Life history, maintenance, and the early origins of immune function.

There is compelling evidence to suggest that early environments are important determinants of immune function over the life course. While current research focuses on proximate mechanisms and clinical implications, an adaptationist perspective may contribute a theoretical basis for explaining, rather than merely describing, the long-term impact of early environments. Life history theory in particular, with its emphasis on the life cycle and investment in maintenance effort-of which immune function is a central component-provides a predictive framework for identifying prenatal and early postnatal factors that are likely to shape immunity. Key life history issues at these stages include avoiding death from infectious disease, investing in immune defenses that are appropriate for the local disease ecology, and optimizing competing demands for investment in immune function and growth. A series of hypotheses derived from these issues are proposed and evaluated with data from ongoing research in the Philippines and Bolivia. Ecologically-informed research on immunity is in its earliest stages, and life history theory has the potential to make important contributions to our understanding of the development and function of this critical physiological system. (c) 2004 Wiley-Liss, Inc.