SALIENT CHARACTERISTICS OF THE ORDER PRIMATES

INTRODUCTION: Primate exhibits a wide range of characteristics. Some primates (including some great apes and baboons) do not live primarily in trees but all species possess adaptations for climbing trees. Locomotion techniques used include leaping from tree to tree, walking on two or four limbs, knuckle-walking and swinging between branches of trees (known as brachiating). Primates are characterized by their large brains relative to other mammals as well as an increased reliance on stereoscopic vision at the expense of smell, the dominant sensory system in most mammals. These features are most significant in the monkeys and apes and noticeably less so in Lorises and Lemurs. Three color visions has developed in some primates most Loris also have opposable thumbs and some have prehensile tails. Many species are sexually dimorphic, which means males and females have different physical traits, including body mass, canine tooth large size and coloration. Primates have slower rates of Lemurs development than other similarly sized mammals and reach maturity later but have longer lifespan. Some species live in solitude others live in malefemale pairs and other live in groups of up to hundreds of members.

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HABIT, HABITAT AND DISTRIBUTION: Primates are usually divided into two suborders Prosimii and Anthropoidea. The suborder prosimian is represented by Lemurs, Aye-Ayes, Lories and Tarsiers. Among them the Lemurs inhabitance of Madagascar were found during the Eocene in both the old and new worlds, their numerous and varied descendents today live only in the tropical regions of the old world. They are the most primitive of the primates small in size, the Lemur go all four, lives in trees and is nocturnal in habit. In brief the Lemur is barely a primate and is important chiefly because he is so little changed since Eocene times and so closely resembles the primitive tree shrew (an insectivore) from which all primates probably originated. AyeAyes are found primarily in low altitudes forests on the east and northwest coasts of Madagascar. It is about the size of a cat and Aye-Aye has large naked ears and a long bushy tail. Lories have been reported from Africa and Asia whereas Tarsiers in South East Asia. It is observed that all the prosimians are Tarsiers nocturnal and arboreal in their habit. The suborder Anthropoidea is represented by super family Ceboidea (New World Monkey) Cercopithecoidea (Old World Monkeys) and Hominidea (Apes and Humans). The super family Ceboidea (New World monkeys) comprises two families Callithricidae and Cibidae Genus Callithrix, Cebulla of South America have radiated widely into the available arboreal niches. The other genus Saguineas and Leontidues of Central and South America are arboreal and nocturnal in their habits. 11 genus of different habitat comprises the family Cibidae. Among them the genus Pithecea of South America are completely arboreal, crepuscular or nocturnal in their habits. Their diet appears to be omnivorous. The bearded sakes of the genus Chiropotes are arboreal quadrupeds and are quad pedal on the ground. The diet is omnivorous. The Uakaris, genus Cacajao of Central and South America apparently 2

live in small bands by river banks in the forests. They seem to stay in the highest trees and are said to be very poor jumpers. As far as is known they are purely vegetarian. The genus Callicibus of Central and South America are diurnal and arboreal to their habit appear to be omnivorous in their diet. But the Aotus of the same habitat is a completely nocturnal animal and is said to sleep in hollow trees in the crotch of branches or in the holes in large trees. Inhabitance of Central and South America Genus Cibus and Saimiri are quite small approximately the size of squirrels. They are arboreal quadrupeds and appear to live completely in the trees. But the Saimiri the active and restless Squirrel monkeys are often kept as pets. Howler monkeys inhabitance of Central and South America live in the highest branches of the largest trees in the forest. They seldom observed on the ground. The diet of the howler monkeys seems to be restricted to fruits, nuts, leaves, buds and bark. The few records of howlers in captivity show that they are omnivorous despite their restriction to a diet of vegetation in their natural habitat. The genus Atiles, Lagothrix and Brachyteles are appear to be arboreal quadrupeds although they have often been observed sitting erect. Their natural diet seems to be fruit and leaves. Ateles are confined to Central and South America whereas Lagothrix and Brachyteles in South America. Old World Monkeys are divisible into two families Cercopithicidae and Colobidae. Cercopithicidae comprises eight genera among which the Guenons and Patas monkey of genus Cercopithecuis and Erythrocebus are found only in Africa. They are arboreal and diurnal in habit. The Mangabeys, genus Cercocebus are relatively large partly terrestrial monkey that are found throughout the forested parts of Africa. They are arboreal but they spend most of the day on the ground; they are relatively unaggressive and they seldom leave the shelter of the trees that are their refuge. Other partially terrestrial monkeys of Africa and Asia are the Baboons (Papio) and the Macaques (Macaca). The Baboons are found throughout Africa whereas the 3

