Independent of ecology, subsistence strategy, social complexity, or other aspects of socioecology, the altricial nature of young humans requires mothers to have help raising their offspring. What seems to be context-dependent, however, is who the helpers are, how they invest, and what the impacts of that investment are. In a series of papers that focus on parental and alloparental investment across five populations, this special issue of Human Nature uses evolutionary theory to examine how socioecological context influences modes of direct (...) parental investment among the boat-dwelling Shodagor of Bangladesh, modes of indirect paternal investment in the modern United States, and the biological outcome of paternal investment for men in Jamaica, as well as direct alloparental investment among village Bangladeshis and indirect alloparental investment in breastfeeding practices in the United States. (shrink)