Group Selection and Theories of Aging

Group/Kin Selection and Theories of Aging

Group and Kin Selection Theories - Alternatives to Traditional Evolutionary Mechanics

Group selection is one of the alternative evolutionary mechanics theories that have been developed in an effort to handle apparent observed discrepancies between observations of living organisms and traditional evolutionary mechanics theory (see Scientific Issues with Traditional Evolution Theory). The general concept is that benefit to survival of a group may offset some degree of individual fitness disadvantage and thus allow for the evolution of organism characteristics that are adverse to individual fitness such as programmed aging or animal altruism.

In 1962 British zoologist Vero Wynne-Edwards published a group selection theory in his book Animal Dispersions in Relation to Social Behavior. This theory was intended as an explanation for altruism and suggested that behaviors that improved group survival could evolve despite individual disadvantage. His theory was vigorously criticized by followers of traditional evolutionary mechanics theory particularly George Williams (author of a non-programmed theory of aging based on traditional evolutionary mechanics).

Critics suggested that group selection was motivated by anthropomorphism and that group selectionists were excessively ascribing human characteristics to animals. Human societies, civilizations, and religions are indeed greatly characterized by the concept of individual sacrifice for group benefit and this concept is certainly counter to the everyone out for himself, dog-eat-dog, situation described by Darwin and traditional evolutionary mechanics. Even though traditional Darwinists agree that humans are descended from prior species they think that humans have special properties, not possessed by animals, that lead to distinctly human (individually adverse) behaviors. However, most theorists now accept that there are many credible observations of animal behaviors that appear to be individually adverse and therefore conflict with traditional evolutionary mechanics.

Critics also raised mechanics issues. How does the genetic data that programs altruism propagate into a population sufficiently that the group benefit can be realized. There is a "cheater problem": Even if a trait benefits survival of the group, why wouldn't animals that did not possess the individually adverse trait be able to better propagate their non-altruistic design? This problem appears to become progressively more severe as the size of the group increases. Eventually this led to several variations of the group selection concept based on the size and nature of the group. Perhaps group selection only works for small groups, for isolated populations, for closely related organisms (kin), etc. For example, W. D. Hamilton is a major figure in development of the kin selection concept along with J. B. S. Haldane.

The mechanics issues depend on one's perception regarding the rapidity with which the evolution process responds to fitness advantage or disadvantage. Our collective experience with selective breeding suggests that enormous phenotypic change can be produced in a very few generations. Does this mean that an individually adverse trait would "select out" very rapidly and that therefore an individual disadvantage (even a very small one) would override a group benefit (even a large one)? Not necessarily. Selective breeders recognize that breeding for one property of an organism generally introduces changes to other properties. This is often inconsequential to the breeder. However, an evolutionary fitness advantage results from the combined net effect of all of an organism's design properties and evolution is therefore different from selective breeding. A mutational change that deleted altruism or some other individually adverse characteristic might well also negatively affect other individually beneficial characteristics. The evolution process, over a much longer period, can eventually sort out these issues producing a net benefit. This sort of analysis combined with recent genetics discoveries suggests that the evolution process is relatively slower and more complex than selective breeding and that therefore a group benefit my not be so different from an individual benefit. Modern genetics discoveries are adding to a mechanics basis for group selection.

Group/Kin Selection and Theories of Programmed Aging

The group selection concept has been applied to theories of programmed aging by Joshua Mitteldorf.

Giacinto Libertini is the author of a programmed aging theory based on kin selection. Libertini's concept, based on examinations of life span data gathered from many wild animals is that a shorter mean life span causes a quicker generational turnover and therefore a quicker diffusion of favorable genes within a species thus creating a competitive advantage.

See Resources for journal articles.