Introducing Anthropology - Laura Pountney

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Bonobo communities have ranges that overlap with other groups. Males are protective of other members of their group and carry out any hunting. Males typically remain among their family group while females range further afield. While males show aggression towards each other, conflict rarely escalates into acts of physical violence. In spite of physical superiority, evidence suggests that males are not aggressive towards females. Bonobos are social animals, and food sharing occurs between males and females, unlike the situation with chimpanzees. Also the female–female relationship is much stronger in this species than it is for chimpanzees. Although they seem very lively, bonobos, like humans, control their emotions when expressing themselves in times of happiness, sorrow, excitement or anger. They are very animated and perform similar gestures to humans when communicating without using language. For example, they will beg by stretching out an open hand or foot and will make a whimpering sound if they fail at something. Females become sexually mature after about twelve years of age and may give birth soon thereafter. They have babies at five- to six-year intervals, so population growth can never be rapid. As with humans, there is a relatively long period of socialization for the young. Females nurse and carry their babies for five years, and the offspring reach adolescence by the age of seven. Females have between five and six offspring in a lifetime. Chimpanzees (Matthew Hoelscher / Wikimedia Commons) (Matthew Hoelscher / Wikimedia Commons) Common chimpanzees, living in tropical forests of Africa, live in small communities. These typically range from 20 to more than 150 members; however, chimpanzees spend most of their time travelling in small, temporary groups consisting of a few individuals that are made up of any combination of ages and sexes. Both males and females will sometimes travel alone. Chimpanzees, like humans, have complex social relationships and spend a large amount of time grooming each other. Grooming is an important way in which alliances are built. Chimpanzee society shows considerable male dominance. Interestingly, male aggression has an important function in establishing a social hierarchy. However, aggression is often only displayed rather than followed through with violence. Males maintain and improve their social position by forming coalitions. These coalitions increase their influence, giving them power that they would not be able to gain alone. Social hierarchies among adult females tend to be weaker. Nevertheless, the status of an adult female may be important for her offspring. Chimpanzees have been described as highly territorial and have been known to kill other chimps for territorial dominance, although there is some suggestion that highly aggressive behaviour by chimpanzees happens only when artificial feeding occurs. A female may mate with several males, though a dominant male may stop other males gaining access to the female with whom they are consorting. Infanticide (the killing of babies) has been recorded among chimpanzees. This is often carried out by male coalitions that invade an existing group, expel their dominant males and kill their offspring: the new males do so in order to mate with the same females and have their own offspring. Care for the young is provided mostly by their mothers. As with humans, babies are dependent on care from an adult for a substantial period. Mothers provide their young with food, warmth and protection and teach them certain skills. In addition, a chimp’s future rank may be dependent on its mother’s status. For their first year, chimpanzees cling to their mothers. By the time they are six, adolescents continue to spend time with their mothers. Like humans, chimpanzees use their highly expressive faces, postures and sounds to communicate with each other. There are many different sounds which signify specific meanings, such as danger, excitement and anger.

       ACTIVITY

      Make a list of the differences and similarities between humans, bonobos and chimpanzees. Are there more similarities or more differences?

       Tool-use

      Tool-use was once thought to be one of the characteristics that set humans apart from other primates, and, indeed, if you look at the variety and complexity of the tools employed by humans, this would seem to be true. However, tool-use has been seen in a number of primate and nonprimate species, both in captivity and in the wild. The study of tool-use provides important information concerning the evolution of human abilities.

      Chimpanzees, for example, often make use of tools. They will adapt sticks, rocks, grass and leaves and use them when foraging for honey, termites, ants, nuts and water. Despite the lack of complexity, there does seem to be planning and skill involved in using these tools. For example, when foraging, chimps will employ modified short sticks to scoop honey out of a hive – that is, if the bees are harmless. With the hives of the dangerous African honeybee, they use longer and thinner sticks to extract the honey. Modification of leaves and branches, and their use as simple tools, has also been observed in elephants, crows and dolphins. However, none of those species created or used more sophisticated tools, such as the stone tools that earlier hominins started to produce more than 2 million years ago. Human tools of course became much more complex and diverse: hunting tools, tools to create and control fire, and much more.

       Bipedalism

      Modern chimpanzees occasionally walk upright, but their skeletons are not adapted for regular walking on two legs. The skeletons of early humans, on the other hand, evolved to support their bodies in an upright position. This means that modern humans have bodies adapted for walking and running long distances on two legs – that is, they are bipedal. Walking upright undoubtedly helped early humans survive in the diverse habitats in which they lived, including forests and grasslands. There are several physical changes that had to occur to make bipedalism possible, among them modifications in foot and knee structure, a curved spine (to absorb shock), broad-shaped hip bones, and a change in the point of attachment between the skull and the neck from a posterior position (as found in other primates) to an inferior position. Bipedalism was an adaptation to the open environments of the African savannah, where the earliest hominins evolved.

      bipedalism Walking upright on two feet for the majority of time

      One disadvantage of bipedalism is that climbing is much harder, as the feet cannot grip trees. Another disadvantage is the back pain and other skeletal problems that occur as a result of walking upright. Placing all the body’s weight on just two limbs can result in back pain and slipped discs. A further disadvantage of bipedalism was that it resulted in the narrowing of the hips and pelvis, resulting in greater risk in childbirth.

       Human pelvis shape and size are different from those of other primates

      As we have seen, bipedalism and the long, slim bodies that go with it were advantageous for humans to be able to move quickly and efficiently in the savannah environment. However, these changes also resulted in changes in the shape, size and position of the female pelvis, which meant a narrower birth canal in females. As a consequence, giving birth became a more difficult and risky process for humans than for most other primate species. The result is that humans give birth to babies that have not achieved the stage of brain development that is typical at birth for apes, monkeys and most other mammals. This particular feature of our evolution appears to be quite recent; it was around 500,000 years ago that there was evidence of the large human brain.

      mammal Any warm-blooded vertebrate animal, including humans, characterized by a covering of hair on the skin and, in the female, milk-producing mammary glands for feeding the young

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