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Hominins: the human branch begins
c. 7–6 million years ago· Event· Human ancestors & us
Strong evidenceGood evidence; dates or details still being refined.
The human branch of the family tree, separating from the line to chimpanzees and bonobos about 7–6 million years ago.
See it on the Life map →What happened
Hominins are all species closer to us than to chimpanzees and bonobos. DNA comparisons suggest the two lines split roughly 7–6 million years ago in Africa, though estimates range more widely. The earliest candidates are Sahelanthropus from Chad, about 7 million years old, Orrorin from Kenya, about 6 million, and Ardipithecus from Ethiopia, 5.8–4.4 million. They had chimpanzee-sized brains, but smaller canine teeth and signs of upright walking.
Why it matters
This is where the human story proper begins: upright walking came millions of years before big brains, tools or language.
The evidence (fossils, genes, rocks)
A handful of fragmentary fossils from Chad, Kenya and Ethiopia, dated by volcanic layers or associated animal fossils, plus genetic clocks comparing human and chimpanzee DNA.
Still debated
Whether the oldest fossils are truly hominins or other apes is debated, and the split may have been drawn out, with interbreeding between the early lines.
Inside this (4)
Connections (3)
▸Apes gave rise to Hominins: the human branch beginsWell established
The connection
Among African apes, the line leading to humans split from the one leading to chimpanzees and bonobos; gorillas had branched off earlier, about 10–8 million years ago. Early hominins kept many ape traits, including small brains and climbing ability, but began walking upright and evolved smaller canine teeth.
When and how
Africa, roughly 7–6 million years ago; DNA-based estimates range from about 5 to 10 million years ago, depending on assumed mutation rates.
The evidence
DNA shows humans are most closely related to chimpanzees and bonobos, and early hominin fossils appear in Africa within the predicted time window.
Debates and open questions
The human–chimp common ancestor has never been identified, and fossil chimpanzees are almost absent, apart from a few teeth from Kenya (2005).
▸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.
▸Hominins: the human branch begins are defined by Walking on two legsStrong evidence
The connection
Scientists usually identify a fossil as a hominin by signs of habitual upright walking, along with smaller canine teeth. Because skulls, hips and legs are rarely found together, each early candidate is judged by whatever bones survive: Orrorin's thighbone, Sahelanthropus's skull base, and Ardipithecus's pelvis and feet.
When and how
Africa, from about 7–6 million years ago; key early evidence comes from Orrorin (Kenya, described 2001), Ardi (Ethiopia, described 2009) and later Lucy.
How sure are we?
Fossil hips, thighbones and feet show the anatomy of upright walking at least by 4.4 million years ago; earlier candidates rest on fewer, disputed bones.
Debates and open questions
Some fossil apes, such as Danuvius from Germany, about 11.6 million years old (described 2019), may have stood upright too, blurring bipedalism as a strictly hominin trait.