The evolution of transfers and life histories

Much of life history theory analyzes life histories of independent, isolated individuals, who grow, forage, reproduce, and die. However, in many species social interactions such as food sharing are a key part of the life history strategy, altering the energetic budget constraint. Transfers and sharing raise reproductive success and also alter the fitness impact of other aspects of the life history. We discuss a variety of traits and behaviors for which transfers are important, synthesizing results from a number of earlier papers. Topics include the U-shaped mortality curve, post reproductive survival, causes of early life mortality decline, why intergenerational transfers evolve and co-evolve with longevity, time preference, sexual dimorphism and sexual differences in transfers, menopause, demographic advantages of social sharing, and consequences of social sharing for life history evolution.

► Intergenerational transfers alter the lifetime energetic budget constraint.
► Transfers co-evolve with and shape other life history traits.
► Transfers help explain postreproductive survival, dimorphism, time preference.
► Social sharing also shapes evolution of fertility and mortality by age.
► Transfers and sharing can raise efficiency and also cause inefficient distortions.