The history of the Neanderthals, the ‘other’ intelligent species that mysteriously disappeared after sharing Europe with Homo sapiens For several thousand years, it is complicated and not quite well known. We know, for example, that they appeared in the old continent around … 250,000 years, and that descend from a series of old populations (the ‘preneanderthals’), who already lived in Europe for at least half a million years.
Once established in the continent, the Neanderthals fell to their wide and without competition for more than 200,000 years until, around 45,000, another species, ours, crossed the urals and also landed, also, in the European continent. From that moment on, the history of the Neanderthals precipitates, and that other human species enters a rapid decline that ends with its total disappearance. Determining the causes of that sudden extinction constitutes one of the greatest challenges facing modern science.
About to disappear
For a long time, it was thought that, since its appearance as a well -differentiated species, there were no significant changes in the evolution of the Neanderthals, but a series of recent research based on DNA samples have shown that, about 110,000 years ago, just in the middle of its long stay in Europe and long before the arrival of Homo Sapiens, a drastic reduction of genetic variability among the first Neanderthals (or ancient Neanderthals) and the last (also called ‘classic’ neanderthals). A genetic ‘bottleneck that endangered the very continuity of the species and that was all likely due to a sudden’ population collapse ‘that caused a significant drop in the number of individuals.
Similarly, scientists also thought that, much earlier, there had been another bottleneck, one related to the origin of the lineage. Therefore, the idea that, as a consequence, the first ‘true’ Neanderthals already emerged with the disadvantage of having a much lower genetic diversity than that of their ancestors, the pre -forests, was extended. However, the existence of that first bottleneck has never been contrasted with genetic data, since sufficient material has been preserved to carry out DNA studies.
Study the internal ear
Now, a team of researchers led by Alessandro Urciuoli, and Mercedes Conde-Valverde, from the Autonomous Universities of Barcelona and Alcalá, and in which the paleoanthropologist Juan Luis Arsuaga participates, has used another method to check if those bottlenecks were really or not.
With that idea in mind, the researchers focused on the study of the internal ear, particularly the so -called ‘semicircular channels’, where the sense of balance lies, and measured the morphological diversity of that structure in different Neanderthal fossils. A type of analysis that does not imply the use of DNA but whose results are comparable to those of genetic studies. The work has just been published in ‘Nature Communications’.
The fossil remains used by the team come from two exceptional collections: the site of the Sima of the bones of Atapuerca (Burgos), dated in 430,000 years and that constitutes the most large sample that exists of pre -pedertral fossils; and the Krapine site (Croatia), which is the most complete collection we have of ancient Neanderthals, between approximately 130,000 and 120,000 years ago.
Urciuoli and his colleagues, therefore, studied the degrees of morphological diversity of the semicircular channels in both samples, and then compared them to those of classic Neanderthals of different antiques and different geographical origins.
Surprising results
The first result of the study shows that the morphological diversity of the semicircular channels of the classic Neanderthals is clearly lower than that of the ancient pre -articles and the neanderthals, which coincides with the paleogenetic results that the bottleneck found 110,000 years ago. «In including fossils of a wide geographical and temporal range-explains Conde-Valverde-we could capture a complete image of neanderthal evolution. The reduction in the diversity that we observe between the Krapine sample and the classic Neanderthals is especially surprising and clear, and provides strong evidence of a bottleneck event ».
However, the study contradicts the alleged anterior bottleneck, related to the origin of the Neanderthals, which forces to propose new ideas that explain their appearance. “We were surprised to discover that the pre -Andaltrales of the Sima of the bones,” Urciuol, had a level of morphological diversity similar to that of the ancient Neanderthals of Krapine. Which challenges the common idea that there was a bottleneck in the origin of the Neanderthal lineage ».
Work, then, is a good example of how science can challenge preconceived ideas and open new windows to our past. The findings of this research, in effect, not only help us better understand the way in which Neanderthals evolved, but will force scientists to ask new questions about the genetic diversity of that other intelligent human species. What other events or processes could have affected the evolution of Neanderthals throughout their history? And how does the genetic diversity of Neanderthals compare with that of other hominid species?
Questions that must be addressed in new investigations, either obtaining older samples of DNA of Neanderthals and Predertrales, or studying other aspects of their biology.
#Spanish #researchers #confirm #Neanderthals #suffered #population #collapse #years
