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Durham University

Department of Anthropology


Publication details for Dr Sharon Kessler

Kessler, S.E. & Nash, L.T. (2010). Grandmothering in Galago senegalensis braccatus (Senegal Galago). African Primates 7(1): 42-49.

Author(s) from Durham


This is the first detailed analysis of allonursing in a galago, a relatively nongregarious African strepsirrhine. Existing
data on allonursing in galagos are scarce due to the difficulties of observing wild infant behavior in nocturnal species that
frequently raise young in nests, and to the rarity of colonies with multiple co-housed lactating females. We determined the
kin relations between subjects, quantified the prevalence of allonursing, searched for opportunities for allonursing in which
it did not occur, and qualitatively compared growth rates of infants that were and were not allonursed. Focal adult and infant
observations of Galago senegalensis braccatus were made in the Arizona State University colony between 1976 and 1990. The
colony contained two matrilines caged separately because unrelated adult females are extremely aggressive to each other. The
groups ranged from two to seven individuals. The availability of simultaneously lactating females within one group varied
over time. Allonursing occurred in both matrilines and in a total of four infants (two males, two females). For one male, this
represented a single event with an older sister. More prevalent allonursing occurred in both matrilines with the remaining
male and two females, each allonursed by maternal grandmothers in 21% (n=104), 25% (n=52), and 27% (n=92) of their
observed nursing bouts, respectively. Qualitative comparisons do not suggest that allonursed and non-allonursed infants
grow at different rates. Intriguingly, maternal grandmothers frequently allonursed grandchildren, but adult daughters rarely
reciprocated by allonursing younger siblings. Overall, our findings suggest that grandmothering may be a form of kin selection
in this species and that it may enable older females, some of which had lost a neonate, to increase their reproductive success.