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Besides Malaria, what other kinds of infectious diseases can be thought to have exerted some kind of selective force on humans?

By selective forces I mean selective force on the human genome or human population. Like for example, there is evidence of ethnic differences in susceptibility to malaria and of the diverse genetic adaptations to malaria that have arisen in different populations.

  • Oct 10 2013: The black death of the middle ages in Europe. It killed about 1/3 of the population, possibly more. In some instances entire towns were wiped out. This means those who were either immune, had some kind of medicine or survived the onslaught remained behind, these then produced people who were more able to deal with outbreaks that camne later.
  • Oct 9 2013: To certain extent, AIDS (HIV) also exert some kind of selective force on humans, even though is not likely to be genetic factors, but who really know.
  • Oct 7 2013: Pretty much any major disease has this impact. Its just more obvious with Malaria because we've managed to isolate some of the genes is all.

    If you compare for example the effects of small pox on Eurasian populations as opposed to Native American or Native Australian people when the disease first came, you'll find that small pox only kills about 30% of the Eurasians (with many of those being the very young and very old), but around 95% of the natives.
    This is by the way why we have so many more people of European descent in the Americas and Australian former colonies than we have in Asian or African colonies by the way. The old world diseases decimated the new world more effectively than steel and muskets ever could (and often, though not always, accidentally as well).

    Part of it is the immune system learning to cope with new diseases, but genetics also plays a significant role, hence natural selection. Even a minor resistance to a commonplace virulent plague is a hell of an evolutionary advantage.
    • Oct 12 2013: So in terms of the small pox death rate in Eurasians vs the indigenous population is the primary difference due to the immune system adaptation benefit brought on by prior exposure (something the European population had from the old world, or is this more a matter of preparedness, better medical expertise rather than a result of selection on the immune system?

      Also, talking about small pox - I was reading this article ( and it states that Small Pox may be the possible root for HIV-1 resistance in European populations. Personally it seems controversial to elude to HIV-1 resistance but it is an interesting read. Does anyone have any thoughts?