Mace, R;
Sear, R;
(2005)
Are humans cooperative breeders?
In: Voland, E; Chasiotis, A; Schiefenhoevel, W, (eds.)
Grandmotherhood: the Evolutionary Significance of the Second Half of Female Life.
Rutgers University Press, New Brunswick, pp. 143-159.
ISBN 9780813536095
https://researchonline.lshtm.ac.uk/id/eprint/21153
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There is evidence to suggest that human
female reproduction is assisted by other
members of her family. In particular studies show that fathers and grandmothers are
important in supporting her reproductive success. In this paper, we examine the effects
of specific kin on specific components of fitness, and show that the contributions of
matrilineal and patrilineal kin are very different. Fathers contributions to child survival
are mixed, possibly being more significant in monogamous societies. Maternal grandmothers and other matrilineal kin tend to
improve child survival but not female fertility, whereas patrilineal grandparents and male kin tend not to he
lp child survival but do enhance the mothers rate of birth. We argue that these different strategies emerge as a response to different relatedness to the mother, because the costs of maternal mortality differ between the two lineages: patrilineal kin are less concerned about women paying
the high costs of reproduction associated with high fertility.
Models of the grandmother hypothesis for the
evolution of menopause generally find that
the magnitude of grandmother effects is not large enough to compen
sate for the loss of
later life fertility. However recent developments in modelling approaches do highlight
the importance of transfers (be it of care or resources) in the
evolution of human
longevity and fertility schedules. These remain the most
plausible explanation for the
unusual features of the human female life
history, including
high birth rates and
menopause.