Blood testosterone levels in sickness and in health

Ruth Sonnweber, Jeroen M. G. Stevens, Gottfried Hohmann, Tobias Deschner, Verena Behringer

As an integral part of the immune response, testosterone secretion is inhibited when an individual is confronted with an immune challenge. Testosterone-mediated physiological, morphological, and behavioral traits are compromised at times of impaired health. Nevertheless, males of some species seem to maintain high levels of testosterone when confronted with an immune challenge, upholding competitive strength but compromising their immune response. It has been argued that this phenomenon will occur only in species living in social systems with high degrees of male-male competition over mating opportunities. Male chimpanzees contest over access to fertile females and dominants sire the majority of offspring. This male mating pattern makes chimpanzees a candidate species where we could expect males to maintain high testosterone levels, compromising their immune response, to ensure immediate reproductive success. We measured blood testosterone levels in male and female chimpanzees, who expressed clinical symptoms (symptomatic) or showed no evidence of clinical disease on assessment (asymptomatic). For females, we expected to find lower testosterone levels in symptomatic individuals than in asymptomatic subjects. In males, we would predict lower testosterone levels in symptomatic individuals than in asymptomatic males, if the immune response leads to a decrease in testosterone secretion. Alternatively, males could have equal levels of testosterone when symptomatic and asymptomatic, upholding competitive strength. Our results show that male chimpanzees exhibit lower levels of testosterone when confronted with an immune challenge than when being asymptomatic. This suggests that male testosterone secretion is suppressed as part of the immune response, which potentially increases survival and lifetime reproductive success. It will, however, negatively impact momentary competitive ability. Also, males may employ different mating strategies, some of which are less testosterone-driven (e.g., affiliative strategies). Consequently, in some individuals, the costs of maintaining high testosterone levels may not outweigh the potential gain in reproductive success.

Department für Verhaltens- und Kognitionsbiologie
Externe Organisation(en)
University of Antwerp, Odisee University of Applied Sciences, Max-Planck-Institut für evolutionäre Anthropologie, Leibnitz Institut für Primatenforschung
American Journal of Primatology
Anzahl der Seiten
ÖFOS 2012
106056 Biologische Anthropologie, 106048 Tierphysiologie, 106054 Zoologie
ASJC Scopus Sachgebiete
Ecology, Evolution, Behavior and Systematics, Animal Science and Zoology
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