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Introduction
Page 1
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Materials and Methods
Pages 2 - 3
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Discussion
Pages 8 - 9
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Conclusions
Page 10
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References
Page 11
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Figures 1- 8
Figures 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8
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Tables I-IV
Tables I - II - III - IV
Vigorous sexual or aggressive behavior occurred in 35 of the 40 tests, usually beginning as soon as the second animal was introduced into the test cage. The time course of these and other social behaviors is shown in Figure 1. Whereas sexual and aggressive behaviors were maximal in the first minute of testing and decreased later in the test, grooming behavior and display behaviors (barking, repeated bouncing, patrol locomotion, and cage-shaking) tended to occur later in the test period.
The form of attack differed as a function of the relative dominance of the two opponents. Dominant monkeys usually attacked subordinates from the side, restraining them roughly and biting the back or shoulder from behind (Figure 2). When two dominants were paired, however, the attacks were different. Although rough restraint and biting-the-back sometimes occurred as part of the sequence, the two monkeys eventually squared off against each other, grasping each other frontally and standing upright facing each other. From this position they bit each other's face and the frontal part of the shoulder (Figure 3). Parallel to a distinction made in other mammals [Adams, 1979,1980], the attack behavior that includes biting of the back will be referred to as "offense", and the behavior that includes biting of the face will be referred to as "defense."
All six of the monkeys used in the experiment showed most of the frequently observed behaviors. The most important exceptions regarded offensive-defensive and submissive behaviors; offense and defense were never shown by the one exclusively subordinate monkey, and submissive behaviors were rarely shown by the dominant monkeys. Of the other behaviors shown in Figure 1, all were shown by all six monkeys except for masturbation which was shown by four monkeys (both dominant and subordinate) and repeated bouncing which was shown only by two monkeys, both of them dominant.
Dominance status affected the relative frequency of almost every act, posture, vocalization, and facial expression, as shown in Table I. The behaviors have been arranged into four groups depending upon dominance effects or lack of a dominance effect ("neutral behaviors"). Since there were fewer minutes of testing between two dominants, the expected frequency for behaviors in those tests was lower than for other categories.
Most of the vocalizations recorded in the study were associated with particular acts and postures, or categories of acts and postures. The combinations that occurred at greater than chance levels (P < 0.001) are included in Table II. Cooing occurred when the animal was sitting. Tremulo exhalations and pant-grunts occurred during sexual behaviors (masturbation and presenting or autostimulation, respectively). Screaming was associated with submissive acts of crouching or running away. Teeth chomping was associated with self-grooming. Barking occurred during S.B. patrol locomotion and during the minute in which repeated bouncing occurred (this association also may be seen in Figure 1). In fact, the only vocalizations that did not occur significantly in association with particular acts and postures were grunting, squeaks, and whines and whistles, and of these, only grunting occurred more than five times during the study.
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