It seems hard to believe but I took the two photos above last Wednesday. I have put them because they are the perfect introduction to today's post. Yes, the Iberian Peninsula is so topographically diverse that you can go from snowstorm to desert and palm trees within a day! For those living in Iberia this simple fact may not seem unduly surprising but it is not self-evident if you come from outside. Yet this simple observation, which seems to have escaped archaeologists and palaeoanthropologists, is the key to the late survival of Neanderthals in this peninsula that is almost a mini-continent.
Those of you who may have read the latest news about the publication of the Neanderthal genome and the revelation that some Neanderthal genes are present in Eurasians today may be wondering why I am still talking of late Neanderthals, and their extinction. As some popular headlines, and even palaeoanthropologists, have proposed the Neanderthals are still among us! This is absolutely ridiculous. The Neanderthals are extinct, make no mistake about it. Their particular body form, physical and behavioural characteristics are gone. But, before going they left us the precious gift of some of their genes.
This latest find fits beautifully in the predictions I have been making in various publications for some years now, against the grain of scientific consensus. I have spent many years debunking the myth of the ape-like Neanderthal. Instead, I have called them humans, to the annoyance of colleagues. Now, we find they were so human that they even mated with our ancestors and thus were also ancestors of ours! Those who have argued that they were so different that they were different species must now bow to this new evidence and accept that they were not because it is a well known fact of biology that different species do not mate freely in the wild!
But let us return to Iberia and its contrasts...
The chart above is also from the paper I published in 2007 with Professor Carrion. It is based on fossil pollen analyses in three sites, numbered in the map above. The top section is Velay in the French Massif Central. It reveals that during the last Ice Age the vegetation went from steppe-tundra when it was cold and dry to an open taiga when it was warmer. In other words vegetation akin to northern Siberia today! The second set is from Navarres near Valencia. We see an improvement along the Mediterranean coast of Iberia with an open Mediterranean woodland when warmer but a conifer steppe when cooler. But when we looked at Gibraltar on the southern coast (the lowest section) the outcome was stunning. Mediterranean savannahs and woodland dominated at all times, no matter how cold it got. In the worst moments all we could pick up were some montane trees, like Black Pines, at the lower elevations. Recall that in the last post we showed how the cold fauna of Europe never reached this far south.
How do we find fossil pollen? In the Gorham's Cave we find it in the sediment that we excavate, but we also find it in hyaena coprolites (below). Coprolite is a nice way of saying fossil dung but how can carnivore dung have pollen? Well the hyaenas that roamed the area fed on carcasses or freshly killed herbivores, like deer. They ate their intestines and so swallowed the pollen. 40 thousand years later the fossil dung provided us with a perfect random sample of the plants that grew outside the cave at the time of the Neanderthals!
40-thousand year old fossil coprolite from a Spotted Hyaena from Gorham's Cave, Gibraltar
We will leave this here for today. Just a parting thought: the topographic diversity that gave me snow and palm trees on the same day allowed pockets of landscape where Neanderthals could seek refuge. In the open plains of central Europe these options were less readily available and the Neanderthals died out sooner than in the south - a simple lesson in geography that seems to have escaped the eye ot the students of the Neanderthals!
VERY interesting Clive, I really appreciate the explanation of the pollen findings as they relate to flora of the era.
ReplyDeleteOn a personal level I've always though an ice age would be as inhospitable as Antarctica. I had no idea it was more akin to Siberia, and more than that, I had no idea the ice age only extended a certain distance.
For some reason I've always though the ice age was global in its reach; I don't know why I think this. Perhaps we are too conditioned by Hollywood films or poor educational curriculum to truly grasp the real history of our ancestors.
Returning to the point about Neanderthal dying out completely yet still remaining with us, and I hope this question doesn't sound racist or discriminatory, but of the people we encounter who have pronounced foreheads, more hair, larger jaws etc, is this normal within Homo Sapiens, or are these people 'throwbacks' to a more ancient physiology. Again my apologies for the wording.
Cheers, Andy
Hi Clive, If Neanderthals could mate with AMH shouldn't we look more carefuly at the proposition that one cause for the Neanderthal extinction in the Iberian Peninsula could be that they have cross-bred with AMH and eventually "merged" with our own species? This hypothesis has been around for some time, and critics pointed out there was no evidence that the two "species" mated. Now there is. So where to we stand regarding this hypothesis now?
ReplyDeleteAndy, I don't think that you are looking at throwbacks, just part of the natural range of variation in humans, like in any other species. What we find when we compare Neanderthals and our ancestors is that they differ in a suite of characters which are largely non-overlapping. It isn't just brow ridges. And also each has some features the other does not. In any case you can have convergence of characters, well known in biology, which need not imply direct relationship. You know, whales look like fish but are mammals...Let me know if this helps. Clive
ReplyDeleteGood one Miguel, I was waiting for it! In my work I have always separated extinction as a mutli-scale process, something my colleagues have missed - for example when they have tried to match the Neanderthal extinction to a specific Heinrich Event (for others Heinrich Events were moments when massive icebergs were discharged onto the Atlantic causing significant cooling).
ReplyDeleteMy argument has been that climate, through habitat and resource change, fragmented Neanderthal populations and this was a long-drawn process, with some reversals, lasting tens of thousands of years. Now, once these populations were fragmented, each went for different reasons which we may never know: inbreeding, Allee effects, random fluctuations, gene swamping (what you are talking about), even competition.
So I have always included gene swamping as a potential cause of the fusion of Neanderthals and Modern Humans. Since the Modern populations were increasing and the Neanderthals decreasing we would expect what we see. But where did extinction happen by fusion? It would have been most probable where they overlapped in time longest. This has to be Central and Western Europe. Maybe also southern Siberia. But for Iberia, maybe the Pyrenees and Cantabria. To the south the Modern Human entry seems to have taken place largely after the Neanderthals had gone. Certainly in Gorham's Cave there is no temporal overlap so they could not have mated here!
Note also that the supposed transitional industries, those that some have claimed to show Neanderthals mimicking Modern behaviour, are not found in the deep south. You find them in Cantabria, Pyrenees, SW France, Alp foothills, Carpathians, etc. In other words on the edge of the Eurasian Plain in the contact zone with the heterogeneous terrain.
What do you think Miguel, as a biogeographer? Does this not make sense to you?
Cheers,
Clive