Challenging Mainstream Thought About Beauty’s Big Hand in Evolution

I think about this when I see wild turkeys in the area during early spring. The males fan their tail feathers and display their bright colors.

From a mate selection standpoint, the healthy ones have a full set of feathers that are brightly colored. Older and less healthy ones are missing feathers, or the colors are dull.

I think what we see in nature is a situation where what began as a selectable trait sometimes carries on evolving, i.e., becoming ever more colorful or pronounced, simply because it was easier to notice and measure, and at the same time, did not become a negative to survivability. If the female is attracted to the intense colors of males, and two perfectly healthy males are standing next to each other, but one is a little more saturated in color, she may select him solely for that reason.

I like how in one paragraph, Prum is espousing an adaptive basis for homosexuality and in the very next one talks about how maybe not everything is selected on. Maybe he has good reasons for thinking that homosexuality is adaptive that have been covered up with the author's "For a full account, you need to read the book", but given how bogus the overwhelmingly vast majority of evopsych is, I'd kind of doubt it.

One thing my wife learned and told me (she’s a biologist so actual science vs my CS background :) ) was actually fairly interesting and is apparently widely considered true among evolutionary biologists:

If you are male of you are likely to carry genes from your father that produce a similar appearance to him. You will /also/ carry genes from your mother that prefer your appearance (your mother choose your father based on appearance). If you are female offspring you will inherit those same genes but won’t express the male appearance ones. You will still pass them on to your offspring.

So you end up with a cycle where offspring look like/prefer the appearance of their parents, and will forward variants of those genes on to their own offspring.

This is effectively a feedback loop that will carry on until limited by some other factor - eg if your tail is too long you may end up dying too quickly to mate, if it gets too small you may not be able to fly at all (some of the old pigeon breeds studied by Darwin are hilarious).

This means that the selection for beauty does not necessarily mean that there’s an awareness of fitness being proxied by beauty.

Once she had labouriously explained it to me it seemed really obvious.

* note I used male/female etc for ease of typing - there are a few species where the role of being attractive is reversed

Enough just-so stories! I have been mostly saying this part for the last several years:

But one particular aspect of his argument is his distress at the idea that almost all evolutionary change is assumed to be adaptive, contributing to fitness. In other words, if a fish is blue, it must be blue for a reason. The color must help it escape predators or sneak up on prey, or be otherwise useful in some way. Beauty, therefore, must be adaptive, or a sign of underlying qualities that are adaptive. Pick a behavior or an ornament or a physical trait, and it is useful until proven otherwise.

That’s backward, says Dr. Prum. Take beauty. Since animals have aesthetic preferences and make choices, beauty will inevitably appear. “Beauty happens,” as he puts it, and it should be taken as nonadaptive until proven otherwise.