Understanding Evolution: Gene Selection Vs. Group Selection By

;;;;;;;;;;;;;;;;;;;;;; English 100 Essay Dawkins and others in the 1960s is the predominant view among modern evolutionary biologists. The Understanding main premise relies on the concept of the ÒgeneÓ as being the ultimate, fundamental unit of natural Evolution: Gene selection. By the basic principles of natural selection, genes that are more successful at replicating Selection vs. Group themselves will, by default, become more numerous in the population. Therefore, a gene that happens Selection to increase the general Þtness of the individual in Michaela Lewis which it is located will be more likely to be passed down to the next generation. This understanding leads us to the concept of the ÒselÞsh gene,Ó where Almost everybody feels that they understand natural selection applies at the level of individual DarwinÕs Theory of Evolution by natural selection. genetic codes; genes which make the organism behave It is as simple as Òsurvival of the Þttest.Ó There is, in ways that ÒselÞshlyÓ increase the chances of the though, an important subtlety that is often omitted by immortal geneÕs survival will become more frequent the biology textbooks, providing a radical shift in the in any given population. The organisms which way we view evolution and natural selection. In the carry thousands of these genes can then be viewed early twentieth century, theorists uncritically assumed as ÒvehiclesÓ of selection, since they constitute a that Darwinian selection could apply and produce coordinated, fairly uniÞed collection of genes. Genes adaptations at many levels of the biological hierarchy, must work together in organizing the survival and from individuals to populations to ecosystems. In reproduction of the host vehicle, because they are all the 1960s and 1970s, a scientiÞc shift occurred and locked in the same Òboat.Ó For example, a gene for evolutionary biologists began viewing genes as the powerful jaws and hunting skills would not help the fundamental unit of selection. Noted evolutionary organism survive if all the other genes were coded theorist Richard Dawkins wrote the revolutionary, for the body of an herbivore; the organism would and now classic, book The SelÞsh Gene in 1976, be less likely to survive and reproduce, thereby explaining the new genetic view and making it more stopping the genetic line and reducing the frequency accessible to lay-people and scientists alike. ÒNaiveÓ of that particular carnivorous gene in the population group selectionism Ð such as the belief that any (Dawkins, 1976). Although natural selection actually and all individuals would unconditionally sacriÞce operates at the level of selÞsh genes, the general themselves for the survival of the species Ð was Þtness of individuals often corresponds with that of expelled from the accepted scientiÞc understanding the genes. This makes it appear as though selection of natural selection, and held up as an example of applies at the individual level, and for the sake of how not to think. Only in recent years has a newer convenience, biologists often refer to Þtness levels version of the group selection theory come back into of organisms determining the selection process. It is the arena of debate, arguing that populations should always important, though, to be able to return to what be viewed as vehicles of selection in the same way Dawkins calls the ÒgeneÕs eye viewÓ of evolutionary that individual organisms are. This new perspective change - justifying organismÕs behavior on the basis of is mainly supported by the writings of E.O. Wilson gene preservation (Dawkins, 1976). and David Sloan Wilson, two respected American Groups or populations can also be viewed evolutionary biologists. The controversy between as vehicles of replicators, but far weaker, and less purist gene selectionism and the Multilevel Selection distinct, than individual physical colonies of genes or Theory (MST) may seem theoretical, but the reasoning cells. In this sense, then, a sort of Ògroup selectionÓ behind the two perspectives profoundly changes could in theory be possible, but it seems unlikely the way scientists understand evolutionary changes, that group-level adaptations between populations kin altruism, and group behavior. The claim now would occur. Lower-level selection likely overrides becomes a question: Òsurvival of the Þttest what? most of the inßuences from higher-level selection, so Gene? Organism? Or group?