Aging in the natural world: comparative data reveal similar mortality patterns across primates

Abstract

Human senescence patterns-late onset of mortality increase, slow mortality acceleration, and exceptional longevity-are often described as unique in the animal world. Using an individual-based data set from longitudinal studies of wild populations of seven primate species, we show that contrary to assumptions of human uniqueness, human senescence falls within the primate continuum of aging; the tendency for males to have shorter life spans and higher age-specific mortality than females throughout much of adulthood is a common feature in many, but not all, primates; and the aging profiles of primate species do not reflect phylogenetic position. These findings suggest that mortality patterns in primates are shaped by local selective forces rather than phylogenetic history.

Fig. 1

Age-specific mortality at age x, u_x, for each study species, illustrating high infant mortality, low juvenile mortality, and mortality increasing with age over the adult life span. No sex-specific first-year mortality estimates are available for sifaka because individuals were not sexed and individually identified until their first birthday. For blue monkey males and both sexes of capuchins and muriquis, mortality estimates extend only through age 6, 20, and 32 years, respectively; in each case, this is much less than the suspected full life span, making it difficult to estimate the shape of the mortality curve at the end of life.

Fig. 2

IMR versus RoA for (A) females and (B) males. Phylogenetic relationships among species are shown in (C). Letters over bars denote statistically significant groupings. [Female IMR: human, gorilla (A) ≤ gorilla, muriqui (B) < blue monkey, chimpanzee (C) < sifaka, baboon, capuchin (D); female RoA: human, chimpanzee, sifaka, baboon, muriqui (A) ≤ muriqui, blue monkey, capuchin (B) ≤ blue monkey, capuchin, gorilla (C); male IMR: human (A) < muriqui, gorilla, chimpanzee, capuchin (B) ≤ capuchin, sifaka (C) < baboon (D); male RoA: human (A) < chimpanzee, muriqui, gorilla, sifaka (B) ≤ muriqui, gorilla, sifaka, baboon, capuchin (C).] See table S2 for tests of pairwise comparisons of IMR and RoA.