Species differences in the interest shown in infants by juvenile female macaques (Macaca radiata andM. mulatta)

Using a focal animal technique, 16 juvenile female rhesus and bonnet macaques (2–3 years old) were observed with respect to the frequency and duration of their contacts with infants (0–1 year old). Each of these subjects was a member of one of four seminatural groups of macaques housed in 0.5-acre field cages at the California Primate Research Center. Rhesus juvenile females became very interested in infants when the latter were quite young, and maintained that interest throughout the study. When the infants were approximately 3–4 months old, the rhesus juveniles spent, on the average, 3.9 min/hr with those infants. By the time the infants were yearlings, the time spent with infants was approximately 6 min/hr. Relative to the rhesus, the bonnet juveniles showed less interest (about 2.2 min/hr) in young (3- to 4- month-old) infants, although by the time the infants were yearlings, the bonnets spent about 5.6 min/hr with them. Rhesus juveniles preferred sibling over nonsibling infants, but the presence of a sibling was not a necessary requirement for infant-directed behavior. The two bonnet juveniles who had infant siblings showed no preference for the latter. These data were interpreted within the framework of Quiatt’s (1979) Am. Anthropol. 81: 310–319 conclusions about allomaternal behavior. Specifically, it was argued that, to the extent that there are species differences in maternal behavior, there should also be species differences in allomaternal behavior. The species differences in the maternal styles of rhesus and bonnet macaques provide a basis for an examination of this hypothesis.