Abstract # 224:

Scheduled for Saturday, August 19, 2006 11:30 AM-11:45 AM: Session 21 (Regency East #3) Oral Presentation

To give or not to give: the effect of accessibility and infant age on infant food sharing relationships in common marmosets (Callithrix jacchus)

R. E. Almond1,2, Y. Van Bergen2, K. N. Laland3 and G. R. Brown4
1University of Wisconsin-Madison, Department of Psychology, 1202 West Johnson Street, Madison, Wisconsin 53706, USA, 2Sub-Dept. Animal Behaviour, Madingley, University of Cambridge, UK, 3Univ. St Andrews, Ctr Social Learning & Cognitive Evolution, Fife, UK, 4School of Psychology, Univ. St. Andrews, Fife, UK
     Although infant callitrichids may obtain nutrients from sharing food with parents and siblings, it is not just a one-way interaction. The success of infant begging depends primarily on the willingness of individuals to tolerate sharing food. Our experiment investigated the effect of food accessibility and infant age on food sharing interactions between common marmoset parents, sibling helpers and infants. Subjects were 2 months old (n=8) and 4 months old (n=9) living in their family groups. Familiar food was presented in conditions where food was either 1) easily accessible to all group members or 2) hard to reach for adults and inaccessible to infants. Food accessibility had no significant effect on the success of infants of either age in obtaining food from parents or helpers. Infant age had a strong effect on the behavior of mothers. Four month old infants were significantly less successful at obtaining food from mothers than 2 month old infants (P<0.05). Age had no significant effect on begging success from fathers or helpers. We concluded that food sharing relationships change with the infant’s age. Mothers share food with younger infants, but as the energetic demands of pregnancy increase the primary food sharers become helpers and fathers. As 4 month old infants develop feeding preferences through sharing, helpers may be a more important source of information about food than previously thought.