The Evolution of Intergenerational Transfers and Longevity: An Optimal Life History Approach

Cyrus Chu, Academia Sinica
Ronald Lee, University of California, Berkeley

How would resources be allocated among fertility, survival, and growth in an optimal life history? The budget constraint assumed by past treatments limits the energy used by each individual at each instant to what it produces at that instant. We develop explicit solutions for this case, extending the current literature that presents numerical solutions and permitting comparative static analysis. Then we consider under what conditions energy transfers from adults (parental care), which relax the rigid constraint by permitting energetic dependency and faster growth for the young, would be advantageous. In a sense, such transfers permit borrowing and lending across the life history. We show that if such transfers are advantageous, then increased survival will co-evolve with transfers. Our formal analysis is most relevant for the demographic context of cooperative breeders, but we expect that the results will hold more generally.