Stories tagged Homo habilis

Homo habilis skull: Photo courtesy Wikimedia Commons and licensed under the GNU Free Documentation License and Creative Commons Attribution 2.5.New fossils found in East Africa are challenging current thought about the relationship between two human ancestors, Homo habilis and Homo erectus.

The two species of hominids had previously been thought to have evolved one from the other (H. erectus from H. habilis), but the new evidence appears to show they co-existed in the same lake region for more than half a million years.

A broken upper jawbone from H. habilis and an intact H. erectus skull were uncovered in the Kenya’s Turkana basin area, and date back to about 1.44 million years and 1.55 million years respectively. Geologists used radiometric dating of volcanic ash deposits to determine the age of the remains. The H. habilis fossil is the youngest of that species ever found.

"Their co-existence makes it unlikely that Homo erectus evolved from Homo habilis," said co-author Professor Meave Leakey, paleontologist the Koobi Fora Research Project. She and her paleontologist daughter, Louise, are co-directors of the research organization.

The fossils were found in 2000 but went through extensive preparation and study before the results were published.

The erectus skull contains the distinctive cranium ridge, and jaw and teeth features found in the species, but the skull’s small size baffles the researchers.

“What is truly striking about this fossil is its size,” said professor Fred Spoor who co-authored the paper. “It is the smallest Homo erectus found thus far anywhere in the world.”

Spoor, a professor of developmental biology at University London College, dismissed that the smaller size could be due to it being from an under-developed specimen.

"By studying how the skull bones are fused together we discovered it belonged to a fully grown young adult rather than a developing juvenile erectus," he said.

Sexual dimorphism (the size disparity between the male and female of a species) could be a factor in the skull’s size, but would mean all other erectus remains found until now have all been male. Some scientists not involved in the study think this may be the case.

With the two hominids inhabiting the same region for such a long a time and still remaining separate suggests the two species didn’t compete directly for resources.

Spoor conjectured on the possibility that an isolated population of Homo habilis living in another part of Africa away from the Turkana basin may have evolved into Homo erectus.

"But that is a much more complex proposition," Spoor said. "The easiest way to interpret these fossils is that there was an ancestral species that gave rise to both of them somewhere between two and three million years ago."

The researchers’ results appeared in the science journal Nature.

SOURCES

New York Times website
BBC Website

Tags : evolution, archaeology, Paleoanthropology, Homo habilis, early man, prehistoric man, Homo erectus

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