All I'm saying is that sickle-cell is an example of mutation and natural selection at work. If it weren't beneficial in the Darwinian sense, it wouldn't occur in 40% of some populations. Do you have another explanation to account for the fact it is found in a fairly large percentage of people in malaria country, but in a very small (zero, really) percentage outside it?
In addition it must be remembered that people without this 'protective' mutation nevertheless survive in malaria infested regions. So this is not necessary for survival.
No-one said, and I explicitly denied, that hemoglobin-S is the *only* protection against malaria.
I think we looked at that once and if it did occur anywhere at 40% it was in a very small area. The death toll would be tremendous from it. As to why it occurs in some places, why are there black people in Africa and Mongoloid in China? We still have many blacks in the US with the trait. A harmful recessive trait can survive in populations for a long time.
No-one said, and I explicitly denied, that hemoglobin-S is the *only* protection against malaria.
Survivability from a disease is due to many things. Few people die from the flu in their 20s and 30s but the death rate rises sharply among seniors. So it is not just one factor.
I do not deny that traits are inherited and that bad traits can dissappear from populations. What I am saying is that this is not the kind of mutation on which evolution - the transformation of one species into a more complex one - can be built upon.