Reproductive endocrinology and aging in human males: An evolutionary perspective

Due to its important role in fertility, reproductive endocrine function has been subject to natural selection in all organisms including human males. Moreover, reproductive endocrine function is subject to change as males age. Indeed, the biology of aging is also subject to natural selection. As males age, hormone function such as variation in testosterone can change as the result of general somatic degradation. However these changes are not universal and can differ between human male populations depending on lifestyle and ecological context. The degree to which this variation is adaptive remains an open question but recent evolutionary anthropology research has provided some clarity. While knowledge of evolutionary approaches has limitations, the benefits of understanding the origins and comparative context of reproductive endocrine function in older human males are significant. This paper discusses our present comprehension of reproductive endocrinology and aging in human males, with a focus on human diversity across varied lifestyles, ecologies, and environments. In addition, comparative great ape research is examined. Current research challenges and future directions related to the importance of evolutionary biology and human diversity for understanding human male aging are discussed.