In some parts of Africa, it is actually an advantage to have mutated, oddly-shaped red blood cells.
This condition, known as sickle cell anemia, is usually a disadvantage, but, ironically, it can actually help protect someone from malarial infection because a sickled red blood cell is less appetizing for the malaria parasite.
Many people mistakenly view this sort of change as an example of evolution in action—because a mutation in DNA has made people better adapted to their environment.
But if microbes really did turn into mankind—which is what evolution teaches—this would require the addition of new DNA information to turn the relatively simple genome of a microbe into the vastly more complicated one of a person.
In the case of sickle cell anemia, the opposite has happened, because DNA information has been corrupted and lost, not gained, because the crippled blood cells are less able to transport oxygen.