue-eyed women.

Before you request a paternity test, spend a few minutes looking at your child’s eye color. It may just give you the answer you’re looking for. According to Bruno Laeng and colleagues, from the University of Tromso, Norway, the human eye color reflects a simple, predictable and reliable genetic pattern of inheritance. Their studies1, published in the Springer journal Behavioral Ecology and Sociobiology, show that blue-eyed men find blue-eyed women more attractive than brown-eyed women. According to the researchers, it is because there could be an unconscious male adaptation for the detection of paternity, based on eye color.

Since blue eyes are a recessive trait the reason for the preference for blue eyes by men is explainable with classical Mendelian genetics:

The laws of genetics state that eye color is inherited as follows:
1. If both parents have blue eyes, the children will have blue eyes.
2. If both parents have brown eyes, a quarter of the children will have blue eyes, and three quarters will have brown eyes.
3. The brown eye form of the eye color gene (or allele) is dominant, whereas the blue eye allele is recessive.
It then follows that if a child born to two blue-eyed parents does not have blue eyes, then the blue-eyed father is not the biological father. It is therefore reasonable to expect that a man would be more attracted towards a woman displaying a trait that increases his paternal confidence, and the likelihood that he could uncover his partner’s sexual infidelity.

Eighty-eight male and female students were asked to rate facial attractiveness of models on a computer. The pictures were close-ups of young adult faces, unfamiliar to the participants. The eye color of each model was manipulated, so that for each model’s face two versions were shown, one with the natural eye color (blue/brown) and another with the other color (brown/blue). The participants’ own eye color was noted.

Both blue-eyed and brown-eyed women showed no difference in their preferences for male models of either eye color. Similarly, brown-eyed men showed no preference for either blue-eyed or brown-eyed female models. However, blue-eyed men rated blue-eyed female models as more attractive than brown-eyed models.

That means there is a place or set of places in the genome where genetic variations give some of us our pronounced preference for blue eyes. I also prefer green eyes. Does the same set of genetic variations cause both preferences?

There's a lesson here for for future parents who will be able to use genetic engineering techniques to choose eye color for their daughters: Choose blue to maximize the appeal of their daughters. The blue color won't cost them any with the brown eyed guys but will boost their appeal to blue eyed guys.

However the very trait that increases attractiveness of women has a different effect in men: It decreases the range of women who they find attractive. If you want your son to find a larger range of women attractive then it actually makes sense to give him brown eyes.

Blue eyed men tend to have blue eyed romantic partners.

In a second study, a group of 443 young adults of both sexes and different eye colors were asked to report the eye color of their romantic partners. Blue-eyed men were the group with the largest proportion of partners of the same eye color.

According to Bruno Laeng and colleagues, “It is remarkable that blue-eyed men showed such a clear preference for women with the same eye color, given that the present experiment did not request participants to choose prospective sexual mates, but only to provide their aesthetic or attractiveness responses…based on face close-up photographs.” Blue-eyed men may have unconsciously learned to value a physical trait that can facilitate recognition of own kin.

Once offspring genetic engineering becomes possible I am expecting we will see a huge surge in births of blue eyed and blond hair daughters. They'll also have larger lips, more bottle-shaped bodies, greater symmetry, higher cheekbones, and every other feature that is considered sexy and beautiful. People will make their sons more physically attractive as well. The future will be beautiful.

By Randall Parker    2006 October 29 03:17 PM   Entry Permalink | Comments (45)
2006 August 15 Tuesday
Women In Secure Relationships Want Less Sex

Natural selection did not create human male and female sexual desires that are mutually compatible. Men in long term relationships sound sexually frustrated.

The researchers from Hamburg-Eppendorf University interviewed 530 men and women about their relationships.

They found 60% of 30-year-old women wanted sex "often" at the beginning of a relationship, but within four years of the relationship this figure fell to under 50%, and after 20 years it dropped to about 20%.

In contrast, they found the proportion of men wanting regular sex remained at between 60-80%, regardless of how long they had been in a relationship.

Women maintain their interest better in men who have higher status than their mates

The Germans found, however, that living apart slows the decline in female libido, confirming the maxim “absence makes the heart grow fonder”.

Women whose husbands or boyfriends have higher educational qualifications than their own also maintain their sex drive. This, speculates Klusmann, is because such men are regarded as a “valuable mate of choice” by other women.

Some people think nature is great. Nature is all about conflict and competition. Natural selection has produced males and females who have instincts which give desires and drives that make them come up well less than perfectly compatible. If men and women ever become more compatible it will be due to genetic engineering and other biotechnologies that adjust us to make us have more mutually satisfying desires.

When sexual desires and drive become far more manipulable with neurobiotechnology will men and women in long term relationships more often increase the woman's sex drive or decrease the man's? I suspect the decision will be made at least partially based on available time. People will turn down their sex drives when working long hours and raising kids but turn up their sexual desire when they have more time. Taking a vacation? Turn up your libido. Cialis, Levitra, and Viagra are already a step in this direction. But they turn up sexual desire in men whereas what's more needed are down switches in men and up switches in women.

To the extent that genetic variations will turn out to predict sex drives in long term relationships I'm expecting some people to genetically evaluate potential spouses based on the expected difference in their sex drives. I also expect them to genetically evaluate for how likely their mate is to cheat on them. I fully expect human geneticists to find genetic variations that increase promiscuity.

By Randall Parker    2006 August 15 10:10 PM   Entry Permalink | Comments (17)
2006 August 05 Saturday
Hungry Men Like Fatter Women

This result opens up all sorts of possibilities. Dr Viren Swami of University College London and Dr Martin Tovée of Newcastle University found that before they eat dinner men find heavier set and less curvy women more attractive.

How full a man's stomach is can dictate the type of woman he will fancy, UK research suggests.

A study of 61 male university students found those who were hungry were attracted to heavier women than those who were satiated.

The hungry men also paid much less attention to a woman's body shape and regarded less curvy figures as more attractive.

The molecular mechanism by which this works might be manipulable some day. Could a drug target brain locations which govern attraction without affecting whether a person feels hungry? If so, a guy could (knowingly or not) take a drug that makes his skinny or fatty mate look more attractive all the time.

