Multimedia Gallery
Earliest evidence of human genus Homo found in Ethiopia (Image 3)
Geologists Erin DiMaggio of Pennsylavania State University (left) and Dominique Garello of Arizona State University (ASU) (right) sample a tuff in the Ledi-Geraru project area near the site where the earliest evidence of our human genus Homo was found in Afar Regional State, Ethiopia. The discovery of the left side of a lower jaw with five teeth was made by a team of Arizona State University (ASU) scientists and students during field research in 2013. The hills behind the camels expose sediments that are younger than 2.67 million year old, providing a minimum age for the fossil jaw.
The fossil has been dated to 2.8 million years ago, which predates the previously known fossils of the Homo lineage by approximately 400,000 years. The jaw was discovered by Chalachew Seyoum, an ASU graduate student from Ethiopia. The Ledi-Geraru Research Project, where the jaw was found, is based in the Institute of Human Origins at ASU.
For decades, scientists have been searching for African fossils documenting the earliest phases of the Homo lineage, but had only been able to recover a few poorly preserved specimens from the critical time interval between 3 million years ago and roughly 2.3 million years ago. The fossil lower jaw falls within that critical period at 2.8 million years old.
Analysis of the fossil analysis found advanced features such as slim molars, symmetrical premolars and an evenly proportioned jaw, which distinguish early species on the Homo lineage, such as Homo habilis at 2 million years ago, from the more apelike Lucy. But the primitive, sloping chin of this latest find links the jaw to a Lucy-like ancestor.
The scientists can also tell that this species walked on two legs and lived in a dry, arid climate in eastern Africa. Research is still being conducted to determine what it ate and whether it used stone tools--something the team will be looking for on future trips to the region.
"The importance of the specimen is that it adds a data point to a period of time in our ancestry in which we have very little information," said William H. Kimbel, director of ASUs Institute of Human Origins. "This is a little piece of the puzzle that opens the door to new types of questions and field investigations that we can go after to try to find additional evidence to fill in this poorly known time period."
The research was supported by the National Science Foundation (grants BCS 11-57351, BCS 13-22017 and BCS 07-25122).
To learn more about this research, see the ASU news story Discovery of jaw by ASU team sheds light on early human ancestor. (Date of Image: February 2015) [Image 3 of 3 related images. Back to Image 1.]
Credit: J Ramón Arrowsmith, Arizona State University
Images and other media in the National Science Foundation Multimedia Gallery are available for use in print and electronic material by NSF employees, members of the media, university staff, teachers and the general public. All media in the gallery are intended for personal, educational and nonprofit/non-commercial use only.
Images credited to the National Science Foundation, a federal agency, are in the public domain. The images were created by employees of the United States Government as part of their official duties or prepared by contractors as "works for hire" for NSF. You may freely use NSF-credited images and, at your discretion, credit NSF with a "Courtesy: National Science Foundation" notation.
Additional information about general usage can be found in Conditions.
Also Available:
Download the high-resolution JPG version of the image. (745 KB)
Use your mouse to right-click (Mac users may need to Ctrl-click) the link above and choose the option that will save the file or target to your computer.