Prof. Pierre Zalloua

You know, during the last glacial maximum,

people escaped the Levant, escaped Arabia.

And I wouldn't be surprised.

Actually, we have evidence to show that they actually moved back into East Africa and some other parts of Africa.

The Natufians, which we'll talk about, we believe that after the Younger Dryas, which is a very cold period that happened around 11,000 years ago, the population of Natufians who lived in the Levant shrunk, and some of them may have actually escaped.

Some of them went north, but others actually went south and perhaps crossed back into Africa.

to escape because we see material culture that in the Tufin culture that is more impacted by Africa, whether because they interacted with them or whether they have actually moved there and interacted with them in Africa and they brought them back.

So really it's a, we have to think about, you know, it's not always one direction of movement.

It's actually, you know, it's a corridor back and forth.

So the reason the 50,000 years out of African migration has been highly documented because we have strong archaeology and we have also strong DNA to show we can time that migration through DNA mutations that happened.

And the fact that, you know, now Homo sapiens, you know,

Initially, we thought, you know, when I first started to study population genetics, the whole idea was like, we are 150,000 years old.

Of course, now we push that to 400,000 years.

We think some Homo sapiens actually are 400,000 years old now.

And again, because of ancient DNA that made us change these theories.

But the most striking idea is that the population in Africa shrunk so much during that time that those who actually migrated out of Africa were very few.

And we're talking maybe in the thousands, maybe a few thousands only.

And that's why we're not as genetically diverse as you would expect.

If we were evolving without this bottleneck,

through 400,000 years ago, we would be a lot more diverse than we are today.