Genetic evidence

Neanderthals, a species of Homo Neanderthalensis originated in Europe and parts of western Asia from about 230,000 to 29,000 years ago, during the Palaeolithic period. The relatively large number of Neanderthal fossils and their good preservation offers the possibility of healthy assumptions about their evolution and paleobiology. Nevertheless, debate still continues on important issues, and this suggests that deeper hypothetical and methodological differences lie at the root of the lack of agreement. Such disagreements are not likely to be determined by further fossil findings, but rather require critical re-evaluation of the evidence at hand and the purpose of novel techniques and perspectives.

The Neanderthals are best known ancient humans for two of the main reasons. Firstly, they lived in the region which has been explored more than any other for its prehistory- Europe. Secondly, many of them lived in caves, and they adopted the habit of burying their dead in the caves in which they lived. This has meant that Neanderthal bodies have had a greater chance of becoming fossilized, since they were protected by burial from destruction through erosion, trampling or scavenging. Moreover, it is these caves that can also hint at intricacy on how these Neanderthals became extinct.

The Neanderthals are seen to be the best embodied and most studied group in the fossil human record, and were distinguished from all other people, fossil or living, mainly in the skull and face. The Neanderthals gained a popular image of being more primitive than we see them today. The skulls were distinctive, being long and low-doomed like those of Homo erectus, but only moderately bro-ridged and of much larger cranial volume. So far as brain size is concerned, their mean volume was greater than that of modern humans, a fact which may reflect the need to control more musculature than we possess.

The face was notable for its huge length and for its extreme forward ridge along the midline, from which both the orbits and the cheeks swept backward. The morphology and wear of the front teeth indicate that the front of the mouth normally functioned as a clamp or vise, and the structure and position of the face were probably related to this behaviour. The jaws were robust with a molar gap between the last molar, the wisdom tooth and the ascending branch of the jaw bone. They may well have had a higher larynx than humans with less capacity for speech but, less likelihood of choking.

They had a ridged occipital protuberance at the back of the skull with a larger nuchal area for neck muscle attachment below it. One feature of interest is the much enlarged nasal cavity with broad, rounded noses. Such a physiological adaptation, in their cold climate, would have conserved both heat and moisture in the freezing air. They had unconventionally enlarged pelves, perhaps to make birth of large-brained infants easier. Possibly females were pregnant for a full year and gave birth to much bigger less helpless infants.

Like earlier people, the Neanderthals had extremely robust postcranial skeletons, suggesting both extraordinary muscular strength and remarkable endurance. Their forearms and lower legs were relatively short, perhaps as a functional correlate of general limb robusticity or perhaps as part of a physical adaptation to the generally cool climate conditions in which they evolved. Evidence for Neanderthal extinction has been a debateable topic for many years. Whether the extinction of the Neanderthals was a result of genetic or a matter of survival of the fittest has been of much interest. There is very little data on the reasons why early human species became extinct.

However the fossil and archaeological record is good enough to make some informed guesses. It is clear their lineage can be traced through increasing specializations in the braincase and face etc over about 300,000 years in Europe. But they disappeared over a period of less than 20,000 years. They lived in western Asia until at least 50,000 years ago, and in Western Europe they may have survived in marginal regions until less than 30,000 years ago.

Between 40,000 and 30,000 years ago, it appears that the last Neanderthals and the first modern people in Europe, the Cro-Magnons, actually co-existed, but it is unclear whether they regularly encountered each other, were in conflict, or at the other extreme, perhaps even interbred. The fossil evidence does not show an evolutionary transition occurring between the last Neanderthals and the first moderns, but it is disputed whether there is evidence of hybridization.

It has also been found that mines at a Spanish site not far northeast of Gibraltar, called Zafarraya Cave, recently revealed new fossil evidence of the Neanderthals, their stone tools and food debris, and indicated that they had remained on in this region much later than had previously been undecided. Evidence from France suggested that the Neanderthals had disappeared from there by about 32,000 years ago, dated by the radiocarbon method. But the same method dates the last Neanderthal occupation of Zafarraya Cave to only about 27,000 years ago.

If this disputed date is accurate, it means that the Neanderthals apparently survived in Southern Spain long after they had disappeared further north and even longer after the appearance of the first modern people in Europe, some 40,000 years ago. Further dates from other sites in Gibraltar, southern Spain and Portugal appear to support this scenario of late Neanderthal survival in pockets, and in this context, areas like mountain ranges and even Britain could have provided refuges. There are comparably late dates from regions such as Croatia, the Crimea and the Caucasus.

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