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Neanderthal and Denisovan blood groups reveal part of their history

The history of our species is reminiscent of a huge puzzle of which pieces are found, assembled and rearranged over the years. The gradual improvement of dating and analysis techniques makes it possible.

A great leap in the study of human evolution was the creation of the palaeogenomics, whose pioneer and founder is the Swedish Svante Pääbo. This technique consists of extracting and sequencing the DNA of ancient organisms through their remains – a tooth or a phalanx – to find out data about the species, which is otherwise impossible to determine.

In 2010, Pääbo published the complete genome of Neanderthals, with great impact in the field of paleoanthropology, and since then he has analyzed 15 more individuals of this species.

With this DNA extraction technique, Pääbo and his team have also discovered a new type of hominid Asian through a single phalanx – the Denisova man or Denisovan – for the cave where it was discovered. This has been the first extinct hominid species to be described thanks to its genome.

Taking advantage of the work of the Swedish scientist, the paleoanthropologist of the National Center for Scientific Research French (CNRS) Silvana Condemi analyzed the genome of four individuals between 100,000 and 40,000 years old, to determine their blood type.

A more comprehensive blood type analysis confirms an African origin for both Neanderthals and Denisovans

The results give expected data, but also some surprises: For a long time the scientific community was sure that Neanderthals would all be group 0, just as chimpanzees are all type A and gorillas type B. Condemi and his team confirm that these hominids already possessed all the variability range sanguine found in modern humans.

Further analysis has also detected alleles (parts of a gene) that confirm a African origin both for Neanderthals and Denisovans, a question that was the subject of discussion among the scientific community, as reflected in the article published in PLOS ONE.

This work confirms the effectiveness of blood groups to study the history of mankind

Stéphane Mazières (Aix-Marseille University)

“This work confirms the effectiveness of blood groups to study the history of mankind. Until now, this analysis technique had been considered obsolete in favor of other more modern ones, such as the polymerase chain reaction ”, he tells SINC Stéphane Mazières, of the University of Aix-Marseille, and co-author of the study.

The cause of its extinction

Thanks to the study of the blood groups of these hominids, “we have also proposed two possible causes for disappearance Neanderthals, today a matter of debate ”continues Mazières. These causes are infections viral type, and a drastic reduction in population growth in these populations due to the Fetal erythroblastosis -Also called hemolytic disease of the newborn-, a blood disorder in which the mother’s immune system attacks the red blood cells of the fetus, by not sharing the Rh type.

The hypothesis that the low genetic diversity, added to the species’ low reproductive success, contributed to the disappearance of the Neanderthals is increasingly becoming stronger.

Stéphane Mazières (Aix-Marseille University)

Especially surprising is the discovery of an Rh allele in three of the Neanderthals studied that does not exist in modern humans – with the exception of an individual from Papua New Guinea and an Australian Aboriginal. This fact suggests a genetic crossing between Homo Sapiens and Neanderthals, before the migration of the former to Southeast Asia.

Finally, this study sheds some light on Neanderthal demographics, confirming that this extinct species of hominin had a low genetic diversity. Likewise, this indicates that they were susceptible to diseases – such as the previously mentioned erythroblastosis fetalis – in cases in which there was a cross between species. “The hypothesis that the low genetic diversity, added to the little reproductive success of the species, contributed greatly to the disappearance of the Neanderthals ”, concludes Mazières.

Rights: Creative Commons.

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