FREE ESSAY ON PRIMATES

PRIMATES

Since the beginning of time, man has evolved through primate evolution. Each primate has
acquired different characteristics over a period of millions of years. The ecosystem has
experienced an enormous change in this phase. Most major changes have occurred due to the
phenomenon of continental drift. Other such factors are deforestation, natural calamities
and, more recently, global warming. These changes have caused primates to become less
arboreal and more and more terrestrial. In order to survive the pressures of natural
selection, terrestrial life and other factors primates have developed more upright
locomotion, changes in body configuration, increase in size and loss of hair.
Over a period of millions of years, the planet has gone through a number of changes. To
adjust to these changes the residents of this planet have also had to adapt. For the time
span encompassing vertebrate evolution, there are three eras: the Paleozoic, the Mesozoic
and the Cenozoic. The highly successful mammalian adaptive radiation is almost entirely
within the most recent era of geological history, the Cenozoic. There are seven epochs in
the Cenozoic - Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene and Holocene.

In Paleocene (65 m.y.a.), the Lemuroids were the group of primates that existed. The
Ruffed Lemur originated in the tropical rainforests of Madagascar. They ate mostly
fruits, flowers, and leaves. Lemurs feature a somewhat elongated snout with a slight
overlap on their eyes. They are large in size and are adapted to the ground. That ahs
made them slower and thus they find it to harder to escape from their predators. They
have gaps between their teeth and are extremely loud because of their strong vocal cords.
They have muzzled faces, which are pointed with whiskers, and wet noses making them look
less like humans. 
The Coquerel's Sifaka are another example from this era. They originated from the forests
of Northwest Madagascar. They eat mostly leaves, flowers and fruits. They are the second
largest lemurs. Sifakas have long legs, which enable them to jump from tree to tree in an
upright position. Another primate belonging to this era is the Galago. They are bushed
babies varying from cat to rat size. The most striking features of the Galago are its
huge eyes, long tail and large hind legs. Brain size is average and their vision and
hearing are well adapted to nocturnal insect hunting. Their limbs enable them to make
rapid leaps from branch to branch. They claim territory with there scent leaving smelly
footprints. 
The Crowned Lemur, which is also an example of this era, is found in extreme Madagascar.
They eat fruits, flowers and leaves. They stay mainly in trees and are active during the
day and at dusk. The crowns on their heads are furry head caps. Females have a lighter
crown then males do. 
The second epoch is Eocene (53 m.y.a.). A group of primates called the tarsiers came into
existence in this era. They came from Southeast Asia in the tropical forests. Tarsiers
usually leap onto their preys from lower branches and shrubs. They classify as prosimians
and are related to lemurs and lorises. The similarities are pertaining to their body
size, large ears and grooming claws. They have very long toes and fingers and their
fingertips seem to be composed of a rubbery and sticky membrane. The Tarsiers also seem
to have very large eyes, which dominates manner. Tarsiers seem to have a combination of
prosimians and anthropoids due to the similarities from both.
The tamarins are another group that existed during the Eocene era and probably one of the
last. Tamarins are the most primitive of monkeys. Tamarins are found in the forests of
Peru, Bolivia, and northwest Brazil. This is one of the species that is not much larger
than a mouse and weighs only 2.5 oz (70 grams) to 2.2 lbs (1000 grams). They have claws
instead of nails and usually give birth to twins. Their diet is composed of tree gum and
fruit. Their locomotion is quadrupedal. Claws allow them to climb vertical tree trunks.
They leap and cling as a form of travel. Tamarins are family oriented and the males are
one of the few that participates in infant care.
The third grade is the Oligocene (35 m.y.a.). In this era the wide spread of the monkeys
occurred. The Spider monkey is the most interesting species of this era. They originate
from rain forest and mountain forest of Central and North America. The food they eat is
mainly fruits, leaves and insects. These monkeys are named for their long arms and legs.
They can move through trees with great skill and are able to aid their movements with
their long tails used as a fifth limb. The tail is used for almost every move they make,
climbing trees, reaching for food, grasping branches, balancing and protecting themselves
from predators. As I observed from personal experience, they mostly hung upside down and
the used their tail to crawl across the ceiling and the walls of the cage like real
spiders. Their long fingers are used to hook and grip branches. Spider monkeys do not
have thumbs on their hands; reason might be that they can get in the way.
The Tufted Capuchin monkey is another interesting species. They come from the tropical
forests of Central and South Africa. Fruit, nuts and insects are part of their diets. The
