Primate

A primate is a type of mammal with flexible fingers and toes, forward-pointing eyes, and a well-developed brain. Humans are primates, as are lemurs, monkeys, and apes. Except for humans, primates, are found in mostly tropical habitats. Primates are the most highly developed group in the animal kingdom.

Most primates either live in trees or have evolved from tree-dwelling ancestors. All are placental mammals meaning that before birth, their young are nourished by a structure in the mother's body called a placenta. There are about 180 species of primates, all which make up the order called Primata. This name comes from the Latin word primus meaning first, and the case can be made that primates are in may ways first among animals.

CHARACTERISTICS OF PRIMATES

Primates have many physical attributes that account for and contribute to their being considered in this manner. First, they have binocular vision, meaning that they use both eyes together. Because both eyes are located in the front of their faces and point forward rather than from the sides, they have sharp three-dimensional vision and good depth perception. Primates also have specially adapted hands for grasping things. Most have five flexible fingers on each hand and five flexible toes on each foot (with flattened nails on their ends instead of claws), as well as an opposable thumb. With a thumb that can be opposed to or that is able to touch the other fingers, primates can fully encircle or grasp something like a tree branch or a tool with their hand. They also can reach out and bring food to their mouth. Some primates are equally agile with their feet as well. All primates have large, well-developed and highly complex brains. Convolutions are folds in the brain that increase surface area and allow for a greater number of nerve cells. This brain enables chimpanzees to make and use tools and humans to reason and solve problems. Primates also have all four different kinds of teeth, meaning that they can eat all types of food. Primate teeth are less specialized for tearing and ripping and more useful for grinding and chewing a plant-based diet.

All primates also have a clavicle or collarbone that gives them a flexible shoulder whose joint allows free movement of the arm in all directions. Wrist and elbow joints are also highly mobile. Primates usually have only two mammae (or breasts), and give birth to one or sometimes two offspring per pregnancy. Compared to other mammals, their young are dependent for quite some time and take a long time to mature.

Primates are very social and exhibit the most complex behavior of all the mammals. They bond together in pairs of two, in larger family groups, or in even larger bands. In the larger groups, there is usually a leader or dominant male and a hierarchy after him. Communication is very important among primate species, and they use many visual signals as well as sounds to interact with one another. Primates regularly send each other messages, whether they are warnings of danger or calls for mating.

PROSIMIANS AND ANTHROPOIDS

Most biologists divide primates into two groups: prosimians and anthropoids. Prosimians are tree-dwelling, squirrel-like insect eaters including lemurs, lorises, and tarsiers. They were the first primates to evolve and are considered primitive compared with anthropoids. Most primates belong to the second group, the anthropoids. Monkeys, apes, and humans are all anthropoids. There are two types of monkeys who were probably split apart when the continents of South America and Africa drifted away from one another. New World monkeys are found in the tropical forests of Central and South America and include howler monkeys, capuchins, marmosets, and tamarins. Many of these monkeys are small and highly vocal. Old World monkeys are found in the tropics of Asia and Africa and include baboons, colobuses, and macaques. They are usually larger than their New World counterparts but have much shorter tails. Another way to tell them apart is by their noses. New World monkeys have flattened noses with widely set nostrils, while Old World monkeys have more definite noses and closely set nostrils.

HOMINOIDS

A separate and useful "superfamily" or extra grouping of primates, called hominoids, is often used by life scientists when they are discussing both apes and hominids. Hominids are humans and their direct ancestors of humans (meaning that humans are the only living species of hominid). Unlike other primates, hominoids have large heads and no tails. They also can move about on their back legs (although many apes cannot do this for a long distance). The ape family is made up of gibbons, who swing from tree to tree with their extra long arms, as well as orangutans, gorillas, and chimpanzees. These are humans' closest relatives in the animal kingdom, and they are able to see in color, move their lips, and even make a great number of facial expressions, all human-like actions. As for hominids, there is only one species living today, and that is Homo sapiens or human beings. While humans are the most intelligent species of primate (Homo sapiens means "wise human") gorillas are the largest and most powerful primate. Deoxyribonucleic acid (DNA) comparisons have shown that chimpanzees are the closest living relatives of human beings.

[See alsoHomo sapiens; Human Evolution; Mammals ]