Williams postulated a "principle of parsimony": that biological adaptations be
explained at the lowest level possible. Therefore,
Williams treated the gene as the fundamental unit of selection. The most
fundamental consequence of selection is differential replication of genes.
The gene is selected through an interaction with the environment at different environmental levels. At the genetic level the environment is the population gene pool, i.e. the other genes. The somatic level in an intermediary level that has to do with the succession of somatic stagesin which a gene expresses itself: its selection depends on its mean success at different stages. The ecological level is the environment, which can be viewed as the strategy employed by nature against the organism. The concept of fitness is appropriate at all epigenetic levels.
By analyzing a number of cases of supposed group selection, Williams proves that group selection is not a significant factor. Natural selection originates from reproductive competition among individuals, and ultimately genes. A gene is selected on the basis of its ability in producing individuals that can maximize the gene's representation in future generations.
Organisms are built according to a design carried out by genes, which are potentially immortal.
Every trait serves some kind of self-interest. Genes that serve that self-interest are more likely to survive (because their vehicles are more likely to survive) and multiply. Thus the corresponding traits are more likely to become widespread among future generations.
Williams explained how evolution extended altruism beyond kinship: an individual's chances of survival are increased by having friends and decreased by having enemies. That simple. Thus it makes sense for any individual to maximize friendship and minimize antagonism. There is no need for conscious calculation: evolution has endowed individuals with "altruistic" instincts and emotions because it helps them survive. Most of the individuals who didn't have them did not survive to make children. Williams thus explained the Darwinian value of friendship.
TM, ®, Copyright © 2005 Piero Scaruffi