Well Svante Paabo has the answer.

(Laughter)

And as for neanderthals,

So that today, the people living outside Africa have about two and a half percent of their DNA from Neanderthals.

That's not necessarily a bad unintended consequence.

And that's indeed the case.

The ones on the left are from Africa, from around a million years ago.

When did this happen?

We don't know, but it's possible that Neanderthals didn't do this.

Svante found that the FOXP2 gene, which seems to be associated with language, was also shared in the same form in Neanderthals as us.

And the way to ask that question is to look at the Neanderthal that comes from Southern Europe and compare it to genomes of people who live today.

What is a Neanderthal like?

To begin with, it's going to be a society that's way in advance of our own.

So, with that little bit of technology, humans went from a small band of 10,000 or so the same number as Neanderthals everywhere and we suddenly exploded.

And to begin to answer such questions, my research group since over 25 years now works on methods to extract DNA from remains of Neanderthals and extinct animals that are tens of thousands of years old.

Does it match one African or the other African?

But this is different if we now look at the European individual and an African.

But as you're thinking about this, one of the interesting things is how small these mutations are and where they take place.

The same is true if we look at a Chinese individual versus an African, the Neanderthal will match the Chinese individual more often.

We find it in every population around the world at all time periods going back tens of thousands of years.

In fact, genetic profiling tells that it may be tens of thousands of years old, which means that this cancer may have first arisen from the cells of a wolf that lived alongside the Neanderthals.

So an interesting question is, what happened when we met?

looking at the two African genomes, finding places where they differ from each other, and in each case ask

So the model we've proposed to explain this is that when modern humans came out of Africa sometime after 100,000 years ago, they met Neanderthals.

Then modern humans emerged somewhere in Africa, came out of Africa, presumably in the Middle East.

Sure enough, their tools were more complicated than those of Homo erectus, but they too showed very little change over the 300,000 years or so that those species, the Neanderthals,

If you look at our ancestors, the Neanderthals and the Homo erectus, our immediate ancestors, they're confined to small regions of the world.

My friends, human nature is exactly the same as it was when my ancestor probably it was my ancestor got his hands around the neck of the last Neanderthal, and battered the bastard to death.

Not just in modern humans, but in one of our distant unrelated ancestors, the Neanderthals.

And the other thing there's no evidence for is exchange between groups, because the objects that you find in Neanderthal remains, the tools they made, are always made from local materials.

This may also be surprising because the Neanderthals were never in China.

For example, in the Caucasus there's a site where you find local Neanderthal tools.

So many of you will be familiar with the idea that there's this gene called FOXP2 that seems to be implicated in some ways in the fine motor control that's associated with language.

And it was well enough preserved so we could determine the DNA from this individual, even to a greater extent than for the Neanderthals actually, and start relating it to the Neanderthal genome and to people today.

There were other forms of humans around, most famously perhaps, Neanderthals these robust forms of humans, compared to the left here with a modern human skeleton on the right that existed in Western Asia and Europe since several hundreds of thousands of years.

We would expect there to be no difference, because Neanderthals were never in Africa.

And this then, in conjunction with these methods that allow very many DNA molecules to be sequenced very rapidly, allowed us last year to present the first version of the Neanderthal genome, so that any one of you can now look on the Internet, on the Neanderthal genome, or at least on the 55 percent of it that we've been able to reconstruct so far.

We don't know quite where the borders between these people were, but we know that in Southern Siberia, there were both Neanderthals and Denisovans at least at some time in the past.

And we found that this individual shared a common origin for his DNA sequences with Neanderthals around 640,000 years ago.

Anthropologists tell us that the one thing we as humans have always required of our community members is to be of use, to be able to contribute.

Had we chosen this option, sometime around 200,000 years ago, we would probably still be living like the Neanderthals were when we first entered Europe 40,000 years ago.

And that's the reason why, as you look at the hominid fossil record, erectus, and heidelbergensis, and floresiensis, and Neanderthals, and Homo sapiens, all overlap.

So this individual comes from a population that shares an origin with Neanderthals, but far back and then have a long independent history.

And if we study those hunter gatherer tribes and the Neanderthal, which are very similar to early man, we find out a very curious thing about this world without technology, and this is a kind of a curve of their average age.