The Cambridge dictionary of human biology and evolution

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Primates, 1995

The average time lag between the last parturition and the disappearance/death was 6.0 years for the Japanese macaque females that survived at least to the age of 20 years in the Arashiyama B troop. Since it may take 1.5 years for the last offspring to become able to survive without the mother, 4.5 years may correspond to the "post-reproductive life span (PRLS)," which occupied about 16% of the average span of their lives (27.3 years). During the PRLSs, the females continued to become estrous and mate with the males for at least several years. On the other hand, one of the oldest females showed neither estrus nor copulatory behaviors. There may be several causes for the lack of reproductive success among old aged females: (1) in spite of ovulation, other physiological functions related to conception may have declined; (2) the old aged females may not have been able to maintain pregnancy, and may have aborted; or (3) the old aged females may have exhibited estrus without ovulation, and may be considered to have been in menopause. In the Arashiyama B troop, PRLS may not be an unusual phenomenon, because, out of the 32 females born from 1954 to 1963, 13 females (41~ survived to the age of 20 yrs and most of them exhibited conspicuous PRLSs. Similar PRLSs were found in a non-provisioned population of the Japanese macaque of Yakushima Island, and in a wild population of the chimpanzee of the Mahale Mountains National Park, Tanzania.

Proceedings of the National Academy of Sciences of the United States of America, 1998

Long postmenopausal lifespans distinguish humans from all other primates. This pattern may have evolved with mother-child food sharing, a practice that allowed aging females to enhance their daughters' fertility, thereby increasing selection against senescence. Combined with Charnov's dimensionless assembly rules for mammalian life histories, this hypothesis also accounts for our late maturity, small size at weaning, and high fertility. It has implications for past human habitat choice and social organization and for ideas about the importance of extended learning and paternal provisioning in human evolution.

Anthropology & Aging

Wild animals were once thought not to age, as their deaths were viewed as the consequences of constant exposure to the perennial risks of nature. Studies of non-human aging were largely confined to biological investigations, focusing upon short-lived species such as fruit flies, mice and nematodes. Over recent decades, this has changed, and studies of non-human aging have begun to investigate aging taking place in social contexts. The present paper reviews such work on social aging in non-human primate societies. Four themes were evident in seeking potential parallels between human and non-human social aging. These were social disengagement, social bonds or social capital, status rank and dominance, and kinship ties. No studies were found that had explored parent caregiving. The lack of clear evidence that agedness is perceived and recognised within non-human primate groups suggests that most age-associated behavioral changes are at best demi-regularities that map quite imprecisely ...