Non-human primates were studied by various scientists for a long time now. They investigate them to make people realize their human nature and nature of species that led to humans. Primates are considered to be humans’ closest relatives. Various studies conducted give people a deep understanding of the humans’ origin. They include observations of animals in wild nature and in captivity. Non-human primates are a subject of research, as they are similar to humans. This research paper focuses on human evolution and examines non-human primates as a model for early hominid behavior.
For more than forty years, primatologists have been making extensive researches of monkeys in their natural habitats. Through such observations, they discovered a lot of interesting aspects of behavior, social organization, learning ability, and communication among humans’ closest relatives: chimpanzees and gorillas.
There were a lot of interesting findings. For example, people used to think that many behavioral features were exclusively human. However, the scientists had found the same characteristics among primates. People have to remember that many differences between humans and primates are related to a degree, rather than kind.
The studies show that first primates appeared approximately sixty million years ago. The common ancestor of humans and apes existed five-eight million years ago. Perhaps, a human ancestor was an African hominoid. Humans and non-human primates have many similar behavioral features. For example, they have a complicated system of communication and social relationships that are analogous to humans’.
Primates are mammals, they are similar in several aspects. Their distinctive feature is viviparity - giving birth. Their females feed the young, as they have the secretion of milk. They are warm-blooded and are covered with hair or fur. Mammals can regulate their body temperature; they have the cooling mechanisms that control body heat. They have rather big brains. All the primates inherited those features. Those features are special for all primates; however, a common predecessor of mammals did not have them. They appeared later, and in the particular family that led to the primates. In fact, some primates, or even their families, have lost these traits or have them, but not developed enough. However, the vast majority of primates have most of these traits.
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Hominids are early human ancestors. They are the members of biological family Hominidae which means “the great apes.” This family includes humans, chimpanzees, gorillas, and orangutans. The humans’ lineage has separated from pongids that included gibbons and the great apeslong ago. Generally speaking about the principal features of hominids, they are two-legged or bipedal, walk upright, have big brains for their body size, and reduced fangs. Under the conditions of evolution, bipedalism is the first evidence of not only morphological and physiological but also behavioral difference between pongids or “great apes” and hominids. The first ones are forelimb knuckle-walkers, while the second ones walk upright, and their hands do not touch the ground (Boyd & Silk, 2009).
As many scientists and anthropologists argue, chimpanzees are humans’ earliest ancestors. The researchers analyze the food-consuming and hunting behavior of chimpanzees, and it gives them almost complete understanding how early hominids behaved. Their social behavior seems similar to the politics of hunting and consuming food of modern non-human primates.
There are many documentaries about apes in their natural habitat. They show how primates hunt and what they eat. The researchers know that chimpanzees live mostly in tropics, and dense forests, although some species live in more open forests or grasslands. They are carnivores. Little monkeys and other small-sized animals are their prey. Now it is obvious what primates, such as chimpanzees, eat. But there is a question if early hominids have been hunting and eating similar small animals. It is very likely that they have. Early hominids ate meat; they used their tools to separate meat from the bones.
The investigation of the body structure gives the scientists more knowledge about evolution. For example, humans are two-legged or bipedal, they walk up right, on two limbs. It is interesting why humans have evolved to such an extent to be two-legged when most of the primates are four-footed or quadruped. However, some kinds of apes are bipedal when they do certain activities. The study of those species of primates that can be two-footed in some cases is crucial to the understanding of the factors that have led to the bipedality in humans (Cachel, 2006).
Besides the body structure, the size of brains and intelligence are essential aspects for evolution. Humans, as well as big primates, have the largest size of brains. They are also the biggest in size and body mass. The brain size controls their abilities to perceive and process the information; however, it also depends on the body size. When an animal is small, it has less informational problems than a big one. That is why, their sensory organs and nervous systems have different sizes and organization. Evolving a large brain depends on a complex balance of several factors(Ward, Flinn, & Begun, 2004).
Interesting theory exists to explain why apes have such big brains. The scientists call this supposition Social Brainor Social Intelligence. This hypothesis has a great scientific support. Among the animals, the brain size corresponds with the body size. However, the exception is the primates. The apes’ brains are large, if correlated with the body size. They are bigger than monkeys’ brains. Respectively, the monkeys’ brains are larger than the prosimians’. Besides the size, the structural differences are also obvious. The chimps have a larger proportion of neocortex than monkeys, who, in their turn, have more neocortex than prosimians. The primates’ brains, as well as the humans’, have enlarged prefrontal cortex. It means that they have a short-term memory, ability to think abstractly and to learn the rules. Perhaps, the large primate brains have evolved to deal with the different kinds of intellectual and social problems. The apes are animals that live in big groups, in which every individual performs its special social role. They have various group compositions. However, the human society accepts only one social structure and criticizes other (Dunbar, 2003).
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It is interesting why chimpanzees work better than gorillas as a model for early hominid social behaviors. According to the scientists, gorillas, orangutans and baboons have social structures built around the competition among males. However, chimpanzees and humans are more cooperative, giving them a greater degree of “humanness”. There was little sexual dimorphism in early hominids. From that, the scientists can extrapolate some behaviors. For example, males were cooperating more than they were competing among themselves. People used to think that this type of behavior is distinctive only for human nature. However, it is nothing else than delusion.
Speaking about chimpanzees’ social system, it is obvious that there are much more similarities than differences, in comparison with the humans’ one. They are social animals. They live in groups that consist of fifty or more individuals. It is also interesting that such groups are divided into smaller ones: adult males, females with their babies. Sometimes they form “families” in which male, female and their young ones live together (Kappeler & van Schaik, 2002).
The scientists also observe the existence of dominance hierarchies among the apes. Such dominance exists to decrease savagery. The dominants control the peaceful atmosphere in a group. They can even make one imperative gesture to stop the violence.Friendly behavior also exists among the primates. They can hug, touch, and hold the hands of each other. Chimpanzees can even kiss. In fact, physical contact is the most essential factor of maintaining peaceful, close and friendly mood in a group. The primates’ grooming is also affecting activity. They clean each other - remove insects from the bodies of their partners. Regarding communication among the primates, they have a lot of calls and movements of the face or body. It is similar to the humans’ gestures.
Chimpanzees make and use tools for a specific purpose, while gorillas do not. Chimps change and improve the tools to make them comfortable and appropriate for specific tasks. They can also use different objects as tools. It indicates their inventiveness. In contrast to chimpanzees, gorillas do not protect their homes. Chimps defend their territories to expel unwelcomed visitors (Matsuzawa, 2001).
To sum up, many researchers imagine human evolution as a long corridor with chimpanzees at one end and modern hunter-gatherers at another one. Such modern hunter-gatherer characteristics as language, pair-bonding and food-sharing come from a common ancestor of primates and hominids. The scientists depict this predecessor like a slightly brainy, tool-using chimpanzee.
It is important to learn more about non-human primates, as it gives people understanding about themselves, their body structure and behavior, their physiology and social manners. Evolutionary theory can help to understand many features of non-human primate biology and behavior. One can use information from non-human primates correctly. It is important to use non-human primate analogies to understand human characteristics. It tries to explain the sequence of changes that led from people’s early ancestors to modern humans.