Neanderthals almost disappeared 110,000 years ago

As our ancient relative, Neanderthals, experienced a dramatic demographic collapse, the delicate structure of the inner ear reveals a critical moment in human evolution, which may have set the stage for their ultimate extinction thousands of years later.

An international team of researchers, including scientists at Binghamton University, found evidence of an unknown population bottleneck event that occurred about 110,000 years ago, which examined nearly 400,000 years of Neanderan evolution. A tiny balanced structure in the inner ear of the fossil specimen.

The study, published February 20 in Nature Communications, challenges long-term assumptions about Neanderthal evolution while providing new insights into the population history of our closest relatives.

Balanced Organ tells an Evolutionary Story

The researchers focused on semicircular tubes (three liquid-filled structures in the inner ear, responsible for our sense of balance), fossil specimens found from sites in Europe and West Asia. These include special “Neanderthal” fossils from Atapuerca, Spain (about 400,000 years ago), early Neanderthals from Krapina, Croatia (about 130,000 years ago) and the “classic” Neanderthal.

“It is well known that the development of inner ear structures is under very strict genetic control because they are fully formed,” explains Rolf Quam, a professor of anthropology at Binghamton University and co-author of the study. “This makes the semicircular tubes Change becomes an ideal proxy for studying evolutionary relationships between species, as any difference between fossil samples reflects potential genetic differences.”

Using advanced three-dimensional imaging and mathematical modeling techniques, the team measured morphological diversity (or “difference”) in the shape of these semicircular tubes in different Neanderthal populations. What they found was that classic Neanderthals of these structures had significantly less variation in these structures than Neanderthal ancestors and early Neanderthal relatives.

Population collapse confirmed

This reduces variation in line with the latest findings from ancient DNA studies that suggest genetic bottlenecks in Neanderthal lineages. This bottleneck usually occurs when population size drops dramatically, resulting in loss of genetic diversity.

The group’s analysis of inner ear morphology provides independent confirmation of this genetic bottleneck and helps locate its time to approximately 1,100,000 years ago, a period consistent with climate change in Europe.

“By including fossils from a wide range of geographical and time ranges, we are able to capture a comprehensive picture of Neanderthal evolution,” Mercedes Conde of Cátedradeotoacúacúasticaevolutiva evolutiva de hm la la la la aalcalá -Valverde) said. . “The reduction in diversity observed between the Krapina sample and the classic Neanderthals is particularly clear, providing strong evidence for bottleneck events.”

Challenge previous assumptions

Surprisingly, the team found that earlier populations of Neanderthal ancestry maintained relatively high diversity. This challenges the obvious loss of genetic diversity previously shown by Neanderthals in evolution with other human lineages.

“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,” noted Alessandro Urciuoli, lead author of the study from the Institut Català de Paleontologia Miquel Crusafont at the University of Barcelona Autònomade Universities. “This challenges the common assumption of bottleneck events in the origin of Neanderthal descent.”

The results show that Neanderthals maintained healthy population levels and genetic diversity hundreds of thousands of years ago, and then experienced a significant decline. This late-emerging bottleneck could make Neanderthals more vulnerable to further environmental challenges and competition with modern humans, which began to expand to Europe about 45,000 years ago.

New research boundaries

Brian Keeling, a graduate student at Binghamton University and co-author of the study, highlighted the innovative approach to the study: “It is exciting to include it in this research project, which relies on some of the latest in our field. The cutting-edge approach. As a student of human evolution, I am always surprised at the research that drives our intellectual boundaries.”

This study represents a novel application of inner ear morphology in solving problems related to population history that can only be accessed by ancient DNA analysis. This method is particularly valuable for older fossil specimens, where DNA is often difficult or impossible to recover.

By combining anatomical and genetic methods, researchers are gradually bringing together more complete images of Neanderthal demographic history – from the emergence about 400,000 years ago to the disappearance about 40,000 years ago.

110,000 years ago, evidence of large population collapse added to the important work of this conundrum, suggesting that Neanderthals faced serious demographic challenges before they met modern humans. These findings may help explain why despite their strong body and large brains, Neanderthals eventually disappeared while our own species flourished.

Our understanding of human prehistoric history, including the mysterious disappearance of our closest evolutionary cousin, will only deepen as researchers continue to develop new ways to extract evolutionary information from fossils.