March 04, 2005
Index And Ring Finger Lengths Partially Predict Violent Tendencies

Higher prenatal testosterone has already been found to be correlated with a higher ratio of ring finger length to index finger length. Now University of Alberta researchers Peter Hurd and Allison Bailey have shown that the higher ring finger to index finger ratio is correlated with physically aggressive behavior in men.

Dr. Peter Hurd initially thought the idea was "a pile of hooey", but he changed his mind when he saw the data.

Hurd and his graduate student Allison Bailey have shown that a man's index finger length relative to ring finger length can predict how inclined that man is to be physically aggressive. Women do not show a similar effect.

A psychologist at the University of Alberta, Hurd said that it has been known for more than a century that the length of the index finger relative to the ring finger differs between men and women. More recently, researchers have found a direct correlation between finger lengths and the amount of testosterone that a fetus is exposed to in the womb. The shorter the index finger relative to the ring finger, the higher the amount of prenatal testosterone, and--as Hurd and Bailey have now shown--the more likely he will be physically aggressive throughout his life.

"More than anything, I think the findings reinforce and underline that a large part of our personalities and our traits are determined while we're still in the womb," said Hurd.

Hurd and Bailey's research, published this March in Biological Psychology, was determined from surveys and hand measurements of 300 U of A undergraduates.

In their study, they found there were no correlations between finger lengths and people who are prone to exhibit verbally aggressive, angry, or hostile behaviors, but there was to physically aggressive behavior.

Hurd is conducting ongoing research in this area, including a study that involves measuring hockey players' finger lengths and cross referencing the results with each player's penalty minutes. He also has a similar study showing that men with more feminine finger ratios are more prone to depression; a paper on this will be published later this year in Personality and Individual Differences.

"Finger lengths explain about five per cent of the variation in these personality measures, so research like this won't allow you to draw conclusions about specific people. For example, you wouldn't want to screen people for certain jobs based on their finger lengths," Hurd said. "But finger length can you tell you a little bit about where personality comes from, and that's what we are continuing to explore."

Every year that goes by more of human behavior is going to be pinned down to biological causes. Mechanisms of operation of each cause will be worked out down at the molecular level. This is going to be quite the challenge to mainstream Western liberal thought and to at least some schools of Christian theology (though perhaps not to those who believe in predestination) as the ghost is shown to have progressively less operating leeway within the machine.

Are you a male that is worried you have too much testosterone that is making you too aggressive? Get married and have kids and your blood testosterone will go down. On the other hand, if you want that aggressive edge and really good visual-spatial abilities then either eschew marriage or wear a testosterone patch. Not that I'm advocating hormone dosing...

Share |      Randall Parker, 2005 March 04 08:59 AM  Brain Violence


Comments
Michael Vassar said at March 4, 2005 1:30 PM:

Visuo-spacial abilities are clearly greater among men than among women, but is there strong evidence at this time that among men there is a positive correlation between visuo-spacial abilities and testosterone?

Randall Parker said at March 4, 2005 2:03 PM:

Michael,

I recently came across a report about the long term cognitive effects of testosterone suupression in prostate cancer patients.
Decreased visuo-spatial ability combined with a small increase in verbal ability as a result of testoterone suppression.

Eeva Salminen, M.D. and colleagues at Turku University Hospital in Turku, Finland investigated the relationship between serum estradiol and cognitive functioning in men with prostate cancer treated with androgen-deprivation therapy.

They found cognitive performance in several specific areas were associated with declines in estradiol brought on by the therapy. Six months into treatment, men were found to have temporary, marginal but significant declines in visual memory of figures and recognition speed of numbers. Tests at twelve months showed marginal improvement in verbal fluency associated with estradiol declines. No other cognitive areas were affected. The degree of cognitive change was related to the magnitude of estradiol declines.

triticale said at March 4, 2005 2:28 PM:

But the little finger didn't factor into this, so there is no link to the symbolism of chopping off the last joint, as practiced by the Yakuza.

