The oldest human genetic data has been analysed

A team of scientists have succeeded in sequencing the tooth enamel proteins from the remains of ‘Homo antecessor' discovered in Atapuerca, Spain more than 20 years ago. The results support the theory that this species would be at the base of a group that gave rise to a new emerging humanity in which modern humans are included.

In 1994, the first human remains were discovered at the site Gran Dolina of Atapuerca, a revolutionary find that had a great impact on the scientific community. In 1997, the team of archaeologists led by Juan Luis Arsuaga, José María Bermúdez de Castro and Eudald Carbonell published in the magazine Science the description of this new species: Homo antecessor, a hominid with a surprising mixture of primitive and modern characteristics.

Their discovery contradicted the prevailing theory, which indicated that the first humans would have arrived in Europe about 500,000 years ago: the remains of Atapuerca were considerably older, about 800,000 years old. The article generated a lot of controversy, since its authors also defended, from the morphological analysis of the remains found, that H. antecessor would be the common ancestor of a group that would later give rise to modern Neanderthals and humans.

Now, the magazine Nature publishes a paper that reveals the results of the sequencing of dental enamel proteins from these fossils using a technique based on mass spectrometry. The analysis provides evidence of a close relationship between Homo antecessor, Homo sapiens, Neanderthals and denisovans. "Our results support the idea that Homo antecessor was a sister group of hominids of which they form Neanderthals, modern humans and Denisovans, so we have to assume that the phylogenetic trees we have obtained describe well the kinship relations between these hominid groups," explained Frido Welker, a researcher at the University of Copenhagen and the first author of the work.

"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 barely exceeds 400,000 years,” explains Enrico Cappellini, associate professor at the Globe Institute and head of the research group.

"Now, the analysis of ancient proteins with mass spectrometry, an approach commonly known as paleoproteomics, allows us to overcome these limits," Cappellini adds.

A revolutionary method

Thanks to this new technique, scientists have managed to recover one of the oldest set of genetic data ever obtained. "These are the oldest proteins recovered so far in human fossils," explains José María Bermúdez de Castro, co-director of the Atapuerca Foundation and who has also participated in the study. "Proteins are formed by DNA, so we could say that the oldest genetic sequences in human history have been obtained. This, in itself, is already a milestone.”

The researcher believes that applying this technique to other hominids remains will open a new era in the study of human evolution. As the expert points out, the morphology of fossil remains gives us information when we have many individuals, as was the case of H. antecessor: “170 remains were discovered at level TD6 of the Gran Dolina deposit of the Atapuerca mountain range, and this gave us a lot of information about what the species was like. This new work reinforces what we had already said, that it is possible that H. antecessor was at some point of the base that gave rise to a new emerging humanity in which we would be Neanderthals, denisovans and modern humans.” However, when we talk about the remains of a single specimen, the information provided by the morphology is very limited. The application of the new technique to these isolated individuals will open, according to the researcher, "a new dimension that will have a very important impact in the next five or ten years", he concludes.

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