Introduction to Part II

Evolutionary theory provides a framework within which the transitions individuals make over their lifetime can be studied from an adaptationist standpoint. Characteristics such as the weight at which babies are born, growth rates, age at first reproduction, choice of mate (or mates), pace of fertility, investment of time and resources into offspring, and rates of senescence can all be characterized as life history traits. While there are species-specific averages for each trait, biologists have long appreciated the variability both within and between populations. Indeed the discipline of human demography focuses on this variability. The special contribution of the papers published here is to focus first on the less studied sex, and second to explore the variability in life history traits under consideration. The traits are adult size (Sear), marriage (Holland Jones and Ferguson), the pace of reproduction and investment (Ravanera), and later life health and mortality (Soneji, Grundy & Tomassini). This volume constitutes the second part of a special edition of Social Biology Journal devoted to publishing the proceedings of a seminar on the Ecology of the Male Life Course, organized by the IUSSP Scientific Panel