The Primate Diaries: publications

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Feb 6, 2008

American Journal of Physical Anthropology, 2008, 135(S46): 126

Career or Family?: Maternal style and status-seeking behavior in captive bonobos (Pan paniscus).

E.M. Johnson
Department of Biological Anthropology & Anatomy
Duke University

ABSTRACT:

This is the first study to show a trade-off between primate maternal style and status-seeking behavior. Maternal styles in non-human primates fall along two orthogonal dimensions: protectiveness and rejection, with protectiveness positively correlated with approaching, restraining, grooming and contact-making the infant and rejection positively correlated with breaking contact, leaving and rejecting the infant. These personality styles are comparable to styles identified in research on human psychology. Maternal behavior and status-seeking activities are not mutually exclusive and status-seeking mothers provide direct benefits to their offspring through intergenerational transfer of rank. High-ranking bonobo females have the highest frequencies of social grooming and grooming competition is positively correlated with dominance rank as well as with rank-related competition among lower ranking individuals. This study investigated two dominant bonobo females with nursing infants of the same age at separate captive facilities. A previous study at one of the facilities (Johnson 2007) determined that alliance formation among females was reduced as the result of matrilineal housing that included three full sisters. It was predicted that a more protective maternal style would be observed due to the reduced activity budget devoted to rank-related social grooming. 60 hours of video footage was analyzed detailing all mother-infant interactions and all social grooming bouts at each facility. The matrineally-housed mother showed significantly higher levels of protective infant care while the second mother demonstrated significantly higher levels of grooming time with conspecifics. This suggests that maternal style and status-seeking behavior involves shifting strategies for maximizing female fitness that are context-dependent.

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Feb 26, 2007

American Journal of Physical Anthropology, 2007, 132(S34): 137

Lack of inbreeding avoidance and reduction of alliance formation in matrilineally-housed bonobos (Pan paniscus).

E.M. Johnson
Evolutionary Anthropology Graduate Program
Washington State University

ABSTRACT:

Wild bonobo females transfer at sexual maturation into groups without kin. Non-related females perform GG rubbing and grooming to form alliances, and females may mate indiscriminately without risk of incest. The present study investigated social dynamics of a captive bonobo group with a matrilineal core: three adult sisters, their offspring, and an unrelated adult male. It was predicted that these females might demonstrate reduced alliance formation with one another as measured through time spent in proximity and GG rubbing, and that incest might occur because females were housed with their sister's adult sons. 79 hours of 10-minute focal animal samples were collected at San Diego Wild Animal Park in January and June 2006. GG rubbing was absent between sisters, as well as between mother-daughter pairs. Maternal females divided their time equally between their sons (28% of total focal observation time) and their sisters (27%). The largest percentages of total grooming time were between the dominant maternal female and the unrelated male (19%) and between the lower ranking mother and her son (17%), suggesting that alliances were strongest between male-female pairs. Adults sons of two of the sisters formed extended sexual relationships with their own aunts (n1=22, n2=16). Sexual interactions also occurred between males (n=8 bouts), father and daughter (n1=6, n2=4) and brother and sister (n1=12). These findings suggest that matrilineal groupings result in reduced sociosexual interaction between females, and that female bonobos may lack behavioral incest avoidance mechanisms for males other than their own sons.

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