Because of the social, moral and ethical implications, the evolution of the human species is the most hotly debated issue in scientific, religious and political circles. For years, scientists were sure that Australopithecus afarensis, or “Lucy” represented the single earliest hominid ancestor, as near to a “missing link” as there ever was. However, a discovery by a group of scientists lead by the curator of the Cleveland Museum of Natural History has scientists rethinking our evolutionary lineage: Lucy was not the only hominid walking the Earth between three and four million years ago.
“This new species from Ethiopia takes the ongoing debate on early hominin diversity to another level,” said project team leader Dr. Yohannes Haile-Selassie. “Some of our colleagues are going to be skeptical about this new species, which is not unusual. However, I think it is time that we look into the earlier phases of our evolution with an open mind and carefully examine the currently available fossil evidence rather than immediately dismissing the fossils that do not fit our long-held hypotheses.”
Dubbed Australopithecus deyiremeda for the word meaning “close relative” in the Afar language, the species was identified by upper and lower jaw fossils found in the Afar region of Ethiopia. The new fossils date to 3.3-3.5 million years ago, whereas Lucy’s afarensis fossil dates to between 2.9 and 3.8 million years ago. In other words, the species are distinct, and probably overlapped. This is the first hard evidence found by scientists that multiple hominid species coexisted at the time.
Earlier thinking held that Lucy was the only game in town at the time, giving rise to new species through evolution one at a time. In fact, until recently this theory was supported by the limited fossil record, making scientists hesitant to think otherwise. The establishment began to change with the announcement of Australopithecus bahrelghazali from Chad and Kenyanthropus platyops from Kenya (both dated to around the time of Lucy), as well as the discovery of a partial foot by Haile-Selassie in 2012 that definitely did not belong to Lucy’s species.
“The new species is yet another confirmation that Lucy’s species, Australopithecus afarensis, was not the only potential human ancestor species that roamed in what is now the Afar region of Ethiopia during the middle Pliocene,” said Haile-Selassie. “Current fossil evidence from the Woranso-Mille study area clearly shows that there were at least two, if not three, early human species living at the same time and in close geographic proximity.”
More specimens are needed to get a more complete record of how multiple hominid species lived alongside each other, but it’s entirely possible our view of evolution may need to change – Lucy may not be everyone’s common ancestor after all. As more records are unearthed, scientists will develop a clearer picture of how multiple species gave rise to modern humans.