Human Evolution Essay, Research Paper

Human Evolution

Ardipithecus ramidus

This species was announced in September 1994. It is thought to

be the oldest known hominid species. It was dated at 4.4 million

years old. The majority of the fossils found were skull fragments.

Other evidence suggests that this species was bipedal. The

individuals were about four feet tall. Some fossils found indicate

that ramidus may have been a forest dweller. The teeth resemble

something between earlier apes and A. afarensis. The fossils were

discovered by a team led by Tim White in Aramis Ethiopia. The

find consists of 17 individuals.

Australopithecus anamensis

This species was named in August 1995. The fossils were mostly

found in Kanapoi Kenya in 1988. Anamensis is thought to have

existed between 4.2 and 3.9 million years ago. The teeth and jaws

are very similar to those of older fossil apes. A partial tibia

supports bipedality. The first fossil of this species was found in

Kanapoi Kenya by Bryan Patterson. The fossil was a lower left

humerous dated to be about 4.0 million years old.

Australopithecus afarensis

This species existed between 3.9 and 3.0 million years ago. It had

an apelike face with a low forehead, a bony ridge over the eyes, a

flat nose, and no chin. They had protruding jaws with large teeth.

The skull is similar to that of a chimpanzee except for more human

like teeth. The canines of this species were smaller than those of

earlier apes but larger than humans. Their pelvis and leg bones

left no doubt that they were bipedal. They had similar hands to

humans and were about 3.5 to 5.0 feet tall. Footprints of this

species were discovered in 1978 by Paul Abel at Laetoli in

Tanzania. The estimated age is 3.7 million years old.

Australopithecus africanus

A. africanus lived between 3 and 2 million years ago. Their body

sizes and brain sizes were slightly larger than afarensis. The shape

of their jaw was fully parabolic, like that of humans, and the

canine teeth have reduced in size. This species fossils were

discovered by Raymond Dart in 1924 at Taung in south Africa.

The find consisted of a full face, teeth and jaws, and an

endocranial cast of the brain. It is between 2 and 3 million years

old.

Australopithicus garhi

It is known from a partial skull that differs from previous

australopithecus species in the combination of its features. They

had extremely large teeth especially the rear ones. The skull was

discovered by Y. Haile-Selassie in 1997 at Bouri in Ethiopia. It is

about 2.5 million years old.

Australopithecus aethiopicus

A. aethiopicus existed between 2.6 and 2.3 million years ago. This

species is known from the Black Skull specimen discovered by

Alan Walker in 1985 near West Turkana in Kenya. The specimen

is almost completely intact. It has a small cranium capacity for a

hominid and has a strange combination of primitive and advanced

features. This species possessed the largest sagittal crest in any

known hominid.

Australopithecus robustus

A. robustus had a body similar to africanus but a larger and more

robust skull and teeth. It existed between 2 and 1.5 million years

ago. The massive grinding teeth indicate that this species had to

chew tough food. The first robustus fossils were discovered by a

schoolboy in 1938 at Kromdraai in South Africa.

Australopithecus boisei

This hominid existed between 2.1 and 1.1 million years ago and

was very similar to robustus, however the face and cheek teeth

were larger. Its brain size was also very similar to robustus. The

first boisei fossils were discovered by Mary Leaky in 1959 at

Olduvia Gorge in Tanzania.

Homo habilis

H. habilis existed between 2.4 and 1.5 million years ago. It was

thought to have used tools. The face is still primitive but it

projects less than A. africanus. The back teeth are smaller but still

larger than modern day humans. The brain shape is also more

humanlike. Habilis is thought to have been 5 feet tall and 100

pounds in weight. The bulge of Broca?s area on the skull indicate

the possibility of it being capable of rudimentary speech. The first

habilis fossils were discovered by the Leakeys in the early 1960?s

at Olduvia Gorge in Tanzania.

Homo erectus

H. erectus existed between 1.8 million years and 3000,000 years

ago. The face resembles that of habilis. The skeleton structure is

more robust than those of modern humans. Erectus may have

been more efficient at walking than modern humans. Erectus

probably used fire. The first erectus fossils were discovered by

Eugene Dubois in 1891 near Trinil on the Indonesian island of

Java. Its age is thought to be 700,000 years old.

Homo sapiens neanderthalensis

Neanderthal man lived between 230,000 and 30,000 years ago.

The brains are larger than those of modern humans. They usually

lived in cold climates and their bodies were much like those of a

modern day cold-adapted human. Their skeletons showed that

they endured brutally hard lives. Neanderthals are known to have

buried their dead. The first neanderthal fossils were discovered by

Johann Fuhlrott in 1856 in the Neander Valley in Germany.

Homo sapiens sapiens

We first appeared about 120,000 years ago. Modern humans have

an average brain size of about 1350 cc. This species looks exactly

like us.