This weekend, I finished off the last of the ‘First Peoples‘ PBS miniseries on prehistoric humans. If you’ve watched other documentaries on human prehistory and found them interesting, then you’ll want to watch this one to get the latest findings. It was fascinating. (A lot of people have mentioned ‘Becoming Human‘ to me, which I’ve seen and enjoyed, but its content is now dated by a few years.)
I did find the sound editing in the first hour to be poor. Often I couldn’t hear what the narrator was saying over the music or sound effects. Hopefully they’ll fix that by the time the series is available in other venues. If not, don’t let it deter you from watching the rest. It gets much better after that first hour. And the actual content of that first hour, on prehistoric native Americans, is fascinating if you can bear with it.
In the final episode, we see anthropologist John Hawks discuss a theory about Neanderthals that I wrote about a few months ago, that they actually didn’t go extinct, but were assimilated into Home sapien societies.
A couple of decades ago, there were two major theories on the evolution of Homo sapiens. One, called the Multiregional theory, posited that modern humans evolved throughout the world, with gene flow between the continents keeping humanity one species. The other was the Replacement, or Out of Africa theory, which held that modern humans evolved in Africa and then spread throughout the world, replacing other archaic human species such as the Neanderthals.
In recent years, the evidence seemed to swing decidedly in favor of the Replacement model. All of the oldest remains of modern humans were found in Africa, and all archaeological signs of behavioral modernity throughout the rest of the world were less than 50,000 years old. Genetic studies revealing the prehistoric migrations that Homo sapiens followed seemed to be the nail in the coffin of the Multiregional model.
All of which didn’t have modern humans looking too good in our relationship with other archaic humans. It was starting to look uncomfortably like we had invaded their turf and drove them to extinction, either directly through conflict or indirectly through resource competition.
Then someone sequenced the DNA of Neanderthals and discovered that all ethnic non-Africans (from relatively recent times) share between 1% and 4% of their DNA with Neanderthals. There was some discussion that maybe that shared DNA went back to the common ancestor of Homo sapiens and Neanderthals, but most scientists now see this shared genetics coming from intermixing.
In other words, Homo sapiens and Neanderthals mated. If they did that, these two groups must have seen a lot more humanity in each other than had previously been supposed. Neanderthals, since their discovery, have moved from an ape like conception to a branch of humanity that most of us have inherited from.
As Hawks discussed, Neanderthal population was probably never more than a few thousand individuals, while Homo sapiens migrating into their regions numbered in the tens of thousands, maybe even hundreds of thousands. Neanderthals didn’t so much as go extinct as get swamped and assimilated. Unless your ethnicity is African (again from recent historical times since we’re all Africans if we go far enough back), then you are part Neanderthal.
Depending on where your ancestors lived, you also may have bits of other archaic human population genetics in you, such as the Denisovans.
So, the verdict of evidence appears to be that the Replacement model was mostly right. All of us are mostly descended from Africans, including the parts that make us modern humans. But the Multiregional model was not completely wrong either since most of us have DNA from other branches of humanity.