hi,
We have an Early Bronze Age J2b2-L283 sample in North Caucasus, so i highly doubt it's Neolithic, i assume the entrance in Europe happened somewhere in 2000 B.C, whether non-IE or IE that i am not sure of. Some of the J2a were present in Neolithic though.
That is what is tricky with this haplogroup, there is very contradictory infos about it.
The easiest explaination for me is to put L283 bottle-neck exit on the coast of the black sea inside a population without steppe admixture.
Admixture-washing is not a very common process.
We have yet t o find a sample of L283 from the Neolithic, although per some old (2 year old) rumors there is a J2b2 in Moldova from the Eneolithic, but this one also in a way points towards the steppe.
Moldova is in a "in-between" situation as you said. Also "eneolithic" is quite vague, Moldova during eneolithic, could relate to early steppe migrants or to south-eastern european farmers. Basically, without more information the "eneolithic moldovan" spoiler is not really helping. In fact, if I have to put J-L283 somewhere when it starts to diffuse again in 5500BP, I would put it on the black-sea cost in south-eastern Europe.
I am sure you will not agree with most of my conclusions.
Who knows ? I'm open to be proven wrong, and always open to accept that what I consider the "most-likely" today might be invalidated in the future
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I will read that later today (tonight for me).
As for the Nuragics, they are from 1300BC. Meanwhile we have ~2000BC Maros as well as Dalmatia samples, with 30-50% Steppe.
It helps to keep in mind that Sardinia was insulated to most movements, at least to a higher degree than Pannonia/Balkans, and if these L283 Nuragics were part of a male dominated movement, their autosomal signature would be close to zero within 5-6 generations(1/2^n formula IIRC).
One could claim that 50% steppe just need one generation to be generated, and if you find a Steppe-like mt-DNA ... the complement needs to be something not from the steppe.
In fact, both samples can be explained with the right "story" created around.
I consider ancient DNA usefull, but ancient DNA mainly helps for dominant haplogroups, for rare ones it is less helpfull.
Mainly, one single line of from M241 to L283 that propagated between 9500 and 5500BP survived until today, thus these lines cannot have reach a "high" level of dispersion. Therefore, it is unlikely to find it in ancient sample between these two dates. In fact finding a neolithic sample would be crazy lucky.
In fact, when we look at haplogroups with ~several millenia bottle neck, most of the time no ancient samples are found.
I would rather believe dynamics of haplogroup (time of spread, location, speed of diffusion), when a male population is conquering new territories, the related haplogroups are spreading very fast. We are not seing that for J-L283 during the main steppe expansion. That's what make's the "steppe" hypothesis suspicious to me.
Anyway, hofully new ancient-samples/modern-lines will be found and help to find which model is the good one
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G.