[clscott]

A trait doesn’t have to be advantageous to persist just non-detrimental.

[rtkwe]

Yeah that's (to me) a more accurate framing, also evolution is bad at revisions so even if there are minor disadvantages to a setup so long as it's not affecting your ability to have and raise kids it's basically completely absent as far as evolution is concerned. For example there are some wild inefficiencies in body layout left over from fish body patterns where the nerve from the brain to the voice box wraps down around your aortic arch because the relative position of the throat, brain, and heart were very different in fish so the path it took then was more direct. It happens in humans and most hilariously in giraffes where it goes all the day down their enormous necks.

[samus]

That remains as it is because it's very difficult to evolve away from. Evolution is very good at chasing and sticking around local optima. Big changes are risky.

[cyanydeez]

If Giraffe could speak, would they then be perceptibly delayed compared to humans?

[EA-3167]

They can be detrimental too, especially if they're linked to beneficial traits. The test is ultimately whether or not the harm done is sufficiently disadvantageous that it interferes with reproductive fitness. Baldness is arguably detrimental, but it's linked to a bunch of recessive genes that function in other ways, and it doesn't impact us until we're likely to have already reproduced.

That's a simplification, but you get the idea.

[TheGRS]

Peacocks with their giant tail feathers are my favorite example. They make flying really difficult, but they make attracting female mates much easier. The reproduction need wins.

[frisbm]

and not even that, I'd narrow it further to not detrimental before and during the prime reproductive periods of a species. After that period, detrimental traits are totally fair game and more dependent on technology, culture, and family care dynamics. Heart disease later in life caused by genetic predisposition to high cholesterol isn't something people generally select for or against in a partner, but its effects happen later in life well after people have children so it passes on.

[toasterlovin]

> Heart disease later in life caused by genetic predisposition to high cholesterol isn't something people generally select for or against in a partner, but its effects happen later in life well after people have children so it passes on.

That depends. It can still affect genetic fitness if it affects an individual's ability to confer benefits on their descendants. Of note: most of the most wealthy and influential people in our society are beyond their reproductive years (not technically true for men, but mostly true in practice).

[samus]

Parents must also be alive for long enough to care for their children until they can sustain themselves.

[CGMthrowaway]

It is detrimental though. It is socially impolite to yawn in public.

Edit: why am I being downvoted for this?

[bc569a80a344f9c]

Even if yawning in public affected sexual fitness: how long has it been socially impolite to yawn in public? Evolution takes a rather long time in species with long reproductive cycles. Almost all mammals yawn, it would take significant genetic changes to breed that out of us. That doesn't happen overnight.

[JoshTriplett]

> It is socially impolite to yawn in public.

No, it isn't. It can be socially impolite to yawn unexcused, when someone is talking to you, as it has come to be interpreted as boredom rather than tiredness or similar. But it isn't inherently impolite to, for instance, yawn when walking down the street, or in a setting where someone isn't talking to you.

[victorbjorklund]

I wonder if that has always been the case or if it is a modern thing (modern in the sense of our evolutionary history).

[frisbm]

is it so detrimental that it leads to a person never finding a mate and reproducing? Maybe for a totally extreme outlier, but probably not

[avazhi]

> why am I being downvoted for this?

Because you don’t know what detrimental means in this context and clearly don’t understand evolutionary timescales?