Primates

 

Appearance

Although there are some notable variations between some primate groups, they share several anatomic and functional characteristics reflective of their common ancestry. When compared with body weight, the primate brain is larger than that of other terrestrial mammals, and it has a fissure unique to primates (the Calcarine sulcus) that separates the first and second visual areas on each side of the brain.

Whereas all other mammals have claws or hooves on their digits, only primates have flat nails. Some primates do have claws, but even among these there is a flat nail on the big toe (hallux). In all primates except humans, the hallux diverges from the other toes and together with them forms a pincer capable of grasping objects such as branches. Not all primates have similarly dextrous hands; only the catarrhines (Old World monkeys, apes, and humans) and a few of the lemurs and lorises have an opposable thumb. Primates are not alone in having grasping feet, but as these occur in many other arboreal mammals (e.g., squirrels and opossums), and as most present-day primates are arboreal, this characteristic suggests that they evolved from an ancestor that was arboreal. So too does primates’ possession of specialized nerve endings (Meissner’s corpuscles) in the hands and feet that increase tactile sensitivity. As far as is known, no other placental mammal has them. Primates possess dermatoglyphics (the skin ridges responsible for fingerprints), but so do many other arboreal mammals.

The eyes face forward in all primates so that the eyes’ visual fields overlap. Again, this feature is not by any means restricted to primates, but it is a general feature seen among predators.

Primate teeth are distinguishable from those of other mammals by the low, rounded form of the molar and premolar cusps, which contrast with the high, pointed cusps or elaborate ridges of other placental mammals.

Members of the order Primates show a remarkable range of size and adaptive diversity. The smallest primate is Madame Berthe’s mouse lemur (Microcebusberthae) of Madagascar, which weighs some 35 grams; the most massive is certainly the Gorilla (Gorilla gorilla), whose weight may be more than 4,000 times as great, varying from 140 to 180 kg (about 300 to 400 pounds).

Distribution

Primates have a wide distribution throughout the tropical latitudes of Africa, India, Southeast Asia, and South America.

Diet

Primates exploit a variety of food sources. Most primates include fruit in their diets to obtain easily digested nutrients including carbohydrates and lipids for energy.Many primates have anatomical specializations that enable them to exploit particular foods, such as fruit, leaves, gum or insects.

Behavior

Primates is a group of species that is well known for being social, smart, and very adept at using their hands. They are also very vocal and communicative with the members of their social group.Primates are among the most social of animals, forming pairs or family groups, uni-male harems, and multi-male/multi-female groups. Non-human primates have at least four types of social systems, many defined by the amount of movement by adolescent females between groups. Most primate species remain at least partly arboreal.

Primates have advanced cognitive abilities: some make tools and use them to acquire food and for social displays; some can perform tasks requiring cooperation, influence and rank; they are status conscious, manipulative and capable of deception; they can recognize kin and conspecifics; and they can learn to use symbols and understand aspects of human language including some relational syntax and concepts of number and numerical sequence.

Reproduction

The stages of the life cycle of primates vary considerably in duration. Among the most primitive members of the group, these stages are broadly comparable to those of other mammals of similar size. Higher in the phylogenetic scale, they are substantially extended. The greatest difference is in the duration of the infant and juvenile stages combined; the least is in the gestation period, which, despite the general belief, cannot be consistently correlated with adult body size. The clear trend toward prolongation of the period of juvenile and adolescent life is probably to be associated with the corresponding trend toward a progressive elaboration of the brain. The extended period of adolescence means that the young remain under adult (primarily maternal) surveillance for a long period, during which time the juvenile acquires, by example from its mother and peers, the knowledge that will allow it to become properly integrated as a fully adult member of a complicated social system.

The potential life span of the Chimpanzee has been estimated at 60 years, and Orangutans occasionally achieve this in captivity. The lifespan of a Lemur, on the other hand, is about 15 years and a Monkey’s 25–30 years.

In captivity

There is no easy formula for success that can be applied to the care of all primates. Each species must be considered on its own. The first step should be to investigate the natural biology of the species under consideration, and the second step is to apply this knowledge to captive management techniques.