Science is publishing today a research that describes, for the first time, the reconstruction of the epigenomes of a Neanderthal and of a Denisovan. An international team, in which the Institute of Oncology of the University of Oviedo participates, has applied a new method that has enabled it to desentangle the pattern of metilation of the DNA of these to extinct species. By comparing their epigenetic patterns with those of modern humans, the researchers have been able to identify the genes whose activity differs between species, and those that mark the evolutionary changes that have configured our species, that is, that have made us like we currently are.

By desentangling how these genes were regulated in Neanderthals and Denosivars, this study provides, for the first time, data on the evolution of the regulation of genes in humans and opens a window to genetic exploration in species that have been exctinct for thousands of years.

In the research, coordinated by Liran Carmel of the University of Jerusalem, have participated the Unit of Epigenetics of Cancer of the University Institute of Oncology of the Principality of Asturias Cajastur Social Work (University of Oviedo), directed by Doctor Mario Fernández Fraga, researcher from the CSIC-CNB. The professor from the University of Cantabria and the Valdecilla Research Institute (IDIVAL), José A. Riancho, has also participated in the work developed by the international team.

"Some of the differences in the epigenetic patterns affect genes related to the development of bones and may explain the differences between the skeleton of ancient species and current humans", Fernández Fraga comments. Other affect the genes related to the cardiovascular system and the nervous system, which have been associated to diseases such as Alzheimer's or schyzophrenia. Although the factors that created these differences are still unknown, since the epigentic patterns are influenced by both their own genetic characteristics and the environmental conditions, as Riancho claims, "we may wonder if these diseases, so frequent in modern society, reflect an inherent predisposition of our species or if, on the contrary, are a consequence of the lifestyle and the environment in which we live".

The Chosen Species

The current world is inhabited by just one species of human beings. But this was not the case in the past. Until a few thousands of years ago, our species, the Homo Sapiens, shared its territory and probably ideas and mates with other species, such as the Neanderthals.

We know very little about the specific genetic characteristics that allowed us Homo Sapiens to survive in adverse conditions, while other species went extinct. We know even less about the epeginetic characteristics that made us the chosen species. Genetics has to do with the changes in the sequences of the DNA, which represents the basic structure of genes. Epigenetics, on the other hand, represents subtle variations of the genes that, without affecting the nucleus of its structure, modulate its activity and may be transmitted through generations. Among them there are some chemical modifications, such as the metilation of the DNA, that controls when and how the genes that control the development of our organism are activated or deactivated.

The specification of the genomes and epigenomes of our antecessors is key to understand the molecular mechanisms that led us to be how we are. To face this challenge, Svante Pääbo, scientist from the Max Planck Institute of Evolutionary Anthropology, has been coordinating for many years the project to sequence the Neanderthal genome. As a result of the research, during last February, Nature published the first full Neanderthal genome. The DNA was obtained from a bone from the foot of an adult individual that lived in the Caves of Altai (South of Siberia) 50,000 years ago. A few months before, the same group published another article that described the genome of the Denisovan, a recently-discovered group of ancient humans.