Macaques in India, Pakistan in both continental and island of South East Asia and in China and Japan. Baboons are quadrupeds and are at home on the ground in trees and climbing on cliffs. Their habitats range from arid savannah to forest though their modal habitat is bush or wooded grassland. Baboons are eclectic feeders mainly on plant food which is frequently dispersed in patches they also eat insects which they catch using their hands. Some group hunt being predators on small game such as young Gazelles or small monkeys. On the other hand the daily activities of Macaques take place on the ground even though they sleep on trees. Thus, they are far easier to observe than arboreal primates. The diet of Macaques is made up almost entirely of vegetable matter. Celebes black ape is a Baboon like animal in Asia. One Cercopithecoid monkey, the Gelada Theropithecus is descended from species that were already part terrestrial with shorter fingers than their arboreal cousins. This reduces stresses on the digits during palm grade quadruped walking. Geladas are now exclusively terrestrial animals and often feed on grass corns and roots which they harvest by digging with their hands using extended fingers together so that their hand becomes a kind of trowel. The family Colobidae is found in Africa and in Asia. The African Guerezas, Genus Colobus are essentially forest dwelling animals seldom found in bush country. They often seen in the highest part of the trees the upper story of the forest as Napier puts it. Their diet consists wholly of vegetable matter. They presumably live on leaves. The Asian Colobines Presbytes, Pygathrix, Rhinopithecus, Nasalis and Simias commonly known as the Leaf monkeys are live on leaves. They are arboreal and diurnal in their habits. Some primates such as the Macaques and Langurs, can exploit human modified environments and even live in cities. The super family Hominoidea involves four families i.e. Hylobatidae, Pongidae, Panidae and Hominidae. Family Hylobatidae include Gibbons and Siamangs of South East Asia. Gibbons are the true branchiators. They progress 4

across the ground when they are forced to do so in bipedal fashion. They are not ungraceful but are rather inefficient bipedalists. Diet is frugivorous and insectivorous but birds’ eggs and small birds are eaten with relish. The Orangutans is represented by a single species of genus Pongo confined to South East Asia. This frugivorous Pongid is almost completely arboreal in their habits i.e. at nightfall the Orangutan builds himself a roofed nest of branches and twigs and leaves up in a tree and there rest through the night. Chimpanzees and Gorilla of Africa comprises the family Panidae. Chimpanzee is the most familiar nonhuman primate. Chimpanzees are forest animals. They are found in large numbers in the tropical forests of Africa. The Chimpanzees are arboreal builds him a nest of leaves in the trees on a foundation of skillfully intertwined branches in which he rests for the night but he has no permanent home. Being a perfect nomad, wandering about during the day as his appetites and desires lead him. Their diets consisting mainly of ripe fruits which are located in trees. The Gorilla, another African habitat of family Panidae being the largest and stoutest among the primates is considered a fiercely aggressive and hostile beast. However, primatologists have described this creature in more human terms than any other primate. Like Chimpanzee, the Gorilla spends time in the trees and on the ground, climbing, swinging and hanging with body relatively upright in the trees, moving quadrupedally or very occasionally bipedally on the ground. Knuckle-walking is the preferred pattern of terrestrial locomotion. Gorillas feed mainly on the ground on up to 100 species of plants, mostly, leaves and shoots. Family Hominidae include only one genus Homo which is represented by human is found all over the world. They are found in most terrestrial communities and generally live at relatively high population densities, frequently in population concentrations. Humans live mostly in ‘complex’ societies with particularly elaborate economic systems and technological patterns. Humans are habitual, upright, striding bipeds and bipedalism dominates the positional repertoire. During bipedal walking and running the body 5

