Shadows of Forgotten Ancestors

[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

Baboons:

In Abyssinia, Brehm encountered a great troop of baboons who were crossing a valley: some had already ascended the opposite mountain, and some were still in the valley: the latter were attacked by the dogs, but the old males immediately hurried down from the rocks, and with mouths widely opened, roared so fearfully, that the dogs quickly drew back. They were again encouraged to attack; but by this time all the baboons had reascended the heights, excepting a young one, about six months old, who, loudly calling for aid, climbed on a block of rock, and was surrounded. Now one of the largest males, a true hero, came down again from the mountain, slowly went to the young one, coaxed him, and triumphantly led him away—the dogs being too much astonished to make an attack.³⁷

Titis and other small monkeys: