AcesNeights,
A mutation is almost exclusively an insertion or deletion of a protein in the DNA sequence. To think that all mutations are bad or deleterious to the host is incorrect. They certainly can be harmful or fatal but aren't always.
That is your preferred belief. It is not supported by investigative science.
Sherpas are born with substantially larger lungs than non Sherpas. That's an evolutionary change not a function of acclimatization.
See the above statement about my friends who can see like 7X binoculars. Those who had the good lungs survived and kept up with the group. Those who didn't didn't and died.
