Demographic and Morphological Perspectives on Life History Evolution and Conservation of New World Monkeys

Abstract

As an order, primates are distinguished by several features of their life histories from other mammals. These include late achievement of sexual maturity, low female reproductive rates and potentially very long lives (Martin 1990). New World primates present a diverse array of life histories and social organizations (Ross 1991; Garber and Leigh 1997). In this chapter we explore primate life history variation relative to demography and development. We also note how an appreciation of life history and particularly the relations between life history, morphology, and demography can contribute solutions to vexing conservation problems. Our interest in these questions comes at a critical moment in life history theory because much of this body of theory is undergoing important revisions. The traditional theoretical viewpoint arranges primate taxa along a continuum of “fast vs. slow” life histories. Primates with “fast” life histories bear young over short gestation periods. These young have brief infant and juvenile periods to begin reproducing at small sizes and young ages. Following these fleeting stages, animals with “fast” life history expect short adult lifespans. A “slow” life history species manifests an opposing set of attributes, with long pre- and postnatal developmental periods, large adult size, with few but protracted reproductive events. This paradigm or general theory of life history has been extremely productive in characterizing variation across the primate order. However, recent studies reveal serious deficiencies with this idea in understanding important variation in growth patterns and life history variables (Pereira and Leigh 2003). Furthermore, we maintain that a perspective of “fast” versus “slow” life histories is a heuristic that, unfortunately, inhibits the investigation and understanding of important variation in primate life histories and demography. This idea also hinders development of effective conservation programs.