Anita Stone: California Lutheran University

The primate juvenile period has been considered a “limbo phase” with few evolutionary consequences, a view that has been challenged. In addition, it has been proposed that juvenility is a high-risk stage in which juveniles are at social and ecological disadvantages compared to adults in their group. Using field data from a population of squirrel monkeys (Saimiri collinsi) in Eastern Amazonia, Brazil, I evaluate the “riskiness” of the juvenile phase. These neotropical primates are small, show delayed maturation, are frugivorous-insectivorous and live in large social groups. Contrary to expectations, juveniles are at no disadvantage compared to larger and older adults, both in terms of time needed to acquire foraging skills or in competitive interactions with older conspecifics. I argue that in this genus of neotropical primate, adults face higher sociecological risks associated with reproductive challenges than do juveniles. I will then discuss the distinct life history pressures that affect adult male and adult female squirrel monkeys.