Laterality of tail resting posture in three species of New World primates

A variety of mammalian species including prosimian and simian primates wrap their tails around their bodies us a means of thermoregulation and for rea sons of comfort during resting or sleep. Adopting such a resting posture re quires an animal to move its tail either to the right or to the left of the midline of its body, and thus to perform a lateralized behavior. The purpo se of this study was to assess the occurrence of lateral biases in tail res ting posture in three species of New World primates. Twenty squirrel monkey s, spider monkeys, and howler monkeys, respectively. were observed and data on tail resting posture were collected and analyzed. The results demonstra te (1) that individual squirrel monkeys and spider monkeys exhibit highly s ignificant lateral biases in tail resting posture: (2) a lack of a lateral bins at the group level: (3) that howler monkeys fail to show side preferen ces in tail wrapping (4) a lack of sex differences in this behavior in all three species: and (5) a lack of significant correlations between preferred side of tail resting posture and preferred side of hand use in simple reac hing tasks which had been assessed with a subset of animals in previous stu dies, Thus, the present study provides evidence for a behavioral asymmetry which is well-known to occur in rats but has not been described so far in n onhuman primatos. and which might offer an additional approach to the inves tigation of the mechanisms underlying functional cerebral asymmetries, (C) 2000 Elsevier Science Ltd. All rights reserved.