New analysis of Neanderthal genomes shows that the ancient blood that once circulated through this long-extinct group of archaic peoples had more in common than scientists thought.Although it was assumed that all Neanderthals had blood type O, a recent study of the previously sequenced genomes from three Neanderthal individuals shows polymorphic variation in their blood. This suggests they may have also been carriers of other types of blood as indicated by the ABO blood group system.This means that Neanderthal blood did not come in the form O blood, which was the only type confirmed before. However, it also included blood types A and C.Based on the identification of a variety of blood groups in the genetic sequences from three Neanderthals (and one Denisovan), the finding suggests that this type of research has been overlooked in light of the rise of DNA analysis technologies.Stphane Mazires (photos: Douka et al./Mafessoni et al./Prfer et al./Green et al.)Above: The geographical origin, blood group and date of the individuals being studied.The researchers led by Silvana Condemi, a paleoanthropologist from Aix-Marseille University, France, as the first author, state that red cell blood groups are powerful indicators of anthropological traits."Curiosity is the reason major red cell blood polymorphisms have not been given much attention in paleogenetic studies, despite their importance and the wealth of genotypic data that is constantly accumulating."The ABO discoveries were confirmed by the researchers. They also stated that the genes underlying these blood groups in archaic humans confirm the idea that Neanderthals or Denisovans originated out of Africa because they lack certain antigens in blood and have ancestral blood groups related to African populations.Researchers write that these features "are in accordance with the Neanderthal- and Denisovan gene pools pre-dating Homo sapiens' departure from Africa."Other genetic clues point to a later passage of history, such as an allele the RHD gene that codes a Rh blood protein. It is not found in modern humans except for two Aboriginal Australians and an Indigenous Papuan.Researchers suggest that the evidence of this link could be evidence of interbreeding between Neanderthals, H. sapiens, and the latter before they migrated to Southeast Asia.The new study also offers insights into what led to the Neanderthals' decline.Researchers found that the Neanderthals had a high number of common alleles in their archaic genomes. This suggests low genetic diversity.Additionally, the Neanderthals could have inherited genetic variants from their archaic blood that would have made them more susceptible to hemolytic disease (HDFN), which is an alloimmune condition where the mother's immune system attacks her unborn child's blood cells.Researchers write that these elements could have contributed towards the demise of the descendants, especially when they were competing with H. sapiens in the same ecological niche.These findings are published in PLOS One.