Randall Parker said at March 4, 2005 2:32 PM:

Michael,

I also vaguely recall studies of fetal womb exposure to testosterone and visuo-spatial abilities and masculine characteristics. I really need to go digging more on what is known about hormones and cognitive development.

SuedeShoes said at March 4, 2005 3:28 PM:

This finding makes sense, but there was a blog entry on Marginal Revolution that discussed research that seems in conflict with the finding. http://www.typepad.com/t/trackback/1308656

Why do men in the sciences tend to have finger ratios that are more common in women? Maybe this is only true for academic in the sciences, or maybe for academics in the pure sciences (although I would think that visuo-spatial abilities would be important in these areas as well). It would be interesting to see what the distribution of finger ratios of engineering professors and males employed in science-related careers in industry. It could be that men who have scientific talents and more masculine finger ratios tend to go into private industry, where their competitive inclinations would serve them better. Then again, if more masculine finger ratios are associated with better visuo-spatial abilities, I would still think that enough of them would end up in academia in the sciences for the finger ratios to be distributed in a shape that is more common for men.

Thoughts?

--SuedeShoes

SuedeShoes said at March 4, 2005 3:37 PM:

My apologies, the link I listed above is incorrect. Here is the correct link:

Are the economic girlie men in the hard sciences?

--SuedeShoes

bb said at March 4, 2005 5:41 PM:

IIRC, the "ideal" level of testosterone for math and science ability is well above the mean (in fact well outside the overall distribution) for women, but is somewhat below the male mean. So yes, at least in my understanding, math and science oriented males have lower testosterone levels (on average) than the general male population. This would square with the relative "girlie-ness" of the finger ratios of males in the sciences.

Theresa said at March 5, 2005 10:21 AM:

A bit of related research: "Sex and ethnic differences in 2nd to 4th digit ratio of children." >>

"The ratio between the length of the 2nd or index finger and the 4th or ring finger (2D:4D) differs between the sexes, such that males have lower 2D:4D than females, and shows considerable ethnic differences, with low values found in Black populations. It has been suggested that the sex difference in 2D:4D arises early in development and that finger ratio is a correlate of prenatal testosterone and oestrogen....

"There were 798 children in the total sample (90 Berbers, 438 Uygurs, 118 Han, and 152 Jamaicans). The 2D:4D ratio was lower in males than in females and this was significant for the overall sample and for the Uygur, Han and Jamaican samples. There were significant ethnic differences in 2D:4D. The Oriental Han had the highest mean 2D:4D, followed by the Caucasian Berbers and Uygurs, with the lowest mean ratios found in the Afro-Caribbean Jamaicans."

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15500996

Randall Parker said at March 5, 2005 11:07 AM:

Theresa,

Thanks for that abstract. Highly excellent. The results are consistent with the view that blacks are, on average, more masculine than whites who are in turn more masculine than East Asians.

The weird thing to me is that Moroccan Berbers are not between the blacks to their south and whites to their north in terms of finger ratio. What's with that?

Patrick said at March 8, 2005 11:37 PM:

Does this have any relation to the way that long ring fingers were supposed to be a sure sign of being a werewolf?

Patrick said at March 10, 2005 3:17 PM:

Every year that goes by more of human behavior is going to be pinned down to biological causes.

Biology may be responsible for inclinations toward behavior, but we say that it is responsible for the behavior? We are more than just biological machines.

Randall Parker said at March 11, 2005 9:11 AM:

Patrick,

So then absolute compulsions to commit an act decrease our free will but extremely strong drives do not?

Do you think, then, that all the people who are obese are to blame for their obesity? Even if their mind is constantly thinking about food when they don't want to be is it their fault that they eat too much?

victor smyk said at May 22, 2005 2:59 AM:


i was a standout athlete and love working with my hands. my index is short compared to my ring finger. as a high level baseball coach i have noticed that most good athletes have the same ratio. i believe this allows for greater manipulation of the hand and its various pressure points.