I've long thought that a drug which increased the range of men or women which a person finds attractive would allow a person to be a lot more satisfied when pursuing the opposite sex. Also, a drug or other treatment that allowed a mind to find a single person the most attractive (say stare at that person while getting the treatment to imprint that shape as ideal) would allow everyone to think their mate is most attractive.

Biotechnological manipulation of feelings of attraction might not cause natural selection problems. In the future people will genetically engineer their offspring anyway. So hooking up with a person who is less attractive due to genetic problems doesn't have to lead to genetically less fit offspring. That will be able to get fixed with genetic engineering at the time of conception.

Male students entering and exiting a school dining hall were shown pictures and women and asked to rate them.

They recruited male university students as they entered or exited a campus dining hall during dinner time.

They asked the men to rate how hungry they were on a scale of one to seven. Using these responses, the researchers selected 30 hungry and 31 satiated men to take part in the study.

The men were then asked to rate the attractiveness of 50 women of varying weights, all within a healthy range, who had been photographed wearing tight grey leotards and leggings.

Skinny women should want to go out to dinner with men since the men will find them more attractive as dinner progresses. Heavier set women might want to go bicycling with a guy to build up his appetite in more ways than one.

By Randall Parker    2006 August 05 08:52 AM   Entry Permalink | Comments (0)
2006 July 23 Sunday
Sleeping With Women Drains Male Brains?

University of Vienna Austria researcher Gerhard Kloesch arranged for childless couples to sleep 10 days together and 10 days apart. Both wives and husbands slept more poorly together and men suffered more degraded performance than the wives did.

While men thought they slept better with a partner, and women believed they didn't, actually both sexes had more disturbed sleep, even when they did not have sex. Lack of sleep led to increased stress hormone levels in men, and reduced their ability to perform simple cognitive tests the next day.

Women can handle interruptions more easily. The reason is probably Darwinian: Natural selection selected for females that can handle the interrupts of babies and children. Whereas men spent more time out concentrating on one task at a time such as hunting.

A sleep expert in England says married couples shouldn't be so determined to sleep together.

Dr Neil Stanley, a sleep expert at the University of Surrey, said: "It's not surprising that people are disturbed by sleeping together.

"Historically, we have never been meant to sleep in the same bed as each other. It is a bizarre thing to do.

"Sleep is the most selfish thing you can do and it's vital for good physical and mental health.

"Sharing the bed space with someone who is making noises and who you have to fight with for the duvet is not sensible.

Once the sex becomes infrequent (or so married men assure me) why not sleep apart some of the time?

Marriage doesn't just make men dumber. It also takes away some of their drive. Previous research has shown that getting married lowers male testosterone and having kids lowers it even further.

Gray studied testosterone in saliva collected from 58 men (48 of them Harvard students) between the ages of 20 and 41. Half were married, and of those, 15 were married with children. He took four saliva samples from each man: two in the morning and two in the evening. The subjects also completed questionnaires about their demographic, marital, and parenting backgrounds. Among other things, the questionnaires asked how much time the men spent with their spouses (instead of hanging out with the guys) on their last day off from work, and measured the effort they expended caring for their children. Analysis showed that marriage, fatherhood, and longer periods spent with wives and children were all linked to lower testosterone levels. Fathers in particular had levels significantly lower than those of unmarried men. Researchers also observed that hormone levels in the morning samples were high and relatively even among the men; the differences appeared at night.

On the other hand, the lower testosterone might reduce the risk of prostate cancer and reduce the general rate of aging.

By Randall Parker    2006 July 23 03:24 PM   Entry Permalink | Comments (6)
2006 June 18 Sunday
Erotic Material Triggers Biggest Brain Response In Women

Using electroencephalogram (EEG) measurements of reactions to a large assortment of types of images shown for several seconds researchers found the minds of women react most strongly to erotic images.

Researchers at Washington University School of Medicine in St. Louis measured brainwave activity of 264 women as they viewed a series of 55 color slides that contained various scenes from water skiers to snarling dogs to partially-clad couples in sensual poses.

What they found may seem like a "no brainer." When study volunteers viewed erotic pictures, their brains produced electrical responses that were stronger than those elicited by other material that was viewed, no matter how pleasant or disturbing the other material may have been. This difference in brainwave response emerged very quickly, suggesting that different neural circuits may be involved in the processing of erotic images.

"That surprised us," says first author Andrey P. Anokhin, Ph.D., research assistant professor of psychiatry. "We believed both pleasant and disturbing images would evoke a rapid response, but erotic scenes always elicited the strongest response."

As subjects looked at the slides, electrodes on their scalps measured changes in the brain's electrical activity called event-related potentials (ERPs). The researchers learned that regardless of a picture's content, the brain acts very quickly to classify the visual image. The ERPs begin firing in the brain's cortex long before a person is conscious of whether they are seeing a picture that is pleasant, unpleasant or neutral.

But when the picture is erotic, ERPs begin firing within 160 milliseconds, about 20 percent faster than occurred with any of the other pictures. Soon after, the ERPs begin to diverge, with processing taking place in different brain structures for erotic pictures than those that process the other images.

I wonder if there is any trend as a function of age where the minds of older women might react less strongly to erotic images. I also wonder whether there is a difference with women on hormone suppressing therapies or who have had hysterectomies without replacement hormones.

Women rate erotic material as less appealing than men do. But their brains react as much to it as do the brains of men.

A great deal of past research has suggested that men are more visual creatures than women and get more aroused by erotic images than women. Anokhin says the fact that the women's brains in this study exhibited such a quick response to erotic pictures suggests that, perhaps for evolutionary reasons, our brains are programmed to preferentially respond to erotic material.

"Usually men subjectively rate erotic material much higher than women," he says. "So based on those data we would expect lower responses in women, but that was not the case. Women have responses as strong as those seen in men."

I would expect people with stronger sex drives to react more strongly to erotic materials. I wonder if one could use the EEG results like a biofeedback machine and train oneself to react more or less strongly to erotic materials. If one could train oneself to react more strongly would it provide any benefit for people who feel frigid or who get little pleasure from sex?

I'd also be curious to know whether a fast IQ test delivered after being shown images that elicit a greater brain response would show higher or lower mental ability. Do images that evoke stronger responses make the mind work quicker in general? Or do they divert mental resources away from problem solving?

