Around the world and across time, women's lives and opportunities vary-but this is patterned variation, produced by the interplay of natural selection (life history theory) and ecological and social constraints. Our evolutionary background (e.g., evolution of anisogamy) and phylogenetic constraints (female mammals' specialization for postnatal care) create different costs and benefits for males and females. These interact with environmental conditions to produce patterned variation in mating and marriage systems, degree of male parental investment, for example. Here, I review how, in response to these conditions, women's strategies (reproductive, resource, coalitional, and political) vary. (C) 2005 Elsevier Inc. All rights reserved.