Title: Evolution of Sex Differences in Spatial Ability
Abstract: Sexual selection, Cognition, Monogamy, Polygyny, Home ABSTRACT Many sex differences are likely to be adaptive conse- quences of sexual selection. Sex differences in spatial ability are well de- scribed for Homo sapiens and laboratory rodents, and such cognitive traits may also be shaped by sexual selection. An evolutionary model is outlined to predict the distribution of these sex differences across species. Sex dif- ferences in spatial ability were previously believed to be universal among mammals, but the evolutionary model has correctly predicted that such differences will evolve only in species where mobility has different effects on male and female fitness. Wild microtine rodents are particularly useful for testing this model. Radiotelemetric data from field studies of ranging behavior, data from lab- oratory studies of maze learning, and neuroanatomical data on the hippo- campus, a structure believed to be critically involved in spatial processing, all support the model. Several alternative explanations for sex differences in spatial ability are reviewed and evaluated. The proximate developmental basis of these sex differences is discussed, and an attempt is made to inte- grate developmental and evolutionary perspectives. Several promising fu- ture research directions are outlined. o 1992 Wiley-Liss, Inc. In most of the life sciences, our understanding of ontogeny and of evolution proceed relatively independently, despite the history of alleged connections be- tween the two. For example, among researchers who study sex differences, some focus on proximate, ontogenetic factors and others investigate the evolutionary forces that ultimately shape and constrain ontogeny. As a result, findings from one area often have a delayed and uneven influence on research in the other. While most of what follows is explicitly evolutionary, an attempt has been made to mesh these findings with current knowledge about the underlying ontogenetic mecha- nisms. We have made considerable progress in understanding how sexual selection (Darwin, 1871) fosters sexual dimorphism (Bateman, 1948, 1949; Trivers, 1972; Wade, 1979; Lande, 1980; Rogers and Mukherjee, 1992). Sexual selection is a type of disruptive selection that favors one phenotype in females and a different phe- notype in males. This kind of disruptive selection should be strong in species with non-monogamous mating systems because, in these mating systems, optimal male and female phenotypes diverge (Williams, 1966; Trivers, 1972). Specifically, sex differences evolve where males and females differ in their maximum reproductive rates (Clutton-Brock and Vincent, 1991). In the most monogamous breeding pop- ulations, the reproductive rates of the two sexes converge. Under these conditions disruptive selection for male and female characters is weak and sex differences are minimal (Kleiman, 1977). Conversely, in most species of primates, including Homo
Publication Year: 1992
Publication Date: 1992-01-01
Language: en
Type: article
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Cited By Count: 74
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