[thedoc (OP)]

Roz Campbell  asked the Naked Scientists:
   
Hi Chris,

Just been reading various things on your website & I could spend a few more hours I'm sure as there's just so many interesting things.

The one thing I saw which made me read it twice was "Dating the Neanderthals of Mezmaiskaya Caves"  I found the part "Neanderthals Mechanism of their dispersal & later their Extinction" but I've been thinking what if they didn't become Extinct, but were merged with incoming Modern Humans?

I've been thinking back to when I was told that O blood group is the oldest blood group, so thought well maybe that blood group came from the Neanderthal's & here we are still here & not extinct like they thought.  As the Neanderthals that were found at Mezmaiskaya Caves & some tests were done on them, did they find out their blood group?

Perhaps something in their DNA could point the way to whether or not they became extinct or not.  Just a thought.  Your website is really great.

Roz Campbell

What do you think?

[cheryl j]

The last article I read about neanderthals (I think it was on www.sciencedaily.com) said that there is neanderthal DNA in humans except in some people of pure African ancerstry. It's not very much though, so yeah, I guess you'd have to say they died out for the most part.

[CliffordK]

One would consider Neanderthals having separated from homo sapiens (or visa-versa), creating two separate species.

Some evidence indicates that later hybrids did in fact occur.  However, the question would then be whether a hybrid is representative of the species of a whole.  It is unlikely that a significant number of original Neanderthal genes have survived the later gene dilution.

Consider the American Buffalo (Bison).  It is possible to cross breed them with domestic cattle to make fertile offspring, often called beefalo.  After a few generations of gene dilution, how much buffalo is left?  If the American buffalo was to go extinct, would we consider it not extinct because of the existence of beefalo hybrids?

[chris]

Funnily enough, quite independently I asked this same question of Diana "Naked Archaeology" Carroll last week. Her answer was similar to the suggestion made by Cheryl J, above: there are shared gene sequences amongst neanderthal and sapiens in Europe and across to east Asia. These shared sequences are absent amongst African lineages, however. This largely rules out coincidental genetic convergence in response to some kind of environmental pressure, since it is hard to envisage a pressure that would be present everywhere except Africa. Instead, this observation fits more closely with a neanderthal / modern human mixing.

[CliffordK]

since it is hard to envisage a pressure that would be present everywhere except Africa.

Certainly there are local responses, such as adaptations for the absorption of Vitamin D leading to lighter skin almost everywhere outside of Africa.  Also adaptations to vector borne diseases such as Malaria that are dependent on the distribution of the disease vector.

It would depend on what the purported Neanderthal genes encode for.

And, in fact, some of the purported Neanderthal genes actually encode for disease resistance.

Indeed, DNA inherited from Neanderthals and newly discovered hominids dubbed the Denisovans has contributed to key types of immune genes still present among populations in Europe, Asia and Oceania. And scientists speculate that these gene variants must have been highly beneficial to modern humans, helping them thrive as they migrated throughout the world.

Disease, of course, can create a highly selective evolutionary pressure.

Another option would be that the genes were inherited from a common ancestor, and lost by certain homo sapien lineages.  However, mutation rates might help with determining when the gene cross-over occurred.

Anyway, I'm agreeing that likely some Neanderthal genes remain in the human population, but these genes are highly diluted. 

So, the offspring of some Neanderthal children have survived as hybrids, but the species as a whole did not.

[JimBob]

There are also two other possibilities to be strongly considered.

First, how far had "separation" from our common ancestor did we humans and neanderthals progress from our same genius brothers and sisters of the genus Homo? There are numerous examples of two highly related species from the same genus that are capable of reproducing inter-species. Are we really that far evolved from our blood kin? The  Breton and Gallic peoples of France and central Europe - or the Gauls - are considered not that far removed from Neanderthal by many anthropologist. I suggest we may still be neanderthals. The mechanism for such gene differentiation from the African Homo Sapiens, etc is time - time in the sun, time in a different environment and the other pressures of environment that were different..

The theory I am most accepting of is the idea that the late evolutionary differentiation of the Neanderthal and H. Sapiens was not divergent evolution from a common ancestor now extinct (the definition of divergence) but just common adaptive divergence from the genus Homo for the late arriving Neanderthals.