Homo antecessor may actually be the missing link, new study shows

Hyperaxion April 1, 2020 11:43 pm

Researchers were able to sequence proteins present in the teeth of a Homo antecessor, the last common ancestor of modern humans and Neanderthals.

In 1994, 800,000-year-old fossil of a Homo antecessor found in the Sierra de Atapuerca, Spain, allowed historians to conclude that this hominid was the last common ancestor of modern humans and Neanderthals. Now, a new analysis of these remains has allowed specialists to more confidently determine the place of this species in our family tree.

Homo antecessor may actually be the missing link
Representation of a Homo Antecessor, possible link between humans and Neanderthals. (Credit: Wikimedia Commons).

That’s because previously the conclusion had been based only on the physical form and appearance of the fossils – which has led anthropologists around the world to dispute how reliable this evidence was. However, the new analysis, conducted by researchers at the University of Copenhagen, Denmark, went further.

According to the article, published by the team on Nature, the experts sequenced the enamel proteins present in the fossils’ teeth. The technique allowed scientists to retrieve molecular evidence to accurately reconstruct human evolution – and thus designate Homo antecessor as the last common ancestor between Homo sapiens and Homo neanderthalensis.

Analysis of 800,000-year-old fossil reveals mysteries about human evolution.
Analysis of 800,000-year-old fossil reveals mysteries about human evolution. (Credit: Professor José María Bermúdez de Castro).

“The analysis of ancient proteins provides evidence of a close relationship between the Homo antecessor, us (Homo sapiens), the Neanderthals and the Denisovans,” said Frido Welker, research leader, in a statement to the press.

Researcher José María Bermúdez de Castro, who participated in the excavations that revealed the fossils in 1994, agrees with Welker. “I am happy that the study of proteins has provided evidence that Homo antecessor may be closely related to the last common ancestor of Homo sapiens, Neanderthals and Denisovans,” noted the scientist.

Researchers were able to sequence proteins present in the teeth of a Homo antecessor.
Researchers were able to sequence proteins present in the teeth of a Homo antecessor. (Credit: Professor José María Bermúdez de Castro).

According to him, the research also shows that some characteristics shared by the species and by modern hominids appeared much earlier than previously thought. “Homo antecessor would, therefore, be a basal species of the emerging humanity formed by Neanderthals, Denisovans, and modern humans,” said Bermúdez de Castro.

Methodology

The chimpanzee is the closest living relative of the modern human – and our lineages separated at some point about 9 to 7 million years ago. That is why studying human evolution is so complicated, according to Enrico Cappellini, who also participated in the research.

As the scientist explains, much of what we know today is based on deductions made from the morphology of the fossils found and the confirmation of these theories from DNA analysis. However, due to the chemical degradation of fossils over time, studying the genetic material of these individuals is particularly complicated.

Digital reconstruction based on fossils found in Spain.
Digital reconstruction based on fossils found in Spain. (Credit: Professor Laura Martín-Francés).

And that is precisely why the new study is so interesting. “Now, the analysis of ancient proteins with mass spectrometry, allows us to overcome these limits,” said Cappellini. For the specialist, findings like this highlight the importance of collaboration between different fields of science, such as biology, chemistry and anthropology.

Anthropologist Tim Weaver, from the University of California, in the United States, who did not participate in the study, considers that it is too early to make such conclusive statements about the Homo antecessor. Still, in an interview with Science, he said he agreed that the study offers good points and that “it is really exciting to start getting proteins from some of these older fossils”.

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