Anthropology, University of Toronto-Scarborough
Thursday 4:30-4:45, Ballroom B
Although most studies of reproductive senescence focus on females, males also experience reproductive decline with increasing age. Among primates, males show decreased semen quality as well as declines in reproductive performance (e.g., sexual stamina) with aging. At present, quantitative data on the effects of aging on male sexual performance are only available for humans and rhesus macaques. Such data are lacking in strepsirhines. Therefore, the goal of this multi-year retrospective study was to evaluate male ring-tailed lemur (Lemur catta) sexual behavior for evidence of reproductive decline. Data were collected across 11 mating seasons on St. Catherines Island, Georgia, USA. Data came from 60 different copulatory events that led to ejaculation involving 27 individual male L. catta. The oldest males in the study were 14 years of age. Results showed that older male L. catta did indeed exhibit a decline in sexual performance, because age was positively correlated with cumulative time spent in mounts before ejaculation was reached (Spearman, p<0.05) and with the total number of mounts needed to reach ejaculation (Spearman, p<0.05). Older males (those between 8-14 years of age) were also less likely than younger males to be the first mates of females entering estrus, which may signal a concomitant decline in the competitive ability of older males, as access to females is largely gained via physically aggressive intra-sexual competition in this species. These results demonstrate that strepsirhine males experience a marked decline in sexual performance with age, making this pattern of reproductive senescence ubiquitous across the primate order.