323: The causes of HIV resistance in Europe

news @ nature.com - Did Black Death boost HIV immunity in Europe? - Experts argue over whether smallpox or plague should take the credit.:

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.

But epidemics of which disease? Researchers claimed this week that plague helped boost our immunity to HIV, but rival teams are arguing that the credit should go to smallpox.

A mutation found in 10% of Europeans is responsible for the HIV resistance. The scientists are arguing over whether smallpox or plague exerted the selective pressure (evolution!) that made this mutation common.

If it was plague, that suggests that it wasn't caused by the bacterium usually blamed for the plague, but a different virus. Evolution offers new insights into our own past.