Mike Bracken said at July 17, 2005 2:20 PM:

My ring finger is 11mm longer than my index.

I'm extremely competitive, want to be the best in the world at everything, get highly frustrated when I fail, I want to know everything, want to own and control everything, hate having a boss, want to have all the gorgeous girls, I want to look the coolest, I want to drive the fastest car and have the biggest house. I love driving fast, love scoring goals in football, love showing off, love hitting a golf ball a long way, hate idle chit chat talking s***e, I want major amounts of fun, the idea of having kids bores me, following the same routine every day bores the hell out of me. I have had lots of arguments, people blocking my way, I get frustrated that I don't know where I'm headed, studying is boring and too slow.

I have a constant battle every day trying to act like I don't give a s**t, but unfortunately I do.

Can all this be explained by what goes on in the womb?

Alan said at August 26, 2005 7:05 AM:

Hang on a minute.
Your finger length is set at the time you are born, and is a result of the testosterone you are exposed to in the womb. However presumably your physical aggressiveness is related to the amount of testosterone in your blood during adulthood. These could be but are not necessarily highly related. Is it not possibe that your genetics or those of your mother can cause an elevated level of testosterone during pregnancy with its resultant impacts, that does NOT continue later through childhood and later life.

So if you were exposed to high levels of testosterone in the womb which dropped off in life, you would end up with a long ring finger, a highly developed right brain side, but would not be physically agressive in adulthood.

And isnt that what other research shows, that testosterone levels do indeed drop off during life.
That might be an explanation for the very weak 5% correlation shown in some literature.

Cheers..Alan

Alex R said at January 16, 2006 1:00 PM:

MIKE said:

"I'm extremely competitive, want to be the best in the world at everything, get highly frustrated when I fail, I want to know everything, want to own and control everything, hate having a boss, want to have all the gorgeous girls, I want to look the coolest, I want to drive the fastest car and have the biggest house. I love driving fast, love scoring goals in football, love showing off, love hitting a golf ball a long way, hate idle chit chat talking s***e, I want major amounts of fun, the idea of having kids bores me, following the same routine every day bores the hell out of me. I have had lots of arguments, people blocking my way, I get frustrated that I don't know where I'm headed, studying is boring and too slow.

I have a constant battle every day trying to act like I don't give a s**t, but unfortunately I do."

Well, that is EXACTLY my type of personality, but in contrast my ring finger looks quite a bit shorter than my index finger.

k said at April 5, 2008 10:23 PM:

I've got pretty much the same type of personality as Mike...

...I'm a woman.

Can you explain that??

k said at April 5, 2008 10:43 PM:

I retract my comment on the grounds that I study my ass off. In fact I can't stop studying. When I'm not studying because I have to, I study because I'm trying to figure out something that I just want to know. I never, ever sleep, unless my body simply gets ill from fatigue. Most of the other things are the same. I'm not so aggressive now that I'm older, but I was very aggressive in my early 20s and teens. I still drive way too fast, I still would rather take a bullet than fail at anything, and there is no other place but "at the top of my game." And I don't do any drugs, and I don't drink, if that helps. And my ring finger is just a bit shorter than my index finger on both hands. And I'm a girl...

In fact, I'm a Philosopher, so I must say the tidbits on the mind-body problem left me a bit bewildered... If I felt like it, I believe I could challenge you, though your point is valid enough. And as for the free-will issue: from your biological standpoint, after you had just stated that "the ghost is shown to have progressively less operating leeway within the machine," I don't know why you used an argument that appealed to that "ghost" to defend "free-will." Why, from that biological view, did you not say that there is no free will?

