In the past several decades, the study of the behavior of nonhuman primates—monkeys and apes—has made rapid progress. We can learn from the dimly perceived past when our ancestors confronted the problems of survival without the sophisticated technological aids so inextricably linked to human adaptation in recent times. Our past is inaccessible to direct study. But by careful observation of our closest living relatives, monkeys and apes, we can begin to understand the nonhuman primate heritage from which our ancient ancestors took a long route over millions of years toward humanity. Nonhuman primates live in groups that are held together by strong and enduring bonds between individuals. These bonds may be reflected in a variety of ways: relationships between adult males and females, between adults of the same sex, between juveniles, and between adult males or females and their young. Altogether, in their natural habitats they have a rich social life. Compared with most other mammals, primates have fewer young at a time. Rather than litters, all Old World monkeys and apes have only one offspring at a time, and they give each one a great deal of attention. The young have longer periods of immaturity than other mammals, including prolonged nutritional dependence on the mother. A corollary of the prolonged physical immaturity and nutritional dependence of the primate infant is a longer and more intense mother- infant relationship and a longer period of tutelage and learning the customs and survival skills of the group. In all higher primates except humans, infants cling reflexively to their mothers from birth, and mother-infant contact is maintained virtually all of the time until the much older infant develops the ability to keep up with the mother on its own. Nursing occurs in many short bouts around the clock; in early infancy, it is initiated and terminated by the infant, an easy process, because the infant is always clinging to the mother’s body, anyway. This combination of clinging, carrying, continuous contact, and frequent nursing is characteristic of all higher nonhuman primates.
A contribution to the debate about social recognition of marriage-like and family-like social phenomena