has frequently only one support at a time, unlike the situation in quadrupeds. Human hunter-gatherers are omnivorous, eating animal food, gathered mainly though not exclusively by females. Included in plant foods are tubers and roots which are underground resources and require digging. Food is generally transported and often shared within and sometimes between families. Foods are frequently prepared by cooking, soaking, mashing and it is often stored for days or in the case of hunters strongly seasonal environments for months. Primates can be classified into four categories on the basis of their social organization; solitary individuals, pairs, one male (harem) and multimale groups. One-male groups contain one adult male, two or more adult females and a variable number of immature individuals; multimale groups have at least two adult males. Gorillas usually live in groups containing a single fully adult male, whereas Chimpanzee groups contain several fully adult males. For all primate species, the primary social link is the mother-infant bond. In group living primates relationship between females and successive generations of their female offspring (matrilines) usually form the core of the group. Primate social groups are stable only in a relative sense as individuals migrate between them when they become sexually mature. In most males leave whereas female remain behind. In the exceptional cases where females leave their natal groups, the core of the group is formed by a set of related males. This happens in Spider monkeys (Atcles) and Chimpanzee. Patterns of relatedness among mammals living in social groups are of course fundamental to theories of the evolution of altruistic behaviour Paternity and migration of individuals between groups is both relevant here. Among the important characteristics of the primates which are related to the evolution of vocal and facial displays are the following: increased visual acuity, particularly stereoscopic vision and colour vision; increased facial mobility with corelative decreased mobility of the ears, increased manual dexterity and manipulative ability; increased problem 6

solving ability and the development of permanent social groups or society. Primate vocalization is one aspect of primate behaviour that is ape to lead to a better understanding of the evolution of human vocal communication and the invention of culture by man. Another interesting evolutionary development among the vocalization of primates is the wailing, territorial song of Indri and Gibbon. This wailing song may well have evolved because it conveys information over great distances about the location of groups in a dense forest. A very striking feature revealed by examining facial and vocal displays of primates is the amount of parallel evolution that has occurred. The grin and lip rounding which have evolved independently as facial displays among the Ceboidea. Cercopethecocdea and Hominoidea are most remarkable cases of parallel evolution. The formation of prolonged calls from series of twitters has occurred in the Lemur, the Ceboidea and Cercopethecoedea. Primate vocal and facial displays are two of the few sources of information about the origin of human symbolic vocal communication language. There are many theories about the origin of language, but some of them are not well sustained or directly relevant here. Man’s imitation of sounds he hears in the environment, including sounds heard from other animals must be one of the roots of origin. It is reasonable to postulate that language arises in an animal in which auditory control over vocalization is developed sufficiently so the animal is able to imitate sounds. Further developments of mimicking or matching may well have depended upon the ability to manipulate the behaviour of others with vocalizations. The evolution of facial displays, closely related to the evolution of vocal displays, is partly understood by changes that occur in the relevant musculature. The muscles of the lips have changed during the evolution of primates, even though the basic plan is more or less the same. Man is unique in the possession of culture and we must evaluate the evidence that bears upon its origin. Culture is a 7

biological event; it is a product of the evolutionary process. It is a trait which only one genus of the order Primates developed. Culture is one of the most impressive adaptations achieved by any evolving organism. Every human individual is born into a culture of some kind on other. This culture determines the language he will speak, the kinds of clothes he will wear the rules for choosing a mate the rituals he will participate in the musical scale he will consider normal, the standard of interpersonal behaviour he must achieve. BRAIN: Brain size relative to body size is large in primates especially in anthropoids. Primates have a high degree of visual acuity with binocular and frequently colour vision, and their auditory sense is also well developed. Olfaction is especially significant among prosimians and although reduced remains important in anthropoids. Neuromuscular co-ordination is highly developed and tactile stimuli, especially from fingers and hand are of considerable importance. Almost all parts of the brain are enlarged in primates but this applies particularly to the cerebrum relative to the mid brain and brain stem. The cerebellum is also important. Anthropoids have larger brains than prosimian by a factor of at least two, relative to body and the large living hominoids have larger brains than the living monkeys. The cortex is divided topologically into several distinct regions. Lying around the edges of the cortex is the limbic system or palaeocortex which is involved in behaviour such as aggression, sex, feeding, fear and a range of attentional biases and behavioural predispositions; namely the physiological substrates of a wide range of emotional behaviours critical for survival and for interactions with other individuals. Primates have well developed limbic systems and they have also elaborated other so called neo-cortical regions. 8

