SEMEN QUALITY IN WILD PRIMATES
Since 1992 I am running a project on wild Japanese macaques on Yakushima Island, Japan. Beside of heterosexual matings, self-masturbation of males frequently can be observed in this population allowing the non-invasive collection of semen samples. My main research question is how semen quality is related to male reproductive success over the life-time. Furthermore, as human sperm quality has been declining heavily in recent years for yet undefined reasons, I have developed a second main interest in detecting the ecological factors that influence annual alterations in semen quality in wild primates.
CHEMICAL SIGNALLING PRIMATES
Chemical signalling in hominids
Humans are considered to be apes for which the sense of smell has lost its importance. However, is this traditional view of humans as "microsmatic" animals actually true? My research compares our own species with the other great apes (chimpanzees, bonobos, gorillas, orang-utans). GC-MS is used to identify semiochemicals that constitute body odours, and to test whether the ability for chemical signalling was actually reduced during human evolution.
Kin recognition via olfactory cues
Can olfactory cues allow primates to discriminate between related and non-related individuals? A prerequisite for this mechanism would be that body odour is heritable, and appears in the phenotype. If so, one would suspect that semiochemicals of related individuals are more similar. I test this possibility by comparing the body odours of paternal half-sisters and non-related females in the rhesus macaques of Cayo Santiago.
DEVELOPING NON-INVASIVE METHODS IN PRIMATOLOGY
My efforts comprise the development of non-invasive semen sampling in wild primates, minimally-invasive blood sampling using distinct insects (patent 2006; DE102004004066B3) and, since recently, non-invasive odor sampling in great apes.