The study of protein material from a tooth of Homo antecessor from Atapuerca, the oldest human genetic evidence to date

A study developed by the University of Copenhagen in which researchers from the National Center for Research on Human Evolution (Cenieh) have participated on the study of protein material from a tooth of Homo ancestor of Atapuerca, becomes the oldest human genetic evidence till the date. This analysis published today in the journal “Nature” allows to clarify a part of human genealogy.

Thus, after scientists recovered one of the oldest human genetic datasets ever achieved, an important advance has been made in studies of human evolution. The achievement has been obtained after analyzing an 800,000-year-old tooth, belonging to the Homo antecessor species, discovered in 1994 at the TD6 stratigraphic level of the Gran Dolina site, in the Sierra de Atapuerca (Burgos).

The findings were made by scientists from the University of Copenhagen (Denmark), in collaboration with the coordinator of the Cenieh Paleobiology Program, José María Bermúdez de Castro, and its director, María Martinón-Torres, as well as researchers from other international institutions. . The scientific director of the Museum of Human Evolution (MEH), Juan Luis Arsuaga, also participated.

As explained by the researcher at the Globe Institute of the University of Copenhagen, Frido Welker and first author of the article, the analysis of ancient proteins provides evidence of a close relationship between Homo antecessor, Homo sapiens, Homo neanderthalensis and the Denisovans. “Our results support the idea that Homo antecessor was a sister group to the hominin group that includes Neanderthals, modern humans, and Denisovans, so we must assume that the phylogenetic trees we have obtained describe well the kinship relationships between these hominin groups.” Welker says.

Reconstructing the human family tree

Using a technique called mass spectrometry, researchers have sequenced ancient tooth enamel proteins, and have been able to pinpoint the position of Homo antecessor in the human family tree.

The new method, developed by researchers at the University of Copenhagen’s Faculty of Health and Medical Sciences, allows scientists to retrieve molecular evidence to accurately reconstruct human evolution from previously unknown times.

The respective genealogies of chimpanzees and humans diverged between seven and nine million years ago. Ever since this information has been available, scientists have striven to better understand the evolutionary relationships between modern humans and all the other species of our lineage, of which only their fossil remains remain.

“Much of what we know so far is based on the results of ancient DNA analysis or on observations of the shape and physical structure of fossils. Due to the chemical degradation of DNA over time, the oldest human genetic material recovered to date is barely older than 400,000 years,” explains associate professor at the Globe Institute, University of Copenhagen, and lead of the research group, Enrico Cappellini. “Now, the analysis of ancient proteins with mass spectrometry, an approach commonly known as paleoproteomics, allows us to overcome these limits,” he adds.

Theories about human evolution

The fossils analyzed in this study were found in 1994 by the team led by Juan Luis Arsuaga, José María Bermúdez de Castro and Eudald Carbonell. Initial observations led to the conclusion that Homo antecessor had been the last common ancestor of Neanderthals and modern humans, a conclusion based on the morphology of the fossils.

For years, the exact relationship between Homo antecessor and other human groups, such as Sapiens and Neanderthals, has been hotly debated among experts. Although the hypothesis that Homo antecessor could be the common ancestor of Neanderthals and modern humans is very difficult to fit into the evolutionary scenario of the genus Homo, the new findings in TD6 and later studies revealed several characters shared between Neanderthals and the species. human found in Atapuerca.

Furthermore, additional studies confirmed that the facial features of Homo antecessor are very similar to those of Homo sapiens and very different from those of Neanderthals and their most recent ancestors.

“I am glad that the study of proteins provides evidence on the possible relationship between Homo antecessor, the common ancestor of Neanderthals, modern humans and Denisovans. The features shared by the TD6 species with these hominins clearly appeared much earlier than previously thought. Therefore, it could be a basal species of the emerging humanity that gave rise to Neanderthals, Denisovans and modern humans”, declares José María Bermúdez de Castro.

Interdisciplinary collaboration

Results like these are possible thanks to extensive collaboration between different research fields, from paleoanthropology and biochemistry to population proteomics and genomics, as well as between different international institutions.

Retrieving ancient genetic material from very rare fossil specimens requires expertise and high-quality equipment. This is the reason behind the ten-year strategic collaboration between Enrico Cappellini and Professor at the Novo Nordisk Foundation Center for Protein Research at the University of Copenhagen and co-author of the paper, Jesper Velgaard Olsen.

“This study is an exciting milestone in paleoproteomics. Using a state-of-the-art mass spectrometry technique, we determined the amino acid sequence of protein residues from Homo antecessor tooth enamel. We can then compare the ancient protein sequences that we ‘read’ with those of other hominins, for example Neanderthals and Sapiens, to establish how they are genetically related,” says Jesper Velgaard Olsen.

The study of human evolution by paleoproteomics will continue in the coming years through the recently started project ‘Palaeoproteomics to Unleash Studies on Human History (PUSHH)’, funded by the European Union and to which many of the co-authors of the article belong. “I really look forward to seeing what paleoproteomics will reveal in the future,” concludes Enrico Cappellini.

“It is exciting to pioneer the application of such an innovative field as paleoproteomics to the human fossil record. The next few years will be full of scientific surprises”, points out María Martinón.

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