The neo-cortex receives input information from sensory systems such as vision, the spectrum of auditory frequencies, the skin surface, and muscles, tendons and joints and sends output instructions to the muscular system. Electrical stimulation of primary sensory and primary motor regions shows that the parts of the body are represented like a map on their surface; the proportions of the map vary depending upon the importance of the particular body part to the species. The brain is made up of functional cells called neurons, which have excitable surface and which sends out signals. They are complex in shape with long appendages known as dendrites which generally receive stimulation from other neurons, and axons which primarily stimulate other cells. At the gross level the brain is heterogenous, with groups of neurons of common morphology and functions, and bundles of connecting axons which carry stimuli between them. Neuron cell bodies and their dendrites are called grey matter, axon bundles are white matter. There are two typical kinds of grey matters, the first are nuclei, usually deep structures which receive inputs from one direction and have outputs exiting from the other. Nuclei typically collect, relay, coordinate and integrate input (sensory) and output (motor). They generally mediate between periphery (sensory and motor), and the organizing and analyzing functions of the cortex. A second kind of grey matter is located on the surface of the brain forming the cortex. Because, it is a surface structure, input and output connections enter and leave from the same side. The surface of the brain increases in area rapidly as its total volume grows; hence larger brains have surfaces which are folded to produce deep valleys known as fissures and Sulci (separating major brain segments). The quality and complexity of the special senses, manipulative and communication systems of especially hominoid primates reflect their eclectic diets; their varied positional repertoires their object using skills and their elaborate social milieu. 9

PRIMATE SENSE ORGANS: The primates’ adaptation to arboreal life involved changes in the form and function of their sensory organs. The sense of smell was vital for the earliest nocturnal, ground-dwelling mammals, smell enables animals to operate at night to sniff out their food and to detect silent predators, moving slowly through the trees at night and ancestral primates relied on their noses to guide them to food. However, for active diurnal arboreal life good vision is a better guide than smell in judging the location of the next branch or tasty morsel. According the sense of smell declined in primates while vision became highly developed. Travelling through trees demand judgments concerning depth, direction, distance and the relationship of objects hanging in space such as vines or branches. Monkey, apes and humans achieved this through binocular stereoscopic vision. The ability to see the world in the three dimensions of height, width and depth required binocular vision with two eyes set next to each other allowing the visual fields of the two eyes to overlap. Three dimensional stereoscopic vision results from nerve fiber travelling from each eye to integrate sides of the brain allowing nerve cells to integrate the image derived from each eye. Many primates also possess colour vision, enhancing depth perception as well as food recognition. Enhanced vision also relates to the individualized appearance and expressiveness of the primate face, vital to primate social behaviours. Visual acuity however varies throughout the primate order both in terms of colour and spatial perception. Prosimian, most of who is nocturnal lack colour vision. The eyes of Lemur and Lories are capable of reflecting light off the back of the retina, the surface where nerve fibers gather images in the back of the eye to intensify the limited light available in the forest at night. In addition prosimian vision is binocular without the benefit of stereoscopy. Their eyes look out from either side of their muzzle or snout with some overlap of visual fields, but their nerve fibers do not 10

