“EDid God… create woman?” The wink could not come at a better time in the city which celebrated the 90th birthday of its most famous resident a few weeks ago. However, it will not be about cinema this Sunday at the Salle Jean-Despas in Saint-Tropez, but about prehistory and paleontology.
This free conference at 10:30 a.m. will conclude, with the conclusion at noon of the two referents (Sacha Brun and Patrick Michel. two local children who have become references in astrophysics), these third “Scientific meetings on the origins of man” organized by the City.
The theme raised this Sunday by Claudine Cohen, university professor, continues the debates started on Friday, where she took an important part.
Alongside other specialists who have been able to popularize their knowledge, in the good sense of the term, with the animation of Alain Cirou, editorial director of the magazine Sky and Space.
To talk about a distant past in connection with our present and the future, simply and precisely. For example, how to define a species? For the paleontologist on criteria of “diagnose”that is to say the description of the bones.
“Among Neanderthals, we only have teeth and bones available. What is interesting is that since their discovery, we have characters that only exist among Neanderthals. The face, as we find it among them, does not exist at all among Sapiens “, specifies Silvana Condemi, paleoanthropologist at the University of Aix-Marseille.
DNA, mosaic of the past
His colleague at the Musée de l'Homme, Antoine Balzeau, indicates the techniques used: “For the body to be preserved, it must be buried. This is why we look in particular places, where we have already found, where there is real potential, with sedimentary deposits. A fossil can be any trace of the past, a body or an imprint, which has passed through time and reached us.” Knowing that certain regions of the world remain inaccessible for political reasons…
Another science which examines Man, genetics, represented by an eminent researcher, Ludovic Orlando (director of research in molecular archeology in Toulouse).
“For a geneticist, what matters is how genes travel between groups. We are less interested in barriers than in discovering what allows exchanges. Since 2010, we can use the sequence, the set of letters forming genetic information, and compare it to that of humanoids of the past. And when we do this exercise, we realize that there is a significant part of our genetic letters which are inherited from an ancestor we call Neanderthal. “
A science that makes you dizzy with certain figures: “The set of chromosomes is 3 billion letters in humans. The great contribution of genetics is to have the total DNA of an individual: this provides us with infinite characteristics in filigree that were not observable. We enter into a much greater biological complexity and once we have this hyper dimensionality to observe, we are much finer. “
DNA also allows us to have an idea of the number of humans in the past: “We realize that during most of our history, there were not very many of us“, underlines Evelyne Heyer, professor of genetic anthropology: “Our species is particularly low in genetic diversity, which complicates the work of paleoanthropologists “.
Because the genetic message is not only of individual interest: “A person always tells us more than themselves because they are part of a genealogy. Through it we can discover a multiplicity that we were still unaware of.“, testifies Ludovic Orlando.
“Your DNA is a bit of a mosaic of what you received from your ancestors “, adds Evelyne Heyer: “ When I compare the DNA of two individuals, I can see if they had common ancestors and date it. We know, for example, that the first Europeans came from Africa 45,000 years ago, then farmers came from Anatolia 10,000 years ago, before people from the steppes 5,000 years ago. It's extraordinary, because twenty years ago, we didn't know how to do it. And alongside migrations, we see local adaptations that take thousands of years. “
