Wallen K, Goldfoot D A, Goy R W
Dev Psychobiol. 1981 Jul;14(4):299-309. doi: 10.1002/dev.420140402.
The display of adultlike foot-clasp mounts by male rhesus monkeys occurs during the 1st year of life in animals reared with their mothers in social groups where peer interaction is possible 24 hr per day. In contrast, this form of mount is rarely displayed if infants are separated from their mothers at 3 months of age and allowed daily .5-hr periods for peer interaction. To distinguish between maternal and peer access-time influences upon the development of this response, we housed rhesus monkeys with their mothers and allowed either .5-hr or 24-hr daily access to peers in the presence of their mothers during the 1st year of life. Male infants restricted to .5-hr periods with peers rarely or never foot-clasp-mounted peers, although 3 of 6 males foot-clasp-mounted their mothers. In contrast, males given 24-hr access to peers regularly mounted peers using the foot-clasp mount. Males from the 2 groups did not differ in total frequencies of all mount types displayed, only in the display of foot-clasp mounts. After maternal separation at the end of the 1st year, rearing effects on the display of mounting persisted into the 2nd year. Males that received 24-hr daily peer access during the 1st year continued to foot-clasp-mount peers whereas .5-hr males failed to do so, indicating that the experience of mounting one's mother with the adult posture was not sufficient to support peer-oriented foot-clasp mounting at a later age. In addition to deficits in peer-oriented foot-clasp mounting. .5-hr infants displayed higher frequencies of threat and withdrawal behaviors to peers and presented to peers less frequently than did infants from the 24-hr rearing condition. These results contradict a motor deficiency hypothesis to account for the rare display of foot-clasp mounts to peers by males receiving .5-hr daily access to peers during the 1st year of life. Instead, data support the view that .5-hr animals either failed to develop positive response patterns necessary for the execution of the foot-clasp mount, or learned negative patterns of social interaction that prevented the display of this cooperative behavior.
雄性恒河猴表现出类似成年动物的抱脚姿势是在其生命的第一年，这些动物与母亲一起生活在社交群体中，每天24小时都有可能进行同伴互动。相比之下，如果婴儿在3个月大时与母亲分开，每天只有0.5小时的同伴互动时间，那么这种抱姿很少出现。为了区分母亲陪伴时间和同伴互动时间对这种反应发展的影响，我们让恒河猴与母亲一起生活，并在它们生命的第一年，让它们在母亲在场的情况下，每天有0.5小时或24小时与同伴接触。限制与同伴接触时间为0.5小时的雄性幼猴很少或从不以抱脚姿势骑跨同伴，尽管6只雄性中有3只对母亲有过抱脚骑跨行为。相比之下，每天有24小时与同伴接触的雄性则经常以抱脚姿势骑跨同伴。两组雄性在所有骑跨类型的总频率上没有差异，只是在抱脚骑跨的表现上有所不同。在第一年结束时与母亲分离后，饲养方式对骑跨行为表现的影响持续到了第二年。在第一年每天有24小时同伴接触的雄性继续以抱脚姿势骑跨同伴，而接触时间为0.5小时的雄性则没有这样做，这表明以成年姿势骑跨母亲的经历不足以支持在以后的年龄出现以同伴为导向的抱脚骑跨行为。除了在以同伴为导向的抱脚骑跨行为上存在缺陷外，接触时间为0.5小时的幼猴对同伴表现出威胁和退缩行为的频率更高，而且比处于24小时同伴接触饲养条件下的幼猴更少接近同伴。这些结果与一种运动缺陷假说相矛盾，该假说认为在生命的第一年每天只有0.5小时同伴接触时间的雄性很少对同伴表现出抱脚骑跨行为。相反，数据支持这样一种观点，即接触时间为0.5小时的动物要么没有发展出执行抱脚骑跨所需的积极反应模式，要么学会了阻止这种合作行为表现的消极社交互动模式。
