Washington (AFP) – The prehistoric footprints that have baffled scientists since the 1970s take a second look: were they left by extinct animals or human ancestors?
When famed paleontologist Mary Leakey discovered footprints in Tanzania 40 years ago, the evidence was murky.
Leakey instead focused his attention on other fossil footprints that might be more clearly related to early humans. That Footprintsfound at a site called Laetoli G, it is the first clear evidence that early humans walked upright.
Decades later, a new team re-excavated the confusing footprints, found at a location called Laetoli A, and made the images and 3D scans available for other researchers to continue the discussion.
The research was published on Wednesday in the magazine. temper nature.
“These footprints have been in the mystery category for 40 years,” said Rick Potts, director of the Smithsonian Institution’s Human Assets Project.
“It’s a really exciting idea to dig up and study it again,” added Potts, who was not involved in the research.
What has long puzzled scientists is that these footprints—large, enlarged fifth-toe footprints, estimated to be about 3.7 million years old—do not closely match anything scientists have identified elsewhere.
“They didn’t have the correct weight and foot movement that would be easily recognizable as humans, so other explanations were sought,” said co-author and paleontologist Jeremy DeSilva, including that it may belong to an extinct species of bear.
He and other researchers returned to the site in 2019 and used Leakey’s original maps to identify the mysterious prints, preserved in a layer of volcanic ash that cooled and solidified.
Ohio University co-author Ellison McNutt studied the mechanics of the feet of young black bears at the New Hampshire Wildlife Rescue Center to see if a young bear walking on its hind legs could leave similar footprints.
She was carrying a tray of apple puree to entice the chicks to walk towards her. Every step in the folder path has been recorded for analysis.
She said that bears that walk upright put their weight on their heels first, like humans. “But the proportions of the foot are not the same.” He concluded that the fossil footprints were not left by the bears.
Other factors, such as the spacing of the footprints, led the study authors to conclude that these footprints were left by species hitherto unknown to the first human ancestors.
Not everyone is convinced.
This is a fluctuation between an ancient bear or an ancient human, said Potts of the Smithsonian, adding that an ancient bear may have walked differently than a modern black bear.
William Harcourt Smith, a paleoanthropologist at the American Museum of Natural History who was not involved in the research, said he was convinced it wasn’t a bear but wasn’t sure it was a primitive human being.
“These footprints still belong to some form of non-human ape,” he said.
If two different species are walking upright in the landscape at the same time, this indicates different simultaneous experiences of walking on two legs – complicating the traditional view of human evolution as strictly linear.
“It’s great to think about it,” said Harcourt Smith.
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