Is there any evolutionary advantages to blushing?

It seems to me like blushing would be something that would be selected against by evolution. Visibly showing embarrassment seems like a sign of weakness.

Since blushing doesn’t impact our ability to reproduce I don’t see how it would have much of an effect one way or the other with regard to evolution.

I dunno. I’ve seen some girls blush and it made me want to do my part to continue the species.

Maybe weakness in some situations, but in others it seems to be sexual signaling. It is a pet theory of cognitive scientist Mark Changizi that trichromatic color vision is designed to recognize changes in facial skin color, and not to recognize ripe fruit as is otherwise believed.

What makes you think showing embarrassment (or weakness) is a disadvantage? Evolution isn’t just about fighting and killing. Perhaps displaying a hard-to-fake emotional cue is useful. Perhaps it encourages bonding. I don’t know, but since we are a social species, I expect signaling to be important.

Well, ‘blushing’ is often also a sign of anger or arousal - lots of animals have some sort of physical display to ward off confrontation or attract a sexual partner. Both are kind of handy for both social and personal reasons.

But, please, remember two things:

Not every phenotype trait is one gene, one dominant allele and one recessive, with a direct correlation to reproduction. Contrary to the highly simplified version of evolution we get in schools, there is more to maintaining a species than popping out lots of babies.

Not every phenotypic trait is a primary expression of a gene.

Blushing could be the result of lowering blood pressure when under stress and very low skin pigment necessary for manufacturing vitamin D with low levels of sunlight, for example.

I think Gould would call that a Spandrel. At times of arousal one physiological response is flushing if that animal has a semi-transparent skin tone we can call it blushing; but that’s just my opinion…

Blushing is a form of communication, and communication in general is a valuable trait for a social species like ourselves.

I blushed today when an unattractive coworker *almost *complimented me. I hate it and I’d like to trade it in for something cooler. Maybe the ability to raise one eyebrow.

Seems very unlikely that it is generally adaptive among humans, since it only is obvious in Caucasians. Facial blood dilation I assume occurs in dark skinned populations as well, but will be mostly invisible. So it’s unlikely that it evolved for the purpose of communicating emotions.

My guess is that it is a side effect of the fight-or-flight instinct, since one normally blushes when embarassed, aroused, angry, etc. Your body opens the flood valves in your blood vessels to get the maximum blood flow out to facilitate whatever course of action you decided to take when the time comes (run away, rip your clothes off, tackle the other person, or any combination as appropriate). The fact that everybody can see it is just a quirk of our thin fur (and, depending on various factors, your skin tone). That said, the fact that it might not have been “designed” for signaling doesn’t mean it doesn’t mean it can’t be used that way.

My qualifications to make this statement are that I flunked out of college as a lib arts major and I work in customer service. :smiley:

Really? I’m pretty sure I’ve seen some black people blush before. It looks a little different and isn’t nearly as obvious, but I’m pretty sure I’ve seen it. Just like I’m pretty sure I’ve seen black people tan, but all it looks like is that their skin gets darker.

Also, do we have any proof that really dark skin came first? It would seem odd that are skin would have been so dark when we had fur. I know every dark furred dog and cat I’ve had has lighter skin than their fur would indicate.

I tend to think that blushing is relatively insignificant and would not be naturally eliminated from our species, so that is the only reason we have it. Hey, perhaps a few people willing to be embarrassed or shameful isn’t bad for the species.

Chimpanzees have light skin under dark hair.

Do you mean African Americans? Because most African Americans are paler-skinned than most sub-Saharan African.

In any case the fact that it isn’t obvious indicates that it isn’t a particularly useful communication signal for a majority of human populations.

While it’s unknown at what point human ancestors evolved dark skin, since modern humans with relatively hairless skin evidently evolved in open savannas of Africa, its very likely that modern populations are descended from ancestors with dark skin. (One of the oldest lineages, the Khoi-san, have skin lighter than that of most other sub-Saharan populations but still much darker than Caucasians. Other old lineages, like Pygmies, Negritos, Andamanese, Melanesians, and Australian Aborigines all have very dark skin.)