Rl. Johnson et E. Kapsalis, MENOPAUSE IN FREE-RANGING RHESUS MACAQUES - ESTIMATED INCIDENCE, RELATION TO BODY CONDITION, AND ADAPTIVE SIGNIFICANCE, International journal of primatology, 19(4), 1998, pp. 751-765
We examined the question of whether the occurrence of menopause in rhe
sus macaque (Macaca mulatta) females approximates that found in women
from a life history standpoint. We used data from two provisioned free
-ranging populations of rhesus macaques to estimate the probability th
at a juvenile female not only will survive to the potentially postmeno
pausal age of 25 years but also will cease to experience menstrual cyc
les between 25 and 27 years. We used the same data to assess whether a
n age-related deterioration in body condition can predict whether fema
les greater than or equal to 25 years old will be acyclic. Our analyse
s indicate that, within our study populations, (1) less than or equal
to 1 in every 10 juvenile females can be expected eventually to underg
o the climacteric, and (2) being in poor condition is strongly associa
ted with being acyclic in old age. Current theory regarding the evolut
ion of senescence in species that do not reproduce by binary fission p
osits that aging is a consequence of the force of natural selection de
clining with age. Inasmuch as the proportion of female rhesus macaque
juveniles that ultimately experience menopause is small and inasmuch a
s reproductive senescence does not appear to outpace organismal aging
in general (as indexed by an age-related decline in body condition), w
e conclude that the occurrence of menopause in rhesus females is parsi
moniously explained by the general evolutionary theory of aging and th
at the invocation of a special adaptive explanation such as the grandm
other hypothesis or a variant thereof, is unnecessary.