Honest signaling of intentions: the importance of performance risk, receiver response, and prior knowledge of opponents in the threat displays of mandrills
Publication Type: |
Journal Article |
Year of Publication: |
2005 |
Authors: |
Mark E Laidre |
Publication/Journal: |
Behaviour |
Keywords: |
individual recognition, mandrillus, reliable communication, sequential analysis, vulnerability handicap |
Abstract:
Honest signaling of intentions was initially rejected by evolutionary game theory because it was believed to be susceptible to cheating mutants. In theory, however, conditions may exist that enable this type of signaling to remain evolutionarily stable. Two such conditions have been proposed: (1) signaling may entail performance risks by making the sender vulnerable to attack (‘vulnerability handicap’ model), or (2) individuals may recognize one another, remember the outcome of past interactions, and interact repeatedly (‘individual recognition’ model). In this paper, I tested predictions deriving from both models by analyzing behavioural sequences involving threats in a species of Old World monkey (Mandrillus sphinx). The results were consistent with the individual recognition model. Subordinates (judged competitively inferior based on approach-avoid interactions) rarely elicited favorable responses with their threats, which were generally ignored. In addition, the honesty of dominants was frequently tested since subordinates responded favorably to dominants’ threats less than half the time. When dominants experienced unfavorable responses to their threats they were significantly more likely to direct further aggression at the subordinate, thus demonstrating an honest commitment to the conflict. The results did not support the vulnerability handicap model since receiver retaliation against threats was essentially nonexistent. Though in partial support of the vulnerability handicap model (a) riskier threats were more effective, and (b) senders were less likely to perform the riskiest threats against more dominant individuals. In primates and other animals that live in long-term, stable groups, individual recognition may be especially important in maintaining honest signaling of intentions. Vulnerability handicaps, however, could also play a role in maintaining honesty in such species, but primarily during interactions between unfamiliar individuals that are transferring groups, or during dominance reversals.