Hunter-gatherers (HG) Mesolithic and neolithic individuals with ancestry that is like that of Mesolithic Europeans.I looked at these alleles in ancient samples dating to the past 12,000 years, all from West Eurasia. Cavalli-Sforza and colleagues thought that this was specifically a mixture between Rh- hunter-gatherers and Rh+ Farmers, largely based on the observation that the Basque population, who they believed to have largely hunter-gatherer ancestry, have a very high frequency of the Rh- phenotype. In fact, the ancient DNA evidence suggests that something like this is close to the truth. A third explanation, suggested by Haldane in 1942 is that the high frequency in Europe is due to the fact that present-day Europeans are recently admixed between a population that has a very high frequency of the Rh- allele and one that a very low frequency. The range of parameters for which this model works is relatively small, particularly since the effect gets worse for subsequent pregnancies. Another possible explanation is reproductive overcompensation – Rh- women have more children to replace the ones that die for haemolytic disease. So this only really works if it is overdominant. On the other hand, no obvious selective advantage is known, there are no obvious genomic signals of selection on the Rh- allele, and if there were a selective advantage to the Rh- allele then we might ask why it hasn’t fixed, since once the Rh- frequency rose above 50%, it would be selected for, rather than against. Effects like this related to malaria resistance are what drive the high frequencies of the sickle cell trait and many thalassemias. First, there might be some (unknown) beneficial effect of the Rh-allele. There are three common explanations for the high frequency of the Rh- allele. In particular, if an Rh- mother has an Rh+ child (because the child inherited a Rh+ allele from its father), then it’s possible for the mother to produce antibodies against the Rh+ antigen leading to haemolytic disease and severe illness for the child. This high frequency in Europe has long been surprising because the Rh- phenotype has an obviously deleterious effect. The allele is recessive, so you need two copies of the Rh- allele to have the Rh- phenotype. This polymorphism is at around 10-20% frequency in African populations, very rare in East Asia, and relatively common (~40%) in Europe. In Europe, the most common such allele is actually a deletion at chr1:25592642-25661222, which completely deletes RHD. Again, this system has a large number of different groups, but the most important is the Rh- group, where the gene is completely inactivated. The Rhesus blood group system is the second most commonly encountered system, determined by polymorphism at the RHD gene. In present-day populations, all three alleles segregate in Africa, A/O are most common in Europe with B~5-10%, B is relatively common in Asia, but O is virtually fixed in Native Americans. The human type O allele is a more recent mutation, but still probably at least one million years old (the Altai Neanderthal is type O, for example). In evolutionary sense, types A and B are the oldest, since those polymorphisms are shared with other primates. Actually it is more common than that, for example there are many other loss-of-function mutations that lead to the O phenotype, but these are relatively rare. In particular, the type O allele is determined by a 1 base deletion (rs8176719) and if that deletion is not present then type A and B are determined by the SNPs rs8176746 and rs8176747. ABO blood group is determined by polymorphisms in the ABO gene. The ABO blood group system was the earliest to be discovered. In particular, Mesolithic hunter-gatherers had a higher frequency of type O than any present-day population, and both hunter-gatherers and bronze-age steppe populations had a higher frequency of the Rhesus negative allele than any present-day population. We show that some ancient populations of Europe had blood group frequencies that were more extreme than any present-day population. Here, we use ancient DNA to estimate the frequencies of the two most commonly discussed groups – specifically the ABO and Rhesus systems – in Europe over the past ten thousand years. They also vary dramatically in frequency across human populations and, probably, across time as well. Different blood groups confer resistance or susceptibility to a wide range of infectious disease and, likely as a result of this, have been under long-term balancing selection across primates. Human blood groups are interesting from both medical and evolutionary perspectives. Please note that this map shows percentages of Rh(D) positive Blood groups in ancient Europe
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