High infant and child mortality rates are suggested to be one of the most enduring and important features of ancestral human environments, referred to as the Environment of Evolutionary Adaptedness (EEA). These rates contrast with the very low rates of infant and child mortality among many industrialized nations since the 19th and 20th centuries. The authors compare data from recent hunter-gatherer and agricultural societies, historical records, and non-human primates in attempt to quantitatively describe infant and child mortality rates during the EEA.

This book chapter examines relationships between the child-training behavior of mothers and the responsibilities of both mothers and others. Child-training behavior is also examined in relation to single and multiple family dwellings.

This chapter examines the relationship between male parental behavior and influences of species, ecological and social factors. The authors first present a cross-phylogenetic perspective on paternal differences between species, then offer two quantitative studies: a comparative study of non-western human societies that correlates father-infant proximity with socioecological factors and another about father-infant proximity among the !Kung.

Researchers looked at four different demographic scenarios (altered mean vital rates (i.e., fertility and mortality), vital rate stochasticity, vital rate covariance, and periodic catastrophes) and their possible effects on the rapid population growth of contemporary human foragers and steady population decline of chimpanzees. They evaluated these variables and the various conditions that would favor a more sustainable zero population growth (ZPG) among 10 small-scale subsistence human populations (Agta, Ache, Hadza, Hiwi, Ju/’hoansi, Gainj, Tsimane, Yanomamo, Northern Territory Aborigines, and Herero) and five wild chimpanzee groups (Gombe, Kanyawara, Mahale, Ngogo, and Taï). The results state that the most effective modifications towards ZPG would include a combination of more than one of the four demographic scenarios tested, with the most realistic solution including both vital rate alteration and an increase in catastrophes.

This article seeks to reevaluate the widespread assumption that hunter-gatherers lack the longevity that people in the modern, industrialized world enjoy. Through modeling life expectancy, mortality, and other demographic trends among extant hunter-gatherer, gatherer-horticulturalists, and horticulturalists societies they are able to challenge this belief. The authors conclude that longevity is a "novel feature of Homo sapiens" and that seven decades seems to be the natural lifespan of a human.

This study examines the relationship between infant stress and early menarche. Empirical analysis suggests that stress in infancy, such as mother-infant separation and head-shaping, are associated with early menarche.

Focusing on 61 preindustrial societies that have information on fertility, the author asks what factors may explain variation in fertility, what devices are used to control fertility, and whether differences in fertility appear to be in line with the societies' environments.

Evolutionary anthropologists have long emphasized the puzzle of short inter-birth intervals, extended childhoods, and long post-reproductive lives of humans, in particular the problem it poses for raising children. While there is agreement that mothers receive assistance from kin to offset the high costs of raising children, opinion is equivocal as to which kin help and to what extent they help. Here the authors review 45 studies from historical and contemporary natural fertility populations to assess the effects of various types of kin on child survival rates.

Researchers examined both why so many language are spoken today, and why they are so unevenly distributed geographically. Instead of looking at correlative tests, this study uses a process-based simulation model that attempted to predict both the number or precolonial languages in Australia as well as the number of languages per unit of land. The model was based upon three basic assumptions: 1) humans fill unoccupied spaces; 2) rainfall limits population density; 3) groups divide after reaching a maximum population. While researchers used the model strictly on the Australia continent, it was able to correctly explain 56% of spatial variation in language richness, and predict the total number of languages across the continent. The accuracy of this model concludes that climatic conditions and changes in group size are important factors in shaping language diversity patterns and therefore global human cultural diversity.

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.