Study: Fossil Bones Add to Evidence about Earliest Ancestor
2022-09-03
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1Researchers say new examinations of arm and leg fossils support existing evidence that an identified species could be our earliest known ancestor.
2The fossil bones were found near a skull that was discovered in 2001 in the African nation of Chad.
3The scientists who found the skull have suggested that it belonged to a being who walked upright and could be our earliest known ancestor.
4Now, researchers say a study involving the arm and leg fossils strengthens that argument.
5The team looked for signs that the species walked on two feet instead of four.
6The move toward upright walking is a main division between human and ape development.
7The fossil species, called Sahelanthropus tchadensis, walked upright while still being able to climb and move around in trees, the team said.
8The species dates back to around seven million years ago, which makes it by far the oldest known human ancestor.
9That is about a million years older than other early known hominins.
10Hominin is a group that includes modern humans and species closely related to humans.
11Researchers - including scientists at the University of Poitiers in France - closely examined the fossil skull, teeth and jaw.
12They argued that the animal must have walked on two feet and held its head upright.
13This argument was based on the placement of a hole in the skull where the spinal cord connects to the brain.
14Other experts, however, have not been persuaded, or convinced, by the early evidence.
15The latest work includes a thigh bone that was not linked to S. tchadensis at first and went unstudied for years.
16Other researchers at the French university found the bone in the laboratory's collection and realized it probably belonged to the fossil species.
17Compared to bones from other species, the thigh was linked closer to upright-walking humans than apes who used their feet and arms, the study found.
18The new findings were recently reported in the publication Nature.
19Study co-writer Franck Guy recently spoke about the fossil examinations to reporters. "There is not one feature.
20There is just a total pattern of features," he said.
21The debate over the species is likely to continue.
22Ashley Hammond is a scientist at the American Museum of Natural History in New York.
23She said more research is needed to find the being's rightful place on the evolutionary tree.
24"I'm not fully convinced yet," Hammond told The Associated Press. "This could still also be a fossil ape."
25Another researcher at the University of Poitiers, Roberto Macchiarelli, examined the thigh bone in the past and decided the species was probably an ape.
26Looking at the new study, Macchiarelli said he still does not believe the species was a hominin, though it might have walked on two legs at times.
27Rick Potts is with the Smithsonian's National Museum of Natural History and directs the organization's Human Origins Program.
28He said the thigh bone puts the species on "better footing" as a possible early human ancestor.
29But he added that the real confirmation will come down to a common saying in the field: "Show me more fossils."
30I'm Bryan Lynn.