1MESA (Math Engineering and Science Association), Las Cruces High School, 2Anthropology, New Mexico State University
Saturday 4:45-5:00, Grand Ballroom II
The cooperative breeding hypothesis suggests that species relying on allomaternal care should show more teaching-like behavior and social learning than independent breeders like chimpanzees. To test this hypothesis in the closest sister group to great apes, approaches to parenting and juvenile learning were examined in a family of siamangs at the El Paso Zoo. The study extends from before the couple had offspring in 2006, through the birth of a female in 2007 and of a male in 2011, to the present. Both the adult male and juvenile female exhibit allomaternal behaviors.
From January 2009 to May 2011 the adult siamangs were observed using a particular set of logs as a latrine, a family custom not practiced by wild siamangs. During 2009 and 2010 the juvenile female always joined her mother on the latrine and expressed great curiosity toward latrine use, but was not observed using it herself. In January 2011 the adult male began actively teaching the juvenile latrine use. On one occasion he pulled her by her hand to the latrine and bared his teeth at her until she sat on it and used it. On another occasion the three year old went to her father and pulled on his throat sac until he took her by the hand down to the latrine, where they both used it while sitting next to each other. This and other examples are interpreted as evidence for direct teaching, social learning and shared intentionality in siamangs, supporting the cooperative breeding hypothesis.