Everything we know about our ancestors’ evolution might be wrong.
A graduate student from Arizona State University discovered a human jawbone in Ethiopia back in 2013 that scientists are dating back to 2.8 million years ago, which is 400,000 years before the next oldest fossil human remains.
The fossil findings, which have been published in a new study by ASU’s Institute of Human Origin, show that the lower mandible is now the earliest evidence of the human genus.
“Honestly, it was an exciting moment,” said Chalachew Seyoum, Ethiopian grad student, in a school news release. “I had a good experience in field surveying and knew where potential sediments are. I climbed up a little plateau and found this specimen right on the edge of the hill.”
Seyoum found the jawbone in the Ledi-Geraru area of the Afar region, which is near the site where Lucy’s skeleton was found, the famous 3.2 million-year-old fossil of the species Australopithecus afarensis found in 1974.
Experts in human origins now believe that the Homo genus could have evolved nearly have a million years earlier than previously thought. The new fossil would provide researchers new evidence to bridge the gap between fossils and better map out the human genus evolution.
“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 Arizona State University’s Institute of Human Origins, in a press release. “This is a little piece of the puzzel 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 jawbone, which has five teeth, has features seen in Australopithecus afarensis and features seen in later specimens of the Homo genus, according to the team behind the study.
The ASU team was also able to establish that the owner of the jawbone walked on two legs and lived in a dry, arid climate. Researchers are still trying to establish what it ate and whether it used stone tools.
“It’s an excellent case of a transitional fossil in a critical time period in human evolution,” said Kimbel.