In Search of Our Earliest Ancestors

In Search of Our Earliest Ancestors

A jawbone (not pictured above), recently discovered in Ethiopia and estimated at 2.8 million years old, is believed to be a link between the ape man and the earliest humans.

Now this jaw bone is a little long in the tooth. Make that a lot long.

An Arizona State University student recently discovered what appears to be the oldest jawbone from man’s ancestors ever found. The fossil was unearthed in the Afar region of Ethiopia and is believed to be 2.8 million years old.

The jawbone – the left side of the lower jaw with five teeth, to be exact – contains elements of both the Australopithecus afarensis, sometimes referred to as the “ape man,” and the genus homo, which is responsible for the human lineage. It most likely involves the species “homo habilis,” an early and primitive human.

The discovery appears to fill in some scientific gaps between the two with fossils dated at 3 million years old and 2.3 million years old having previously been found. The fossils from the latter are more similar to man. The implications for this discovery, published in the journal “Science,” are major.

Michael Rogers, professor of anthropology at Southern, says the anatomical characteristics are consistent with an intermediate between Australopithecus and homo. “The surprise here is that it fits almost too perfectly as a transitional form, exactly what some have predicted would be found,” Rogers says.

Rogers – who has led many Southern student anthropological expeditions to the Afar section of Ethiopia, including a trip two months ago in Gona – says discoveries rarely fit this neatly into scientific hypotheses. But he said the discovery is exciting and potentially enlightening.

“It was found in a drier, more open grassland type of environment than that of any earlier human ancestor, which could mark a significant adaptive shift that began with the origin of our genus,” Rogers says.

“This adaptive shift also eventually included the use of stone tools, the earliest of which are found at the Gona site and are dated to 2.6 million years ago. This new find gives more weight to the suggestion that my colleagues and I have made that evidence of stone tool use will eventually be found earlier than 2.6 million years ago.”

Rogers was part of an international research team credited more than a decade ago with the discovery of those stone tools. The findings were reported in the September 2003 issue of the “Journal of Human Evolution.”

Meanwhile, the search into man’s past continues