ASU-Led Discovery Closes In On Human Origin

By Andrew Bernier
Published: Wednesday, March 4, 2015 - 12:50am
Updated: Wednesday, March 4, 2015 - 12:38pm

Photo credit: Brian Villmoare
Close up view of the mandible just steps from where it was discovered by Chalachew Seyoum, ASU graduate student, who is from Ethiopia.
Close up images of LD 350-1 mandbile
Photo credit: William Kimbel
Detailed map of where the Ledi-Geraru site is located in reference to other important fossil sites in Ethiopia.
Image credit: Erin DiMaggio

The exact point of when humans evolved into our current form has been debated. But now a team from ASU has made a new discovery of something very old which may help answer the debate.

An international effort led by ASU researchers uncovered a jawbone fossil that changes the original thought of when humans evolved into our current genus Homo. The lower left half jaw bone contains five teeth and dates to 2.8 million years ago. Bill Kimbel is with ASU’s Institute of Human Origins. 

“It’s the earliest fossil representative of the genus homo that has yet been found," said Kimbel. "It pushes back the probable time of origin by at least 500,000 years.”

Kimbel refers to genus which is a biological grouping of similar species. He said the area in Ethiopia dates back to 2 to 3 million years ago, where human’s fossil record is poor. With the quality of the find, Kimbel said this is a big discovery in human evolution.

“It helps us narrow the time in which we should be focusing our research to define the exact time and place of origin of the homo lineage,” he said.

The jawbone is similar to the famous “Lucy,” an early hominin skeletal find made nearby. While Lucy was a different genus and dated 200,000 years earlier, it’s also like early versions of our own genus, such as Homo habilis and Homo erectus, leading to our own species, Homo sapien.

EDITOR'S NOTE: This article has been modified to reflect the bone was not carbon dated.

Updated 3/4/2015 at 12:28 p.m.

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