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
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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
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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
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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
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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
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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
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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.
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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.
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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
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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,
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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
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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
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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
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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
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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,
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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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