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Comment by Nevermark | Hacker News Reader

Wouldn’t its very reliable high prevalence across a wide diversity of today’s gene pools strongly suggest an early, not late or isolated, origin?

That seems scientific enough.

Given that strong persistence over time and population, the assumption that it must have advantages becomes a sensible and supported conjecture. And identifying what benefits it might have bestowed a sensible area of research toward verifying that.

Anything conclusive would require many more experiments & more evidence of course. Most individual papers in historical and behavioral evidence fields can’t settle something definitively on there own.

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> Wouldn’t its very reliable high prevalence across a wide diversity of today’s gene pools strongly suggest an early, not late or isolated, origin?

There are plenty of things which are common across a wide diversity of today's gene pools that, as far as we know, were rare in the past.

For example: Type II diabetes, Dental caries (pre agriculture), or Cancer.

Those all seem like things that can be explained as being more common just because humans live significantly longer now. I don't think that's the only reason, just that it's not an obviously fair comparison - ADHD doesn't seem to increase with age, but the ailments you listed do.

That's simply wrong.

While life expectancy at birth has increased a lot, that was mainly due to infant survival rates. Life expectancy once a person reaches, say, 25, has not increased by that much.

Diabetes type II was vanishingly rare not long ago. Now we have teenagers suffering from it. Teenagers with Diabetes type II is not due to humans living significantly longer.

Similarly with dental caries, which is quite common in childhood these days. This is not due to people living significantly longer.

Similarly with Cancer. There are cancers that are relatively common in young people today. Testicular, or breast cancers occur quite often in young people. Missionary doctors in Africa, among the native Americans, or the Inuit, report not diagnosing a single case of cancer for years. It is not a matter of diagnostic failure. An untreated late stage breast cancer or testicular cancer is quite easy to diagnose.

Or it might be just like insomnia - a syndrome that can have multiple different causes many of which don’t have a genetic origin.

That is certainly a possibility. My guess is most outliers in development are the result of less common combinations of useful variation.

Some combinations inevitably don’t work as well as others, but the variation in combinations is still net valuable.

And some outliers may be valuable in the context of being a limited part of the population. I.e. we need some day dreamers, some OCD people, etc.

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