cross from each eye to both halves of the brain. By contrast, monkey, apes and humans possess both colour and stereoscopic vision. Colour vision markedly improves the diet of the primates compared to most other mammals promoting the identification of food by allowing anthropoid primates to choose ripe fruits or tender immature leaves due to their red rather than green colouration. In addition, anthropoid primates possess a unique structure called the fovea centralist, or central pit in the retina of each eye. Like a camera lens, this feature enables the animals to focus on a particular object for acutely clear perception, without sacrificing visual contact with the objects surroundings. The primate’s emphasis on visual acuity came at the expense of their sense of smell. A large protruding snout however, may interfere with stereoscopic vision. But smell is an expendable sense to tree dwelling animals in search of insects. The anthropoids have the least developed sense of smell of all land animals Prosimians by contrast, still rely on smell, possessing numerous scent glands for marking objects in their territories. Arboreal primates also possess an acute sense of touch. An effective feeling and grasping mechanism help prevent them from falling and tumbling while speeding through the trees. The early mammals from which primates evolved possessed tiny touch sensitive hairs at the tips of their hands and feet. In primates, sensitive pads backed up by nails on the tips of the animals’ fingers and toes replaced these hairs. These sensitive tissues also found on the underside of the tails of New World Monkeys who use their grasping tails like an extra limb. TEETH & DEIT: Among the primates, the trend in evolution has been towards reduction in the number of teeth. Thus two incisor teeth are the rule. The teeth of early primitive mammals have certain characteristic structures that are the roots from which the dentition of the Primates developed. The incisor teeth are relatively small, rather flattened, resembling small spatula. The canine is large, pointed, 11

rather sharp, slightly curved and projected beyond the other teeth. The premolars in this generalized mammalian dentition are relatively simple and cone shaped. They have a cusp, the major elevation on the crown of a tooth. The base of the crown of the premolars is thickened to form a ring of enamel around the base of the tooth. This ring is called Cingulum. It is an important feature for it is believed that the Cingulum developed later in evolution into additional cusps as the premolars and molars developed into the forms they now have Premolar crown in living primates are considerably more elaborate than the crown of the simpler ancestral mammals. The upper molars of the primitive mammal have three large or major cusps. These cusps are called the PROTOCONE, PARACONE and METACONE. These three main cusps of each upper molar form a triangle on the crown called the trigogen. This three cups or tritubercular pattern is believed to be the source of all the more complicated dentitions of later, living mammals. The crown of the lower molar generalized mammalian dentition is divided into two segments. The front part is called the Talonid. The trigonid is high than the talonid in this generalized dentition. The general trend of dental evolution in the Primates has been the retention of a fairly primitive molar pattern and specialization of the other teeth. The incisor- teeth are reduced in number; usually to two. The canines tend to become large and very sharp. The canines are usually much larger in males than in females. The last two in the premolar series grow larger and cusps grow up from the cingulum. The upper molars become quadritubercular inform specializing away from the tritubercular primitive morphology. The lower molars also develop a quadritubercular crown. Among the primates, cercopithecoid monkeys differ from hominoids, which have retained a more primitive pattern, in their derived nature of their molar teeth. Cusps are paired linked by crests or loph running from side to side. Particularly in colobids, cusps and crests are high and 12

self-sharpening. This ‘bilophodont’ pattern in cercopithecoids is probably an adaptation to efficient reduction of folivores habit. Propositions of different teeth vary according to broad dietary categories. Frugivores have relatively large incisor and often smaller cheek teeth (Pre molar and molar), folivores smaller incisors, while species eating tougher or more abrasive food often have large cheek teeth. The alimentary canal is relatively unspecialized in most primates. The most derived species are the colobids, predominantly eaters of leaves. This food source is high in the structural carbohydrate cellulose which is tough and indigestible and also in alkaloids and other secondary compounds. Colobines have evolved complex sacculated stomach, in which gut bacteria break down cellulose and potentially toxic substances, Cercopithecines have developed cheek pouches in which food is stored and softened for preliminary digestion. Gorillas have enlarged large intestines, related to their predominantly folivorous diet. Relative to Chimps, humans have smaller stomach and larger intestine, and larger small intestines, presumably as adaptations to more omnivorous diets. As a generalization, primates having diets in which food items are unpredictably distributed spatially and temporally tend to be both large bodied and large brained. Food and its distribution are critical factors in moulding adaptations of several kinds. SKELETON: The skeleton gives animals with internal backbones or vertebrates, their basic shape or silhouette, supports the soft tissues and helps to protect vital internal organs. The form of the skull differs between prosimians and anthropoids. Prosimians have larger and more projecting faces, partly related to the importance of olfaction and the relatively large peripheral sense organs and partly to the biomechanical requirements of tooth use in mainly insectivorous forms which use their projecting incisors and canines as dental combs or gum scoops, and partly 13

