Human Evolution Essay, Research Paper

Evolution is the complexity of

processes by which living organisms established

on earth and have been expanded and modified

through theorized changes in form and function.

Human evolution is the biological and cultural

development of the species Homo sapiens

sapiens, or human beings. Humans evolved from

apes because of their similarities. This can be

shown in the evidence that humans had a decrease

in the size of the face and teeth that evolved. Early

humans are classified in ten different types of

families. Creationists believe that humans were

always humans. Humans are classified in the

mammalian family Primates. In this arrangement,

humans, along with our extinct close ancestors,

and our nearest living relatives, the African apes,

are sometimes placed together in the family

Hominidae because of genetic similarities. Two-leg

walking seems to be one of the earliest of the

major hominine characteristics to have evolved. In

the course of human evolution the size of the brain

has been more than tripled. The increase in brain

size may be related to changes in hominine

behavior (See figure 3). The third major trend in

hominine development is the gradual decrease in

the size of the face and teeth. According to the

Microsoft Encarta Encyclopedia ?98, the fossil

evidence for direct ancestors of modern humans is

divided into the category Australopithecus and

Homo, and begins about 5 million years ago (See

figure 1). Between 7 and 20 million years ago,

primitive apelike animals were widely distributed

on the African and, later, on the Eurasian

continents (See figure 2). Although many fossil

bones and teeth have been found, the way of life

of these creatures, and their evolutionary

relationships to the living apes and humans, remain

matters of active discussion among scientists. The

evidence for human evolution begins with the

australopithecines. All the australopithecines were

bipedal and therefore possible hominines. In

details of their teeth, jaws, and brain size,

however, they modify enough among themselves

to be divided into five species: Australopithecus

anamensis, A. afarensis, A. africanus, A. robustus,

and A. boisei. Genus Homo are also divided in

five different spices: Homo erectus, H. habilis, H.

sapiens, and H. sapiens sapiens. According to

Britannica Encyclopædia, Australopithecus

anamensis lived in Kenya between 4.2 million and

3.9 million years ago. A. afarensis lived in eastern

Africa between 3 and 4 million years ago. This

australopithecine had a brain size a little larger than

chimpanzees. Some had canine teeth more sticking

out than those of later hominines. No tools of any

kind have been found with A. afarensis fossils.

According to Microsoft Encarta Encyclopedia

?98, between about 2.5 million and 3 million years

ago, A. afarensis clearly evolved into A. africanus.

A. africanus had a brain similar to that of its

ancestor. However, although the size of the

chewing teeth remained large, the canines, instead

of sticking out, grew only to the level of the other

teeth. No stone tools have been found in

association with A. africanus fossils. The more

recent include the A. robustus, limited to southern

Africa, and A. boisei, found only in eastern Africa.

The robust australopithecines represent a

specialized adaptation because their principal

difference from other australopithecines lies in the

large size of their chewing teeth, jaws, and jaw

muscles. According to Microsoft Encarta

Encyclopedia ?98, Homo erectus lived from about

1.8 million to 30,000 years ago. Until recently,

Homo erectus was considered an evolutionary

ancestor of modern humans, or Homo sapiens.

Homo erectus had a larger brain than earlier

hominines. Homo erectus was also a taller, with an

evenly face and smaller tooth. Scientists believe

this species lived in Africa between 2 million and

1.5 million years ago. H. habilis is the earliest

known member of the genus Homo. H. habilis had

a larger brain than australopithecines.

Australopithecines had long arms and short legs,

similar to the limbs of apes. Even, H. habilis were

similar modern humans with its limbs and small

body size relative to its height. H. habilis had

smaller molars teeth and a less raised face than

earlier Hominines. H. habilis was taller than

australopithecines, but shorter than Homo erectus.

H. sapiens are not identical in aspect with modern

humans. H. sapiens sapiens, first appeared more!

than 90,000 years ago. The opposition doesn?t

think the same way as scientists do. Creationists

say that human ancestors were not apes. They

were always humans, although they were smarter

and larger than humans are today. Evolutionary

theory is a myth. God created everything. People

that believe in creationism say that if man

descended from ape-like creatures, then humans

should be like them. Yet humans have very

different DNA. The number of vertebrae in our

backbone is different. Human cranial capacity is

totally different. No evidence is available about

human remains from earlier times, which support

evolutionary theory. In some areas, ancient

humans moved into difficult climatic areas and, for

a time, lived in "stone-age cultures" until they had

opportunity to build cities, plant, and become

adapted to animal agriculture. Sometimes people

lived in caves for a time until they could become

settled in homes. There is evidence that ancient

people lived in homes at the same time that others

were living under trees or in caves. The theory of

evolution is the most reasonable theory today.

Creationists don?t have any historical proof. The

creationist theory is only written and the

evolutionary theory is actual living proof that

humans did evolve from apes and why the

environmental adaptations have made humans the

dominant creatures on earth. In the course of time

a split occurred between humans and apes, both

have some similar characteristics and that explains

humans evolving from type of ancient ape.

325