A genetic analysis of an ancient bone revealed a hybrid between Neanderthals and Denisovans

Views of the Denisova 11 bone (Image courtesy Thomas Higham, University of Oxford)
Views of the Denisova 11 bone (Image courtesy Thomas Higham, University of Oxford)

An article published in the journal “Nature” describes the results of the analysis of DNA extracted from a piece of bone discovered in 2012 and cataloged as Denisova 11. A team from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) in Leipzig, Germany, recovered DNA from that bone and its sequencing revealed that the mother was a Neanderthal while the father was a Denisovan and therefore belonged to another species of hominin. This is yet another proof of the fact that populations of different hominins interbred leading to the birth of hybrids, the reason why the DNA of most Homo sapiens contains Neanderthal or Denisovan genes.

The discovery of a piece of bone in the Denisova Cave on the Altai Mountains in Siberia in 2008 began a series of discoveries of more fragments of bones belonging to hominins. The issue became even more interesting because in the meantime genetic techniques made remarkable progress leading to the development of paleogenetics, the application of genetic techniques to extinct species to be able to obtain at least fragments of DNA from very old bones.

The MPI-EVA has been at the forefront of this field by contributing to it with many discoveries, starting with the fact that the hominins of Denisova cave were of a different species from Homo sapiens and Neanderthals. In an article published in September 2015 again in “Nature” a team coordinated by the MPI-EVA has tried to reconstruct the human family tree.

Over the years, new research and genetic comparisons made it possible to better understand the relationships among these hominins and also the interbreedings among them. Research on the remains found in the Denisova Cave continued as well and the bone cataloged as Denisova 11 was found to be a hybrid with a Neanderthal mother and a Denisovan father. The team that carried out this new research includes Matthias Meyer and Svante Pääbo, two of the most important paleogenetists not only of their institute but of the whole world and from the beginning involved in paleogenetic research on Denisovans.

Bence Viola of the University of Toronto, another of the authors of this research and also involved in the paleogenetic research on Denisovans from the beginning, explained that the examinations of the Denisova 11 bone fragment suggest that it belonged to a girl who was at least 13 years old who lived over 50,000 years ago. Discovered by Russian archaeologists in 2012, it was brought to the MPI-EVA for a genetic analysis that gave very interesting results.

Today there are various more or less complete genomes of Neanderthals belonging to various populations, including the one that lived in the Altai Mountains, which are offering a picture of their migrations and of the relationships among them, even if still quite approximate. Thanks to this knowledge, it was possible to establish that the mother of the girl who was the subject of this research was genetically closer to the Neanderthals who lived in western Europe than to those who lived in the Denisova Cave long before her.

As for the girl’s father, he was a Denisovan but the genes inherited from him indicate that among his ancestors there was at least one Neanderthal. Basically, at the time there was not only an occasional interbreeding between these two species of hominins but it was possible to trace at least two of them in this girl’s DNA.

Svante Pääbo pointed out how striking it is to have found this hybrid among the few remains of individuals whose genome has been sequenced. Perhaps Neanderthals and Denisovans didn’t have many opportunities to meet but when this happened they must have mated frequently, much more than previously thought.

Neanderthals and Denisovans generally lived in distant areas but occasionally at least one population of one of the two species went as far as an area inhabited by the other one such as the Altai Mountains. The discovery of a hybrid between the two species revamps the discussions about hominin crossbreedings but also on the definition of species because there were fertile hybrids that left their genetic traces in the girl subject of this research but also in most of modern humans. Advances in genetics and paleogenetics are leading to new discussions on definitions and classification that will certainly go on for a long time.

The valley above the Denisova Cave (Photo courtesy Bence Viola, Max Planck Institute for Evolutionary Anthropology)
The valley above the Denisova Cave (Photo courtesy Bence Viola, Max Planck Institute for Evolutionary Anthropology)

Leave a Reply

Your email address will not be published. Required fields are marked *