Modern Primates and Primate Behavior

1. Modern Primates and Primate Behavior Primate Behavior

2. Why Study Primate Behavior? The idea of studying nonhuman primate behavior is based on the same premise as is our use of physical comparisons with other primates We share a common heritage with the other primates and so have inherited out shared features from the same source, a common ancestor. It is not a coincidence that all the primates have prehensile hands. Our common prehensile ability is a synapmorphies, coming from the same ancient ancestor and serving the same basic function.

3. Such traits, shared by multiple species through inheritance from a common ancestor, are called homologies. Traits shared by two or more species through inheritance from a common ancestor. It should be noted that homologous traits need not share a common function. Your arms and the wings of a bat, though they are used of different things, are homologies. The traits are similar by virtue of having evolved from the same source, an early mammal. The wings of a bat and the wings of an insect though they share a similar function, have evolved independently and are not all similar in structure. These functionally similar but evolutionarily unrelated straits are known as analogies.

4. Baboons These primates have long been of interest to anthropologists because of the complexity of their social organization and because of their savanna habitat�an important habitat for your early hominid ancestors. Baboons groups range in size from 20 to 200 individuals. One of the most striking aspects of baboon behaviors is the aggressive competition for dominance among the males. Males are twice the size of females Endowed with huge sharp canine teeth.

5. The male who is the largest, strongest, most aggressive, becomes, for a time, the dominant animal. This position is recognized and acknowledged by the whole group. The dominate male is the group leader and decision maker. He has first rights to food and females. He may produce the most offspring, perpetration those traits that allowed him to achieve dominance. It is also the role of the dominant male and his immediate subordinates to protect the more vulnerable members o the group�females and infants.

9. Chimpanzees Most of what we know of chimp ethology comes from the more than 30 years of research at Gombe led by Jane Goodall. The bond between mother and infant is strong in chimps These apes have large complex brains and infants have a lot to learn about their world before they can become functioning adults. As a result, the mother/child bond is long-lived and important.

10. The chimps in a group are arranged in a dominance hierarchy. Males are generally dominant over females, but among females a loose hierarchy also exists. Males compete with one another in an attempt to achieve the highest position possible. The reward for this is access to feeding places and to females, the latter being another example of male reproductive strategy. Social position is maintained through a series expressions, gestures, and vocalization. One of the most important actions is grooming which maintains social cohesion and on occasion is a sign of dominance. Other expressions include kissing, hugging, bowing, extending the hand, sexual gestures, grinning, and various vocalizations.

11. Chimp society is marked by cooperation and mutual concern (mother/child bond, bothers helping each other). Care also extends outside the family unit. Offspring are important to the group as a whole and adults will come to the aid or protection of a youngster threatened with some harm. Group membership is somewhat fluid. Chimps will, for various reasons, leave a group and outsiders will enter. Despite group fluidity there is a sense of group identity and territory. EX: hunting and killing Tool use

14. Bonobos Are even more intriguing and occupy the lowland forest of the DRC Genetic studies estimate that bonobos have been separate from chimps for 930,000 years. Are more peaceful and gregarious than chimps There is a dominance hierarchy among males, but unlike the case with chimps the hierarchy is easily established with brief aggressive chases. Female hierarchy appears to be based on seniority with females dominating males.

15. Bonobos more readily share food with one another. Unlike chimps they have not been observed killing their kind Their sexual behavior plays an important role in group cohesion. Bonobos, especially when feeding, constantly posture toward one another, rubbing rumps or �presenting� themselves as if imitating sexual activity. When sex does follow, it is usually face-to-face, a behavior uncommon in other primates but common in humans. Sexual activity is not limited to opposite-sex partners. Females commonly rub genitalia with other females and males will mount each other.

16. Moreover, the signs of fertility, the estrus signals, seem nearly always present in bonobo females. In both chimps and bonobos, the fertile and therefore sexual period is marked by a swelling and coloration of the skin in the genital area, which stimulates sexual interest on the part of the male. In chimps, the swelling occurs when the female has ovulated and is fertile. In bonobos, however, there is some swelling almost all the time, and they seem almost constantly sexually receptive. Sexual activity in this species has become separate from purely reproductive activity and is responded to on a conscious level.

17. The function of this friendly posturing and sexual receptiveness seems to be the same as that of grooming and as that of some expressions and gestures among chimps. To prevent violence, to ease tension, to serve, as greeting, to single reconciliation, or to reassure another group member, sex is used. Do these behaviors sound vaguely human? We share certain general behavioral patters because we inherited them from a common ancestor. Our evolutionary line and that of chimps and bonobos have been going their independent ways for 5 or 6 million years And even shared features have had a chance to become modified by all the processes of evolution.