By Randall Parker    2006 June 18 07:27 PM   Entry Permalink | Comments (5)
2006 May 28 Sunday
Dopamine Receptor Genetic Variant Influences Sexuality

Genetic variations in a dopamine receptor influence sexuality (same article here)

New evidence that individual differences in human sexual desire can be attributed to genetic variations has been revealed by a research group headed by a professor of psychology at the Hebrew University of Jerusalem. The findings are believed to have an impact on people’s understanding of their own sexuality as well as to how sexual disorders may come to be treated in the future.

An article on the topic appears currently in Molecular Psychiatry online. The study represents the combined efforts of researchers directed by Prof. Richard P. Ebstein, of Herzog Hospital and the head of the Scheinfeld Center for Human Genetics in the Social Sciences of the Psychology Department at the Hebrew University, and a research group headed by Prof. Robert H. Belmaker of the Psychiatry Division of Ben Gurion University of the Negev.

The article provides, for the first time, data that common variations in the sequence of DNA impact on sexual desire, arousal and function and lead to differences and diversity of the human sexual phenotype.

Did anyone previously not expect this to be the case? The press release gushes on about how this is a revolutionary discovery that will affect how we look at sexuality. Maybe that is true for some people who do not want to accept that genetic variations play a large role in determining our desires, dislikes, and behavioral tendencies and abilities. But I expect genetic roles in all sorts of aspects of cognitive function and in the peripheral nervous system. I just am eager and impatient to get to the details so we can work out the implications.

Self-reports on sexuality correlate with DRD4 dopamine receptor genetic variations.

In this latest study, the Israeli investigators examined the DNA of 148 healthy male and female Israeli university students and compared the results with questionnaires asking for the students’ self-descriptions of their sexual desire, arousal and sexual function. The results showed a correlation between variants in the D4 receptor gene – which is responsible for producing the dopamine receptor protein (DRD4) – and the students’ self-reports on sexuality.

Sounds like only 10% had moderate sexual desire and most were in the "depressant" category. I bet divorces are more likely between members of a couple who have radically different levels of sexual desire. Therefore genetic tests may eventually help to predict likelihood of marital success.

Interestingly, some forms of variants in this gene were shown to have a depressing effect on sexual desire, arousal and function, while other common variant had the opposite effect – an increase in the sexual desire score. The latter is believed to be a relatively new mutation, and it is estimated that it appears in Homo sapiens “only” 50,000 years ago at the time of humankind's great exodus from Africa. Approximately 30% of many populations carry the heightened arousal mutations, while around 60% carry the depressant mutation.

Did the migration from Africa take humans into areas where so much food was available that it was selectively advantageous to mate and reproduce more often?

Which are the populations that have a higher average level of sexual arousal? Does the level of sexual arousal correlate with other characteristics?

The discovery of a role for DRD4 in sexual arousal makes it a candidate target for drug development. Further research into the mechanism for how it causes this effect will likely lead to identification of other targets for sexual arousal drugs.

The investigators predict that as a result of their work, and other advances in neurosciences focusing on sexual behavior, a conceptual change will result, in which new therapeutic pathways will be developed for treatment of sexual dysfunctions based on a rational pharmacogenetic strategy. Additionally, the investigators note that many variations such as “low sexual desire” may be quite normal and not necessarily a product of dysfunction.

Viagra, Levitra, and Cialis are not enough. People want more ways to make themselves sex-crazed. Don't worry. The cheaper genetic sequencing gets the more genetic variations we'll discover that contribute to sexual arousal and the more targets for drug development that will be identified.

When it becomes possible to select the genetic variants offspring will get will more people select higher, lower, or medium sex drive genetic variations? I'm guessing women will want to give their daughters genetic variations that make multiple orgasms very easy. Will people want their kids to walk around constantly craving sexual experiences?

By Randall Parker    2006 May 28 04:00 PM   Entry Permalink | Comments (17)
Brains Recognize Male Versus Female Gait

The brain can identify male versus female gaits when the only visible features of walkers are only 15 dots of light attached to major body joints.

LA JOLLA, CA - It doesn't take John Wayne's deliberate, pigeon-toed swagger or Marilyn Monroe's famously wiggly sway to judge a person's gender based on the way they move. People are astonishingly accurate when asked to judge the gender of walking human figures, even when they are represented by 15 small dots of light attached to major joints of the body.

And not only that, when human observers watched the walking motion of a male so-called "point light walker," they were more sensitive to the female attributes when watching the next figure in the sequence. This suggests that the human brain relies on specialized neurons that tell gender based on gait, report researchers at the Salk Institute for Biological Studies in the May 21 advance online edition of Nature Neuroscience.

"Our judgment of gender can adapt within seconds," says senior author Gene Stoner, a neuroscientist in the Vision Center Laboratory at the Salk Institute. "The gaits of males and females may vary geographically or culturally and this mechanism allows us to adapt very quickly to local ways of walking," he adds.

How humans move reflects, in part, gender-specific differences in shape such hip-to-waist ratio and the like. Such inherent differences in gait might then be exaggerated by an individual to emphasize their gender. "Our new data suggests that there are neurons selective for gender based on these motion cues and that they adjust their selectivity on the fly," Stoner explains.

Although much work has been done on how the brain represents so-called low-level features, such as "redness" or "left-moving," scientists have been unable to put their finger on more abstract concepts such as gender. "We wanted to know whether gender is represented in a similar way to low-level visual features such as color, or if it is a more semantic concept such as good and evil," says experimental psychologist and first author Heather Jordan, a former post-doc in the Vision Center Laboratory and now an assistant professor at York University in Toronto.

Individual neurons in the visual cortex are finely tuned to certain attributes of visible objects such as the color red, a certain shape or objects moving in a specific direction. These specialized neurons reveal their existence through a telltale effect called adaptation. For example, if you stare at a red patch and then look at a neutral color you tend to see green. This "adaptation" reflects a mechanism in the brain that exaggerates differences between objects to increase the sensitivity and optimize the output of individual neurons.

I think the ability to recognize differences is something that one could enhance with thoughtful control of one's environment. What differences do you want to get better at recognizing?

These scientists expect to eventually identify a single neuron that activates for male gaits and another neuron that activates for female gaits.

