This article reviews aspects of cooperative breeding in humans and nonhumans. Life history characteristics, childcare helpers, and demographic implications of cooperative breeding are examined. Cross-cultural data is presented, though no empirical hypotheses are tested.

Grooming of conspecifics is thought to play an important social role among nonhuman primates, but the function and relative importance of such grooming among humans is unknown. Here the authors compare time spent grooming and conversing among six small-scale societies with grooming data from 69 nonhuman primate species. They test the hypothesis that conversation evolved among humans as an alternative way to obtain the social benefits (such as building and maintaining social alliances) of grooming in large groups.

Grooming of conspecifics is thought to play an important social role among nonhuman primates, but the function and relative importance of such grooming among humans is unknown. Here the authors compare time spent grooming and conversing among six small-scale societies with grooming data from 69 nonhuman primate species. They test the hypothesis that conversation evolved among humans as an alternative way to obtain the social benefits (such as building and maintaining social alliances) of grooming in large groups.

This article examines marital residence and sibling coresidence among horticulturalists in the South American lowlands. The authors reject a hypothesis that patrilocality is the defining trait of Amazonian tropical forest culture. Results on horticulturalists are compared with findings on hunter-gatherers: horticulturalists tend to be more uxorilocal. Empirical analysis also suggests that women tend to live with more kin later in life, and in large villages headmen live with more kin than nonheadmen.

This article examines marital residence and sibling coresidence among horticulturalists in the South American lowlands. The authors reject a hypothesis that patrilocality is the defining trait of Amazonian tropical forest culture. Results on horticulturalists are compared with findings on hunter-gatherers: horticulturalists tend to be more uxorilocal. Empirical analysis also suggests that women tend to live with more kin later in life, and in large villages headmen live with more kin than nonheadmen.

This paper seeks to understand the roles played by children and adolescents in hunter-gatherer societies in relation to their social and ecological context. The authors set out to investigate how environmental factors, ecological risk, and the energetic contributions of adult men and women to food production may have influenced children/adolescent allocation of time to child care, domestic work, food production, and play. In order to carry out this study, the authors logged the behaviors of 690 children and adolescents from twelve hunter-gatherer and mixed-subsistence societies (Agta, Aka, Baka, BaYaka, Dukha, Hadza, Matsi-genka, Maya, Mayangna, Mikea, Pume, and Tsimane), totaling 85,597 unique observations. The study found that harsh environmental factors were not associated with child/adolescent time allocation, but that local ecological risk such as dangerous animals and lack of water availability predicted decreased time allocation to child care and domestic work, and that increased adult female participation in food production was associated with less time invested in child care among boys. It also found that all gendered differences in time allocation among children were stronger when men made greater contributions to food production than women. The authors interpret these results to signify that parents may play a role in preparing their children for environmental and ecological difficulty in order to help them develop skills that will help them become useful community members as adults.

This paper seeks to understand the roles played by children and adolescents in hunter-gatherer societies in relation to their social and ecological context. The authors set out to investigate how environmental factors, ecological risk, and the energetic contributions of adult men and women to food production may have influenced children/adolescent allocation of time to child care, domestic work, food production, and play. In order to carry out this study, the authors logged the behaviors of 690 children and adolescents from twelve hunter-gatherer and mixed-subsistence societies (Agta, Aka, Baka, BaYaka, Dukha, Hadza, Matsi-genka, Maya, Mayangna, Mikea, Pume, and Tsimane), totaling 85,597 unique observations. The study found that harsh environmental factors were not associated with child/adolescent time allocation, but that local ecological risk such as dangerous animals and lack of water availability predicted decreased time allocation to child care and domestic work, and that increased adult female participation in food production was associated with less time invested in child care among boys. It also found that all gendered differences in time allocation among children were stronger when men made greater contributions to food production than women. The authors interpret these results to signify that parents may play a role in preparing their children for environmental and ecological difficulty in order to help them develop skills that will help them become useful community members as adults.

This paper seeks to understand the roles played by children and adolescents in hunter-gatherer societies in relation to their social and ecological context. The authors set out to investigate how environmental factors, ecological risk, and the energetic contributions of adult men and women to food production may have influenced children/adolescent allocation of time to child care, domestic work, food production, and play. In order to carry out this study, the authors logged the behaviors of 690 children and adolescents from twelve hunter-gatherer and mixed-subsistence societies (Agta, Aka, Baka, BaYaka, Dukha, Hadza, Matsi-genka, Maya, Mayangna, Mikea, Pume, and Tsimane), totaling 85,597 unique observations. The study found that harsh environmental factors were not associated with child/adolescent time allocation, but that local ecological risk such as dangerous animals and lack of water availability predicted decreased time allocation to child care and domestic work, and that increased adult female participation in food production was associated with less time invested in child care among boys. It also found that all gendered differences in time allocation among children were stronger when men made greater contributions to food production than women. The authors interpret these results to signify that parents may play a role in preparing their children for environmental and ecological difficulty in order to help them develop skills that will help them become useful community members as adults.

In this article, the authors reconsider the polygyny threshold model in order to account for the "polygyny paradox." This paradox, as the authors define it, is the trend away from polygyny as societies adopt stratified agricultural economies. This is despite an increase in both the importance of material wealth and greater leaves of wealth inequality both of which would otherwise suggest increased polygyny. The authors develop a new model that does account for this paradox.

In this article, the authors reconsider the polygyny threshold model in order to account for the "polygyny paradox." This paradox, as the authors define it, is the trend away from polygyny as societies adopt stratified agricultural economies. This is despite an increase in both the importance of material wealth and greater leaves of wealth inequality both of which would otherwise suggest increased polygyny. The authors develop a new model that does account for this paradox.