Hominid Evolution

2424 Words Feb 21st, 2011 10 Pages
Hominid Evolution

The evolution of hominids has been and still is a heated topic of debate. Many scientists

debate over which species can be classified as “human”. The root "hominid" refers to members

of the family of humans, Hominidae, which consists of all species on our side of the last

common ancestor of humans and living apes. The time split between humans and living apes

used to be thought of fifteen to twenty millions of years ago, but now the time period has shifted

to around five million years ago.

Ardipithecus ramidus is said to have live around 4.4 million years ago. The original

fossils from this species were placed with the Australopithecus genus; however, a new genus was

designated to this group by Tim White.
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Australopithecus robustus is a hominid species that was first discovered by Dr. Robert

Broom in 1938. Dr. Broom had a habit of collecting fossils from a lime quarry worker. He came

across a skull with a molar still in it on June 8, 1938. He began working on a monograph of the

australopithecines, and it was published in 1946. This book had such a contribution to the

understanding of australopithecines that it was given a U.S. National Academy of Sciences

award. The A. robustus remains generally are from three sites: Swartkrans, Dreimulen, and

Kromdraai and can safely be dated to 2.0 to 1.0 million years ago. The massive face is flat or

dished, with no forehead and large brow ridges. It has relatively small front teeth, but massive

grinding teeth in a large lower jaw. Its diet would have been mostly coarse, tough food that

needed a lot of chewing. Bones excavated with A. robustus skeletons indicate that they may

have been used as digging tools. This is a significant change in behavior and once again shows

evolution to the modern day human.

It was a great discovery when Zing, the Australopithecus boisei was found by Mary

Leakey in Olduvai in 1959. A. boisei was very important in clearing up a controversy that

occured in the 1960s over the idea of the "Single Species Hypothesis". The single species

hypothesis states that each individual environment can only support one species, and that in

hominids, "monkey-see monkey-do" holds…