Increasing certainty in an uncertain world: the importance of signals and cues among wild male vervet monkeys

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Lucas, Miranda
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Lethbridge, Alta. : University of Lethbridge, Dept. of Psychology
Too much uncertainty in the world you live in can cause undue stress. Not knowing where to find your next meal or the prospect of being eaten at any moment are two examples. During aggressive encounters, creating uncertainty in your opponent may be the objective, where acts of aggression may be used to test the boundaries of other group members. The primary aim of this thesis was to explore whether the postural displays and aggressive threats used by male vervet monkeys are aggressive in the combative sense or communicative, affording the negotiation of social space. First, the existence of the red-white-and-blue (RWB) and broadside displays was confirmed in a population of wild vervets monkeys, although rarely in the archetypical way as described previously. Through an exploration of male vervet genital displays during the mating season, I found that eye contact played an important role in whether a display escalated into additional threatening, both displays and threats occur within striking distance (equal to or less than one monkey body length apart), and that males were constantly striving to maintain a stable face-to-face perception of their opponent. These overt signals are likely also accompanied by cues, some of which may indicate dominance rank. Two samples of observers, undergraduates and experts, were able to detect the relative dominance of male vervets in a non-social setting. These cues could be important in a variety of contexts, both during and outside of postural displays.
vervet monkey , display , signal , cue