Natural Selection

Resistance to atherosclerosis- Atherosclerosis is a disease that is produced by modern diets and lifestyles. Atherosclerosis is a type of arteriosclerosis. This is the thickening and hardening of arteries as people age. It involves deposits of fatty substances, cholesterol, cellular waste products, calcium and other substances in the inner lining of an artery. The deposits build up and cause a plaque. Plaque blockages are especially harmful when they break up and move forming a blockage elsewhere which may lead to a heart attack or even a stroke.There is, however, a town in Italy whose residents are resistant to atherosclerosis. The resistance can be traced back all the way to the original host of the mutation. Natural selection has kept this resistance present even in the most recent generations.

Natural selection is a process by which biological populations are altered over time, as a result of the propagation of heritable traits that affect the capacity of individual organisms to survive and reproduce. It is one of several mechanisms that give rise to the evolution of biological species (other mechanisms include genetic drift and gene flow.) However, natural selection has a special significance because it is believed to be the one responsible for organisms being adapted to their environment. The theory of natural selection was proposed by Charles Darwin and Alfred Russel Wallace in 1858, though vaguer and more obscure formulations had been arrived at by earlier workers.
Natural selection can be subdivided into two types: (i) ecological selection, which arises from the portion of an organism's environment not related to direct sexual competition (such as the availability of food, the presence of predators, and so forth); and (ii) sexual selection, which arises from the competition for mates between individuals of the same sex. The reason for this division is that the effects of sexual selection can produce results that seem counterintuitive from the point of...