1Department of Anatomy and Neurobiology and Department of Anthropology, Washington University School of Medicine and Washington University, 2Department of Anthropology, New York University, 3Human Genome Sequencing Center, Baylor College of Medicine, 4Wisconsin National Primate Research Center, University of Wisconsin-Madison
Thursday Afternoon, 301D
Prolactin, the "maternal hormone", is now understood to be more generally related to nurturing behavior, in males as well as females. We examined prolactin levels in male baboons (Papio) of three species: P.anubis, P.hamadryas and P.kindae. We predicted a difference in prolactin profiles, paralleling their distinct social behavior. Samples came from baboons captured in the Awash National Park (anubis and hamadryas) and in Kafue National Park (kindas). Mean adult male prolactin in kindas (X=10.6) did not differ significantly from hamadryas (X=7.94) , but each was higher than anubis (X=5.74; p=0.002). In each species, prolactin levels increase from early sexual maturity (about 6 years ) to young adulthood, but the trajectories differ. In anubis, mean prolactin concentration rises gradually, leveling at about 13 years. In hamadryas, prolactin concentration shows a marked, high peak between 8 and 11 years, when, as young adult bachelors, males often assume a mother-like role in carrying and caring for a female infant, as a first step toward One Male Unit formation. In kindas, prolactin levels rise until c 9 years, and remain high. We suggest that this may be related to the uniquely high frequency of male-female grooming interactions in which the male is the groomer (70 %, vs. 13% in anubis), behavior reminiscent of the prolonged grooming of infant baboons by their mothers. Thus elevated prolactin levels in both hamadryas and kinda baboons when compared with anubis, may reflect species variation in behaviors that can be described as ‘pseudo-maternal’ .
Research supported by National Science Foundation,Harry Frank Guggenheim Foundation and Earthwatch/Center for Field Research (Ethiopia) and National Science Foundation National Science Foundation NSF1029302, LSB Leakey Foundation, National Geographical Society, Washington University and New York University (Zambia)