"In the past, when adaptation in behavior was observed for specific features, neurophysiologists have subsequently been able to find individual neurons which fire only when they encounter this feature," says Jordan. "We think that the same is true for maleness and femaleness - that there are neurons in the brain that fire if, and only if, they 'see' a male gait and others that fire if, and only if, they 'see' a female gait, explains Jordan.

"We know lots about individual neurons that are sensitive to the direction of moving objects. But in this case, motion provides information about the structure of what is moving," says Stoner.

The mind compares gaits to recently seen gaits of other walkers. So you are more likely to be seen as masculine after the mind has just seen an especially feminine walk and you are more likely to be seen as feminine after the mind has just seen an especially masculine walk.

For their experiments, the Salk researchers morphed the gait of averaged male and female walkers -- resulting in varying degrees of "maleness" and "femaleness" .When the figure consisted of less than 49 percent male contribution, the observers reported seeing a figure that appeared female. Once there was more than 49 percent maleness in the figure, they reported seeing a figure that was mostly male. But these numbers were not stable: Viewing the gait of one gender biased judgments of subsequent gaits toward the opposite gender. "If you want to appear particularly feminine you should walk behind a very masculine-looking male and vice-versa," jokes Jordan.

If it all comes down to individual neurons then I'd expect an age-related degeneration in the ability to recognize male versus female gaits. Should just the right neuron die then one might lose the ability to tell apart males and females. Though the odds of losing that neurons are low the odds rise with age. Though perhaps there's a mechanism where another neuron can take over the job if the one neuron doing the job dies or starts to misfire.

Given that there are individual neurons that consolidate information for a large assortment of pattern recognition tasks one might have a better chance of identifying loss of function due to deaths of individual neurons if one measured a large number of capabilities (e.g. ability to tell colors apart, direction of movement, various types of shapes, and ability to identify male and female gaits) through time. Error rates might rise before total failure sets in.

Question: If you've just heard a speech from an obviously dishonest person then are you likely to think the next person is honest if they sound relatively less dishonest? If so, this might explain why politicians and political activists can get away with telling so many lies. They get compared to each other rather than to an absolute standard of honesty.

More generally, are there specific types of images or other stimuli one could present to one's brain before examining some evidence or issue as a way to increase one's ability to see a contrast and recognize key differences?

By Randall Parker    2006 May 28 08:07 AM   Entry Permalink | Comments (2)
2006 May 09 Tuesday
Women Can Detect Child Friendliness In Male Faces

Women are wired up to detect which men like children.

(Santa Barbara, CA) – Women are able to subconsciously pick up cues in men's faces and use those cues to determine if they are attracted to the males for long-term or short-term relationships, according to a new study conducted by researchers at the University of California, Santa Barbara and the University of Chicago.

The study was published online today by the Proceedings of the Royal Society of London, the UK's national academy of science.

Men whose faces reflected an interest in children were intuitively perceived by woman as candidates for long-term commitments, whereas men whose faces indicated high testosterone levels were determined to be short-term prospects for relationships.

"Women are surprisingly accurate in being able to determine interest in children and testosterone levels," said James Roney, assistant professor of psychology at the University of California, Santa Barbara, who is the lead author of the paper. "Our data suggest that men's interest in children predicts their long-term mate attractiveness even after we account for how physically attractive the women rated the men," he said.

For the study, the researchers recruited male undergraduate students from a variety of ethnic backgrounds who were tested for testosterone and for their interest in children.

Researchers took saliva samples to measure testosterone levels. To determine interest in children, researchers showed the men a pair of pictures, one each of an adult and a baby. They were then asked which picture they preferred. Slightly more than twelve percent of the men expressed no interest in the baby pictures, while the rest expressed a range of interest, up to nine out of ten preferences for the infants.

The researchers then took pictures of each man, asking them to display a neutral expression. An oval frame was placed around each photo to focus attention on the faces and the photos were shown to undergraduate women from diverse backgrounds at UCSB.

The women were asked to rate the men according to whether they thought the men liked children, whether they appeared masculine, physically attractive, or kind. They were then asked to determine men's attractiveness as short-term romantic partners or as long-term partners for relationships such as marriage.

The men chosen as being most interested in children were also the same men who had expressed the most interest in children in the photo test. The women were also able to determine from their photos which men had high testosterone levels because they perceived the men as looking masculine.

Although women said they were attracted to the men who tested high for testosterone, an important factor in their attraction to men for a long-term relationship was their perception of a man's affinity for children, even after accounting for their perceptions of men's general kindness.

"The research suggests that men's interest in children may be a relatively under-appreciated influence on men's long-term mate attractiveness," Roney said.

What I'd like to see: Test women for estrogen levels and body shapes and see if the more feminine women are better or worse at detecting which men are more child-friendly. I bet the higher estrogen or perhaps high estradiol women are better at identifying good mates.

Also, are higher testosterone men more likely to get divorced?

By Randall Parker    2006 May 09 11:11 PM   Entry Permalink | Comments (18)
Lesbian Brains Respond Differently To Pheromones

Using positron emission tomography (PET) and Magnetic Resonance Imaging (MRI) Swedish researchers have found that the brains of homosexual women responded to pheromones in ways more like heterosexual men than like heterosexual women.

Lesbian and heterosexual women respond differently to specific human odours, a brain-scanning study has found. The homosexual women showed similar brain activity to heterosexual men when they inhaled certain chemicals, which may be pheromones, the researchers say.

"But our study can't answer questions of cause and effect," cautions lead researcher Ivanka Savic at the Karolinska Institute in Stockholm, Sweden. "We can't say whether the differences are because of pre-existing differences in their brains, or if past sexual experiences have conditioned their brains to respond differently."

Anyone surprised?

They used two candidate human pheromones labelled "AND" and "EST" and found that lesbian brains responded more like heterosexual male brains.

Lesbian and heterosexual women showed different patterns of brain activity while sniffing AND and EST, the study shows.

While smelling AND and EST, the brain activity pattern for lesbian women was closer to that of heterosexual men than heterosexual women, Savic and colleagues note.

Previously homosexual men and heterosexual women were found to have even greater similarity in their brain patterns when exposed to these compounds.

Lesbians didn't react in their anterior hypothalamus while heterosexual women did.

The results showed that while a part of the brain called the anterior hypothalamus -- which is linked to sexual behavior, among other things -- tended to light up in the straight women, the lesbians showed no reaction.

