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Rejuvenation of prehistoric Europeans

HumanRemainsAround 14,500 years ago, in a period of climatic instability (to day the less), the European prehistoric population was almost completely renewed (a nice way to day that the previous inhabitant were extinguished). Witness the remains of 35 hunter-gatherers’ DNA, who lived between 35.000 and 7.000 years ago in current Italy, Germany, France, Czech Republic and Romania, analyzed in a study published in the journal “Current Biology” at Cosimo Posth (University of Tübingen, Germany), and colleagues in an international collaboration, which also includes the University of Siena. “We cast a light on an unknown chapter of human history, at the last glacial maximum” said Johannes Krause, coauthor of the study. “The data from this period have always been poor, and that’s why, so far, very little was known about the structure and dynamics of the first modern human populations in Europe”. The authors have studied the mitochondrial DNA, material gene that is found in cells called mitochondria (a symbiosis organism living inside our cells), which is inherited only from the mother and which can then be used to reconstruct the ancient matrilineal descent through the identification of the different haplogroups, that the families of several genetic variants on different observable chromosomes. The analysis showed that the mitochondrial DNA of three individuals, who lived before the last glacial peak in the region currently occupied by Belgium and France, belonged to a specific genetic group, haplogroup M, practically absent in modern European populations but very common in modern Asian populations, Australians and Americans. Based on the absence of  the haplogroup M in Europe and on its presence in other parts of the world, some anthropologists have suggested that the colonization of Eurasia and Australasia by non-African populations had occurred multiple times. Krause and colleagues believe that the discovery of the haplogroup M in an ancient European branch filophylogenetic indicates that all the non African of the world have originated from the diaspora of a single population, occurred about 50.000 years ago. Later, haplogroup M apparently disappeared from the Old World. “When, about 25.000 years ago, began the Last Glacial Maximum, the populations of hunter-gatherers retreated to the south, focusing in some limited areas: the result is a genetic “bottleneck” which caused the extinction of this haplogroup”, Posth added. The result, that surprised mostly the researchers, was evidence of profound renewal of the European population occurring 14.500 years ago, when the climate began to warm up. “Our model shows that during this period of climate change, the descendants of the surviving hunter-gatherers at the last glacial maximum was largely replaced by people of different origins” said Adam Powell, senior author of the study.

So, that’s the fact: 14.500 years ago, when the climate started to warm up, this haplogroup literally disappeared from Europe. Was it due to warmer weather itself? I guess not so but, what would happen if the climatic changed abruptly? I’m not sure but, some could suggest a good candidate might be a great flood…

The great flood

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