What necropsy reports can tell us about menopausal and age-related changes in Western lowland gorillas (Gorilla gorilla gorilla)

Abstract

This paper explores age-related post-mortem changes in zoo-housed gorillas. Our previous research examined hormonal changes in zoo-housed ageing western lowland gorilla (Gorilla gorilla gorilla) females in order to assess whether they experienced hormonal menopause. We had the opportunity to investigate whether these females showed post-mortem changes similar to those seen in ageing human females, and whether or not these changes are associated with general patterns of ageing, or hormone-mediated changes, or both. We reviewed necropsy reports for 14 females, ranging in age from 30 to 56 years at time of death. We evaluated all females for cardiovascular and reproductive tract anomalies. There were no significant differences in occurrence of cardiovascular disease (P = 0.256) or reproductive tract abnormalities (P = 1.00) between females considered to be menopausal at time of death and those for whom we could not definitively ascertain reproductive status. Females over 45 years of age were significantly more likely to exhibit reproductive tract pathologies (P = 0.031) than were females 45 and younger. To our knowledge, this is the first study to report on post-mortem changes in the reproductive tracts in aged gorillas. These findings highlight the importance of long-term monitoring and post-mortem follow-up to more clearly discern patterns in older females and to shed light for comparisons between taxa.