Steve sez, ‘Devastating epidemics that swept Europe during the Middle Ages seem to have had an unexpected benefit – leaving 10% of today’s Europeans resistant to HIV infection.’
The mutation, which affects a protein called CCR5 on the surface of white blood cells, prevents HIV from entering these cells and damaging the immune system.
Around 10% of today’s Europeans carry the mutation, a significantly higher proportion than in other populations. Why is it so common in Europe? One possibility is that it favours carriers by protecting them from disease. But geneticists know that the mutation, called CCR5-Delta32, appeared some 2,500 years ago – long before HIV reared its head.
‘You need something that has been around for generation upon generation,’ explains Christopher Duncan of the University of Liverpool, UK, who led the latest analysis. Plague fits the bill, he and his colleagues conclude from a mathematical modelling study published in the Journal of Medical Genetics.
Everybody go marry a European.