Not really. Say I'm shortsighted, and still a potential mating partner due to a variety of other traits (being a billionaire, or looking suspiciously similar to Ryan Gosling). In that case, I would be able to transmit my genes to my eventual offspring.

The case with gay genes is different. Regardless of any other trait, I'm genetically prone to not have any offspring. Thus, eventually my genes would be less and less common.

Incorrect.

All that's required for a trait to persist is that it benefits the pool.

If the pool benefits from have 1% of members being blind, then so they shall be.

We don't have to understand the benefit for it to exist either.

You're presenting group selection, natural selection at the level of the group, as an established theory. But that's not the case.

From Wikipedia, quoting evolutionary biologist Jerry Coyne: "Group selection isn't widely accepted by evolutionists for several reasons."

https://en.m.wikipedia.org/wiki/Group_selection

>All that's required for a trait to persist is that it benefits the pool.

Or that it's less bad than whatever beneficial trait it's coupled to.

Humans consume a lot of water in order to shed heat. Our backs are pretty f-d up. Our brains waste a lot of energy and require a very long childhood. But on the flip side we're basically terminator compared to the African fauna our primitive ancestors hunted.

I'm assuming you're right since I don't know much about this subject, but how does that mechanically work? How does a trait, even if it is beneficial to the community, get passed down if the members that have that trait don't have offspring?

It could be recessive, so it only gets expressed if an individual has two copies of the recessive gene.

"If there was a genetic cause for shortsightedness, why is it still around?" - because myopia doesn't significantly affect your chances to produce offsprings.

It seems reasonable that being gay does significantly reduce your ability to have children; therefore it is reasonable to expect that if it was an inheritable trait it would have been selected against.

Everyone keeps saying that, but it's simply not true.

We have understood how this is not true for decades or even hundreds of years, and it's not even some impossible concept to grasp.

All that's required for a trait to persist, is for it to benefit the pool, not the individual.

The only way the seemingly obvious but incorrect idea you descibed applies is, a trait which is good for the group at the expense of the individual, if it's 100% effective like sterility unlike say alarm-calling which merely carries a risk for the individual, is that such a trait can never grow to where all members exhibit it.

But it can absolutely be strongly selected for maintaining whatever the optimal percentage is. IE, if it benefits the pool for 10% of members to be sterile, then the percentage of sterile members will not decrease through the mechanism you and so many imagine, but will stay at 10% for as long as the benefit exists.

And everybody keeps saying THAT. The problem is, that's a secondary effect. A secondary effect is going to have to be pretty strong to counter an obviously anti-competitive primary effect. You can construct scenarios, but I haven't seen any that seem particularly compelling. It seems to me that the default position of "it's not genetic" is much better supported by the data.

> All that's required for a trait to persist, is for it to benefit the pool, not the individual.

This is a well debunked belief. Genes are selfish, and they only reproduce to the benefit of the gene.

Group selection does not occur.

An example is evolutionary stable strategies, where cheaters persist in the population, even though the pool would be better off if all individuals in a pool were selfishly altruistic towards pool members.

A much better example of counter-intuitive evolution, one that's literally textbook, is sickle-cell anaemia. It's a genetic disease (bad) that offers protection against malaria (good), so it's more common in areas where malaria is a fatal problem for significant numbers of people. This illustrates the principle that genes do more than one thing, and can be simultaneously adaptive and maladaptive at the same time. As a hypothetical example, maybe the same genes that make a man fractionally more likely to be gay could protect his sister from ovarian cancer or stop him going bald.