Did Neanderthals disappear because of their long social and genetic isolation?

This is the hypothesis put forward by researchers in a study published in Cell Genomics. Neanderthals, by remaining in a restricted population, without mixing, would have been victims of inbreeding and genetic impoverishment.

It is one of the greatest mysteries in the history of humanity: how did Neanderthal man disappear 40,000 years ago? When did we, Homo Sapiens, end up conquering the entire world? A study published in the journal Cell Genomics opens a new avenue. If Neanderthal disappeared, it is because he did not mix enough with others.

To understand, we must go back to the source of this work and the discovery of Neanderthal bones in a cave in the Drôme in 2015, an extremely rare event. At the time, these bones were analyzed at length to reveal their secrets, explains Ludovic Slimak, author of the study and researcher at the CNRS. “We are going to try to understand what this body has to tell us about this incredible human extinction. My colleagues who work on DNA are going to give me results fairly quickly and we are faced with an enigma. The geneticists tell me that this body cannot be less than 105 millennia old while all the elements of archaeology show me that this body can only be between 45 and 42 millennia old, at the time of the extinction.”

It will take seven years to resolve this inconsistency. This Drôme specimen is indeed about 45,000 years old but has the genetic characteristics of a Neanderthal 105 millennia old, because he and his fellow Neanderthals remained isolated for 60,000 years: no interaction with other groups, no mixing and therefore this almost unchanged genetic profile. This Neanderthal population was not adventurous. “How can humanity remain isolated knowing that the other Neanderthal groups are ten days, even two weeks’ walk from the cave. They are right there,” asks the researcher.

Could this isolation have caused the loss of Neanderthals? The answer is that a restricted population, closed in on itself, is inbreeding, genetic impoverishment and therefore greater vulnerability to diseases or climatic hazards, to the point of being supplanted by us, Homo Sapiens. Ludovic Slimak speaks of a behavior “less efficient” Neanderthal which did not allow it to prosper. “What characterizes Sapiens is this desire for a network, to be all united, it gives incredible efficiency. At the same time, we have small Neanderthal groups, who are very happy like that, but the moment they come into contact with Sapiens, they will be swept away.”

This is not the end of the mystery of the extinction of Neanderthal Man, by Ludovic Slimak’s own admission, it is just one more element. But the researcher sees in these conclusions a “revolution” in understanding how our distant cousin lived just a few tens of thousands of years ago.