Peter Frost's anthropology blog, with special reference to sexual selection and the evolution of skin, hair, and eye pigmentation

Saturday, June 11, 2011

Hue and luminosity of human skin: a visual cue?

The inferotemporal cortex is involved in both face perception and color perception. It may be in this region that the brain processes visual data on the hue and luminosity of human skin.

If you are a member of the International Society for Human Ethology, you can read my latest article: Hue and luminosity of human skin: a visual cue for gender recognition and other mental tasks.

Abstract

Face recognition takes place within a distinct heritable module of the brain and includes the ability to distinguish between male and female human faces. To identify gender, this module targets a number of sexually dimorphic features, particularly the hue and luminosity of facial skin. Men look browner and ruddier in hue because melanin and blood are more present in their skin’s outer tissues. Women have a higher luminous contrast between their facial skin and their lips and eyes. Hue seems to provide a “fast channel” for gender recognition. If the observer is too far away or the lighting too dim, the brain switches to the “slow channel” and targets luminosity. In addition to assisting gender recognition, the skin’s hue and luminosity may also alter the observer’s mental state in a number of areas, ranging from sexual attraction to emotional distancing.

6 comments:

"Men look browner and ruddier in hue because melanin and blood are more present in their skin’s outer tissues. Women have a higher luminous contrast between their facial skin and their lips and eyes."

I'm one of those people who others have insisted has uncanny gaydar. Even in simply looking at the head-shot only photos of young sons colleagues would pull out of wallets to share over my 35 year career, I'd later say to good friends, "The kid looks gay." Years later, we'd find out I had been right.

"How did you know?" they'd demand. I had given thought to this question years before. I explained it was in the lips, both of these boys and of grown men. Sometimes the lips were a bit fuller and smoother, but I insisted that the tell-tale sign was something in their color. Pressed to think about color, I concluded that they appeared more full of color or darker than the lips of non-gay boy or man. However, the word "color" didn't satisfy me because I couldn't actually say that their lips were pinker or redder, say, than those of other boys.

I realized that my perception of their having more "color" might have been a function of contrast with their own skin color. Straight men's lips seemed to fade into the rest of their face whereas gay men's lips stood out a bit more, like those of lipstick-less girls or women.

I realize I am offering up my testimony to ridicule and I've no scientific proof of my assessment skills, but I offer it for what it's worth.

Perhaps if there is indeed a hormonal effect that renders the gay man different from the straight, maybe it is reflected in subtle facial characteristics that a few of us pick up on.

Interesting. There is evidence that a gay sexual orientation is set very early in life, either prenatally or not long after birth. The pigmentary characteristics of male and female skin seem to be likewise set prenatally (as indicated by digit studies).

Tod,

Gender recognition seems to focus on the difference in pigmentation between the lips and the surrounding skin (and also the eyes and the surrounding skin). This might have generated a selection pressure to reduce the ruddiness of female skin near the lips and less so on the cheeks.

This difference in ruddiness between the cheeks and the rest of the female face could, in turn, have become a target of sexual selection.

The idea of using a fast, simple test that works for a lot of cases first and then a more developed but slower test only for those cases that aren't resolved by the first test is something thst is used in software all the time.

That doesn't prove anything other than that a dual mechanism can be more efficient but i thought i'd mention it.

Welcome to my blog! For the most part, this page will be an extension of my website, with comments relating to my research. But it will also branch out into more general discussions of human evolution.