quote:
Originally posted by schrafinator:
I don't think we have adapted to pneumonia. Pneumonia kills plenty of people, and the reduction in deaths would be mostly due to better treatment and drugs.
A better example of our species adapting to a pathogen would be the AIDS virus.
There are individuals who test positive for exposure to the HIV virus, but never develop symptoms of AIDS, or develop them very slowly.
By looking at the DNA of these people, scientists have isolated a shared beneficial mutation. Due to genetic variation, some people in the population possess a mutation in the CCR(5) gene which causes these individuals to not develop AIDS if they have two copies of this mutant gene. If they have only one copy of the mutant gene, they have a very slow onset of AIDS.
The ancestry of the people carrying this HIV-resisting mutation is quite fascinating; they very strongly tend to come from countries which were affected by Bubonic Plague. Most of the world's population lacks this mutation.
Actually,no one of europeen decent dies of Pneumonia,even untreated by any drugs unless they are of frail health to begin with. I got pneumonia twice in my life and the first time i got,i didn't even treat it...didn't have time to be sick. I felt lousy for a couple of days but once the worse was over i was ok... The same could be said of europeen settlers in southern america...but the native,the disease was 100% fatal,whatever their individual health because they had no genetic imunity at any level to it.