The Seven Daughters of Eve by Bryan Sykes Read Free Book Online Page B

Rhesus negative mother bears the child of a Rhesus positive father (whose red blood cells do carry the Rhesus antigen), there is a high probability that the foetus will be Rhesus positive. This is not a problem for the first child; but, when it is being born, a few of its red blood cells may get into the mother’s circulation. The mother’s immune system recognizes these cells, with their Rhesus antigen, as foreign, and begins to make antibodies against them. That isn’t a problem for her until she becomes pregnant with her next child. If this foetus is also Rhesus positive then it will be attacked by her anti-Rhesus antibodies as they pass across the placenta. New-born babies affected in this way, who appear blue through lack of oxygen in their blood, could sometimes be rescued by a blood transfusion, but this was a risky procedure. Fortunately, ‘blue baby syndrome’ is no longer a severe clinical problem today. All Rhesus negative mothers are now given an injection of antibodies against Rhesus positive blood cells, so that if any do manage to get into her circulation during the birth of her first child they will be mopped up before her immune system has a chance to find them and start to make antibodies.
    The significance of all this to the thinking about European prehistory is that Mourant realized that having two Rhesus blood groups in a single population did not make any evolutionary sense. Even the simplest calculations showed that losing so many babies was not a stable arrangement. There was no problem if everybody had the same Rhesus type. It didn’t matter whether this was Rhesus positive or Rhesus negative, just so long as it was all one or the other. It was only when there were people with different Rhesus types breeding together that these very serious problems arose. In the past, before blood transfusions and before the antibody treatment for Rhesus negative mothers, there must have been a lot of babies dying from haemolytic disease. This is a very heavy evolutionary burden, and the expected result of this unbalanced situation would be that one or other of the Rhesus blood groups would eventually disappear. And this is exactly what has happened – everywhere except in Europe. While the rest of the world is predominantly Rhesus positive, Europe stands out as having a very nearly equal frequency of both types. To Mourant, this was a signal that the population of Europe was a mixture that had not yet had time to settle down and eliminate one or other of the Rhesus types. His explanation was that modern Europe might be a relatively recent hybrid population of Rhesus positive arrivals from the Near East, probably the people who brought farming into Europe beginning about eight thousand years ago, and the descendants of an earlier Rhesus negative hunter-gathering people. But who were the Rhesus negatives?
    Mourant came across the work of the French anthropologist H. V. Vallois, who described features of the skeletons of contemporary Basques as having more in common with fossil humans from about twenty thousand years ago than with modern people from other parts of Europe. Though this kind of comparison has since fallen into disrepute, it certainly catalysed Mourant’s thinking. It was already known that Basques had by far the lowest frequency of blood group B of all the population groups in Europe. Could they be the ancient reservoir of Rhesus negative as well? In 1947 Mourant arranged to meet with two Basques who were in London attempting to form a provisional government and were keen to support any attempts to prove their genetic uniqueness. Like most Basques, they were supporters of the French Resistance and totally opposed to the fascist Franco regime in Spain. Both men provided blood samples and both were Rhesus negative. Through these contacts, Mourant typed a panel of French and Spanish Basques who turned out, as he had hoped, to have a very high frequency of Rhesus negatives, in