Since 2002, we have been conducting a long-term study of the evolution of “monogamous” or “pair-bonded” social systems in primates using three species of New World monkeys – owl monkeys, titi monkeys, and sakis – as models. This work represents an international collaboration with Dr. Eduardo Fernandez-Duque (Fundación ECO, Argentina and CRES (Conservation and Research for Endangered Species), Zoological Society of San Diego), who studies one of these taxa (owl monkeys) at his field site in Argentina.
Monogamy is a rare social system in mammals, and the specific pressures leading to its evolution are still debated. Early hypotheses forwarded to explain the evolution of monogamy tended to fall into one of two classes. Some proposed that monogamy evolved in response to the need for biparental care in order to successfully rear offspring, while others envisioned monogamy as the default social system imposed upon males in cases where the dispersion of females makes it difficult for single males to successfully defend access to more than one. More recently, emphasis has turned to the role of direct mate guarding of individual females by males and to the importance of specific male-female bonds as an infanticide-prevention strategy, with “monogamy” then emerging as a tradeoff between the competing reproductive strategies of males and females. In this project, we are trying to evaluate these various hypotheses for the origin and maintenance of monogamy in primates using a comparative approach, collecting comparable behavioral, ecological, demographic, and genetic data on all three genera at my study site in Ecuador and on one of the taxa (owl monkeys) at study sites in both Ecuador and Argentina. We have developed novel molecular genetic markers to allow paternity and population structure analyses for these monogamous species.