Many sex differences are likely to be adaptive consequences of sexual selection. Sex differences in spatial ability are well described 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 differences 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 laboratory studies of maze learning, and neuroanatomical data on the hippocampus, 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 integrate developmental and evolutionary perspectives. Several promising future research directions are outlined.
