Grandmothering age at maturity interbirth intervals and fecundity

In CM, aM is approximately invariant because longer life spans favour more advanced age at maturity. More time to accrue the benefits of increased production associated with growing longer before reproducing offsets the cost of delay. If gains from growing longer continue to pay off after menopause, as the grandmother hypothesis proposes, then a should be adjusted accordingly. It is. These authors found that the late age at maturity for humans high a combined with our long life spans low M...

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To test these predictions, logged values of female body weight, brain size, group size and the amount of leaves in the diet percentage folivory have been used and regressed against the length of the juvenile period a . The results Table 4.8 show some support for the 'brain growth constraint' model, with a showing a significant positive relationship with brain size with both the species and older contrast values, indicating that the evolution of late maturation is linked to the evolution of...

Sex and social evolution in primates

VAN NOORDWIJK AND CHARLES L. NUNN Life history and male infanticide risk Infanticide by males unlikely or unable to have fathered a female's current dependent offspring is an adaptive male reproductive strategy if the mother can soon be fertilised again and the infanticidal male is in a position to be the likely sire of her next infant Hrdy, 1979 Hrdy, Janson and van Schaik, 1995 . It is remarkably common among primates Hausfater and Hrdy, 1984 Struhsaker and...

Age at first birth

Hill and Hurtado 1996 report their intensive investigation of demography of the Ache hunter-gatherers of Paraguay by means of carefully interlinked interviews conducted between 1977 and 1995. The information covers a 'pre-contact' or 'forest' period, which ended in 1971, a brief but decimating from 544 in 1970 to 338 in 1976 period of epidemics during the first years of settlement, and a subsequent period during which most people spent most of their time at settlements, and the population...