Researchers have uncovered dental fossils from around 2.65 million years, belonging to a hitherto unknown human evolution line. This species would have lived in the same place and at the same time as the oldest known member of the genus Homo, to which our own species belongs.
Scientists discovered, in the Ledi-Geraru research area, in the Afar region northeast of Ethiopia, ten teeth-six molars, two incisors, a premolary and a canine-which they attribute to a new kind of Australopithecus. These teeth come from two distinct individuals.
Until now, six species of the genus Australopithecus, an important human ancestor with both similar and human features, were known thanks to fossils found on various African sites. According to the researchers, the newly discovered teeth have characteristics indicating that they belong to a seventh species.
A genus includes closely related species sharing similar characteristics. For example, lions and tigers belong to the same genre but represent different species.
Scientists have also uncovered three other teeth, dated 2.59 million years, presenting features specific to the oldest known species of the genus Homo. This species had been revealed for the first time by a jaw discovered in the same region in 2013.
The researchers have not yet attributed names to the species of Australopithecus and Homo represented by these thirteen teeth, due to the incomplete nature of the fossil remains. Our species, Homo Sapiens, is the most recent member of the genus Homo, which appeared about 300,000 years ago in Africa before spreading around the world.
These new dental fossils offer lighting over a period that is poorly understood by human evolution. Age very close to the teeth suggests that this new species of Australopithecus coexisted in the region with the early species of Homo, raising the question of possible competition for the same resources.
The teeth also indicate that four hominines – name given to species of the human evolutionary line – populated East Africa at that time. Other fossils had already shown the presence of another species of Australopithecus and a kind of paranthropus, hominin with a specialized skull for intensive chewing. An additional species of Australopithecus also lived in southern Africa, bringing five the number of hominines on the continent at this period.
The simultaneous presence of these hominines illustrates the complexity of the human evolution process.
“This strengthens the idea that the history of human evolution is not that of a single line evolving slowly over time,” explains Brian Villmoare, paleoanthropologist at the University of Nevada in Las Vegas and the main author of the study published Wednesday in the journal Nature.
“On the contrary, the scheme of human evolution resembles that of other organisms, with repeated ramifications in multiple species throughout the fossil register, many of which have coexisted,” he adds.
Researchers are now trying to understand the nature of the interactions between the species of Australopithecus and Homo represented by these thirteen teeth.
“We are currently analyzing the teeth to determine if they consumed the same food,” says Kaye Reed, paleoecologist at the state University of Arizona and co -director of the project.
If this was the case, they could have argued the resources, specifies Reed. Rudimentary stone tools dating from the same period have also been discovered nearby, probably manufactured by the Homo species.
The researchers determined the age of the teeth thanks to a technique based on the dating of the feldspar crystals contained in the volcanic ashes of the sediments where they were found, based on the radioactive disintegration of the Argon.
The AFAR region, one of the hottest and lowest places in the globe, is today an arid extent of badlands. But at the time of these species, rivers crossed a vegetated landscape, throwing itself into small lakes, within an environment populated by a remarkable fauna: giraffes, horses, pigs, elephants, hippopotams, antelopes, as well as predators such as salt tooth felines and hyenas.
It is generally considered that the genus homo descends from a kind of Australopithecus, even if the exact species and the chronology are still debated. Australopithecus ended up going out.
Australopithecus notably includes the famous fossil Lucy, member of the species Australopithecus Afarensis, which lived around 3.18 million years ago. Lucy’s remains were discovered in 1974, also in the AFAR region. The new up -to -day teeth have characteristics proving that they did not belong to the species of Lucy, specify the researchers.
“This new kind of Australopithecus is in no way a” missing link “, and we do not necessarily think that it is ancestral to a known species,” said Villmoare.
“The species appeared, many have disappeared,” concludes Reed. “Each discovery is a piece of the puzzle that makes human evolution a tree with multiple branches, rather than a straight line. »»