The oldest representatives of mankind were already bipedal seven million years ago

Toumaï, the oldest representative of humanity, walked well on his two legs seven million years ago but retained the ability to climb trees, according to a study published Wednesday in Nature and based on three bones from a representative of his species. , Sahelanthropus tsatensis.

The story begins in Doros-Menalla, in northern Chad, when a team from the Franco-Saadian paleoanthropological mission discovered the skull in 2001. Sahelanthropus tsatensisToumaï, who is close to him, is then expelled Ororin dugenensis, six million years old and discovered in Kenya, is the oldest representative of mankind. The position of the foramen magnum in Tumai’s skull, with a vertebral column located under the skull and not behind the quadrupeds, places it as a bipedal primate. A few experts dispute this conclusion and argue that the fossil is incomplete.

The study by researchers from PALEVOPRIM, the Evolutionary Laboratory of the University of Poitiers, CNRS and Chadian academics makes a decisive contribution to this discovery. “The skull says it Sahelanthropus part of the human lineage,” Frank Guy, a paleoanthropologist and one of the study’s authors, explained Tuesday. The latter, “bipedalism was his preferred mode of locomotion, depending on the situation,” he added during a press conference.

Very close to hominin

This bipedal gait was “common, but not limited to arboreal locomotion”. A Hypothetical Common Ancestor of the Human Line and the Legacy of Chimpanzees. The team demonstrates this through a detailed study of the femur and the ulna, two bones of the forearm. We will never know if the bones are related to Tumai as an individual, but were found at the same site and belong to a hominin, the human line, similar to him.

read more: Australopithecus lusi walked, but climbed trees

The scientists of the Franco-Saadian mission studied them for several years, with a complete battery of tests and measurements. They identified 23 morphological and functional traits, before comparing them to other species and fossil hominins and great apes.

Their conclusion is that “this set of traits is much closer to what we see in hominins than in other animals,” Guillaume Daver, a paleontologist in the PALEVOPRIM team and first author of the study, said during a press conference. . For example, when a close relative of man, a gorilla or a chimpanzee, leans forward on the back of the phalanx of his hand in a quadruple pattern, this is not noticed. Sahelanthropus.

Forests and wet savanna

The bones of the person thus examined weighed between 43 and 50 kg. The barren desert landscape today consists of mixed forest with his remains, palm groves and humid savannah in his time. A structure favorable to both walking and “warning” is quadruped foliage. The study provides “a more complete picture of Toomai and finally a picture of the first humans,” hailing the “very substantial” work, Antoine Balcio, a paleoanthropologist at the National Museum of Natural History, told AFP.

This brings further arguments to the proponents of the “bushy” evolution of the human line, with many branches, “against the simplistic image of humans imitating each other, with skills that improve over time. Over time”, notes Antoine Balzeau. did Sahelanthropus According to the PALEVOPRIM researchers, humans had the ability to adapt to a given environment, stressing the importance of not seeing bipedalism as a “magic trait” that strictly defines humanity.

In an article accompanying the study, Daniel Lieberman, a professor of evolutionary biology at Harvard, believes the study still does not provide a “conclusive solution” to the question of Toomai’s nature. The PALEVOPRIM team intends to resume its research in Chad next spring “if safety permits,” Franck Guy said. That’s because teams at the site are “trying to find sites older than Douma,” as Clarice Nekolnong, a Chadian paleontologist at the National Center for Research and Development, points out.

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