reflecting a small brain. The orbits are surrounded by a bony ring which is quite large facing more forwards than sideways. In Anthropoids the skull is more globular, the brain case being larger and rounder while the face is less projecting and deeper from top to bottom. Anthropoids have a prominent large domed cranium which protects the large brain. The two sides of the mandible are fused at the symphysis, the back wall of the orbit is formed by bone, and orbits face directly forward. This allows larger and differently oriented chewing muscles. Whole skulls and bones of the skulls like teeth are a most important part of the record left by the primates. The characteristics which distinguished primate skulls from those of other mammals are result of the following functional changes that occurred during primate evolution. 1. The development of forelimbs to take over the grasping functions of the teeth. 2. The development of various degrees of upright posture 3. The high degree of development of the visual apparatus and the correlative reduction in the sense of smell. 4. The enlargement of the brain. These four major functional adaptive transformations in the primate had profound effects on the form of the skull. Actually the changes in the skull plus our knowledge of living primates led to the deduction that the four major functional, adaptive changes occurred. When the forelimbs took over the grasping functions of the teeth and jaws, a reduction in the size of the jaws resulted. The development of upright posture is one of the reasons for the movement of the foramen magnum (orthrograde) forward on the base of the skull. The enormous development of the visual sense led to the enlargement of the eye sockets, rotation of the sockets to the front of the skull and development of a bony ring around the sockets. The enlargement of the brain led to increase in the size of the braincase and to the rounded shape of the skull of man. The forward movement of the foramen magnum is partly a consequence of the enlargement and rounding off of the brain case. These are 14

the simplest and most generalized statements we can make about the relationship between the changing form of the skull and the changes in way of life of the evolving populations. CLAVICLE: Below the primate skull and the neck is the clavicle or collarbone, a bone found in ancestral mammals, though lost in mammals such as cats. The size of the clavicle is reduced in quadrupedal primates like monkeys who possess a narrow sturdy body plan. In the apes, by contrast, it is broad orienting the arms at the side, rather than at the front of the body and forming part of the suspensory hanging apparatus of these groups. The clavicle also supports the scapula and allows for the muscle development that is required for flexible, yet powerful, arm movement allowing large bodied apes to hang suspended below the tree branches and to brachiated or swing from tree to tree. TRUNK: In primate arm or leg, the portion of the limbs has a single long bone, the lower portion two long bones, and their hand or feet with five radiating digits. Their grasping feet and hands have sensitive pads at the tip of their digits backed up (except in some prosimians) by flattened nails. This unique combination of pad and nail provides the animal with an excellent prehensile (grasping) device for use when moving from branch to branch. The structural characteristics of the primate foot and hand make grasping possible; the digits are extremely flexible, the big toe is fully opposable to the other digits in all but humans and their immediate ancestors, and the thumb is opposable to the other digits in varying degree. The retention of the flexible vertebrate limb pattern in primates was a valuable asset to evolving humans. It was in part having hands capable of grasping that enabled our own ancestors to manufacture and use tools and to embark 15

on the evolutionary path that led to the revolutionary ability to adapt through culture. Among the quadrupeds (prosimians) such as Lemur catta the trunk is long, especially the lumbar region and acts rather like a springy bow, hind limbs are somewhat longer than forelimbs, and there is tail. Among the vertical clingers and leapers like Indri or Galago, species which habitually cling to and leap for vertical supports. Hind limbs are longer and forelimbs shorter than in prosimians quadruped, and some joints-hips and knees for example are better adapted for the habitual motions involved in powerful springing. Among the slow quadruped prosimians such as Perodici ticus, the Pottos have no leaping phase in their deliberate and careful locomotion. Turning to anthropoids, the ceboidea of South and Central America are arboreal forest species which are predominantly quadrupedal. Some smaller species such as marmosets have an active springing components to their quadrupedalism, hence they have low fore to hindlimb length ratios. Large species such as the capuchins of the genus cebus are more typical quadrupeds. The largest New World species the Howler (Alouatta), Spider (ateles), Woolly monkey (lagothrix) and Woolly Spider monkeys (Brachytiles) show modification to varying degree on the basic quadrupedal patterns. Cercopithecoid monkeys are predominantly quadrupedal in the trees and on the ground, and their repertoires are basically rather unvarying. With their narrow, deep chests and long lumber regions, Old World Monkeys are similar to many other quadrupeds. Such variation as exists lies mostly in the extremities. For example, terrestrial species like Baboons (papio) or Patas monkey. (Erythrocebus) have forelimbs longer than hind limbs and hands and feet with relatively short digits. Hominoids are more heterogeneous in positional behaviour than cercopethecoids, and this is mirrored in their anatomy. All hominoids have broad shallow chest and relatively short lumber regions. This probably reflects a common ancestor which climbed hung, swing and stood with the trunk more vertical than horizontal. Gibbon, 16

