This study investigated motherϪinfant interactions in lowland gorillas (Gorilla gorilla gorilla) with particular focus on the relative role of mothers and infants in creating situations that are potentially conducive to infant social learning. Eleven gorilla motherϪinfant dyads were focally observed in weekly 1-hr sessions for 12 months. Spatial relationships were affected by age as well as by ambient temperature. Although the youngest infant was encouraged by its mother to walk and climb, mothers showed little or no encouragement in other contexts. In contrast, infants were quite interested in their mothers' activities, on some occasions repeated their mother's behavior, and actively encouraged their mothers to share food, play, or follow them. These findings suggest that gorilla infants are more active than their mothers in creating situations that are potentially conducive to the acquisition of knowledge or skills.Over the last 3 decades, the study of motherϪinfant relationships in primates has concentrated on understanding the proximate determinants and adaptive function of interindividual differences in maternal behavior, with particular emphasis on the regulation of contact and proximity between mother and infant (Fairbanks, 1996). Most of this research has been conducted with Old World monkeys, notably macaques, baboons, and vervet monkeys, because of the ease with which large populations of these primates can be studied for long periods of time. Recently, a growing interest in primate communication and cognition has stimulated attention to the exchange of signals and the transmission of information between mothers and infants through social learning pro-

In this study we investigated whether infant characteristics play a causal role in the occurrence of maternal abuse of offspring in rhesus macaques (Macaca mulatta) and whether abusive mothers differ from controls in their tendency to adopt alien infants in a cross-fostering procedure. To this end, 13 infants born to mothers with a previous history of infant abuse were cross-fostered shortly after birth with infants born to nonabusive mothers and subsequently observed for 12 weeks. Abusive mothers were significantly more likely to reject foster infants than control mothers were. When adoption was successful, all of the abusive mothers maltreated their foster infants whereas none of the control mothers exhibited infant abuse. These findings suggest that infant characteristics do not play an important causal role in the occurrence of infant abuse and that abusive mothers may differ from nonabusive ones in maternal motivation or reactivity to stressful procedures.

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