The controversial 7-million-year-old skull may not be as we thought


The question is whether the 7-million-year-old primate’s nickname ‘Toomai’, which runs on two or four legs, has killed off drama among palaeontologists – with a fading femur.

Since the discovery of Sahelanthropus takadensis The first fossil in 2001, it is often cited as our earliest hominin ancestor. Preliminary analysis suggested that Sahelanthropus The routine went upward and had a combination of monkey-like and human-like characteristics.

These findings, however, were based on a single skull.

The skull has physical features that presumably indicate that this primate had a pillar, and therefore spent some time walking on only two legs. Its small teeth also appear more human like apes. A later reconstruction supported these findings.

But other researchers have argued that this alone is not enough evidence for the classroom Sahelanthropus As a hominin – an ancestor directly related to man – rather than a paternal one, but not a directly paternal homo.

Around the same time and at the same place where the skull was found, a partial left femur was also recovered at Toros-Menalla in Chad. The femur disappeared after another researcher began investigating it in 2004, believed to be coincidental.

Aude Bergeret-Medina and his supervisor, palaeoanthropologist Roberto Macchiarelli from the University of Poethers in France, eventually continued their analysis based on measurements and photographs. They have just published their findings, which are suspected Of Sahelanthropus Our family tree has a place.

“Based on our analysis, partial femur lacks any features consistent with regular bouts of terrestrial bipolar travel,” MacChirelli and team write in their paper.

“Thus, if there is compelling evidence that s. Tachdensis One stem is hominin, then bipedalism cannot be seen as requiring the inclusion of hominin Z. “

Another paper is still awaiting peer review from one of the authors of the original Sahelanthropus The study disputes this, claiming that the femur has a hard top ridge that supports an upright stance.

Meanwhile, another paleontologist at the French National Museum of Natural History, Martin Pickford, wondered if the femur was also that of Taumai, or at least another Sahelanthropus.

Still, others agree with Machiarelli’s assessment of femur.

“I looked at the photos from 10 or 12 years ago, and it was clear to me that this is more akin to a chimp than any other hominin,” University of Tubingan paleontologist Medelaine Bohm, who was not involved in any study , told. New scientist.

Analysis of molecular differences in our DNA suggests that humans partnered with chimpanzees and bonobos (our closest living relatives) about 6-8 million years ago. The only other fossil evidence of possible hominins of that time is Ororin tagenensis.

Machirelli and team compare Femur to one O. Tuganensis And determined that there is at least a species-level difference between them.

fter also compared them Australopithecus, Gorillas and modern humans believe that these differences suggest that the two oldest species had different methods of control.

They suspected Sahelanthropus One can have an ancestral relative with a leftover lineage – an eccentric lineage that became extinct.

They also point out that others have suggested that the small teeth found in the original study may only indicate that the woman is female. But the team agrees that compelling questions still remain, particularly around the lines we use to define what truly makes a human a human, the 2017 paper of his Cites in conclusion:

“Exactly in Africa, and under what circumstances, human-human demarcation began, and when, how and why the wan-human boundary became irreversibly established, there are significant research challenges that are still unresolved.”

We will need many more fossils before we know the answer.

This research was published in Journal of Human Development.

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