Researchers have unearthed tooth fossils in Ethiopia dating to an estimated 2.65 million years ago of a previously unknown species in the human evolutionary lineage, one that lived in the same time and place as the earliest-known member of the genus Homo to which our own species belongs.
The scientific discovery took place in the Ledi-Geraru research project area of Northeastern Ethiopia’s Afar region. Scientists discovered 10 teeth – six molars, two incisors, one premolar and one canine – that they concluded belonged to a new Australopithecus species. The teeth came from two individuals.
To date, six species of the genus Australopithecus, an important early human ancestor that displayed a mix of ape-like and human-like traits, were known from fossils at various African sites. The researchers said the newly found teeth bore traits indicating they belonged to a seventh species.
The scientists also discovered three other teeth dating to 2.59 million years ago that had traits showing they belonged to the oldest-known species of Homo, one that was first revealed by a jawbone unearthed in the same vicinity in 2013.
Scientists have not yet assigned names to the Australopithecus and Homo species represented by these 13 teeth because of the incomplete nature of the fossil remains. Our species Homo sapiens is the most recent member of the Homo genus, first appearing roughly 300,000 years ago in Africa before later spreading worldwide.
The new discovery has been published in the journal Nature. In the research, the authors conclude that the newly discovered fossils suggest that Australopithecus and early Homo co-existed in Ethiopia’s Afar region before 2.5 million years ago. The research also highlights that the hominin—as species in the human evolutionary lineage are known—fossil record is more diverse than previously known. Accordingly, there were as many as four hominin lineages living in East Africa between 3.0 and 2.5 million years ago: early Homo, Paranthropus, A. garhi, and the newly discovered Ledi-Geraru Australopithecus.
Homo is generally thought to have descended from a species of Australopithecus, though the exact species and the timing have been a matter of debate. Australopithecus eventually died out.
Australopithecus includes the famous fossil Lucy, who was a member of the species Australopithecus afarensis who lived approximately 3.18 million years ago. Lucy’s remains were discovered in 1974, also in the Afar region. The newly discovered teeth had characteristics that showed they did not belong to Lucy’s species, the researchers said.
Ethiopian Policy Institute 