Relation of Neanderthals to man

[lavinia]

If Neanderthals and humans interbred, then they must have had a common ancestor that was also human. What is known about this common ancestor?

 

[SW VandeCarr]

If Neanderthals and humans interbred, then they must have had a common ancestor that was also human. What is known about this common ancestor?

http://www.sciencemag.org/content/314/5802/1113.abstract

The Wiki article tentatively identifies Homo Heidelbergensis as the common ancestor but not much is known about this species. The linked article above used gene sequencing to identify the existence of the common ancestor about 700,000 years ago and the separation of the populations that led to modern humans and Neanderthals at about 375,000 years ago. Neanderthal remains are found, I believe, entirely in Europe and parts of western Asia while the earliest evidence for modern humans is from southern Africa.

http://www.pnas.org/content/early/2011/03/01/1017511108

 

[lavinia]

thanks for the links.

So it seems that man and Neanderthal man would have both been able to interbreed with Homo Heidelbergensis?

 

[SW VandeCarr]

thanks for the links.

So it seems that man and Neanderthal man would have both been able to interbreed with Homo Heidelbergensis?

We clearly had a fairly recent common human ancestor and the Neanderthals apparently migrated to ice age Europe before modern humans did. When modern humans arrived, there may have been both competition and some interbreeding.

http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002947

 

[lavinia]

We clearly had a fairly recent common human ancestor and the Neanderthals apparently migrated to ice age Europe before modern humans did. When modern humans arrived, there may have been both competition and some interbreeding.

http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002947

interesting. If man and Neanderthals were not able to interbreed with their common ancestor and branched separately away from it, it would seem that the same species, mankind, evolved twice.

 

[SW VandeCarr]

interesting. If man and Neanderthals were not able to interbreed with their common ancestor and branched separately away from it, it would seem that the same species, mankind, evolved twice.

Well, if H Heidelburgensis is the common ancestor, we would expect a mixed interbreeding population sometime during the period between -700 ka and -375 ka. With divergence, separate populations looking like modern humans and looking like Neanderthals would have developed. Since H Heidelburgensis was present in Europe, I suppose it's possible that the Neanderthals, as we know them, first appeared there and were adapted to the conditions there. It doesn't mean modern humans would have evolved twice. It means that if modern humans arrived but did not interbreed in Europe, they simply would have replaced the Neanderthals as they became extinct. If they did in fact interbreed, it challenges the idea that modern humans and Neanderthals are really distinct species.

You can imagine H Heidelburgensis living over a large area, with a population evolving toward modern humans in southern Africa and toward Neanderthals in Europe.

 

[DiracPool]

interesting. If man and Neanderthals were not able to interbreed with their common ancestor and branched separately away from it, it would seem that the same species, mankind, evolved twice.

That all depends on where you want to say where mankind begins and tribe hominini leaves off. Take your pick. Where do you want to start? Australopithecines? Homo? Homo what? Habilis? Erectus? Sapiens? It's just an evolutionary process like any other. I'm not exactly sure what your question is. Perhaps getting a handle on how many different human species there were, or whether Sapiens and Neanderthals interbred and we currently are a combination of both. There's a large literature on the latter question that you can explore very easily with a search. As far as the former, again, it depends on where you place your rubric.

 

[lavinia]

Well, if H Heidelburgensis is the common ancestor, we would expect a mixed interbreeding population sometime during the period between -700 ka and -375 ka. With divergence, separate populations looking like modern humans and looking like Neanderthals would have developed. Since H Heidelburgensis was present in Europe, I suppose it's possible that the Neanderthals, as we know them, first appeared there and were adapted to the conditions there. It doesn't mean modern humans would have evolved twice. It means that when modern humans arrived but did not interbreed in Europe, they simply would have replaced the Neanderthals as they became extinct. If they did in fact interbreed, it challenges the idea that modern humans and Neanderthals are really distinct species.

You can imagine H Heidelburgensis living over a large area, with a population evolving toward modern humans in southern Africa and toward Neanderthals in Europe.

Nice description. What seemed remarkable was this: If Neanderthals and man could not interbreed with their common ancestor then they were both different species from that ancestor. Yet they branched separately and became the same species - since they could interbreed. This seemed amazing to me. I guess what you are saying is that they actually did branch away from an ancestor that was the same species.

 

[Grant Gussie]

You're statement
"If Neanderthals and man could not interbreed with their common ancestor then they were both different species from that ancestor"
is not quite right.

If humans and neadertals could (as seems likely) interbreed, they would most certainly have been able to interbreed with their common ancestor (if they were provided with the requisite time travel technology).

The ability to interbreed is really just a guidline for defining two different species. Fertile hybrids between recognized species are not common, but they are seen. For example wolves and coyotes are perfectly capable of interbreeding, but in the wild almost never do because of "cultural" reasons (they don't like each other) rather than biological. The genetic differences are not great enough to prevent cross-fertilization, but they are great enough that reproductive adults do not see each other as potential mates.

The barriers to human/neadertal interbreeding would similiarly be cultural, not biological. They would almost certainly have seen each other as rivals, and probably quite ugly (it is odd to thnk that a neandertal would find you quite homely). And if either saw a living heidlebergensis, they would have regarded him as being quite odd looking and not a particularily good catch either.

 

[SW VandeCarr]

You're statement
"If Neanderthals and man could not interbreed with their common ancestor then they were both different species from that ancestor"
is not quite right.

If humans and neadertals could (as seems likely) interbreed, they would most certainly have been able to interbreed with their common ancestor (if they were provided with the requisite time travel technology).

The ability to interbreed is really just a guidline for defining two different species. Fertile hybrids between recognized species are not common, but they are seen. For example wolves and coyotes are perfectly capable of interbreeding, but in the wild almost never do because of "cultural" reasons (they don't like each other) rather than biological. The genetic differences are not great enough to prevent cross-fertilization, but they are great enough that reproductive adults do not see each other as potential mates.

The barriers to human/neadertal interbreeding would similiarly be cultural, not biological. They would almost certainly have seen each other as rivals, and probably quite ugly (it is odd to thnk that a neandertal would find you quite homely). And if either saw a living heidlebergensis, they would have regarded him as being quite odd looking and not a particularily good catch either.

I agree that interbreeding between similar species is possible, but when it happens, and one species cannot be studied directly, it raises questions as to whether the process of forming distinct species is complete. I used the word "challenge", not "rule out". In any case, I'm not sure if any low level interbreeding between Neanderthals and modern humans is all that important in understanding our origins. It just means we were genetically closer to Neanderthals than previously thought.