2009 December 29 Tuesday
Facial Proportions Key For Facial Beauty

Ideal beauty down to facial proportions.

TORONTO, ON – Beauty is not only in the eye of the beholder but also in the relationship of the eyes and mouth of the beholden. The distance between a woman's eyes and the distance between her eyes and her mouth are key factors in determining how attractive she is to others, according to new psychology research from the University of California, San Diego and the University of Toronto.

Pamela Pallett and Stephen Link of UC San Diego and Kang Lee of the University of Toronto tested the existence of an ideal facial feature arrangement. They successfully identified the optimal relation between the eyes, the mouth and the edge of the face for individual beauty.

In four separate experiments, the researchers asked university students to make paired comparisons of attractiveness between female faces with identical facial features but different eye-mouth distances and different distances between the eyes.

They discovered two "golden ratios," one for length and one for width. Female faces were judged more attractive when the vertical distance between their eyes and the mouth was approximately 36 percent of the face's length, and the horizontal distance between their eyes was approximately 46 percent of the face's width.

You can see from this one of the limits to beauty enhancement from plastic surgery today. Even if we had stem cell therapies, gene therapies, interference RNA therapies, and other means to totally rejuvenate the face changing facial proportions is another level of problem that involves cutting into bones to shorten and extend bone lengths.

Anyone still alive 30 or so years from now with the money to afford it will be able to go in for a full facial rejuvenation. Grow new teeth. Gradually replace stem cells to generate new skin and collagen layers. New stem cells for the bones will help refill the bones. But achieving absolute beauty will require much more radical changes.

Regardless of how difficult facial reshaping remains in the future ideal beauty will become commonplace. For new babies ideal beauty will increase due to embryo selection but will really take off once embryo genetic engineering becomes possible. Enabled by the massive and continuing declines in the cost of DNA sequencing some scientists will find genetic variants that create differences in facial proportions. Then the problem becomes how to get the right genetic variants into an embryo. Once we can put beauty genes into embryos we are going to have one sexy world.

By Randall Parker    2009 December 29 11:06 AM   Entry Permalink | Comments (9)
2009 November 22 Sunday
Mixed Genetic Ancestry And Mating

Mexicans and Puerto Ricans of mixed races tend to marry those of similar racial mix ratios.

A team led by Neil Risch and Esteban González Burchard of the University of California, San Francisco, took DNA samples from married couples in Mexican and Puerto Rican populations, examining around 100 genetic markers from across the genome. From these markers, the researchers were able to discern the proportions of Native American, European and African ancestry for each person.

They found that within Mexican populations, people tended to pick partners with similar proportions of Native American and European ancestry, while in Puerto Rican populations couples had paired up based on their shared balance of European and African ancestry.

Some easily measured physical characteristics do not appear to explain all of the mate selection results. How about sense of smell?

Quite how our DNA influences our desires remains mysterious. Risch and his colleagues did not find that geography or socio-economic status could explain the ancestral influence on romance, and factors like hair, eye and skin colour individually only had a minor role. According to Burchard, "Certainly physical characteristics, such as skin pigment, hair texture, eye color, and other physical features are correlated with ancestry and are likely to be factors in mate selection. However, the spouse correlation for these traits and the correlation of these traits with ancestry were actually below what would be required to fully explain the phenomenon".

Socioeconomic profile did not explain the mating patterns as well as genetic markers. I'd like to know what causes these results. I can imagine a number of genetic mechanisms by which mating preferences would track with genetic markers. Among the potential explanations that come to mind:

  • Genetic sequences might code for preferences for facial shapes, skin color, and other visible attributes.
  • Parental facial features and other physical features get imprinted on a baby and that causes the baby to prefer others who have similar features. So the brain doesn't directly code for preferences but (rather like Konrad Lorenz's geese) we are sensitive toward imprinting at some stage of development.
  • Genetic sequences might code for personality and cognitive attributes that track with the genetic markers. People might be attracted to similar personalities.
  • Settling. Preferences might not differ but competition results in like marrying like.

I would like to see studies done that use a combination of genetic marker comparison and pictures of people to see to what extent physical attraction tracks with similarity of genetic markers. To distinguish between the first two explanations above children of transracial adoptions could be included in the study.

Has much imprinting research been done about human attraction across races?

By Randall Parker    2009 November 22 06:54 PM   Entry Permalink | Comments (1)
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