labeled branchiators has a long hind limb and very long arms and there is some muscular control of pelvic and truncal till associated with balancing the body during bipedal walking along branches. The chimpanzee and gorilla have relatively long arms, hands and fingers with joints adapted for suspension. Superimposed on these features are those associated with forelimb use as a strut during quadrupedal knuckle walking. The thorax is broad and flat, the lumber region reduced, the pelvis both board and deep. Hind limbs are relatively longest in Bonobos, shortest in Gorillas. Orangs have very long arms, with long and curved hands and curved feet and toes. All limb joints allow considerable mobility as with the African hominoids, the lumbar region of the vertebral column is reduced, to four vertebrae. REPRODUCTION: The primates consists of slow matures and they live long and also a long gestation period. Almost all anthropoids produce one large brained and dependent offspring per birth. They reproduce relatively late and infrequently. In reproduction females are more important because their biology places constraints on reproductive rates although many species have physiological and behavioural cycle related to reproduction. The sexual cycle in females consists of three linked phenomena (1) a menstrual cycle of variable length, but averaging around 30 days in anthropoids, involving the gradual build up and then rapid shedding of the uterine lining, generally with blood loss (2) an ovarian cycle which may or may not be of similar length, involving the release of generally one ovum or egg from the ovaries (3) an Oestrus cycle consisting of the rise and fall of mating associated behavior, often including changes in female receptiveness and attractiveness. Gestation lasted 6-9 months in anthropoid primates. Infant are normally born with brains roughly half the volume of those of adult females, they are dependent on their mothers for long period after birth. The transfer of energy 17

in the form of milk is very efficient but it imposes nutritional cost on the mother. During lactation and prior to weaning sexual cycling is first totally and then partially suppressed. This is the period known as post-partum or lactation amenorrhea. BIOCHEMICAL & METABOLIC FUNCTION: Genealogical reconstruction based on amino acid sequence among the primates has been helpful in revealing the history of primates for example. Calmodulin, which is involved in calcium binding, allows us to trace the deeper roots of the primates back to their first eukaryotic organism. Studies of this kind show that protein evolution accelerated when life radiated into new physical and ecological environments, as advantageous mutations were then selected at new functional sites in proteins. Natural selection favoured mutations that adapted the novel functional sites and a multitude of other molecular sites to work more efficiently together and hence protected these improved arrays of molecular sites from further change. A striking example of a speed up in protein evolution followed up by a slow down occurred in primates when advantageous mutations transformed embryonic haemoglobin of earlier primates into a fetal haemoglobin that helped extend the period of fetal life. The 1 st method of amino acid sequencing was developed in the 1950s and within a few years was being used on the fibrinopeptides A and B from various mammals. Hominoid fibrinopeptides have evolved even more slowly than those of the birds. The fibriropeptide sequences of humans, chimpanzees and gorillas are identical and differ from those of orangutan in only two of their 30 positions and from those of the Siamang and Gibbon in one or three further positions respectively An amino acid replacement is shared by Oranguttan, Gorilla, Humans and Chimpanzees and two further amino acid replacements are shared by gorillas, humans and chimpanzees. Most of the amino acid sequences from different animals have come from myoglobins and 18

haemoglobins. The myoglobin of mammals and other vertebrates is a single chained protein, typically 153 amino acid residues long. It is involved in oxygen storage in muscle. Haemoglobin the oxygen transporting protein of R.B.C. is made up of four chains two identical Alpha chains and two identical Beta chains. Each Alpha chain is 141 residues long and each Beta chain has 146 residues. The amino acids in the Alpha and Beta chains of haemoglobin in hominoids vary in seven positions. In the myoglobin sequence, the differences among hominoids show up in four positions. The 7 position of Beta and Alpha haemoglobin sequence showing amino acid differences among primates.