On the other hand, lesbians tended to react to male as well as female hormones in the part of the brain that handles routine odors.

We have preferences and desires that come up from deep in our subconsciouses which we have little control over. We have some control over how we react to the desires. But little control over the nature of the actual desires.

By Randall Parker    2006 May 09 10:48 PM   Entry Permalink | Comments (12)
2006 April 24 Monday
Men More Jealous When Their Mates Are Fertile

Women like more masculine men when they are fertile and men feel more jealous about their mates when their mates are fertile.

Men become more jealous of dominant males when their female partner is near ovulation, researchers at the University of Liverpool have found.

Previous studies have found that women's preferences for male physical appearance vary according to their fertility status. During ovulation women tend to find masculine looking men more attractive and prefer their voices and odour. During this fertile phase women are more likely to have an affair with a masculine-looking man, as their features are linked to high testosterone levels, demonstrating good genetic qualities that can be passed on to offspring.

New research at the University has found that men sense this preference shift in their female partners and find masculine men more threatening during their partner's most fertile phase. Rob Burriss and Dr Anthony Little, from the University's School of Biological Sciences, also found that men only behave in this way if their female partner does not use oral contraception – and is therefore more fertile.

Images of male faces that were either high or low in dominant features, such as a strong jaw lines and thinner lips, were shown to male participants who provided ratings of dominance for each image. A dominant person was defined as someone who looked like they could 'get what they wanted'.

Participants were asked to provide information on whether or not their female partner used oral contraception and the date of her current or previous menses. Male participants whose partners did not use oral contraception and were near ovulation rated masculine faces more dominant than those participants with partners who did use oral contraception and were not near ovulation.

I think of Ray Davies and the Kinks singing "I'm an ape man, I'm an ape ape man, I'm an ape man. I'm a King Kong man. I'm a voodoo man. I'm an ape man". Do not be fooled by all the technological civilization you see around us. We are still primitive products of natural selection.

By Randall Parker    2006 April 24 10:15 PM   Entry Permalink | Comments (5)
2006 April 19 Wednesday
Scantily Clad Women Make High Testosterone Men Drive Lousy Bargains

Economists Siegfried Dewitte and Bram Van den Bergh havd found that the sight of attractive women makes men who experienced high testosterone in the womb to drive weaker bargains in betting games.

It seems that the more macho a man is — at least according to his hormones — the more the sight of an attractive woman will affect his judgement.

Researchers at the University of Leuven in Belgium asked men to play an ultimatum game, in which they split a certain amount of money between them. High-testosterone men drove the hardest bargain — unless they had previously viewed pictures of bikini-clad models, in which case they were more likely to accept a poorer deal.

The sight of flesh had less effect on the bargaining tactics of low-testosterone men.

A low testosterone executive could benefit from bringing sexy female administrative assistants to negotiations with higher testosterone representatives of other businesses.

They tested for previous testosterone exposure by looking at the relative lengths of ring fingers and index fingers.

The men's testosterone levels were also tested - by comparing the length of the men's index finger compared to their ring finger.

If the ring finger is longest, it indicates a high testosterone level.

The researchers found that men in the study who had the highest levels performed worst in the test, and suggest that is because they are particularly sensitive to sexual images.

Dr Siegfried DeWitte, one of the researchers who worked on the study, said: "We like to think we are all rational beings, but our research suggests ... that people with high testosterone levels are very vulnerable to sexual cues.

"If there are no cues around, they behave normally.

"But if they see sexual images they become impulsive."

What masculine men need is some sort of drug that'll suppress their reaction to sexy women. The ability to turn it off would enhance one's ability to think rationally. But we'd want the effects to be temporary of course!

Also see my previous post "Index And Ring Finger Lengths Partially Predict Violent Tendencies".

By Randall Parker    2006 April 19 09:22 PM   Entry Permalink | Comments (6)
2006 January 18 Wednesday
Men Feel More Pleasure Than Women Watching Punishment

The brains of men feel pleasure when they see unfair actors get electric shocks.

Men appear to get greater satisfaction than women when witnessing retribution, a brain imaging study funded by the Wellcome Trust biomedical research charity has revealed.

This evidence of male schadenfreude, or pleasure at seeing revenge exacted, was highlighted during an experiment, published online by Nature today (Jan 18th), undertaken to compare empathy in the brains of people watching someone they either liked, or disliked, suffering pain.

A series of tests was undertaken involving 32 male and female volunteers plus four ‘confederates’ who were actually actors, but this was kept secret from the rest of the group.

In the first part of the experiment volunteers played a monetary investment game giving cash to one of the actors who had to then decide how much to give back. During each “transaction” the amount was tripled, so it was beneficial for both volunteer and actor to send as much as possible.

The study was designed to allow one actor to behave fairly, by returning a similar amount, while the other, unfair actor, tended to send back very little, if anything at all.

In the second part of the experiment at the Wellcome Department of Imaging Neuroscience in London, at UCL (University College London)**, the volunteer was placed in a magnetic resonance imaging brain scanner, to allow researchers to measure empathic responses as he or she watched the actors receiving a mild electric shock. When the “fair” players received this stimulation –the equivalent of a short bee sting- both female and male volunteers showed empathy activation in pain related areas of the brain – the fronto-insular and anterior cingulate cortices.

When the unfair actor received a shock the women taking part in the experiment showed empathy with them. However brain images of the male volunteers showed no increased activity in the empathy-related pain areas, but did reveal a surge in the nucleus accumbens, the “reward” region of the brain.

This reward- related activity was not seen in the majority of female participants, who appeared to have empathy for both the fair and unfair actors suffering pain.

I'd love to see follow-up investigations of how the females who felt the pleasure differ from the females who didn't feel the pleasure. Do females who feel more pleasure when watching punishment have other more masculine traits than the females who do not feel the pleasure? Do they tend to work in different kinds of occupations? Have different values?

Empathy declines when people are seen as unfair.

Dr Tania Singer, who led the study, said: “During breaks in the tests you could tell from the body language that both the male and female volunteers did not like the actors who had cheated them. They tried to stay away from them as much as possible.

“These emotional responses were later confirmed in questionnaires completed by the volunteers who were asked to judge the actors. They consistently rated the fair player as being more agreeable, more likeable and even more attractive than the unfair actor.

