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Comment by crazygringo | Hacker News Reader

Exactly -- if the rate of change is as high as they state -- from 10% to 30% of people in a little over a century -- it seems it would be essentially impossible for it to be the result of natural selection or genetic change.

As you say, the obvious explanation is hormonal/environmental factors.

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What do you mean by environmental factors? The environment drives evolution, so changes in the environment would change who survives, which would lead to evolution. If it is an environmental factor that led to selection of individuals having this vein being more likely to propagate, that would still be evolution. This also some very simple scenarios that could lead to such a pressure, like the artery having some minor benefit in reproduction, but a disease we eradicated would disproportionately kill people with the artery.

They mean within a lifespan factors, like pollution, diet, lifestyle, etc.

Evolution is of a change in the genes. Environmental factors can influence the expression of a gene (think Testosterone or Estrogen) without a change of genetics.

The change in expression over time and participant count the study highlights is not compatible with a natural selection driven evolution.

But this would still present an environmental pressure, which would drive evolutionary change. Maybe not this specific gene, but if the environment is driving changes to our anatomy, it will drive changes in to reproductive fit. Maybe not this specific artery, but some other anatomical change.

Epigenetics is the missing term here.

Yes - in order to have a change be that fast it would have to be something that makes those people dramatically better at surviving, like X-men type mutations, or reproducing. I don't think the change of this blood vessel is really turning the tables between survival and death, or making these people that much more successful at reproducing. But with the prevalence of online dating these days, maybe it is a big help by allow people to navigate faster? /s

A mutation will also stick around if it doesn't prevent the person from reproducing.

That can still be considered evolution even if it doesn't provide an obvious benefit.

Just to clarify, the parent comment was stating that for a change (read: evolution) to be that _fast_, it would have to help either survivability or reproduction. In other words, increasing survivability or reproduction speeds up a mutation's proliferation throughout the species.

> makes those people dramatically better at surviving

Better at reproducing. Death after reproduction has much less effect on evolution than death before reproduction.

It is unfortunate that it is so often misstated (I am guessing you already know the difference, but I want to clarify it for those who are not so aware). As an aside, I think the article is complete and utter bollocks.

I am guessing this is misstated because so often lack of survival is the reason there is less reproduction. But yes, it comes down to who passes their genetic material to the most offspring.

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