Genetic destabilisation  Natural selection is the process whereby people mate, have children and those children enrich the gene pool – if they survive. Occasionally genetic mistakes are made in that reproduction. As long as the result is not fatal, that mistake can begin to infiltrate the gene pool. More people may come to have this mistake in built into their genome. Whilst we may see it as a mistake in our current living conditions, that mutant gene may be a defense to future conditions.  For instance, the spread of sickle cell anemia in Africa. This disease causes red blood cells to carry less oxygen due to the squashed nature of all the red blood cells. This condition causes people to die younger, in 1973 life expectancy for a sufferer was 17, and it is now 50 and above. However, sickle cell anemia is a natural immunity against malaria. The life expectancy for someone with malaria is far lower.[[Sickle cell disease, QualityHealth, 13th January 2011,  accessed 25/05/11]]  We need different genes in the human gene pool even if we do not see the benefit of them now.