My main interest is the evolution of social relationships, i.e. patterns of cooperation and conflict between individuals living in the same and in different groups. With natural selection and sexual selection being the main mechanisms of evolution, my research involves investigation of the costs and benefits associated with supporting another individual in terms of survival and differential reproduction. Hence, I study the accumulative, the long-term effects of repeated interactions among the same individuals.
Ever since my first independent project I investigated the effect of resource characteristics on patterns of competition. I believe that without a good grasp on what is at stake it will be impossible to understand whether and how individuals cooperate. Selection for cooperation should be strongest where the potential benefit is the largest. Across primates it is usually the females paying the burden of lactation and gestation, hence male reproductive success is limited mainly by access to fertile females and that of females mainly by access to food resources. Since food and fertile females are fundamentally different resources it seems likely that cooperative behaviors evolved along different lines in males and females. I address this issue in studies on the causes and consequences of both food competition among females living in their natural habitat and of male mate competition in the same species.
Together with Julia Ostner I lead a field project on the social evolution of wild macaques in Phu Khieo Wildlife Sanctuary where we study a group of Assamese macaques since 2005 (more). Students, PhD students and assistants jointly supervised by Julia Ostner and Oliver Schülke also work at Affenberg Salem and in Morocco (field project of Dr. Bonaventura Majolo, Lincoln University, UK) on Barbary macaques, Macaca sylvanus, in Indonesia on Mentawai macaques, Macaca siberu (Siberut Conservation Project von Dr. Keith Hodges, DPZ) and on Sulawesi on crested black macaques, Macaca nigra (field project of Dr. Antje Engelhardt, DPZ).