I saw a fascinating documentary on Discovery about the great plague of 1666 and Eyam just before Christmas. Eyam is still fairly isolated and there are a lot of people living there now who are descended from the survivors of the plague outbreak. Geneticists and immunologists have studied their genes and found a particular gene which may be responsible for their ancestors' survival. Those with one copy of the gene from a parent caught the plague but recovered, while those with two copies, one from each parent, were immune and did not catch the plague at all. This gene apparently is present in about 14% of people of European descent because of the repeated plague outbreaks but very rare in people originating from elsewhere. The same gene also gives immunity from AIDS in the same way. If you have one copy you get HIV but survive much longer than other people, if you have two copies you don't get HIV.

Bingley

Bingley