The soap opera of our evolutionary tree becomes complicated again. At the last annual meeting of the American Society of Human Genetics , researcher Ryan Bohlender, from the University of Texas, revealed the details of a genetic study that points to the existence of another human species that has disappeared and with which our own had sexual relations. ancestors.
Until now it was known that a small fraction of modern Homo sapiens DNA comes from crossing with Neanderthals and Denisovans, the latter species of which some bone fragments were found in a cave in Siberia eight years ago. The initial goal of Bohlender and his team was to determine what percentage of genetic material has remained as a vestige of contact with those extinct Europeans using a new computational model.
And according to their results, both Asians and Europeans share the same proportion of Neanderthal DNA : 2.8%, exactly. Recent research suggests that these genes may be responsible for increasing the risk of contracting certain diseases or health problems that afflict humanity today, such as depression, heart attacks, certain skin conditions or greater vulnerability to the papillomavirus. human.
Denisovan inheritance would be much more diluted : while it has disappeared from the genome of modern Europeans, it only contributes 0.1% of that of Asians.
The problem arose when analyzing the autochthonous population of the Melanesian islands, in Oceania, which not only have a significantly higher percentage of Denisovan DNA – 1.1% – but also have unidentified genetic traces , probably of a third species that it was also crossed with individuals of Homo sapiens .
The finding is supported by an independent study by researchers from the Danish Museum of Natural History, who analyzed the genetic material of 83 Australian Aborigines and 25 Papua New Guinea natives. Although the mysterious DNA resembles Denisovan, it contains enough distinctive features to assign it to another human race .
Photo: inhabitant of Papua New Guinea. Jialiang Gao via WIKIMEDIA / GNU / CC
