Male Life History, Reproductive Effort, and the Evolution of the Genus Homo New Directions and Perspectives

The evolution of male life history traits was central to the emergence of the genus Homo. Compared with earlier hominins, changes in the behavioral and physiological mechanics of growth, survivorship, reproductive effort, and senescence all likely contributed to shifts in how males contributed to the evolution of our genus. For example, the range of paternal investment in modern Homo sapiens is unusual compared with most mammals and primates, all but certainly contributing to the evolution of the suite of life history traits that define Homo, including high fertility, large bodies, altricial offspring, large brains, and long lives. Moreover, the extensive range of phenotypic and behavioral variation in somatic and behavioral reflections of male reproductive effort across modern H. sapiens is especially noteworthy. We propose that selection for a broad range of variation in traits reflective of male reproductive effort was important to the evolution of Homo. We examine factors that contribute to this variation, proposing that selection for paternal and somatic investment plasticity across the entire male life span was important for the evolution of Homo. Potential research strategies and directions for new research for exploring these issues in the fossil record are also discussed.