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Sahelanthropus tchadensis
c. 7 million years ago (Chad, found 2001)· Fossil or site· Human ancestors & us
DebatedScientists disagree about when, how or why.
A roughly 7-million-year-old skull from Chad, nicknamed Toumaï, that may be the oldest known hominin.
See it on the Life map →What happened
In 2001 Ahounta Djimdoumalbaye, on Michel Brunet's French–Chadian team, found a crushed skull in the Djurab Desert of northern Chad. Nicknamed Toumaï, 'hope of life' in the local Goran language, it is about 7 million years old. Its brain was chimpanzee-sized, but its canine teeth were small and its face fairly flat. The opening where the spinal cord leaves the skull may sit farther forward than in chimps, hinting at upright posture.
Why it matters
If it is a hominin, it is the oldest known, close to the human–chimp split, and its location, about 2,500 km west of East Africa's Rift Valley, widened the search map.
The evidence (fossils, genes, rocks)
One skull, jaw pieces, teeth and limb bones, dated by beryllium isotopes and associated animal fossils to about 7.2–6.8 million years ago. First described in Nature, 2002.
Still debated
Whether it walked upright is contested: a 2020 study of its thighbone said no, while a 2022 study and later work said yes. Some argue it was an ape, not a hominin.
Connections (2)
▸Sahelanthropus tchadensis may be the earliest of Hominins: the human branch beginsDebated
The connection
At about 7 million years old, Sahelanthropus sits close to when DNA suggests humans and chimpanzees split. Its small canines and fairly flat face resemble later hominins, so its discoverers placed it at the base of the human line. If they are right, it is the oldest known hominin.
When and how
Djurab Desert, northern Chad, 2001; described in Nature by Michel Brunet and colleagues in 2002.
How sure are we?
Canine and face features shared with later hominins, and a date of about 7 million years. But only one crushed skull and a few other bones are known.
Debates and open questions
Critics argue it could be an early ape, or from before the human–chimp split; a 2005 digital reconstruction supported hominin status, but debate continues.
▸Sahelanthropus tchadensis may show early signs of Walking on two legsDebated
The connection
Two lines of evidence suggest Sahelanthropus may have walked upright at times. The opening at the skull base where the spinal cord exits appears positioned forward, as in upright walkers, and a thighbone from the same site may show bipedal features. It probably also climbed trees using strong arms.
When and how
Toros-Menalla, Chad; skull described in 2002, thighbone and forearm bones described in 2022 by Guillaume Daver, Franck Guy and colleagues.
How sure are we?
Skull-base angle and thighbone shape compared with apes and humans; the thighbone is assumed to belong to the same species, though it was found apart from the skull.
Debates and open questions
A 2020 analysis of the same thighbone concluded it was not from an upright walker; later studies found hip-muscle features typical of bipeds. Opinion remains split.