Fossil discovery in Ethiopia could rewrite history of human evolution

Scientists in Ethiopia have discovered a fossilised jawbone which they believe could push back the beginning of humankind by almost half a million years.

The 2.8 million-year-old fossil was unearthed in the Ethiopian desert by local graduate student Chalachew Seyoum, who said he was "stunned" by the discovery.

The jawbone that may be a window into the moment humans first emerged . http://t.co/daF3bMHaxH #awesome pic.twitter.com/boWC6ko5nq

 

— Pallab Ghosh (@BBCPallab) March 4, 2015

"The moment I found it, I realised that it was important, as this is the time period represented by few (human) fossils in Eastern Africa," he told the BBC.

The bone, which is the left side of the lower jaw and has five intact teeth, is believed to belong to one of the world's earliest humans. It could shed light on a crucial period of human evolution.

Scientists believe the fossil will help narrow the evolutionary gap between the primitive "ape man" known as Australopithecus afarensis and the more "human" Homo habilis.

"It's an excellent case of a transitional fossil in a critical time period in human evolution," Bill Kimbel, director of the Institute of Human Origins at Arizona State University in Tempe told The Independent. 

Homo sapiens, our species, appeared only 200,000 years ago and until this discovery, the oldest remains from the human genus came from the Homo habilis species 2.3 to 2.4 million years ago, according to Reuters. 

"By discovering a new fossil and re-analysing an old one we have truly contributed to our knowledge of our own evolutionary period, stretching over a million years that had been shrouded in mystery," said Fred Spoor of University College London. 

"The dating of the jawbone might help answer one of the key questions in human evolution," says the BBC's science correspondent Pallab Ghosh. "What caused some primitive ancestors to climb down from the trees and make their homes on the ground?"