Several years ago, an Australian team published their results from research on fossils from Lake Mungo – perfectly ‘modern’ specimens, I should add. The mtDNA they found fell outside the accepted tree rooted in the famous ‘African Eve’, and as a result, their research was largely disregarded. Whether or not their results were caused by contamination, as some critics claimed, such a result is exactly what one should expect – on purely statistical grounds.

who you are talking to? you notice i mentioned this in my post right, since you read it?

In a stable population, one where each reproducing female leaves exactly two reproducing children, 90 % of the original mtDNA lines will be broken in just 34 generations. That’s less than 1.000 years. So if you start with 1.000 female Neanderthals in a mixed population, less than 100 Neanderthal mtDNA lines will survive after 1.000 years. After another 1.000 years, less than 10. After yet another 1.000 years… You can do the same type of calculation regarding Neanderthal Y chromosome lines. All taken together: If Neanderthals were a small minority of our common ancestors, it is extremely unlikely that any two Neanderthal genes would survive after 30.000 years. (In effect, mtDNA and the Y chromosome are inherited as just one gene, since they’re inherited in one piece.) Conclusion: We don’t have to construct intricate theories of marriage customs or patterns of reproduction in order to explain the lack of Neanderthal mtDNA or Neanderthal Y chromosomes today; we only have to do some reasonable math.

For thirty years, the ruling orthodoxy – the ‘Recent out of Africa’ school – has been leaning heavily on just one gene, out of our 25.000. In reality, each gene has its own tree of ancestry! The total picture will be incredibly complex, and we’ve just started to put together a few pieces of the jigsaw. What we do know is that the average person carries approximately 1.000 genes inherited from our Neanderthal ancestors. (My own ‘Neanderthal bun’ at the back of my skull confirms my mixed ancestry!) Most of the rest of our genes in all likelyhood are of recent African origin (‘recent’ meaning 100.000 years or less), but we don’t KNOW this yet. We’ll know much more once we start seeing DNA from Asian Homo Erectus, and I’m convinced we’re in for a lot of surprises. There’s a revolution going on in the way we perceive who we are and where we come from.

“geeze dialects!” . Don’t you speak with a dialect?

The video is definitely for entertainment only.

Can’t be. The Africans must have been the aggressors, and they got the women. Otherwise we would be Neanderthals wondering what happened to the Africans.

While this is possible, there doesn’t seem to be particularly strong evidence of natural selection playing a strong role in modern human mtDNA variation. The mtDNA variation looks like is a better fit for selective neutrality with it coming along for the ride of trends driven by other genetic and/or cultural drivers of natural selection that happen to coincide with mtDNA variants.

Hawks recent findings that the Neanderthal DNA found in East Eurasians is mostly different than the Neanderthal DNA found in West Eurasians also argues for the case that most of our Neanderthal DNA legacy, while not decisively counterproductive from a selective perspective, also didn’t provide decisive selective advantages. The case for selective advantage can only be made if the number of genes found in both West and East Eurasian Neanderthal DNA legacies are a larger share of the total than one would expect from random chance.

The selective factors related to mtDNA would probably relate to metabolic rate, as mitchondria are intimately involved in regulating metabolism. This is a trait that one would expect Neanderthals in colder climes to have better adapted to for colder climates than modern humans who would be more recent African expatriots where it is warmer, at least for those modern humans migrating to colder areas as many were doing in the era of Neanderthal-modern human interaction. Thus, it would be quite surprising that modern human mtDNA would have selective advantage relative to Neanderthal DNA.

I also don’t think that Eze @14 is correct that a random DNA test has much of a chance of discovering a Neanderthal Y or mtDNA lineage in a modern human in the next 5-15 years. The aggregate sample size of all Eurasians who have had uniparental DNA haplogroup typing already is on the order of tens of thousands if not the hundreds of thousands, with atypical relict populations mostly oversampled, with not a single such case identified so far.

Given the amount of population expansion (something on the order of ten thousand fold) that the world has seen in the last 30,000 years (the youngest possible origin for Nenaderthal DNA), it is very hard to imagine that a gene with a thousand plus generations of age in a period of profound population expansion would have stayed in the population, but be so rare that it or a phylogenetic descendant of it, wouldn’t have shown up in a sample as large as the one that already exists.

“I keep seeing people, who really ought to know better, saying that the new Neandertal genome results show that the gene flow must have been Neandertal men mating with modern human women, and not the other way around.

You see, they’re fixated on the idea that the mtDNA showed no signs that the Neandertal clade survived into the present-day population. That result really convinced some people that interbreeding was impossible. They’re flummoxed that some of the rest of the genome has significant signs of intermixture. It’s like their world is spinning out of control. I’m not naming any names, but if you’ve followed much of the press around the Neandertal genome, you’ve probably seen this suggestion.

I don’t know why it hasn’t occurred to them that the Neandertal mtDNA type was probably lost because of natural selection.”

I like a more balanced approach though, such as in the post as I read it.

@ dave chamberlain:

Don’t you think Vendramini, a movie producer/writer/director, haven’t thought about that? From the beginning, perhaps.

[Ouch! He turned up in the ads too.]

What if Neanderthals had the upper hand in these interactions? Hunter-gatherers can’t steal material possessions, but they can steal women. If you’re talking about a prolonged tributary relationship, it’s also conceivable that the Neanderthals were able to recognise (and claim) hybrid sons. (It wouldn’t be such a stretch to imagine Neanderthal society prizing sons more than daughters – it would fit well within what we find in many modern human societies.)

I’m thinking of the Island Caribs as a (partial) model. Men and women spoke different languages – the men reportedly spoke the Carib language, while the women spoke an Arawakan language (presumably reflecting the long-term import of captive Taino women).

There’s a weakness to such a model – if most hybrid sons were recovered by their fathers, then the contact would have to be prolonged. If there was prolonged contact, then the human-to-Neanderthal introgression would probably be more pronounced than in Neanderthal-to-human. The paucity of putative hybrid fossils might argue against this…though, on the other hand, despite the lack of fossils, we know that hybrids existed.

Also, there is a pretty easy way to solve the question of why all Neanderthal admixture in modern humans comes from Neanderthals males, which is the missing link in the analysis above. All you need is a scenario in which Neanderthal-human relationships are in the nature of rape/flings/seasonal meetups rather than being stable long term marriages, or (probably less plausibly) with Neanderthal-human relationships being matrilocal (which seems to be at odds with the very little that we know about Neanderthal social structure). Either way, the hybrid kids end up with their mother’s tribes.

In the case of modern human mothers (who were pregnant from Neanderthal fathers) those hybrid kids join the modern human gene pool. In the case of Neanderthal mothers (who were pregnant from modern human fathers) those hybrids end up in the Neanderthal gene pool.

The trouble is that the Neanderthal gene pool is a pond that goes dry when the Neanderthals go extinct, so that mixed species kids with Neanderthal mothers go extinct along with their Neanderthal maternal extended families, leaving only the hybrid kids of modern human mothers in the modern gene pool.

To back up Miko’s point about degree of genetica relatedness and similarity of appearance, Papaun tribesmen are more closely related to Han Chinese then West Africans were appearances would indicate quite the opposite.