David Reich

I mean, it's almost certainly the case that Neanderthals were using...

sounds and communicating in ways that are probably pretty complicated, complex, and amount to some kind of language.

But some people think that language in its modern form is not that old and might coincide with the later Stone Age, Upper Paleolithic Revolution, 50,000 to 100,000 years ago, and might be specific to our lineage, and that there might be a qualitative shift in the type of language that's being used.

There's been one incredibly interesting and weird...

line of genetic evidence that was so weird that a lot of people I know dropped off the paper.

They just didn't want to be associated with it because it was so weird and they just thought it might be wrong.

But it's stood up as far as I can tell.

It's just so weird.

So this is one of the things that surprises that genetics keeps delivering.

I think that that's probably going to come across in this conversation, which is I am

pretty humbled by the type of data that I'm involved in collecting.

It's very surprising, this type of data.

Again and again, it's not what we expect.

And so it just makes me think that things are going to be surprising the next time we look at something that's really not looked at before.

So the line of evidence I'm talking about is one based on epigenetic modification of genomes.

So just to explain what that means, the genome is not just a sequence of letters, DNA letters, adenines, thymines, guanines, and cytosine, A-C-T-G.

It also is decorated in anybody's cells by modifications that tell the genes when to be on and off in what conditions.

So an example of such a modification is methylation in cytosine-guanine pairs.

So this turns down a gene and makes it not functional in certain tissues.

And this methylation is bestowed by cellular environments and differs in different cells and also in different species to identify which genes are more active or more passive.