The newly discovered human, named Australopithecus deyiremeda, overlapped in both time and region with yet another prehistoric human, "Lucy" (Austrolithecus afarensis). The find is strong evidence for the presence of more than one closely related early human ancestor species prior to 3 million years ago.
Because this particular species' teeth had super thick enamel and its jaws were built to last, "it probably engaged in heavy chewing and consumed harder, tougher, and more abrasive dietary resources," lead author Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History, told Discovery News.
Haile-Selassie and his team analyzed the remains, which were collected from the central Afar region of Ethiopia. Combined results from three established different dating processes yielded the estimated age of the fossils.
The location where the fossils were found is just 21.8 miles south of where "Lucy" lived in Hadar, Ethiopia. The researchers think the species could have lived in even closer proximity. The two might have co-existed, which would be like Homo sapiens now sharing turf with another type of human.
While such a scenario today seems unfathomable for humans, it was likely common back in the day.
As for why, Haile-Selassie said, "There is some evidence that during the middle Pliocene time period (about 3.3 million years ago) when multiple hominins (early humans) were running around, there were rivers supporting gallery forests that laterally extend to woodlands and grasslands."
"It was an ecosystem that supported numerous and varied habitats," he continued. "With niche partitioning, a number of related taxa can co-exist in such an ecosystem."
Anthropologists debate about which species is the stem of Homo sapiens, meaning that it should be positioned at the very bottom of the human family tree. Candidates now include two other early humans, Ardipithecus ramidus and Australopithecus anamensis, but it could also be an as-of-yet undiscovered species.
Whichever it was, the stem species, via evolution and divergence, could have later resulted in more than 20 different types of humans, including Homo sapiens.
In terms of what happened to this crowded field of early relatives, Haile-Selassie said, "Some of them gradually gave rise to a new form and went extinct. Others went extinct with no descendants."
He added, "When the environment changes and their habitat diminished, or when they faced harsh competition with others for resources and failed to be good competitors, they had no alternative but extinction."
The fossil evidence for the earliest anatomically modern humans comes from Ethiopia, so it cannot be ruled out that A. deyiremeda and/or "Lucy" is our direct ancestor.
Read more at Discovery News
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