Ó the relevance of any possible group adaptations is The gene selectionist perspective proposed by debatable. Genes are still central as the only units of 114 replicator selection (Cronin, 1991; Dawkins, 1976). relatively stable ESS. It is possible for humans to The controversy regarding group selection enter into conscious pacts which, in the long term, has its roots in the question of demonstrated animal improve the survival and reproduction beneÞts of altruism: why do individuals sacriÞce themselves every member of the group, but in general terms or their time and energy in order to help other of animal strategies, ESSs will evolve that give an organisms? In the early days of group selectionism, average beneÞt to all members and that penalize any this sort of behavior was thought to have evolved deviance from the norm. Òfor the good of the speciesÓ or Òfor the good of the The second and opposing point of view in this group.Ó The most common form of altruistic self- controversy is the new version of group selection, also sacriÞce is reproduction and the care of offspring. known as Multilevel Selection Theory. Evolutionary Altruistic behaviors are also common between theorists who support the view that selection can close family members. This altruism results in operate on higher biological levels include E. O. the increased Þtness, survival, and likelihood of Wilson, V. C. Wynne-Edwards, David Sloan Wilson, reproduction of non-descendant relatives, also called and Elliott Sober. These renowned scientists do kin selection. As Dawkins explains in his 1976 book not renounce the gene as a basic unit of selection, The SelÞsh Gene and in a 2008 journal article entitled but instead argue that since individuals can be ÒThe Evolution of Altruism: What Matters in Gene regarded as populations of coordinated, cooperating Selection,Ó kin selection is still indirectly driven by genes, groups Ð as long as there is some degree of selÞsh gene behavior. Individuals are programmed coordination and harmony in their parts Ð should by their genes to help close kin survive and reproduce also be viewed as distinct ÒorganismsÓ that can act because, by doing so, they help perpetuate copies of as vehicles of natural selection (Wilson & Wilson, their genes Ð since offspring and relatives share up 2007). Proponents of this perspective contend that to 50% of the altruistic individualÕs genetic material. these vehicles of selection are the important factors This explanation of kin selection provides a very around which the entire view of selection must be acceptable model of the evolution of cooperative restructured. behavior. Sociobiologist W. D. Hamilton delineated In the new perspective of Multilevel the mathematical model of kin selection, calculating Selection theory, it is vital to differentiate between the probability that two individuals, either directly the environmental pressures and competitions descendent or with common ancestry, will share within a group versus the competition between genetic material (Hamilton, 1964). separate groups or populations. David Sloan Wilson Patterns of group behavior can be predicted accepts that within-group selection follows the within the selÞsh replicator theory by the use of basic principles of individual, selÞsh competition John Maynard SmithÕs concept of Evolutionarily (McAndrew, 2002). In a 1997 journal article, Wilson Stable Strategies (ESS); Dawkins describes this argues that group-level adaptations do not evolve important idea as Òa strategy which, if most members into adaptive units for all traits, but instead only for of a population adopt it, cannot be bettered by an certain traits which increase the evolutionary ÒÞtnessÓ alternative strategyÓ (Dawkins, 1967). This means of each group in relation to other populations that the most effective survival plan for an individual, (McAndrew, 2002). He states that although the and the genes which inhabit it, depends upon what occurrence of individual altruism may appear to the majority of the population is doing. For example, reduce the Þtness of the organism, Òit may sometimes if all the members of a group of animals are altruistic, become adaptive because groups of altruists will be the best reproductive strategy for one individual more Þt than groups of non-altruists under the right might be to act selÞshly. Since these ÒselÞshÓ conditionsÓ (McAndrew, 2002). individuals are more successful reproductively, Some of the main evidence for group the population will eventually become almost selectionism theories is based upon entomological entirely ÒselÞsh,Ó at which point, there might be a studies. E. O. Wilson, in particular, has done a large reproductive payoff to acting altruistically. As the amount of research in the Þeld of Myrmecology, group dynamics oscillate back and forth between the study of ants, a branch of entomology. For these two extremes, the most effective strategy for ants, group selection theories appear very useful each individual will converge on some average, for explaining their behaviors and physiology. Ant evolutionarily stable, strategy. Following any colonies can be, and

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