Capuchins are very active and intelligent. Again we see a species with a grasping talk
and an opposable thumb that they can move around and touch other fingers like humans.
Capuchins are fast learners and can easily be taught to perform tricks. They have also
been observed using twigs to search for insects in tree hole, just like chimps. At the
zoo, I saw a person pointing his finger at the monkey and the rotating it. The monkey
looked at that and started rotating its head. I found that very impressive. 
The Colobus monkey comes from the tropical forests of Central and West Africa. Its diet
is composed of leaves. This diet has caused the evolution of a leaf-digesting organ. It
is situated in the same place as a human appendix. At the time of birth they are white
colored creatures, but within six months they get adult coloration. Most of their time is
spent in treetops. Locomotion is quadrupedal and they are considered to be one of the
most spectacular leapers.
Now we come to the remaining three epochs, the Miocene (25 m.y.a.), Pliocene (5 m.y.a.)
and Pleistocene (1.8 m.y.a.). These eras marked the first appearance of modern primates,
including man. At the time of the Miocene appeared the Gorilla. It first appeared in the
tropical forests of West Africa. The diet of a gorilla consists of fruits, vegetation and
insects such as termites and ants. Gorillas are the largest of the living primates the
male weighs up to 475 pounds and the female weighs up to 250 pounds. The leader of a
group of gorillas is called the silver back as it has gray hair on its back. They have
the ability to walk on two extremities but generally they walk using all fours. But, it
is enough proof that as time has gone on the primate has become more and more erect. This
has enabled them to adjust easily to the perils of terrestrial life. They can use there
fore limbs to hold things and thus making them similar to humans. All though gorillas
have been given the reputation of being ferocious killers, they are very shy and harmless
animals. As I watched them in the zoo, they seemed very harmless. Most of them just sat
on the rocks and were acting as if there was no one watching them.
The Orangutan comes from the tropical forests of Borneo and Sumatra. They are different
from other apes as they are more solitary animals. They eat fruit, leaves, eggs, and
bark. They are knuckle-walkers and tend to have social gestures towards each other by
grooming each other. Their hair length is longer, skin coloration is almost transparent,
and their hands and feet are very similar in size and shape. They use these strong
extremities to move around trees. They build nests from large branches and twigs. They
never use the same nest for more than one night. They are also quiet animals and like to
be alone from all the noises.
The chimpanzees are the most intelligent of all the apes. They are considered as the
closest relatives of humans their DNA has been estimated to be as much as 99% identical
to that of ours. Chimps are found in equatorial Africa. They have a very similar gait to
the gorilla. The eyes, nose and especially the ears of a chimp are very similar to that
of a human. They see color just as humans. Their expressive, individual faces communicate
well. Hands and feet consist of five fingers and toe. They too can carry objects in their
hands. They also have the ability of grabbing on to branches with their feet, something
that we can't do. Chimpanzees can use simple tools such as small sticks to take termites
out of their holes as the food. Their powerful Jaw muscles and teeth let them chew coarse
food. Chimpanzees make sounds and move their bodies to show what they know and how they
feel. We know they make at least 34 different calls. They are screams of surprises and
squeaks of nervousness. Their large canine teeth can intimidate rivals, and do real
damage during fights. Chimpanzees hug when they are excited or need reassurance. They
kiss to comfort or to show respect. Jane Goodall said that "let us hope that out
understanding of the chimpanzees will lead also to a better understanding of the nature
of other non-human animals, as a new attitude towards other species with which we share
this planet." The Chimpanzees seldom have fleas or any other kind of bugs. They are just
grooming each other, picking our bits of dirt and dried skin. I also noticed that when
there is a pink swelling on female chimpanzees (it is only on female) it tells the males
that she is ready to mate. The swelling is sensitive, but does not hurt. It may last for
two weeks.
Man made its entry on this planet during the final to epochs of the Cenozoic- the
Pliocene and the Pleistocene. Man appeared about 5 m.y.a. The earliest discoveries of
that were made in South Africa. It is believed that Man originated from the primates and
different eras do show that primates underwent a lot of changes and the most recent ones
are very similar to humans.
We have seen the changes that have occurred in the primates over a period of about 63
million years. We have observed that all these changes have been made to make the primate
adapt better to its surroundings. These changes include the modification and then
disappearance of the tail. As time passed and the forests became less dense the primates
became more adapted to terrestrial life.