R
rossum
Guest
There are two responses here. First, the general response. Mutations are random. They may protect against things that do not currently exist in the environment. The Luria–Delbrück experiment shows this clearly.This still does not explain reactions to relatively modern diseases like HIV/AIDS.
Secondly, a more specific response. There are some similarities between the ways HIV and smallpox attack cells. Hence, populations with an inherited resistance to smallpox tend to have a better level of resistance to HIV.
Some people indeed are resistant to a greater or lesser degree.Some people appear to be resistant.
Exactly. That is the meaning of “random” in “random mutations”. They do not fit a pattern, but are random. In the absence of HIV, any HIV-resistant mutations are neutral or deleterious, and would have no advantage. With the presence of HIV in the environment, those mutations will have an advantage and hence tend to spread by natural selection.This does not fit a pattern
rossum