In recent years there has been a resurgence of interest in the historical demography of American Indians. Early attempts at reconstructing Native American demography and estimating population sizes at European contact (e.g., Mooney 1928; Kroeber 1939) were followed by an era "when such studies were not only unfashionable but even a bit unrespectable" (Meister 1980:153). Such a bias against historical reconstruction of American Indian populations may be attributed in large part to the incompleteness and inadequacies of the data available to the researcher in historical demography of the New World. In response, however, Henry Dobyns (1976:7), following Sherburne Cook (1960), succinctly observes, "one either uses such data as may be available and learns something, however inad- equate, or abjures such data and learns nothing." A major concern of most researchers in American Indian historical demography has been that of estimating the aboriginal population of the New World and tracing the effects of European contact on Native populations. In pursuit of these objectives, however, there are strong differences of opinions. Donald Joralemon (1982:108) neatly summarizes the issues: There are few who would doubt that the indigenous population of the New World suffered a severe decline as a result of the arrival of European conquerors and settlers. How much of a decline, and its causes, remain subjects of controversy. In both cases debate arises from the simple fact that in the absence of reliable historical data, researchers must devise methods of retrospective projections

Paternal behaviour and pair-bond formation are defining characteristics of social monogamy. However, in comparison to pair-bonding, the endocrine factors associated with the male care of young are not well studied. In the present study, plasma concentrations of oxytocin, vasopressin and corticosterone (CORT) were measured in reproductively naïve male prairie voles as a function of exposure to an infant or control manipulations (i.e. handling or exposure to a wooden dowel). Plasma oxytocin concentrations were transiently elevated within 10 min of pup exposure. Although plasma CORT concentration typically increases after handling, after 10 min of pup exposure, the concentration of plasma CORT was not increased, suggesting an attenuation of CORT release by pup exposure. Group differences in the concentrations of plasma hormones were no longer detected at 20 or 60 min after treatment. These patterns of rapid change in the concentrations of plasma oxytocin and CORT were observed in both juvenile and adult males but not detected after control procedures. Plasma vasopressin, assessed only in adult males, did not vary as a function of pup exposure or other manipulations. In the paraventricular nucleus of the hypothalamus, pup exposure also increased activation (as assessed by the measurement of c-Fos) of neurones that stained for either oxytocin or vasopressin, whereas it decreased c-Fos expression in neurones stained for corticotrophin-releasing hormone. In addition, brief pup exposure (20 min) facilitated subsequent partner preference formation when alloparental males and pup attackers were considered as a group. In the context of other studies, these data support the hypothesis that neuroendocrine changes associated with male alloparental behaviour are related to those implicated in pair-bonding.