Thank you for entertaining the "Devil's Advocate" in me.. I know I've stumbled across this very late.

victoria.taus@gmail.com said at January 12, 2009 9:21 PM:

Hmm I am a girl as well but my ring finger is MUCH longer than my index finger (a strong male pattern)... A very strange find since I don't consider myself that competitive or masculine acting. Then again I do have some issues with anger, most people don't even know this about me cause I'm such a sweet person day to day but I can truly snap when provoked and then it comes out mostly physically (breaking stuff, smashing my fists on walls, etc), I can't really lash out verbally when I'm THAT worked up, it doesn't help! lol And I heard that is supposed to be "male" type of aggression. I'm also very possessive with my partner and like what are considered feminine facial features on men (small noses, big eyes, roundish paedomorphic faces, etc), not sure if that means anything though. Other than that I'm a normal girl, quite feminine looking too :)

victoria.taus@gmail.com said at January 12, 2009 9:37 PM:

Oh yeah I'm really good in math but at the same time I HATE studying LOL But as far as kids and getting married I would like that and I'm very sensitive to others' feelings :)

footballplaya said at May 7, 2009 2:26 PM:

My ring finger is about 0.9 of my index (index being 1.0) so my ring finger noticeably smaller. Im VERY competitive in sports, but definatly not an angry person, always take in to account others feelings (even though i dont act like it). Like the above post, i love the thought of getting married and having kids some day (after my sports career if all goes well....). Also, im good at math, HATE studying, hate hate hate. Ive got a great body with no work, six pack after eating mcdonalds and sitting on my couch for a year not doing anything (heard that had something to do with the ring finger being shorter?). Also im very unmotivated to do anything im not interested in, however, if im interested in something and truely enjoy it, ill do whatever it takes to be the best or achieve whatever needs to be done, hard work isnt a problem.

Jan lin said at October 11, 2009 6:37 AM:

So...What if your index and ring fingers look the same size?

When I look at mine, it is extremely difficult for me to tell which is truly longer (but most times the ring finger appears a teensy bit longer but not noticably). I'm a girl who barley reaches 5 ft, I like writing, am very creative, but when I get angry I find myself entertaining some violent thoughts though I never act on them.

Suggestions?

T.S. said at December 22, 2009 7:35 PM:

I am a girl and my ring finger is much longer than my index finger. I look very feminine, but as stated above I am slow to anger, however when I do act on it it is much about throwing things or breaking something and it's pretty much uncontrollable, and no talking. Normally, I very rarely raise my voice, put people down, and I am very sensitive to other's feelings. I lash out about twice a year, and that usually tides me over. As above (again) round face, very big eyes, and normal size nose. And I am very possession, but not in a psycho way. Although my family says that my personality and physical traits are consistent with being a Taurus.... Anyhow, my husband and I were watching Manswers, and the finger thing came up...Freaked me out about my fingers and here I am. Wondering if it's normal for a girl, a non mistakable real girl, to have masculine fingers. Oh, and I'm petite built. 5'4/120lbs, and loves art, reading, writing, hiking, canoeing, fishing, and just about anything outdoorsy.

Damian said at April 9, 2010 6:28 AM:

@Randall Parker

I have naturally (possibly too high) testosterone for a fifteen year old (I had a very early puberty and developed well beyond the normality for my age). I have exhibited aggressive behaviours in the past, both verbal and physical. My index finger is much shorter than my ring finger. I also have above average verbal ability. Perhaps there is less correlation between verbal ability and testosterone levels than you are suggesting?

gejala stroke said at August 29, 2016 7:31 PM:

Gejala Storoke ringan dan cara menanganinya secara alami harus diperhatikan selalu secara serius , karena saat ini kasus penyakit stroke banyak terjadi dikalangan masyarakat dari mulai stroke ringan hingga stroke berat.
Meski yang dialami masih gejala stroke ringan tapi penanganannya harus secara tepat karena bisa berakibat fatal jika tidak diatasi dengan obat stroke yang ampuh. Sebelum kita membahas lebih lanjut mengenai pengobatan stroke, maka kita harus mempelajari dulu tentang apa itu penyakit stroke, penyebab penyakit stroke, gejala stroke,
serta bahaya apa yang bisa muncul? Setelah itu baru kita bisa memilih obat stroke yang tepat yang akan kita gunakan.

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