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Something Bad Happened to Neanderthals 110,000 Years Agoand It May Have Sealed Their Fate
gizmodo.com
By Margherita Bassi Published February 28, 2025 | Comments (0) | A Neanderthal reconstruction in London's Natural History Museum. Neil Howard DNA studies suggest that Neanderthals underwent a steep decline in genetic diversity around 110,000 years agoa forbidding omen of the species disappearance approximately 70,000 years later. Recent research has reexamined this so-called bottleneck phenomenon by analyzing an unexpected feature: Neanderthal ears. An international research team, led by Universitat Autnoma de Barcelona paleontologist Alessandro Urciuoli, studied Neanderthal semicircular ear canalsthe three tiny tubes in the inner ear that control balanceacross different time periods to detect significant changes in genetic diversity. Their analysis confirmed that our now-extinct relatives did, in fact, undergo a bottleneck event, as detailed in a study published February 20 in the journal Nature Communications. This genetic bottleneck (i.e. a loss of genetic diversity due to small population size) did not immediately result in the extinction of the Neanderthals, but it potentially set them in that fateful direction, according to the research. The development of the inner ear structures is known to be under very tight genetic control, since they are fully formed at the time of birth, Rolf Quam, a Binghamton University anthropologist who participated in the study, explained in a university statement. This makes variation in the semicircular canals an ideal proxy for studying evolutionary relationships between species in the past since any differences between fossil specimens reflect underlying genetic differences. The present study represents a novel approach to estimating genetic diversity within Neandertal populations. Quam and his colleagues analyzed three groups of Neanderthals, comparing the semicircular canals of pre-Neanderthal and early Neanderthals to those of classic Neanderthals. The 400,000-year-old Atapuerca fossils, belonging to pre-Neanderthals (or proto-Neanderthals), were discovered in Spain. The early Neanderthal remains, called the Krapina fossils, date back approximately 130,000 years and were unearthed in Croatia. The classic Neanderthal remains come from different regions and time periods.The comparison revealed that the morphological diversity (the variation in physical features) of classic Neanderthals semicircular canals was noticeably lower than that of their forebears. This confirms previous DNA studies, which had identified a substantial loss of genetic variation between early Neanderthals and classic Neanderthals. By including fossils from a wide geographical and temporal range, we were able to capture a comprehensive picture of Neanderthal evolution, said Mercedes Conde-Valverde, a paleontologist from the Universidad de Alcal and co-author on the study. The reduction in diversity observed between the Krapina sample and classic Neanderthals is especially striking and clear, providing strong evidence of a bottleneck event.However, the researchers also made an unexpected discovery. According to the study, paleontologists widely agree that Neanderthals also experienced a significant loss of diversity at the beginning of their evolution. Consequently, the team expected to find clear differences in morphological variation between the pre-Neanderthal semicircular canals and the early Neanderthal semicircular canals. However, we were surprised to find that the pre-Neanderthals from the Sima de los Huesos exhibited a level of morphological diversity similar to that of the early Neanderthals from Krapina, Urciuoli explained. This challenges the common assumption of a bottleneck event at the origin of the Neanderthal lineage. The inconsistency will likely prompt further study of early Neanderthal demographics, specifically into whether or not their separation from our ancestors could have been impacted by such an event.Neanderthals went extinct around 40,000 years ago and for reasons that arent entirely clear. We know that anatomically modern humans (Homo sapiens) and Neanderthals interbred, resulting in their eventual absorption into our species. That Neanderthals suffered from a lack of genetic diversity and low population sizes fits in with this latest finding. Bottlenecks happen when thered a sudden and dramatic decline in population due to factors such as environmental disasters, climate change, and poor access to food, among other things. The study doesnt specify a potential cause for this Neanderthal bottleneck 110,000 years ago, but the lower genetic diversity likely made them more vulnerable to ongoing stressors and less able to adapt from an evolutionary perspective.It took a while for Neanderthals to go extinct after this unexplained population crash, but it potentially sealed their fate, as the new research suggests. Ultimately, the new study sheds light on the demographic evolution of our ancient relativeswhose genetic impact on modern humans is still visible today.Daily NewsletterYou May Also Like By Passant Rabie Published February 7, 2025 By Margherita Bassi Published January 31, 2025 By AJ Dellinger Published January 23, 2025 By Passant Rabie Published January 23, 2025 By Margherita Bassi Published January 17, 2025 By Margherita Bassi Published January 14, 2025
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