In 1975, Harvard biologist Edward O. Wilson published Sociobiology: The New Synthesis, wherein he outlined a framework for investigating the biological basis of social behavior. As a branch of evolutionary biology, sociobiological theory aims to use demographic parameters (e.g., growth and mortality rates, gender and age distributions) and the genetic structure of populations to predict patterns of social organization across species. One of the conceptual tools sociobiology contributes to investigations of social behavior is an analysis of ultimate causation. Whereas proximate causal analyses focus on, for example, the behavioral, developmental, physiological, or neural mechanisms operating within an individual’s lifetime to produce a particular phenotype, an ultimate causal analysis focuses on the selective forces that operated over generations and led to the evolution of the specific phenotype manifest in the individual.
In this way, proximate explanations answer the question of how mechanisms operate (e.g., the catalog of hormones, neurotransmitters, and brain regions governing behavior); ultimate explanations answer the question of why they were selected for (i.e., how a particular trait affected the probability of survival and reproduction).
Sociobiologists have made progress in understanding a wide range of behaviors, both their proximate mechanisms and ultimate functions, including altruism, patterns of communication, aggression, mating systems, and parental care of offspring. Such behaviors have been investigated in a wide range of species including ants, birds, frogs, and chimps. Wilson’s volume sparked heated controversy regarding his last chapter, which extended the principles of evolutionary ultimate causation and population genetics to explain the social behavior of humans.
Among the many reasons for this controversy were (a) misunderstandings about sociobiology and genetic determinism and, (b) the long-held view in the social sciences that social behavior in humans is the product of cultural forces, rather than biological ones. Many opponents mistook sociobiology for arguing that social behaviors are genetically fixed and immutable when, in fact, much of sociobiology focuses on how evolved social behavior is capable of adapting to different environmental situations (e.g., morphological and behavioral change given particular environmental cues). Controversy also occurred because sociobiology ran counter to the prevailing view in the social sciences. Indeed, one goal of sociobiology is the reshaping of the humanities and social sciences to make them consistent with the principles of modern evolutionary biology.
Though based on many of the same principles, sociobiology is distinct from evolutionary psychology. Although both disciplines consider ultimate causal explanations, evolutionary psychology uses this level of analysis to construct models of the information processing circuitry (i.e., the cognitive programs) required to produce an adaptive response. In contrast, sociobiology steps from selective forces (e.g., limited resources) to social behavior (e.g., aggression) without making explicit the kinds of cognitive programs required to produce a particular behavior. So, though related, there exists a set of non-overlapping goals distinct to each field. Nevertheless, sociobiology and its related disciplines take seriously the claim that principles derived from the modern synthesis, which united Darwin’s theory of evolution and Mendelian genetics, can be used to explain the constellation of behaviors in humans and nonhumans alike.
- Wilson, E. O. (1975). Sociobiology: The new synthesis. Cambridge, MA: Belknap.