David Reich

And it's not directly encoded by the ACTGs locally.

It's encoded by something else and sometimes even passed on by your parent directly.

So it's really very interesting.

So this can be read off ancient genomes.

the methylation pattern survives in Denisovan and Neanderthal genomes, and we can actually learn which genes were turned down and turned up.

So work by David Gochmann and Liron Carmel and colleagues created these maps of where in the Denisovan genome

where in modern human genomes, genes are turned on and off.

And there's a lot of technical complexity to this problem, but they identified differentially methylated regions, several thousand sections of the genome that were consistently and very differently turned down or turned up in Neanderthals and modern humans.

And when they looked at the set of differentially methylated region, roughly a thousand of them, that were systematically different on the modern human lineage, and asked what characterized them, was there particular biological activities that was very unusual on the modern human-specific lineage, there was a huge statistical signal that was very, very surprising and very, very unexpected, and it was the vocal tract.

So it was the laryngeal and pharyngeal tract.

And because you can actually learn from little kids with congenital malformations when you knock out a gene, when a gene gets knocked out by an inborn error of genetic transformation, of genetic...

Kids will have, for example, a face that looks different or a vocal tract that looks different and so on.

You know what the effect of knocking out these genes is.

We can actually imply directionality to how the modern human specific changes are.

And the directionality is to change the shape of the vocal tract, which is soft tissue not preserved in the skeletal record, to be like the way ours is distinctive from chimpanzees.

So in the shape that we know is very helpful for the articulation of the range of sounds we use that chimpanzees don't have in their laryngeal and pharyngeal tract.

So even though we don't have surviving hard tissue like skeletons from this part of the body, we now have this methylation signature which suggests that these changes have occurred specifically on our lineage and are absent in both the Neanderthal and Denisovan lineages.

So if you think this change in the vocal tract is important in language, which seems possibly reasonable, then maybe that's telling you that there's very important changes that have happened in the last half million or a few hundred thousand years

specifically on our lineage that were absent in Neanderthals and Denisovans.

We don't know that.