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The Human Lineage

Dateline: 04/29/99

In a stunning announcement, a team of researchers revealed their discovery of a new species of a human ancestor dubbed Australopithecus garhi. The cranial and tooth remains are estimated to be approximately 2.5 million years old.

The remains were found outside of Bouri in Ethiopia. Garhi means "surprise" in the local dialect. The remains were so named because the discovery was completely unexpected.

These hominids provide insight into a crucial period of human evolution some 2 to 3 million years ago. Scientists are attempting to unravel the exact method of branching and determine human forbearers. This period in the Cenozoic era began with the bipedal chimps and ended with large brain hominids. Elucidating what happened is of intense interest to scientists.

Based on anatomical characteristics, A. garhi is a strong contender for a direct human ancestor. Perhaps one of the most contested questions in the field has been: from which evolutionary branch did humans come? Current research has focused on A. africanus, a small upright walking hominid that was found in eastern Africa. Many scientists thought that the direct human lineage would be from this branch. The anatomical evidence from garhi presents a sharp differentiation from A. africanus and provides startling evidence that modern humans may have later branched from garhi.

The researchers discovered other remains, which could also be garhi. These remains indicate that the hominids walked on legs similar to modern humans and used rudimentary tools to strip away animal flesh. This is perhaps the oldest example of the use of tools by hominids to strip away flesh. These remains didn't have cranial fossils and "dentition," so positive identification is not certain. In addition, the limb proportions were intermediate, between those of apes and humans.

Interestingly, the famous Lucy had long upper arms in comparison to her legs, while H. erectus had the proportions of modern humans. The proportions of the unidentified species were between the two. This suggests that the femur extended before the forearm condensed.

This same team of researchers is also responsible for previously finding the oldest known hominid.

What do you think? Where does Australopithecus garhi fit into the timeline of human evolution? Was garhi more ape-like, human-like, or neither? Come over to the Biology Forum and share your thoughts, opinions, and feelings.

For related information see:

New Species of Human Ancestor
Original news release from Science Daily.

Evolution
View plant, human, and dinosaur fossils.

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