“These results suggest that fairness in social situations shapes the nature of the emotional link we have to other people. We empathize with others if they cooperate and act fairly. But, in contrast, selfish and unfair behaviour compromises this empathic link. So, when the unfair player received a painful shock there was, at most, very little sign of anything registering in the empathy-related region of the men as opposed to the reward-related area where there was activity. They expressed more desire for revenge and seemed to feel satisfaction when unfair people were given what they perceived as deserved physical punishment.

“This type of behaviour has probably been crucial in the evolution of society as the majority of people in a group are motivated to punish those who cheat on the rest. This altruistic behaviour means that people tend to protect each other against being exploited by society’s free-loaders, and evolution has probably seeded this sense of justice and moral duty into our brains.

“We will need to confirm these gender differences in larger studies because it is possible the experimental design favoured men as there was a physical rather then psychological or financial threat involved. However this investigation would seem to indicate there is a predominant role for men in maintaining justice and issuing punishment.”

For every quality of the brain where the sexes differ or where different groups of people differ due to genetic reasons I always ask myself what will happen to that quality when people can choose genetic variations for their offspring. Will the desire to carry out altruistic punishment become more or less prevalent in genetically engineered humans? What effects will the change have on society? My guess is the desire to carry out altruistic punishment is essential to cause people to keep each other in line and acting fairly. Take away that trait and people would become far less likely to protect each other from thugs, thieves, fraudulent government workers, fraudulent businesses, and other manner of unfair actors.

See my previous posts "Brain Rewards For Carrying Out Altruistic Punishment" and "Altruistic Punishment Seen As Explanation For Mass Political Behaviors".

By Randall Parker    2006 January 18 10:48 PM   Entry Permalink | Comments (4)
2005 November 02 Wednesday
Women With Higher Estrogen Seen As More Attractive

Sex appeal comes from a hormone. More estrogen makes a woman's face prettier.

Women with high levels of the sex hormone oestrogen have prettier faces, research suggests.

The findings make evolutionary sense - men are attracted to the most fertile women, the University of St Andrews team told a Royal Society journal.

Measurement of estrogen levels combined with attractiveness ratings showed a relationship.

Miriam Law Smith and colleagues photographed 59 women, aged between 18 and 25, every week for six weeks. On each occasion, they provided a urine sample for hormone analysis and gave information on where they were in their menstrual cycle. None of the women wore make-up, nor were they taking the contraceptive pill.

The researchers then selected the photograph of each woman that had been taken at the time of her highest urine-oestrogen level. As expected, this correlated to the point of ovulation in the women’s menstrual cycles. These photographs were rated by 14 men and 15 women, also aged 18 to 25, for attractiveness, health and femininity.

Make-up hides the effect.

Women with higher levels of oestrogen were rated as more attractive, healthy and feminine looking. Interestingly, no relationship between appearance and oestrogen was found in women wearing make-up. The researchers believe that while make-up improves facial appearance it may be masking cues normally seen in the face.

That men should be attracted to more fertile women makes sense from an evolutionary perspective. Also, the relationship between hormone levels, shapely bodies, and fertility is well-established. Women with higher levels of estradiol are about 3 times more likely to get pregnant. See my post "Women With Hourglass Bodies Have More Reproductive Hormones".

Eventually stem cell therapy and gene therapy will be widely used by women to enhance their feminine appearance. The average level of attractiveness of both men and women will be far higher in the future. Once Strategies for Engineered Negligible Senescence (SENS) become available everyone will look young and highly attractive.

By Randall Parker    2005 November 02 11:45 AM   Entry Permalink | Comments (34)
2005 July 22 Friday
Facial Appearance and Smell Produce Conflicting Desires For Mates

Women normally (with exceptions) prefer the smell of men who are immunologically different from them. The desire for mates who have differences in sequences in Major Histocompatibility Complex (MHC) genes is probably the result of selective pressures to give offspring more genetic variations against diseases to increase the odds that at least some of a woman's offspring would survive. But Craig Roberts of the University of Liverpool found that women prefer the faces of men who have more similar MHC genes.

Previous research on smell suggests that humans prefer odours from potential partners who are genetically dis-similar. But new research in which women rated the facial attractiveness of men suggests the exact opposite. So sight and smell appear to be giving contradictory messages about which partners to choose.

The curious thing about this effect is that MHC variations are tied to facial shape variations. Are the genes for each located on the same chromosome? Do MHC variations cause facial shape differences?

“It’s a subtle effect,” says Craig Roberts of the University of Liverpool, who led the team which made the discovery. “We’re not saying it’s something that rules who we find attractive.”

Roberts and colleagues recruited 92 women and 75 men, and recorded differences in their MHC by analysing DNA from blood samples. Then each woman was asked to rate photographs of six men, three with similar and three with different MHC.

The results showed that, visually, the women preferred men with similar MHC. The preference applied both to long and short relationships, but was strongest for potential long term relationships.

Amerinds (a.k.a. indigenous peoples of the Americas) have fewer MHC variations than Europeans and Europeans have fewer than Africans (and this fact majorly contributed to the massive die-offs of Amerinds when the first European explorers showed up carrying many diseases that were new to the Americas). It would be worth investigating whether the same patterns of attraction to the opposite sex with similar or different MHC genes are found in Africans, Europeans, and Amerinds.

Since the Amerinds have fewer MHC variations and less selective pressure was present for MHC variations did they also experience less selective pressure for preference to mate with people who are immunologically different? Do the Amerinds have perhaps even indifferences to smell differences caused by MHC differences? Is the opposite the case among Africans? More generally, do particular MHC types which are found in some races or sub-racial groups produce smells that are either extremely desirable or extremely revolting in some other racial group?

By Randall Parker    2005 July 22 12:33 PM   Entry Permalink | Comments (0)
2005 July 06 Wednesday
Ovulating Women Prefer Smell Of Dominant Men

Natural selection has produced human females who prefer to mate with dominant men when the females are most fertile.

A group of 65 women then smelled the pads and rated the sexiness and masculinity of the scent. Women in the middle week of their menstrual cycle, the point at which fertility is at its peak, tended to prefer the smell of the men who scored highest on the dominance quiz. This preference was not shown by women at other points in their cycle. What's more, the effect was only significant for women in long-term relationships, the researchers report in the journal Biology Letters1. This shows that both menstrual phase and relationship status can have an effect on which men women tend to prefer, says Havlícek.

