The scientists discovered a jawbone they believe is approximately 2.8 million years old, which means that its 400,000 years older than what the experts believed was the first human.
The jawbone was discovered in Ethiopia and scientists believe climate change was responsible for the transition of our ancestors from tree dwellers to walking on both feet.
Professor Brian Villmoare from the University of Nevada, and the leader of the research, said that the discovery is actually extremely important because it provides the first insight into what is known as the most important transition in the evolution the human species.
Professor Villmoare said that the discovery is related with what is believed to be the oldest human ancestor ever discovered, Lucy, the 3.2 million year old hominin. Lucy was discovered in the same are back in 1974.
The researchers are trying to determine whether Lucy (Australopithecus afarensis) could have evolved into the first human ancestors.
The 2.8 million year old jawbone was discovered in the Ledi-Geraru research site by Chalachew Seyoum, an Ethiopian student. He said that finding the fossil left him stunned.
The ancient fossil consists of the left side of the lower jaw and five teeth. Experts say that the back molar teeth in the jaw are smaller than those of other species of hominins who lived in the same area.
This is one of the features that differentiate humans from other more primitive ancestors, according to the researchers.
Professor Chris Stringer from the Natural History Museum in London, said that the new discovery challenges that experts to reconsider the definition of “humans”.
The oldest fossils that belong to the genus Homo discovered before this one consist of an upper jaw and were found in Hadar, Ethiopia.
Professor Stringer said that the fossil is approximately 2.3 million years old.
The recent discovery pushes the human evolution 400,000 years back which brings it very close to its pre-human ancestor, Lucy.
The jawbone which some researchers believe to have belonged to the first human may help answer a very important question in human evolution: what made the ape ancestors come down from the trees and live on the ground?
Image Source: bbc