Mother-infant contact as contingent behaviour in gelada baboons
Barrett L., Dunbar RIM., Dunbar P.
Trivers (1974, Am. Zool., 14, 249-264) suggested that weaning behaviour in mammals is the outcome of parent-offspring conflict over the amount of investment (in the form of milk) that the offspring should receive. However, it is also possible that such conflicts are disputes about the timing of investment in the offspring: conflicts occur as mothers attempt to train their infants to suckle only when their presence on the nipple does not interfere with the mothers' ability to engage in other activities. Data from eight mother-infant pairs of wild gelada baboons, Theropithecus gelada, were used to examine the relationship between maternal activity and infant suckling/contact behaviour in order to test whether disputes are more likely to occur over the quantity or timing of investment. Infant gelada more than 4 months old were more likely to be out of contact when the mother was feeding, and suckled only when the mother was resting or socializing. This relationship resulted from a bias in the level of rejection of infants towards those activities in which the presence of an infant hindered the mother. Further analyses confirmed that mothers were more concerned with training their infants to make appropriate forms of contact, rather than with limiting the infants' access to the nipple; whilst the level of ventro-ventral contact declined rapidly, time spent on the nipple changed relatively little during the period covered by the sample. Comparison of the data with that for other baboon species suggested that differences in the onset and development of this relationship can be attributed to the constraints imposed by contrasting diets and feeding styles. © 1995.