a1 School of Psychology, University of Central Lancashire, Preston PR1 2HE, United Kingdom. email@example.com http://www.uclan.ac.uk/scitech/research/rae2008/psychology/staff_profiles/jarcher.php
I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained.
John Archer, Professor of Psychology at the University of Central Lancashire, Preston, United Kingdom, is the author of more than 100 articles, in a wide range of journals, in the areas of animal aggression and emotionality, testosterone and behavior, human sex differences, human aggression, grief and loss, and evolutionary psychology. He is also the author of several books, including The Behavioural Biology of Aggression (1988), The Nature of Grief (1999), and Sex and Gender (2nd edition, 2002). He is a former President of the International Society for Research on Aggression (ISRA), and is a Fellow of the British Psychological Society.