This paper reviews demographic trends in longevity and the sex ratio, marriage and fertility, and household composition for the illumination they provide to an understanding of parenting in individual lives and to the social ambiance surrounding childbearing and -rearing in contemporary society. Second, the paper reviews gender differences in parenting as reflected in recent research on solo fathering and mothering, nontraditional family arrangements, and egalitarian marriages that show significant paternal involvement in childrearing. Third, the paper assesses the adequacy of current social explanations of gender differences in parenting, and demonstrates the relevance of an expanded explanatory model that draws upon bio-evolutionary theory and the neurosciences.