Q&A for History of Mankind (16)
Sped-up human evolution, the most important thing you never heard of
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This is the sixteenth Q&A for History of Mankind. Paying subscribers received an email asking for questions; and those are right below the paywall.
Before we get to that, let me again remind you that my book ”Emperor Whisperers: a comparative history of ancient Western and Chinese philosophy” is available at Amazon here and also free for all paid subscribers of A History of Mankind, who get an electronic copy.
So, let’s get to the important stuff: I’ve written quite a bit about the impact of genetics on human evolution and history, and will continue doing so, but I wanted to call your attention about this very good writeup of a very important idea that any history lover should keep in mind while reading about human development:
As Peter puts it, when studying the history of mankind, we must remember that humans are still evolving, same as any other animal:
The dominant view is that we have evolved by changing our environment rather than ourselves. Genetic evolution has thus given way to cultural evolution. For instance, we adapt to the cold by making clothes or even a controlled environment, like a home with a fireplace. Culture has allowed us to adapt to a diverse range of circumstances, and it has diversified accordingly. Yes, we too have diversified—in shape, color, and size—but those differences are trivial. Everything else is the same, or almost.
That view has been challenged by two studies of human genetic evolution. In both cases, the research team measured the speed of evolutionary change by estimating how fast new SNPs (single nucleotide polymorphisms) have appeared on the human genome. Both teams came to the same conclusion: cultural evolution did not replace genetic evolution or even slow it down. In fact, the growing importance of culture caused the human genome to evolve faster.
The go-to example provided by many geneticists is dogs’ evolution: dogs have very quickly evolved from wolves into the many breeds that humans have created, of extremely different sizes and shapes. Humans are evolving slower, because breeding experiments with animals have been (thank God) less expansive, but the same natural mechanics are at work.
In Murderous Tribesmen, from Arabia to Japan, I discussed human genes extensively, and those of dogs somewhat less extensively:
Some four thousand kilometers to the northeast and a couple of centuries earlier, by 6400 BC, a small community of hunter-gatherers inhabited Zhokhov Island in the Arctic Sea as a side-effect of long, persistent chases of bison and reindeer herds running away from the well-armed humans, on sledges drawn by dogs that they used for transport across the snow. This created the first known settlement in the High Arctic on what is now an inhospitable tundra of bogs, mosses and lichens, but likely was then covered by forests that experienced hot summers for centuries after the Younger Dryas, much like northern Scandinavia[6].
In Skateholm on southern Sweden, much warmer by comparison, dogs were regularly buried close to humans, with some killed right after their owners died, from about 5300 BC. This is evidence that dog domestication had extended far and wide by then, some 10,000 years after the so-called Bonn-Oberkassel dog[7] was buried with his owners in Germany, providing the first evidence of such domestication anywhere in the globe.
Those Skateholm fellas themselves already display a very visible, prominent sign of human genetic divergence: a mutation in the HERC2 gene, perhaps inherited from Neanderthals and favored by low sunlight in northern Europe; this mutation tweaks the expression of the OCA2 gene promoter leading to reduced melanin production and blue eyes, rather than the brown eyes of the majority of mankind, before or since.
This mutation appears to have been already widespread by around 5000 BC – more so than the variant of the KITLG gene that triggers lighter-colored hair, which was slower to spread around and didn’t become dominant in parts of northern Europe until the 2nd millennium AD — which leads to another fascinating go-to tidbit for many geneticists: that medieval Vikings, contrary to modern depiction, weren’t quite as blond on average as the native populations of Scandinavia, among which genes for blond hair have quickly spread over just the last few centuries.
All of this and more, as you know, can be easily found here. Now, for the readers’ questions:
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