January 24, 2012
Bonobos‘ Unusual Success Story
Dominant males invest in friendly relationships with females
Mate competition by males over females is common in many animal species. During mating season male testosterone levels rise, resulting in an increase in aggressive behavior and masculine features. Male bonobos, however, invest much more into friendly relationships with females. Elevated testosterone and aggression levels would collide with this increased tendency towards forming pair-relationships.
In a current study, Martin Surbeck, Gottfried Hohmann, Tobias Deschner and colleagues of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, found that in wild bonobos high-ranking males were more aggressive and their mating success was higher when compared to lower-ranking males. Contrary to other species in which males compete fiercely over access to females, there was no correlation between dominance status or aggression with testosterone levels. In addition, the researchers found that high-ranking males invested more often than lower-ranking group members into friendly relationships with females. This suggests that these friendly relationships between the sexes are associated with lower male testosterone levels.
“Our study suggests that in bonobos — as in humans — intersexual friendships result in hormonal patterns that we know from species in which male individuals are actively participating in raising their young and in which the two sexes enter lasting pair-relationships“, says Martin Surbeck.
Reference: Martin Surbeck, Tobias Deschner, Grit Schubert, Anja Weltring, Gottfried Hohmann. Mate competition, testosterone and intersexual relationships in bonobos (Pan paniscus). Animal Behavior, January 9, 2011
Image Caption: Bonobos grooming each other in Lui Kotale, Salonga National Park, Democratic Republic of Congo. © Caroline Deimel/Lui Kotale Bonobo Project
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