[falaki]

I haven't read the papers in detail, but can someone explain how genetics can be used to trace spread of languages? For context, you don't need population movements for a language to spread (it is similar to religion). See this article for a logical explanation: https://medium.com/incerto/a-few-things-we-dont-quite-get-ab...

[adastra22]

You can’t. But if population A and population B share a ancestor X years ago, and they also speak languages that appear to have drifted apart by X many years, the inference that their ancestor spoke a common proto-language is the simplest explanation.

[eddiewithzato]

Well you can and in fact they have narrowed down the language to a haplogroup even. R1b in the case of greek for example

[philwelch]

You are correct that the spread of genetics and the spread of language do not have to coincide. However, in this case, it seems that they do.

If you study the genomes of the populations of Europe as well as parts of Central and South Asia, you can reconstruct a very broad family tree rooted in a shared genetic ancestry from in a population who lived somewhere in Eurasia at a certain point in time. If you also study the languages of those same populations, you can independently reconstruct a family tree of languages that culminates in the reconstructed Proto-Indo-European language that would have existed at the same point in time. The simplest explanation for this is the spread of Indo-European-speaking populations, and not merely the language itself, from a single ancestral population.

[astrange]

Well, you can't. In this case I believe they're already pretty confident about who the PIE speaking people are (the "Yanmaya") and this study is about tracking down where they originally lived. And they have shown that they mostly replaced the previous European population rather than transferring the languages to them.

David Reich is aggressive about these genetics results though. IIRC I read a NYT story once where he came in and claimed to have upended all of Polynesian history based on the genetics of a few historical skulls they found, but it didn't seem like strong enough evidence to me.

[wqaatwt]

> replaced the previous European population

Primarily the male population. Genetically much higher proportion of the female population survived.

Of course that’s an exaggeration as well. In much of Southern Europe and other areas the replacement was far from full.

[acadapter]

Maybe this is how the branches of Indo-European evolved.

Laryngeals replaced by vowel lengthenings, merging of consonsants, vowel shifting based on other sounds, etc. It's like there were many different events where "Indo-European with a heavy foreign accent" suddenly emerged.

[4gotunameagain]

For people that are interested to read more:

https://en.wikipedia.org/wiki/Kurgan_hypothesis

[leoc]

I can't find it now, but I've seen at least one claim that the ancestral-human-DNA world inside biology is fairly dominated by a clique, and if you're not seen as fully on the team you can't expect to be funded, published and so on. Which isn't to say that any specific claim is wrong, of course, and on the whole it seems very unlikely that they're far wrong on the bare facts, as opposed to more speculative interpretations.

[bregma]

You don't need rationalism or the scientific method if you really really strongly believe you are right.

This is absolutely true.