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When modern humans journeyed out of Africa , a speedy evolution in their red blood cell may have help them live — but it may have also led to the eventual disappearance ofNeanderthals , a new study find .
By sequence the genomes of dozens of people who lived between 120,000 and 20,000 years ago , researcher institute that Neanderthals had a rarified blood group that could have been fateful to their newborn baby . Their work was print Thursday ( Jan. 23 ) in the journalScientific Reports .
Skulls of a Neanderthal (front) and earlyHomo sapiens(back).
Humans’blood groupsare characterized by proteins and sugars — called antigens — find on the control surface of red blood cells . Many people are conversant with the ABO blood typing system , which lumps line into the group A , B , AB and O. The antigen on a person ’s red blood cells are recognized as safe by theimmune system , but someone with case B blood will have antibodies that attack type A antigens , for example .
Another significant antigen is the Rh gene , which founder the " positive " and " minus " signs to stock types . So , nowadays , knowing which of the eight potential combinations of rakehell radical and Rh factor a person has is key to a successful rake transfusion .
But red blood cells are even more complicated than this — there are century of other , lesser - know antigens known to hang out on the surface of these cells in New humans , as well as differences in the inside of the cells . Since these variations in ruby-red line cells are turn over down over the contemporaries , a squad of researcher at Aix - Marseille University in France decide to look into ancient genomes to good interpret the evolutionary history of Neanderthals , Denisovansand human beings .
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" Neanderthals have an Rh blood chemical group that is very rarefied in modern human race , " subject field lead authorStéphane Mazières , a population geneticist at Aix - Marseille University , narrate Live Science in an email . This Rh variant — a type of RhD , another carmine pedigree electric cell antigen — is not compatible with the stochastic variable the team found in the Denisovans or the earlyHomo sapiensin their study .
" For any case of inbreeding of a Neanderthal female with a Homo sapiens or Denisova male person , " Mazières said , " there is a mellow risk of exposure of hemolytic disease of the neonate . " The consideration can lead to icterus , severeanemia , brain damage and decease .
" This could have contributed to the dying of the Neanderthal population , " Mazières said .
expert are n’t trusted why most modern man have theRh proteinon the open of their cell , nor why some multitude lack the protein , but an issue can arise if an Rh - negative person is pregnant with an Rh - positive fetus . In this scenario , calledRh inconsistency , the fraught person ’s resistant system may create antibodies and assault the foetus ’s red blood cells , leading to haemolytic disease of the newborn infant .
Treatment today for Rh incompatibility involve the antepartum administration of animmunoglobulin , a lab - made antibody , which preclude the pregnant person from make antibody against the foetus ’s stock . But 100,000 year ago , this type of red blood cell incompatibility would have been impossible to plow .
Mazières and fellow worker found that the Rh gene variants found in many people today come from earlyHomo sapiensancestors , who appear to have evolved them shortly after leave Africa , possibly whileliving on the Persian Plateau . Neanderthals , on the other hand , had Rh variants compatible with one another but that remained largely unchanged throughout the last 80,000 years of their beingness .
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WhileNeanderthals ' general isolationcould explain why their reddened blood cells did not evolve much over the old age , there are still questions about why early humans ' red blood cells diversified so much and so quick — over a span of at least 15,000 years .
" My first thought was because of a demographic expansion , " Mazières state . " Then , probably that the new environments of Eurasia may have helped to observe them throughout the generations . "
This inquiry into crimson blood cell variations fits in well with archeologic and familial studies , Mazières intimate , showing that fresh transmissible lineages and new stone tool industriesarose in the Persian Plateaubetween 70,000 and 45,000 years ago . The deficiency of variety in the cerise blood cellphone of Neanderthals and Denisovans over the same time straddle could bespeak inbreeding and reject population numbers , eventually conduct to the extinction of these groups .