What other differences are there in men who score high in dominance? I'd love to see hormone levels in men who score higher in dominance characteristics versus men who score lower. Keep in mind that testosterone levels drop in married men and drop even further in married men with children. Are men who "smell dominant" more likely to be single? Or are they more likely to have jobs that put them in positions of responsibility and power over others? Do they have higher average incomes than men who smell less desirable? Or is that dominant smell always there in some men due to genetic reasons regardless of their station in life?

Whatever characteristics make a man dominant also makes him smell like better genetic material.

Researcher Dr Craig Roberts told the BBC News website: "There seems to be some sort of physiological mechanism that directs women to indicators of good genes.

"The offspring of such a coupling would therefore be likely to have better genes."

Some women use their long term mates for child raising while preferring other men as sperm donors.

"A strong association between male odour-sexiness and psychological dominance was only found for non-single women in the fertile phase of their menstrual cycle."

They added: "A mixed-mating strategy may have evolved in females - they prefer genetically superior males for short-term or extra-pair sexual partners while, at the same time, they seek males who are more willing to invest in their offspring as long-term or social partners."

Could that dominant smell be put in a perfume bottle? Perhaps. Or is dominance more detectable by the absence of some other smell? Say, whatever smells comes out when you feel fear?

One problem I see coming up when offspring genetic engineering becomes possible is that people may make all their male offspring so dominant that we end up with a society where men can't cooperate very well because no one wants to take orders. Oh, and fights and murders might become more frequent as well. Hey, technology creates problems. I'm not a utopian about the future.

By Randall Parker    2005 July 06 09:23 PM   Entry Permalink | Comments (23)
2005 May 26 Thursday
Oral Contraceptives Permanently Reduce Libido?

Oral contraceptives for women cause the female body to overproduce sex hormone binding globulin (SHBG) which is a protein that binds to testosterone. Testosterone enhances sexual desire in women just as it does in men. Researchers led by Irwin Goldstein and Claudia Panzer at Boston University have found that SHBG levels remain elevated even a year after women stop taking the pill and women may suffer sexual dysfunction as a result. (same article here)

Hormonal changes induced by oral contraceptives (OC) are not immediately reversible after discontinuation of use, according to new research issued today at the American Association of Clinical Endocrinologists (AACE) Fourteenth Annual Meeting and Clinical Congress.

Despite the benefits of OC, their use has been associated with sexual dysfunction and androgen insufficiency. OC are known to decrease serum testosterone levels by decreasing ovarian production of testosterone and by increasing production of sex hormone-binding globulin (SHBG) from the liver. It has been assumed that these changes are reversible after discontinuation of OC use.

In the study of 102 pre-menopausal women with female sexual dysfunction, SHBG values in the OC group were seven times higher than those in the never-user group. OC lowers the free androgen index, in part, by substantially increasing SHBG levels. Despite a decrease in SHBG values after discontinuation of OC use, SHBG levels remained continuously elevated for up to one year in comparison with those in the control group. The free androgen index may remain low for a prolonged period.

Decreased libido, problems havng orgasms, painful intercourse, and other side effects of the Pill may be long lasting and perhaps even permanent for some women. Dr. Panzer warns:

"It is important that when doctors advise women to take oral contraception that potential side-effects, including loss of sexual appetite and arousal, are pointed out.

"If, as our study suggests, the Pill can cause a long-term or permanent loss of libido, that is something women need to be made aware of."

Parenthetical aside: The Pill has been in use for 45 years and yet a major side effect from its use is only being discovered now. Keep that in mind the next time a fairly new drug is found to have an unexpected side effect and the US Food and Drug Administration comes under a chorus of criticism for failing to foresee some problem. Discovery of drug side effects is hard to do even when a drug has been studied for decades.

Will women who have suffered a decreased desire for sex from taking oral contraceptives have to resign themselves to permanently reduced libidos? Maybe not. Drugs exist which suppress SHBG production.

The picture following treatment with tibolone was quite different. There was only a minor influence on circulating estrogens, and SHBG levels were reduced by 50%. Androgens are known to suppress SHBG production at the hepatic level [9,10,26,27]. After oral intake, tibolone is rapidly converted into 3α- and 3β- hydroxy tibolone, both having estrogenic properties, and the Δ4 isomer, which is known to possess progestogenic as well as androgenic activity. In fact, the receptor affinity for this isomer is about 40% of that of the potent androgen dihydrotestosterone [3,4]. The marked reduction in SHBG levels and as a consequence increased concentrations of free testosterone implies an enhanced circulating androgenic activity. This may be important as regards some clinical effects of tibolone.

A drug to suppress SHBG production would need to be either safe to take for the long term or capable of resetting liver SHBG production in a way that sticks once the drug is stopped. It is time to start looking in earnest for such a drug.

By Randall Parker    2005 May 26 07:08 PM   Entry Permalink | Comments (22)
2005 January 27 Thursday
Pheromone Increases Sexual Attractiveness Of Postmenopausal Women

Researchers Susan Rako M.D., a medical doctor in private practice as a psychiatrist in Newton Massachusetts, and Joan Friebely Ed.D., a researcher at Harvard's psychiatry department, have demonstrated that a synthesized pheromone applied to postmenopausal women appears to make them more sexually attractive to their partners. Here is the abstract of the paper "Pheromonal Influences on Sociosexual Behavior in Postmenopausal Women".

To determine whether a putative human sex-attractant pheromone increases specific sociosexual behaviors of postmenopausal women, we tested a chemically synthesized formula derived from research with underarm secretions from heterosexually active, fertile women that was recently tested on young women.

Participants (n=44, mean age = 57 years) were postmenopausal women who volunteered for a double-blind placebo-controlled study designed “to test an odorless pheromone, added to your preferred fragrance, to learn if it might increase the romance in your life.” During the experimental 6-week period, a significantly greater proportion of participants using the pheromone formula (40.9%) than placebo (13.6%) recorded an increase over their own weekly average baseline frequency of petting, kissing, and affection(p = .02). More pheromone (68.2%) than placebo (40.9%) users experienced an increase in at least one of the four intimate sociosexual behaviors (p = .04). Sexual motivation frequency, as expressed in masturbation, was not increased in pheromone users. These results suggest that the pheromone formulation worn with perfume for a period of 6 weeks has sex-attractant effects for postmenopausal women.

