Lemurs:
In Lemur catta, the incidence of aggression within groups is high, particularly between males. Aggression takes the form of-chasing, cuffing, scent marking, and, in males, stink fighting … Acts of submission include retreat or cowering as a dominant animal approaches, and low-ranking males habitually walk with lowered head and tail carriage, lagging behind the group and generally avoiding other animals. Females are much less frequently aggressive than males, and the female dominance hierarchy is less easy to detect, although the few agonistic encounters observed suggest that it is stable. Yet, “at any time … a female may casually supplant any male or irritably cuff him over the nose and take a tamarind pod from his hand.”27
Monkeys:
In most monkeys with multimale groups, tolerant or cooperative relationships among males are rare or unknown. Male-male grooming, for example, is virtually nonexistent in rhesus monkeys … [I]f grooming ever occurs, it is given entirely by subordinates to dominant males …, unlike the more reciprocal system in chimpanzees. As another example, Watanabe … studied alliance formation among Japanese macaques. Out of 905 cases only 4 alliances were between adult males. Relationships between males in these groups are thus primarily competitive.28
Stumptail monkeys:
The two newcomer adult females … were thus repeatedly mounted as well as bullied by the three subadult males and the higher ranking juvenile male throughout their stay. This forced mounting might be considered as rape, in the sense that the female was obviously unreceptive and unwilling. She kept crouching while the male forcibly lifted her hindquarters, shook and even bit her, and ignored her screams and dismount signals.29
Stumptail monkeys:
At the very moment that the round-mouthed expression appeared on the female’s face and the hoarse vocalizations were uttered, the equipment registered a sudden acceleration of her heart rate, from 186 to 210 beats per minute, and intense uterine contractions.
Actually, this experiment concerned reassurance behavior. The female’s partners were other females … [It] can be demonstrated that the sexual posture that stumptails often adopt during reconciliation is accompanied by physiological signs of orgasm. This is not to say that sexual climax is achieved during every reconciliation.… [Nature] has provided stumptails with a built-in incentive for making up with their enemies.30
Colobine monkeys:
[I]nfants are often passed around to other females from soon after birth. This pattern may continue for the first few months of life. In particular contrast to some macaques and baboons, every colobine infant has free access to every other infant, and females of all ranks have free access to all infants. Swapping of infants may be one of the roots of the [comparatively] nonaggressive colobine society …
A very interesting feature of colobine intertroop encounters is the fact that they have readily available means of avoiding such contact. As arboreal animals occupying upper story vegetation which provides a relatively unobstructed view of surroundings, and as possessors of loud, sonorous vocalizations, colobine groups could rather easily avoid contact. Nevertheless, contact is frequent. Colobines maintain troop separation by one or a combination of the following: variable movement patterns, the male whoop vocalization, and male vigilance behavior.
… Excitement is high during this stage, which includes tremendous leaping and running through the tree tops, as is evidenced by frequent defecation and urination. Another indication of high excitement and/or tension is the fact that males may have penile erections …
The most common dominant signals include grinning, staring, biting air, slapping the ground, lunging, chasing, bobbing the head, and mounting another animal. Submissive gestures include presenting the hindquarters, looking away, running away, turning one’s back to another animal, and being mounted … The higher the animal’s position in the dominance hierarchy, the wider the personal space it controls which a less dominant animal may not enter without first clarifying its intent.31
Monkeys:
[A]s long as the infant monkey should be riding on its mother, whether it is injured or even dead, its mother will continue to carry it. If she stops carrying it, an adult male is likely to go to her and to bark at her and in this sense make it clear to her that she should continue carrying the infant. We had one case in our small colony at Berkeley where a mother carried her dead infant for two days and dropped it, and then the dominant adult male of the troop picked the infant up and carried it for two more days before discarding it.32
Vervet monkeys:
In 1967, T. T. Struhsaker reported that East African vervet monkeys gave different-sounding alarm calls to at least three different predators: leopards, eagles, and snakes. Each alarm elicited a different, apparently adaptive response from other vervets nearby. Struhsaker’s observations were important because they suggested that nonhuman primates might in some cases use different sounds to designate different objects or types of danger in the external world …
Seyfarth, Cheney, and Marler … began by tape-recording alarm calls given by vervets in actual encounters with leopards, eagles, and snakes. Then they played tape-recordings of alarm calls in the absence of predators and filmed the monkeys’ responses.
[W]hile adult vervet monkeys restrict their eagle alarm calls to a small number of genuine avian predators, infants give alarm calls to many different species, some of which present no danger. Eagle alarms given by infants, however, are not entirely random and are restricted to objects flying in the air … From a very early age, therefore, infants seem predisposed to divide external stimuli into different classes of danger. This general predisposition is then sharpened with experience, as infants learn which of the many birds they encounter daily pose a threat to them …
[But] … experiments offer no proof that primates in the wild recognize the relationship between a vocalization and its referent.33
Squirrel monkeys:
The Gothic variety of the male squirrel monkey provides a most graphic example. He signals 1) his aim to dominate another male, 2) his intention to assault him, and 3) his amorous ideas about a female—all three—by shoving his erect phallus into the face of the other monkey while grinding his teeth. The courtship display is identical to the aggressive display. Ethologists have found this crossed-wire phenomenon in numerous reptilian and lower forms.34
Hamadryas baboons:
[Y]oung males … present in situations which provoke fear. They employ sexual approach in obtaining access to each other and to entice a fellow for play. They masturbate and mount each other. They mount and are mounted by adult males and by adult females, their heterosexual activities not provoking aggressive responses from the overlords. They engage in manual, oral and olfactory ano-genital examination with animals of their own age and with adults of both sexes. They frequently end a sexual act by biting the animal with whom they have been in contact. This end to sexual activity, which is not usually seen in the behaviour of adults, often appears to be playful.35
Baboons:
Sir Andrew Smith, a zoologist whose scrupulous accuracy was known to many persons, told me the following story of which he was himself an eye-witness; at the Cape of Good Hope an officer had often plagued a certain baboon, and the animal, seeing him approaching one Sunday for parade, poured water into a hole and hastily made some thick mud, which he skilfully dashed over the officer as he passed by, to the amusement of many bystanders. For long afterwards the baboon rejoiced and triumphed whenever he saw his victim.36