FASCINATING FACTOID:
12% of caucasians (Zwickey) are immune to HIV because they are descended from bubonic plague survivors. The Black Death had a 90% death rate and killed 147 million people. It swept Europe 3 times, in the 6th, 14th and 17th centuries. Those who survived (natural selection) don't have a certain chemokine receptor (CCR5) which is necessary for HIV to get into host macrophages. This may explain why some partners of HIV positive people never get the disease even though they do not practice "safe" sex.
( lots of info hereCollapse )