The question of whether humans are even capable of response to pheromones looks increasingly to have the answer of "Yes". This of course creates all sorts of possibilities for the future. But it also brings up some interesting issues about individual rights and free will.

Does the wearing of a pheromone violate the rights or integrity of others by invading their bodies and changing their desires and behaviors? Or does the efficacy of pheromones demonstrate limits to trying to organize societies around the idea of human rights? After all, if wearing artificially synthesized pheromones is a rights violation because it stealthily manipulates others then doesn't the natural excretion of pheromones do the same? Does it matter whether the person giving off the pheromone scent consciously chose to do so?

Then there is the question of free will. Doesn't every discovery of how chemicals alter behavior eat away at the idea of a core in every person that is free to choose?

The full paper appears to be on the web as well.

To determine whether a putative human sex-attractant pheromone increases specific sociosexual behaviors of postmenopausal women, we tested a chemically synthesized formula derived from research with underarm secretions from heterosexually active, fertile women that was recently tested on young women. Participants (n = 44, mean age = 57 years) were postmenopausal women who volunteered for a double- blind placebo-controlled study designed "to test an odorless pheromone, added to your preferred fragrance, to learn if it might increase the romance in your life." During the experimental 6-week period, a significantly greater proportion of participants using the pheromone formula (40.9%) than placebo (13.6%) recorded an increase over their own weekly average baseline frequency of petting, kissing, and affection (p = .02). More pheromone (68.2%) than placebo (40.9%) users experienced an increase in at least one of the four intimate sociosexual behaviors (p = .04). Sexual motivation frequency, as expressed in masturbation, was not increased in pheromone users. These results suggest that the pheromone formulation worn with perfume for a period of 6 weeks has sex- attractant effects for postmenopausal women.

Postmenopausal women may get better results from longer use since many of them are starting out without being involved in any kind of physically intimate relationship.

Within specific behaviors, a significantly higher proportion of pheromone than placebo users increased over their baseline behaviors in average weekly frequency of petting/affection and kissing6. However, the other sociosexual behaviors did not significantly increase.

Results in the menopausal group appear to be more modest than the results for men and women in their fertile years. Several explanations are possible. A reduced availability of male sexual partners occurs after 50. There is some evidence36 that with increasing postmenopausal age, there is a decreasing interest in sexual intercourse.

Moreover, in contrast with younger women, there is a reduced availability of male sexual partners for postmenopausal women. In fact, partner status at baseline (p=0.01) as well as pheromone use (p=0.03) were the two independent variables that significantly increased the likelihood that postmenopausal women would increase at least one intimate behavior during the 6-week experimental period. Postmenopausal women may require a longer experimental period, particularly if they need to find a partner, to bring about increases in more intimate sexual behaviors.

Details of the chemical used are being kept secret until its patent protections have been granted.

However, Winnifred Cutler, who discovered the pheromone, has said she will keep its true identity secret until patents have been granted to her Women's Wellness Research Centre, in Chester Springs, Pennsylvania.

But aren't patent applications in the public domain? Also, once patents are applied for is there any need for continued secrecy? My impression is that there isn't. Anyone know?

One could imagine the use of such a pheromone helping to keep together marriages of middle aged and old aged couples. But we can also expect to find that young males and females differ in the amounts of pheromnes they excrete. So expect young low pheromone producers to go for pheromone perfumes that level the playing field. Also expect eventually to see tests that measure your pheromone output. Perhaps more natural pheromone compounds will be discovered and we will be able to be tested for our pheromone profiles. There might be chemicals that elicit lust and other chemicals that elicit love from others.

Further into the future expect to see the development of gene therapy-carrying viruses on the black market that will reprogram the sexual and romantic feelings of any intended target. One can imagine these illicit treatments being used both to hook and to dump objects of desire at different stages in relationships.

By Randall Parker    2005 January 27 11:59 AM   Entry Permalink | Comments (4)
2005 January 25 Tuesday
Israel Scientist Develops Libido-Meter Brain Wave Test

Dr. Yoram Vardi, in charge of neurology at the Rambam Hospital and professor of urology at the Technion Israel Institute of Science, both in Haifa, Israel, has demonstrated that p300 brain waves are most reduced by exposure to sexually arousing images.

Vardi conducted experiments on 14 male and 16 female volunteers with normal sexual function. Using standard EEG equipment, a pair of headphones and a computer monitor, the subjects listened to music and other sounds to stimulate p300 brain waves. These waves, produced 300 milliseconds after an event, are the brain's normal response to stimuli.

While reduction in p300 brain wave amplitude occurs in response to visual stimuli in general the greatest reduction in p300 brain wave amplitude came in response to es

"What we found was that, in all subjects, the most significant reduction in p300 amplitudes was found when viewing sexual clips. At the end of the testing session, we also asked the subjects via the questionaire how much they were attracted to the sexual content. We found a very significant statistical correlation between what the subject told us and the amount the brain waves were diminished."

For all subjects, a lesser degree of reduction, but still statistically significant from baseline, was found when viewing sports and romantic clips. According to Vardi, what the study shows - and the questionnaire verifies - is that the p300 testing accurately reveals if and how much a person's brain waves react to the film clips of sexual content.

The extent of reduction of p300 brain waves correlated with self-reported sexual interest in the sexual images shown.

This has all sorts of potential uses. One use would be to test people in court cases who claim they have suffered a loss of libido in response to an accident. Also, men who claim they are interested in sex but can't get it up could be tested to see if they really have an unexpressable interest. Another idea: Test for pedophilic and other forbidden tendencies. Want to test a treatment to stop pedophiles from desiring children? Show them pictures and monitor their brain waves. Some day such a test might even need to be passed as a condition for parole.

In medical research an objective test for libido would make clinical testing of drugs for treating sexual dysfunction and for the development of aphrodisiacs even for normal people. Also, diagnosis of types of sexual dysfunction could be done more quickly and accurately.

By Randall Parker    2005 January 25 02:56 PM   Entry Permalink | Comments (10)
Site Traffic Info