Jacob Kimmel

That's true in both cultures from the East and cultures from the West.

That seems unlikely to me.

I think a much simpler explanation is that for whatever reason, our fluid intelligence is roughly maximized at the time where the population size during human evolution was maximal.

If you had to pick an age at which fluid intelligence was selected most strongly for, it's probably around 25 or 30.

That's probably about the age of the adults in the large populations that were being selected for during the rest of evolution.

And so I think there's a lot of reason here to think that actually there's interplay between many features of modern humans and how long we were living and how that dictates some of the features that occur that rise and fall throughout our lives.

Do you know the Alexander von Hummelt story?

No.

So Alexander von Hummelt is one of the most famous scientists in history.

He's kind of forgotten now.

But he had this one expedition to South America where he climbed Mount Chimborazo at a time when very few Europeans had done that.

And so he was able to observe various ecological layers that were repeated across latitudes and across altitudes.

Mm-hmm.

And it caused him to formulate an understanding of how selection was operating on plants at different layers in the ecosystem.

And that one expedition was the basis of his entire career.

And so when you see something named Hummel, just to give you a sense of how famous this guy is, it's usually Alexander von Hummel.

It's not like this is some like massive, prosperous German family name that just happens to be really common.

It's this one guy.

And so really it was like this singular year in which he conceived a lot of our modern understanding of botany and selective pressure.

Yeah, so then the next piece of the evolutionary story is like, is there anything selecting against longevity?