Essay/Term paper: Human evolution

Essay, term paper, research paper:  Science

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.