Schizophrenia is the price we pay for minds poised near the edge of a cliff

This is fascinating, and makes me wonder if human intelligence itself is such a cliff edge trait. For most of human history our advanced intelligence has obviously been a benefit, but now we see, as people and societies become wealthier and better educated (both correlated with intelligence), their reproduction rates drop precipitously. Perhaps we've overshot the intelligence cliff and evolution is now gradually pulling us back. (Evidence of this would be less intelligent people having more children on average than more intelligent ones.)

Humanity is changing so quickly nowadays, biological evolution most likely doesn't matter at all anymore, at least for the kind of questions and time scales you're discussing.

There is no evidence people are measurably more intelligent now than two-three decades ago.

I think there is evidence: https://en.m.wikipedia.org/wiki/Flynn_effect

Humanity is still subject to evolutionary pressures. We are "natural" and what we do is "natural", and if something like our environment were to drastically change as an evolutionary pressure, selection would absolutely happen.

Consider a change in environment where, for example, oxygen levels drastically drop. That might make living at altitude deadly for those who don't have genetic adaptions to high altitude living.

As an extreme example, in ~500 million+ years when the sun starts expanding, you can bet natural selection will finish off non-extremophiles that aren't living deep within the Earth.

Yes, the genetics wouldn't have significantly changed over such a short period, but the environment has.

Sure, I never claimed otherwise.

What I'm saying is that evolution matters across large timescales. By contrast, I believe the topics I was commenting on concern timescales where effects of biological evolution are negligible compared to the effects of memetic evolution.

Thus, biological evolution doesn't matter at all for predicting what will happen (or is happening right now) to humanity, unless predicting so far into the future as to be completely futile speculation (imagine someone 200 years ago wondering how biological evolution might affect humanity during the next couple thousand years).

Genetics isn't all that matters. Things like malnutrition (and a lot more things) very much also do.

I think the point is that the evolution of human intelligence reached a point that enabled us, over evolutionarily short timescales, to develop an environment (social structures etc.) that broke evolution as it was – the meaning of "fittest" is now rather arbitrary in human context.

And there is evidence that this trend has been reversing in the last decade(s) (Reverse Flynn Effect):

https://www.popularmechanics.com/science/a43469569/american-...

I'm not sure it is arbitrary, just different from what it was a hundred or a thousand years ago. There's no real survival differentiation in modern society, and while classically beneficial traits like physical fitness and intelligence do help with finding partners, most people are able to do so regardless. The other big difference now though is that people can have sex without choosing to have children. So istm the most successful traits from an evolutionary perspective at this point are those that encourage a desire to have more children. (If there's a genetic predisposition toward religious adherence, that's a likely example.)

Nearly everything around you save for a sliver of software was invented (and often built) by people over the last hundred years. There is no empirical evidence for qualitative difference in intelligence, certainly not to account for sudden onset of infertility.

If the effect from 1934 to 2008 had been 14 points (believable given advances in nutrition and education), what had it been from 2008 to 2025? And is it reasonable to believe that those hypothesized couple points from the old median did it?

Its impossible to properly seperate biological evolution from current day enviromental pressure. There have been many natural and man-made disasters that have killed or otherwise economically robbed millions of people from a good future in their lifetime. Its difficult to say what the fitness function actually selected for.

If you could look back far enough and understood most of the enviromental pressures we faced, then we are all lottery winners of our tumultous history.

Again, sure. However, this is still looking at things at the timescale of millenia at best.

In my original comment, I was claiming that biological evolution is not relevant for this:

> as people and societies become wealthier and better educated (both correlated with intelligence), their reproduction rates drop precipitously. Perhaps we've overshot the intelligence cliff and evolution is now gradually pulling us back.

Biological evolution is also impossible to measure on small timescales. that does not mean it does not exist, clearly it exists. It has an exponential effect on the future. I think we fully agree on this definition.

>as people and societies become wealthier and better educated (both correlated with intelligence), their reproduction rates drop precipitously.

There is also the unmistakeable influence of evolutionary psychology on people throughout human history, that seems to have accelerated. When people decide to have fewer kids, especially the more affluent ones, doesnt yet point to any biological influence. Other than the correlation between wealth, IQ and genetics. I dont think there are any risks of a reduction of intelligence through evolution. The world population reduction we're seeing might accelerate it instead.