Evolutionary Origins of Men's and Women's Behavior
What sex differences are innate characteristics of the human species, and what ones reflect culture? This question is hotly debated. Its answer depends on what assumptions you make about evolutionary pressures on human ancestors and how these influenced men's and women's innate psychology.
Sexuality and mating practices are a key to understanding a species' evolutionary history because differential reproduction, along with survival selection, drives evolutionary outcomes. In cross-cultural investigations of industrialized and pre-industrial societies, considerable variability is evident in human sexuality and mating (Eagly & Wood, 1999; Wood & Eagly, 2002, 2007). This variability reflects humans' sensitivity to local circumstances. Humans plausibly are endowed with this flexibility because they evolved in diverse environments with changeable conditions that impinged in differing ways on survival and reproduction.
Flexibility does not imply that the mind is a blank slate. Human ancestors adapted by developing language, theory of mind, and forms of social learning that allow for complex cultural traditions that cumulate across generations. The result, as described by Lumsden and Wilson (1981), is "a complicated, fascinating interaction in which culture is generated and shaped by biological imperatives, while biological traits are simultaneously altered by genetic evolution in response to cultural innovation" (p. 1).
In this logic, Wood and Eagly (2002, 2005) proposed a biosocial origin model. Sex differences in behavior within a given society arise from the dynamic interaction between (a) biologically-based sex differences, especially that women bear and nurse children and that men have greater size, strength, and speed, (b) developmental processes, and (c) local culture, technology, and ecology. The social roles that emerge from this interaction are characterized by a division of labor, because the physical endowment of each sex allows its members to perform certain tasks efficiently, depending on a society's circumstances and culture. Specifically, childbearing and nursing of infants enable women to care efficiently for very young children and cause conflict with roles requiring extended absence from home and uninterrupted activity. Men's greater speed and upper-body strength facilitate their efficient performance of tasks that require intensive bursts of energy and strength.
To illustrate the biosocial model, men but not women hunt in most known societies. The demands of hunting typically are incompatible with childcare (e.g., requiring extensive time from home, exposure to danger) and are facilitated by men's size and speed. In the few known societies in which women hunt (Agta of the Philippines, Aka Pygmy of Central Africa), game is available close to home, and thus women of almost all reproductive statuses can hunt accompanied by children. Women in these societies hunt with nets, small bows and arrows, and/or dogs. Cultural customs have developed that sanction women's hunting.
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Wood, W., & Eagly, A. H. (2007). An evolutionary biosocial theory of human mating. In S. Gangestad & J. A. Simpson (Eds.), The evolution of mind: Fundamental questions and controversies (383-390). New York: Guilford. [request paper]
Eagly, A. H., & Wood, W. (2005). Universal sex differences across patriarchal cultures ≠ evolved psychological dispositions. Behavioral and Brain Sciences, 28, 281-283.
Wood, W., & Eagly, A. H. (2002). A cross-cultural analysis of the behavior of women and men: Implications for the origin of sex differences. Psychological Bulletin, 128, 699-727. [request paper]
Wood, W., & Eagly, A. H. (2000). A call to recognize the breadth of evolutionary perspectives: Sociocultural theories and evolutionary psychology. Psychological Inquiry, 11, 52-55. [request paper]
Eagly, A. H., & Wood, W. (1999). The origins of human sex differences: Evolved dispositions versus social roles. American Psychologist, 54, 408-423. [request paper]
What sex differences are innate characteristics of the human species, and what ones reflect culture? This question is hotly debated. Its answer depends on what assumptions you make about evolutionary pressures on human ancestors and how these influenced men's and women's innate psychology.
Flexibility does not imply that the mind is a blank slate. Human ancestors adapted by developing language, theory of mind, and forms of social learning that allow for complex cultural traditions that cumulate across generations. The result, as described by Lumsden and Wilson (1981), is "a complicated, fascinating interaction in which culture is generated and shaped by biological imperatives, while biological traits are simultaneously altered by genetic evolution in response to cultural innovation" (p. 1).
To illustrate the biosocial model, men but not women hunt in most known societies. The demands of hunting typically are incompatible with childcare (e.g., requiring extensive time from home, exposure to danger) and are facilitated by men's size and speed. In the few known societies in which women hunt (Agta of the Philippines, Aka Pygmy of Central Africa), game is available close to home, and thus women of almost all reproductive statuses can hunt accompanied by children. Women in these societies hunt with nets, small bows and arrows, and/or dogs. Cultural customs have developed that sanction women's hunting.