Ella Al-Shamahi

And this is where genetics is kind of really interesting because we have Neanderthal DNA all over our genome.

If you are from outside of sub-Saharan Africa, if you're from inside of sub-Saharan Africa, you have some Neanderthal DNA and you may be, but not necessarily.

Outside of sub-Saharan Africa, it's about 2% on average for an individual.

And it spreads all over your genome.

So it's important to say that my 2% is going to be different from your 2%, right?

But there are a few places where there are these Neanderthal deserts where you don't see much Neanderthal DNA.

And the main place you see it is on the sex chromosomes.

And that usually indicates that Haldane's rule is at play.

Now Haldane's rule is, we were probably taught this at school, the biological species concept.

So biological species concept is that two things are two different species, two animals are two different species.

If when they have sex, the offspring is infertile, right?

That's like, oh, you're two different species.

Now, one of the things about that is that the sex chromosomes will basically have less DNA from the other because of Haldane's rule.

It's kind of the way it goes.

So there is that.

So initially we were like, okay, well, Haldane's rule is at play.

It's that we're becoming two different species or we are two different species.

And that's why there is this desert there of Neanderthal DNA.

Only just in the last few weeks.

There's been some research coming in and the suggestion is that actually there's another possible explanation for why there's no Neanderthal DNA on the Homo sapiens sex chromosomes.