Life history theory

Life history theory is the study of how organisms allocate limited resources across growth, reproduction, and maintenance over their lifespan, treating these allocations as strategic decisions shaped by natural selection. The theory predicts that organisms facing high mortality will evolve faster life histories — earlier maturation, more offspring, less parental investment — while organisms in stable environments will evolve slower histories with greater investment per offspring. These trade-offs are not merely biological; they are the substrate from which behavioral ecology derives its predictions about social behavior, foraging, and reproductive effort across ecological gradients.

The theory reveals that there is no optimal life history in absolute terms — only optimal allocations given the mortality schedules and resource distributions that a lineage has experienced. What looks like biological diversity is, from the life history perspective, a spectrum of solutions to the same fundamental allocation problem.