A new report disproves the theory that Sahelanthropus tchadensis, a hominid that lived more than 6 million years ago, was our earliest known human ancestor.
French paleontologists discovered the Sachelanthropus in Chad almost two decades ago.
Nicknamed “Tumai”, they portrayed the creature as early – with a skull indicating a straight spine.
But a new report suggests that Tumai is just an ancient primate, more closely related to a chimpanzee than a human.
The researchers base their claim on the shape of the femur, which they say belongs to Tumi.
They keep the femur, curved like ape, deliberately left unchecked, as this would discredit the two-legged theory.
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French paleontologist Michel Brunet discovered the remains of Sahelanthropus tchadensis in northern Chad in 2001. Brunet keeps a creature called the Tumai, a two-legged creature from more than 6 million years ago and is humanity’s oldest known ancestor.
French paleontologist Michel Brunette first discovered the remains of the Sahellantropus in 2001 in the Uraurab desert in northern Chad.
Brunette, a researcher at the University of Poitiers in France, was nicknamed the “Tumai” specimen and claimed in a 2002 Nature report that it was bipedal.
His main proof was that the base of her skull would be connected to an upright spine.
Using radiometric dating, his team determined that Tumai was between 6.8 and 7.2 million years old and lived at some point in the Miocene era.
Brunette maintains the base of Tumai’s skull showing that she would lean on a straight spine. But doubts about whether Sahellantropus was bipedal only grew with the release of a new report suggesting the creature’s femur showed that it walked on all fours, like a monkey.
That makes Tumai more than twice the size of mankind’s oldest known ancestor, Lucy, discovered in Ethiopia in 1974 and dating back about 3.2 million years.
The left bone and two bones of the forearm were also found, but for some reason Brunette never published anything on them and few other researchers had access to the bones.
In 2004, Ode Bergeret-Medina, a researcher in Poitiers, identified an unmarked bone as the femur – it probably theorized, from a primate.
Eventually, she and her mentor, paleoanthropologist Roberto Machiavelli, believed they had tripped over Tumai’s thigh bone.
Ode Bergeret-Medina, a researcher in Poitiers, identified an unmarked bone as Tumai’s femur. The femur is not straight but curved, which Bergeret-Medina said was more typical of a monkey.
But after Bergerett-Medina took measurements and photographs, the bone disappeared and none of the scientists saw it again.
When Brunette’s team failed to publish anything about the femur, she and Machiavelli took advantage of her notes and prepared their own report.
They tried to present their findings at a conference held by the Anthropological Society in Paris, but were rejected.
Their hypothesis that Tumai is not standing up was finally published in December 2020 in the journal Journal of Human Evolution.
The photos of the femur were examined by Bergeret-Medina and her mentor Roberto Machiavelli. Machiavelli claims that Brunette blocked access to the femur because it would discredit Tumai’s two-legged theory
According to the report, the femur is not straight, but curved, which is more typical for a monkey.
Others suspected that Tumai was a human ancestor before.
Shortly after the publication of Brunette’s initial findings, Milford Wolfoff, a professor of anthropology at the University of Michigan, questioned them.
“Tumai may be a common ancestor of apes and humans, but it is not directed directly at humans,” Wolfoff wrote in a letter to Nature. “We think Tumai is a monkey and we think she is probably a female because of her dog teeth.”
The teeth were small, he said, but could easily belong to a female gorilla or chimpanzee.
Wolff also pointed to scars on the skull left by the neck muscles, arguing that they suggested that Tumai was walking on all fours with his head horizontal to his spine.
A translation of what Sahelanthropus tchadensis looked like when he was alive
Geographer Alain Bovilain, who helped excavate the Tumai, even raised questions about where and when the bones were found – suggesting they were disturbed by locals at some point in the past.
In September, paleontologist Frank Guy, co-author of the original paper Sachelanthropus, published a separate study doubling the bipedal theory.
He claims that the femur has a hard ridge near the top, which would support an upright body.
But his report was published on a print server, which means it has not yet been reviewed by reviews.
Brunette still believes that his Saelanthropos is the missing link in the family tree of humanity.
“Tumai’s skull is, in essence, a hominid skull,” he told China’s state-run Xinhua news agency in 2019. He has a “very small” dog tooth, like a human. “Only a dog can prove that he is not a big monkey.”
Machiavelli claims that Brunette and his colleagues blocked access to the femur, and that his presentation was blackmailed because it would discredit their theory that Tumai was on two legs.
But Brunette insists there is “no controversy”.
“No one can scientifically say that the femur belongs to Tumai.”