Human testes are relatively small for body size: Copulatory and Postcopulatory Sexual Selection in Primates

Copulatory and Postcopulatory Sexual Selection in Primates. A F Dixson. Folia Primatologica 2018;89:258–286. https://doi.org/10.1159/000488105

Abstract: Many aspects of primate reproductive anatomy and physiology have been influenced by copulatory and postcopulatory sexual selection, especially so in taxa where multiple-partner matings by females result in the sperm of rival males competing for access to a given set of ova (sperm competition). However, the female reproductive system also exerts profound effects upon sperm survival, storage and transport, raising the possibility that female traits influence male reproductive success (via cryptic female choice). Current knowledge of sperm competition and cryptic choice in primates and other mammals is reviewed here. The relevance of these comparative studies to our understanding of human reproduction and evolution is discussed.