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Sunday, August 06, 2006

The latest from evolutionary psychology: Colour vision evolved to detect blushing, NOT snakes

Recently, we learned that colour, detail, movement, and 3-D vision evolved in order to help us avoid snakes (as opposed to all the other dangers, nuisances, and hassles that flesh is heir to). It now turns out that colour vision evolved to help us detect others blushing.

... a team of California Institute of Technology researchers has published a paper suggesting that we primates evolved our particular brand of color vision so that we could subtly discriminate slight changes in skin tone due to blushing and blanching. The work may answer a long-standing question about why trichromat vision (that is, color via three cone receptors) evolved in the first place in primates.

"For a hundred years, we've thought that color vision was for finding the right fruit to eat when it was ripe," says Mark Changizi, a theoretical neurobiologist and postdoctoral researcher at Caltech. "But if you look at the variety of diets of all the primates having trichromat vision, the evidence is not overwhelming."


So let me get this straight: For one hundred years, we were expected to absolutely believe (in publicly funded systems) that the evidence that colour vision evolved to help us find the right fruit to eat was overwhelming - but it now turns out it wasn't. Now we are informed of a "speculation" that colour vision evolved to detect blushing.

Of course, for blushing detection to be a really important factor in the development of the modern human, we must assume that original humans were only lightly pigmented, so that blushing was easy to detect. Do we know this? How?

(In that case, we must also assume that other methods of detection of lying and cheating were not readily available. Why not?)

I have lived all my life among very light-skinned people, and I cannot clearly recall a single instance where blushing was used to determine a person's intentions. For one thing, blushing can be brought on by a number of factors - heavy labour in hot weather, overheated rooms, vigorous exercise, emotional stress, menopause, pregnancy, disease, heavy drinking, surface skin freezing in very cold weather, to name just a few. Awareness of these possible causes of blushing does not require a high level of education, just observation of the people in one's own environment - if one is usually surrounded by very light-skinned people.

No discerning person would take seriously an explanation of truthfulness/intentions based only on blushing. It's a good thing that all this evo psycho is only a "speculation." That's okay with me, really, except, how does it come to be classified as science?
If you like this blog, check out my book on the intelligent design controversy, By Design or by Chance?. You can read excerpts as well.

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