Abstract # 46:

Scheduled for Thursday, June 18, 2015 03:45 PM-04:00 PM: (Cascade E) Oral Presentation


K. Boose1, E. Midttveit1, F. White1, A. Meinelt2 and J. Snodgrass1
1University of Oregon, 304 Condon Hall, 1218 Kincaid St, Eugene, OR 97403, USA, 2Columbus Zoo and Aquarium
     Testosterone has been connected to competition and reproductive success through its facilitation of competitive behaviors. Known as the ‘Challenge-Hypothesis,’ research on numerous species supports the connection between circulating levels of testosterone and aggression. However, in some species including bonobos, alternate strategies such as male-female affiliation confer greater selective advantage and testosterone is not always correlated with rank or aggression. Although recent data suggest a connection between affiliative behaviors and oxytocin in bonobos, less is known about the relationship between aggression, oxytocin, and testosterone. This study presents data on aggression, oxytocin, and testosterone in the Columbus-Zoo bonobos (N=16 individuals, N=91 urine samples). Mean urinary testosterone was positively correlated with rank for females (p<0.05) but not for males (p=0.396). Although there was no relationship between testosterone and participation in aggressive dyads (p=0.239), testosterone levels were positively correlated with initiation of aggression (p<0.05). Conversely, mean urinary oxytocin levels were negatively correlated with participation in aggressive dyads (p<0.05) and with initiation of aggression (p<0.01). In females, initiation of aggression was not correlated with testosterone (p=0.734) but was negatively correlated with oxytocin (p<0.05), whereas in males, initiation of aggression was positively correlated with testosterone (p<0.05) but not with oxytocin (p=0.0965). These data support the hypothesis that testosterone facilitates some competitive behaviors, in particular the initiation of aggression in males, and suggest an inverse relationship between oxytocin and aggression in bonobos.