Evolution's New Heretics
Lewin, Roger, Natural History
Like an old-time preacher, David Sloan Wilson has the appearance of a man with mission. An evolutionary biologist at the State University of New York at Binghamton, Wilson is given to marching up and down, flailing his arms, and proclaiming passionately, even in informal conversation. His message is as clear as it is bold: A whole generation of evolutionary biologists has been misled into believing that natural selection grinds inexorably at the level of individual interests, and only at that level. Instead, Wilson argues, biologists must recognize that groups of organisms have evolutionary interests, too, and that natural selection sometimes operates at this "higher" level. "Group selection" means that, occasionally, individuals within a group--for instance, an ant colony, a baboon troop, a nomadic band of human hunter-gatherers, or even a human population united by a common culture--may sacrifice their own reproductive future if, by doing so, the group benefits This benefit comes through increased fitness, that is, through contributing more offspring to the next generation than do other, competing groups. Similarly, individuals may cooperate if the common end enhances the group's fitness.
For more than twenty years, Wilson has been working unceasingly--initially very much as a loner, but now with a growing band of supporters--advocating a theory that has been viewed by some as nothing less than heretical. Although much of his writing is couched in the arcane language of mathematical models, Wilson is concerned with a form of behavior that is very basic and, intuitively anyway, easily understood: altruism.
Humans may pride themselves on being genuinely altruistic, selflessly helping others, whether it is by dying for one's country or giving a couple of dollars to homeless person on the street. But, modern evolutionary biologists ask, can animals other than humans be described a sometimes acting altruistically? Is the honeybee that dies in the act of stinging an intruder to the hive being altruistic? And what of a lioness that suckles the young of others in the pride as well as her own? Humans think of altruism as doing good for its own sake, but most of us would deny such motives to other animals. Two decades ago, Harvard biologist Edward O. Wilson proclaimed in his important and controversial book Sociobiology: The New Synthesis that altruism is "the central theoretical problem" of evolutionary biology in a social context.
Darwin was aware of apparently altruistic behaviors in nature. His theory of evolution by natural selection is principal about the survival of individuals in the "struggle for existence," in which they a always seeking ways of promoting the own reproductive success. Nevertheless he recognized that individuals might sometimes act selflessly if, as a result, the success of the group is promoted instead. In The Descent of Man, Darwin used this line of argument to explain the evolution of morality. If this sounds uncannily like David Sloan Wilson's position, it is. So why has Wilson been called a heretic for championing something that Darwin expressed a century ago? How is it, as Wilson recently noted, that "the rejection of group selection was treated as a scientific advance comparable to the rejection Lamarckism, and like Lamarckism, its memory was kept alive as an example how not to think?"
During the century following the publication of The Descent of Man, Darwin's clear vision of group selection was superseded by a fuzzy view of life as a harmonious enterprise, with individuals acting toward a collective good. Most scientists, for instance, saw territoriality as individuals acting to control the density of the population for the good of all. Similarly, dominance hierarchies--the pecking orders so common among social animals--were seen as a means of reducing wasteful conflicts within the group.
This naive version of group selection culminated in the 1962 publication of V. …