The main goal of this pilot study is to develop a comparative database of captive and wild owl monkeys (Aotus spp.) and titi monkeys (Callicebus spp.), two monogamous primates that show striking similarities with humans in their relatively slow life history, extent of sexual dimorphism and social organization (e.g. pair bonds, biparental care). The pilot study will result in the consolidation of an international group working on biodemography of pair-bonded non-human primates, the implementation of a comparative database, the expansion of demographic data collection from wild owl monkeys in Argentina and preliminary analyses on life history and demographic traits that are informative to understand the evolution of paternal care. The study makes theoretical and empirical contributions to three central debates in evolutionary demography, biological anthropology and primatology: 1-the evolution of monogamy and pairbonds, 2-the evolution of allo-parental care and its potential role in the structuring of human societies and senescence patterns, and 3-the relationship between behavioral and morphological sexual dimorphism that regularly inform reconstructions of early hominin behavior. The working hypothesis is that obligate biparental care and monogamy are intimately related to species-specific life-history traits. To begin evaluating this hypothesis, we will examine the relationship among biparental care, infant developmental trajectories and species-specific life-history traits. We will examine postnatal growth rates in both captive and wild individuals, under a variety of conditions (e.g. presence of one or two parents). We will also investigate the differences between mortality trajectories of adult males and females, and we will assess environmental effects by examining wild populations and comparing mortality differentials in captivity and the wild. The pilot study will allow us to explore analytical techniques (e.g. Bayesian analyses) that are not normally used in the study of wild primate populations and to develop new methodologies for the collection, preservation, export and import of biological markers from population-wide demographic surveys (i.e. large number of social groups). In conclusion, this pilot study will lay out the foundations for a multi-year exploration of sex differences in the life-history and demography of monogamous non-human primate taxa that can inform our understanding of human patterns of growth, development and mortality.