Human Common chimpanzee Pygmy Chimpanzee Gorilla Orang Utan Gibbon Old world monkey New World Monkey Tarseer Lorises Lemurs

β 80 N N

β 87 T T

β 104 R R

β 125 P P

α 12 A A

α 23 E E

α 113 L L

N

T

R

P

A

E

L

N N D N

T K K Q

K R R K

P Q Q Q

A T T A

D D D E

L L H L

N

Q

R

Q

A

D

H

N N N

K K Q

R R T

Q Q A

A A T

D D E

H H H

Amino acid residues are departed by the Davhoff single letter code (Each of the 20 amino acids is represented by a different letter) A= alanine, R= arginine, D= asparagines, N= aspartic acid, C= cycteine, E = glutamic acid, Q = glutamine, G = glycine, H = Histidine, I= Isoleucine, L = leucine, K = Kysine, M = methionine, F= phenylalamine, P= proline, S = 19

serine, T = threonine, W= tryptophan, Y = tryrasine, V = valine. Three amino acid replacements are shared by human, chimpanzees and gorilla but not by gibbons or orangutans. In addition there is an amino acid replacement (at Alphahaemoglobin position 23) in Homo and Pan (Both pygmy and common chimpanzees) but not in gorilla and the Asian hominoids.The principal techniques of two-dimensional starch-gel electrophoresis and agar-gel precipitin testing with a variety of antisera to proteins of different primates are used for a comparative study of the serum proteins. These methods provide data on the phylogenetic relationships of man and other primates. In addition the data of the precipitin method (Goodman, 1960b, 1962 a) demonstrate that certain types of proteins have evolved more slowly than other types during the radiation of the primates. Two-dimensional starch-gel electrophoresis (filter paper electrophoresis in one dimension followed by starchgel electrophoresis in the other) separates the proteins of serum into 19-25 components. The arrangement of these components in starch–gel provides a pattern which is characteristic of the species of the organism whose serum is analysed Perodictus and Galago have quite divergent patterns, whereas Galago crassecaudatus and Galago senegalinos have almost identical pattern. When the patterns of members of the Hominodae are compared with each other, the differences among the various hominoid types are much larger than those found between macaques and baboons or between macaques and Vervets. Indeed the various species of the subfamily Cercopithecinae examined by two dimensional starch-gel electrophoresis show a high degree of similarity. Although the starch gel pattern of each hominoid type diverges sharply from the others, there is a constellation of about ten, faster migrating proteins in man, Chimpanzee and Gorilla but not in Gibbon or Orangutan. The faster migrating proteins of the Gibbon and Orangutan present 20

patterns in each case which are quite dissimilar from those of other hominoid. A large body of data (Goodman, 1962 in Press) demonstrates that man is most closely related to the African apes (Chimpanzee and Gorilla) than the Asiatic apes (Orangutan and Gibbon). CONCLUSION: Primates are divided into Prosimians and anthropoids. Prosimian are mainly nocturnal, arboreal creatures found in Africa and Asia. Anthropoids are diurnal, mostly arboreal and found in Africa, Asia and America. They usually live and travel in groups. Primates have elaborate system of communication, based on vocalization and facial displays along with increased visual acuity, particularly stereoscopic vision and colour vision, increase problem solving ability, increased manual dexterity and manipulative ability and an enlarged brain. The diet of primates is made up of a variety of fruits, leaves and insects and proportion of different teeth vary according to their diet. Frugivorous have relatively large incisor and often smaller cheek, teeth, folivores smaller incisors while species eating tougher or more abrasive food often have larger cheek teeth. The form of the skull showed a reduction of the snout and an enlargement of the brain case. Skeleton has numerous adaptations for upright posture flexibility of limb movement. The study of amino acid sequence among primates along with replacements reveals the similarity and dissimilarity between various primates. The arrangement of components of serum protein in starch gel also provides a pattern which is the characteristic of the species of the organism whose serum is analyzed. ***

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