The general idea is that host cell line infections can occur (TVT, Tasmanian devil facial tumor, and a contagious leukemia in Syrian hamsters), can mutate into something that is nonlethal and/or chronic if selection favors that (TVT usually goes away with time), can infect related species (TVT can be experimentally transmitted to wolves, jackals, coyotes and red foxes), and might exist in humans today. There are human diseases that appear infectious for which the transmissible agent has not been identified - sarcoidosis, for example. So modern humans might suffer from infectious organisms directly derived from Neanderthals or other archaic humans. As far as I know, no one has yet thought of looking for Neanderthal-derived cells inside people. Since such cells would have the required genetic code for making human signal molecules, they might be particularly likely to employ baroque forms of host manipulation.
… there _could_ be Neanderthal-derived cell line infections, and this is really the only scenario I've been able to come up with that gives us live Neanderthals - hiding in your sinuses, or maybe your prostate. The only one so far. There are other known infectious diseases in which some metazoan has completely chucked complexity and gone back to being a germ: whirling disease in fish, for example.
Will it then be possible to resurrect Neanderthals à la Jurassic Park? Another GNXP commenter, Eric J. Johnson, poured cold water on the idea:
… the problem would be a lack of purifying selection on all the morphogen genes, not to mention all the neuron-specific genes, etc. The tumor doesn't need any of that stuff. How fast they would all turn to garbage, I don't know. Probably pretty fast.
ReplyDeleteBaroque forms of host manipulation".
My guess is that what G.C.'s getting at here is the manipulation was responsible for the High notes of the singing Neanderthals among other things.
I bet he wouldn't have said that to their faces though.
Is there any records of neanderthal depiction in cave paintings ?
ReplyDeleteRG
The infectious organism sounds like the one mentioned in The 85% truism
ReplyDelete"a dog tumor that has developed the ability to spread to other dogs through sexual contact: canine transmissible venereal sarcoma (CTVS). It looks and acts like an infectious microbe, yet its genes would show it to be a canid and, conceivably, some beagles may be genetically more similar to it than they are to Great Danes (Cochran, 2001; Yang, 1996).
The lack of contact with (or genetic influence from) Neanderthals is what one would expect if they looked and acted like big apes.
Accelerated genetic drift on chromosome X during the human dispersal out of Africa
ReplyDeleteAnon,
ReplyDeleteThere are no portraits of neanderthals in cave paintings, at least nothing realistic. The neanderthals had much less artistic ability than early modern humans had, probably because they were less able to imagine objects in three dimensions. This is reflected in the crude detail of their artifacts.
Tod,
I wouldn't rule out sexual contact between modern humans and neanderthals. There was one skeleton from Spain (dated to 25,000 BP) that seems to exhibit a mosaic of neanderthal and modern human traits. I suspect that mixed neanderthal/modern human populations occupied an environmental niche (high altitude uplands) that modern humans did not manage to occupy until later.
mixed neanderthal/modern human populations occupied an environmental niche (high altitude uplands) that modern humans did not manage to occupy until later.
ReplyDeleteIf EMH did not manage to occupy this niche then why would Neanderthal/EMH hybrids have the inside track.
If Neanderthals did bring something to the table it would have to have been be something really good - so where is it?
" Neanderthals possess neither the microcephalin gene, linked to bulging brains in humans, nor humans’ increased fertility gene".
Peter, is this hybrid squeleton found in Spain been tested for DNA ?
ReplyDeleteThe nearest high altitude habitat from southern Spain is the Pyreneans, but why do you think these hybrids would prefer high altitude, because the couldn't stand the heat in summer and were looking for cool areas ?
thanks,
RG
How about this line of thought:-
ReplyDeleteIf vitamin D played any part in the evolution of Europeans' white skin - why then do they have a mechanism for destroying vitamin D which kicks in after 20 minutes in the summer sun (10am-2pm) even in the extreme low UVB environment of Scotland?
It seems to me that in northern Europeans evolution ought to have disabled this mechanism to a certain extent to optimize Vitamin D before evolving white skin. The excess Vitamin D being stored in the body for the winter.
(The wikipedia article Vitamin D contains the following statement Exposure to sunlight for extended periods of time does not cause vitamin D toxicity.[31] This is because within about 20 minutes of ultraviolet exposure in light skinned individuals (3–6 times longer for pigmented skin) the concentration of vitamin D precursors produced in the skin reach an equilibrium, and any further vitamin D that is produced is degraded.[31} The reference given is Environmental factors that influence the cutaneous production of vitamin D. MF Holick . The paper does not say this as far as I could see).
Anon,
ReplyDeleteNo, the apparently hybrid skeleton was not tested for DNA, at least not yet. That would certainly be an interesting line of research, all the more so because anything Neanderthalish in the results could not be blamed on contamination from modern humans.
Tod,
I don't have access to all of Holick's articles here. From what I recall, he found that there was no danger of vitamin D overproduction because excess
precursors are not converted to vitamin D beyond a certain level.
Anon & Tod,
The thinking is that the first modern Europeans were adapted to tropical environments (as indicated by their morphology). They would have thus initially colonized low-altitude Mediterranean environments and then gradually moved upward and northward into cooler environments.