When Humans Caught Up With Evolution

I certainly didn't know this, but the spleen acts as a biological SCUBA tank during extended periods underwater.

There are some people from the southern Philippines, Indonesia and Malaysia who evolved bigger spleens because they spend a lot of time diving deep underwater. They live on houseboats, rarely go on land, and spend 8 hours a day repeatedly diving underwater. They split from a very similar group of people nearby about 15,000 years ago - the one group stays on land and the other in the water. Their genes are very similar, except for this distinction, and so the spleen enlargement is correlated to this behavior/culture change.

This is a discovery worthy of reporting because most of the basic body plan that includes our organs is pretty similar across all humans, or so we thought.

We have this idea of a Human Genome being uniquely human, and as a thing we all share in common. (Or at least I do; maybe I just haven't been to 5th grade for a long time, kind of like people who don't realize that just about every star we can see in the night sky has planets revolving around it, a discovery of only the past few years.)

But there is this thing that happens about 10-15 thousand years ago, where human creativity (i.e. technological memes or cultural evolution) evolves faster than our genes. Diving in the ocean all day long doesn't by itself constitute a technological advance, but then again, this is at the 15,000 mark. 10,000 years ago, we see the genetic changes resulting from dairying practices. Because of this, some people continued to be able to digest milk into adulthood (not possible for other mammals).

The change in dairying practices must have relied on some techological change, but it's still hard to call this technology. Is agriculture a technological development? Animal husbandry? Because this is where 'drinking milk' comes from. Leaving the land to live on the water is not so much a technological advance as a group-behavior advance - cultural evolution we could call that. Memetic evolution some would call it.

The main idea here is that at some point around 10,000 years ago, humans began changing themselves faster than their environment changed them. When you hear Ray Kurzweil talk about the Singularity (a moment in our near future where humans learn to evolve ourselves at will), note that we have been evolving ourselves already for thousands of years.

Notes

Bajau people 'evolved bigger spleens' for free-diving
Apr 2018, BBC

Evolution of lactase persistence: an example of human niche construction
Philosophical Transactions B, 2011

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