Dr. Henry Gee
speaker
130 appearances
1 recordings
1 series
first heard Apr 2025
last heard Apr 2025
Dr. Henry Gee’s voice in public audio — every appearance, attributed to the second.
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Yeah, well, who knows? By about 40,000 years, yeah, I suppose so. Yeah, 50,000 years ago, there were lots and lots of humans. 40,000 years ago, there was just one. It was just us. And we lived all over the old world. And by the end of the last glaciation, modern humans lived from the Arctic to the tropical forests, and even have moved into the Americas.
And only Antarctica, Madagascar, and New Zealand and some oceanic islands had not seen the tread of a human foot. But even those would succumb quite quickly.
I think the thing that one has to emphasise, though, is that this is not a tale of manifest destiny. there was nothing written to say that humans would succeed and drive all the other hominins to extinction. I mean, as we've seen, hominins tried to invade Neanderthal territory several times and failed. And another thing, it's about genetic diversity.
Neanderthals were unbelievably famey genetically. Now, it's known in Neanderthal history that most of them died out sometime in their history and that their range was recolonized by other Neanderthals from elsewhere. Well, the same is true for Homo sapiens. Humans have always been very, very rare. They've always been one meal from starvation and two or three meals from extinction.
They always lived in very, very small groups, which tends to be inbred and very thinly scattered over the landscape. And there have been times, maybe several, where humans have almost died out altogether. There was an episode about... 100,000 years ago, maybe a bit more, when humans almost died out and only lived in refuges in southern Africa, that's actually quite contentious.
But there is genetic evidence for repeated what's called genetic bottlenecks. That means that the population shrinks to a tiny, tiny amount and then reestablishes from that tiny, tiny population. And because there are only a certain amount of genetic variation in that tiny, tiny population, the subsequent population becomes very samey.
Everyone looks very similar because it's built from only a limited amount of genetic variation. And way back in hominin history, around a million years ago, there's been some recent work published in Science that described what must have been a very awkward age, about 800,000 years ago, where for a million years, there were only about 1,000 breeding humans at any one time.
So there was a long period, and this was before Neanderthals, this was sort of Homo erectus time, but it's looking at the genes of people alive today. There are signs that humans and our immediate ancestors almost became extinct many times. So the fact that we're alive today is really quite remarkable, and the fact that we are not only alive today, but we spread throughout the Earth,
with a genetic variability in the entire human species that is no greater than a tribe of chimps living in Côte d'Ivoire today. So we have this extraordinarily low genetic diversity. Maybe we succeeded because Neanderthals didn't, was because their genetic diversity was even worse than ours.
It is called The Decline and Fall of the Human Empire, Why Our Species is on the Edge of Extinction. And it's published by Picador in the UK on the 13th of March this year, and in America by St. Martin's Press on the 18th of March.
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