[leblancfg]

I read the following:

> The focus of this study was not to analyse the prevalence of the occurrence of the median artery in relation to ethnicity, geographic origin or variations by sex, but to identify the global trends in its occurrence.

and thought "well that explains the astronomical precision of the p-value, they didn't take ethnicity into account!". You would expect to see variation prevalence vary by ethnicity, no big news here.

But no! Thinking about it more, that's exactly what is says on the tin: global ethnic populations changed in the last ~140 years, and with it, the prevalence of generic variations. Makes perfect sense ¯\_(ツ)_/¯

edit: I mean... assuming the causal link ofc. I'm assuming this makes more sense than some kind of evolutionary pressure that is selecting for forearm median arteries.

[aredox]

We need to retire the idea that evolution has a goal, or that evolutionary pressure explains everything. There are tons of things in the human body that are very suboptimal or are purely accidental, from the tons of "junk" DNA, our difficult birthing, the appendicitis, wisdom teeth, the way our knees fold, differences in earwax, etc, etc.

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

https://www.scientificamerican.com/article/no-humans-have-no...

"Evolution" is just a (fairly tautological when you think about it) observation that "traits that manage to get passed on, subsist". It weeds out very bad traits, but the rest? It's just a giant lottery, not a great design with a teleological goal of "improving".

(And the human species has been short-lived so far, and may wipe out themselves without the "help" of a meteorite. In the same vein, cockroaches could be argued to be the pinnacle of evolution.)

[somenameforme]

While I agree with you, and also find the evolution = improvement views kind of annoying, I think you're also stating something that's accurate but perhaps misleading. Because when you say "good" or "bad" people are going to mistake that for what they personally think would be good or bad. When in reality good = makes you more likely to successfully reproduce, and bad = makes you less likely to successfully reproduce.

The best example of this is intelligence. In modern times, intelligence has become substantially inversely correlated with fertility. And as intelligence has high heritability, we are actively selecting against intelligence. And in fact we are already seeing generational declines (which had been previously been increasing for as long as IQ has been measured) in intelligence. [1] And this trend will continue until the point that intelligence and fertility once again become positively correlated. Nobody would ever say intelligence is a "bad" trait, but in evolutionary terms it has become one.

[1] - https://www.sciencedirect.com/science/article/pii/S016028962...

[aredox]

The study you linked to doesn't find heredity to be the driver of decline of IQ (which they pointedly reminded is not a measure of intelligence):

Regardless, we believe education, test-taking, and media exposure emerge as potential moderators for explaining the observed gains in three-dimensional rotation scores and declines or stagnation in matrix reasoning, letter and number series, verbal reasoning, and composite ability scores.

[philwelch]

> There are tons of things in the human body that are very suboptimal or are purely accidental, from the tons of "junk" DNA, our difficult birthing, the appendicitis, wisdom teeth, the way our knees fold, differences in earwax, etc, etc.

Right, but evolution also can explain those; many of these are tradeoffs for things that do deliver benefits. Difficult, premature births are the cost of big brains, for instance.

> "Evolution" is just a (fairly tautological when you think about it) observation that "traits that manage to get passed on, subsist". It weeds out very bad traits, but the rest? It's just a giant lottery, not a great design with a teleological goal of "improving".

The tautological explanation is extremely powerful, because it means even a small variation that delivers a marginal but consistent advantage is going to be selected for. For instance, a person with dark skin can survive in Northern Europe, and a person with light skin can survive in sub-Saharan Africa, but the ideal skin tones for those regions that optimally trade off vitamin D production with protection against skin damage from the sun are probably pretty close to the ones typical to their indigenous populations.

The actual catch is that there’s a lot of path dependence and all changes are stepwise. You can’t just install a new trait or body part that’s been designed from scratch; it has to evolve from an earlier, similar thing. If you look at the bones of your hand, the bones of a bat’s wing, and the bones of the front paw of a dog, the bone structure is basically the same; it’s just by changing the proportions that you can get the structure of a flapping wing, a front foot, or a hand with an opposable thumb.

[IshKebab]

Evolution does have a goal - spreading genes. Of course when we say "it has a goal" that doesn't mean it intelligently plans how to get there. Nobody* thinks that.

I think what you probably meant to say is that evolution isn't a perfect optimiser.

[ceejayoz]

It's also not optimizing for "maintain health in your 70s/80s/90s". A faster decline is probably evolutionarily advantageous to the small group of hunter-gatherers.

[vkou]

A bigger group of hunter-gatherers is more evolutionarily advantageous when it comes in conflict with a smaller group.

[ceejayoz]

Not in a lean winter, and not if you’re worrying about a bunch of frail revered elders during battle.

[moi2388]

Not if half of them are 80 >.> Seriously not every trait is revelations beneficial nor had to be

[penteract]

From section 4:

> The present study used an Australian sample of European origin. These results were comparable to those reported in black South Africans, their white counterparts and Malaysians of similar birth years; all these groups had a prevalence of approximately 30%

[akdor1154]

Simpson's paradox...