History › Human origins
First hominins: apes that walk upright
c. 7–6 million years ago, Africa· Event· Life & early humans
Mostly agreedGood evidence; some details, dates or numbers uncertain.
In Africa, a line of apes split from the ancestors of chimpanzees and began walking upright on two legs.
See it on the History map →What happened
Hominins are humans and our extinct relatives after the split from chimps, about 7–6 million years ago. Early candidates include Sahelanthropus from Chad and Orrorin from Kenya. Upright walking came millions of years before big brains or stone tools. Later Australopithecus, such as Lucy (3.2 million years ago), walked well but still climbed trees. The Curious Life map covers human evolution.
Why it matters
Upright walking freed the hands, setting the stage for tools, and began the line that leads to every human alive.
How we know
Fossil skulls and leg bones from Chad, Kenya and Ethiopia; footprints at Laetoli, Tanzania, about 3.7 million years old; DNA showing chimps are our closest living relatives.
Still debated
Whether the earliest fossils truly walked upright, and why upright walking evolved (heat, energy, carrying), are debated.
Inside this (4)
Connections (4)
▸First primates gave rise, via apes, to First hominins: apes that walk uprightWell documented
The connection
Primates gave rise to monkeys, and later to apes. In Africa, one ape lineage split from the ancestors of chimpanzees about 7–6 million years ago. Its members began walking upright on two legs, becoming the first hominins: the human branch of the family tree.
When and how
In Africa, about 7–6 million years ago; early hominin fossils come from Chad, Kenya and Ethiopia.
How we know
Fossils trace a series from early apes to upright walkers; DNA shows humans and chimpanzees share a common ancestor.
Debates and open questions
Which fossil species is the very first hominin, and why upright walking evolved, are still debated.
▸First hominins: apes that walk upright made First stone toolsMostly agreed
The connection
Early upright-walking hominins, their hands no longer needed for walking, began knocking sharp flakes off stones. The oldest known tools, about 3.3 million years old, predate our genus Homo, so a pre-human species, perhaps an australopith, made them. Toolmaking did not make us human; it started before us.
When and how
Lomekwi 3, west of Lake Turkana, Kenya; found in 2011 by a team led by Sonia Harmand and Jason Lewis, published in 2015.
How sure are we?
The tools lie in dated sediment layers, but no hominin bones were found with them, so the maker is inferred, not observed.
Debates and open questions
Which species made the first tools, and whether even older evidence exists, such as disputed 3.4-million-year-old cut-marked bones from Dikika, Ethiopia.
▸Lucy (Australopithecus afarensis) is the best-known fossil of First hominins: apes that walk uprightWell documented
The connection
Lucy's species, Australopithecus afarensis, lived about 3.9 to 2.9 million years ago and is one of the best-studied early hominins. Her pelvis and knee show she walked upright while keeping long climbing arms, a snapshot of the in-between stage the first hominins went through.
When and how
Hadar, Afar region, Ethiopia, November 24, 1974; Donald Johanson, Tom Gray and the International Afar Research Expedition.
How we know
The skeleton itself: hip, thigh and knee angles match upright walking. The 3.66-million-year-old Laetoli footprints, likely made by her species, confirm it.
Debates and open questions
Older hominins such as Sahelanthropus, about 7 million years old, are known from fewer bones, so how and why upright walking first evolved is still argued.
▸First hominins: apes that walk upright gave rise to Homo erectusMostly agreed
The connection
Over several million years, African hominins branched into many species. One branch, the genus Homo, appeared about 2.8 million years ago with larger brains and more tool use. By about 1.9 million years ago it had produced Homo erectus, with long legs, a bigger body and a much larger brain.
When and how
East Africa, especially Ethiopia, Kenya and Tanzania, between about 3 and 1.9 million years ago.
How sure are we?
A sequence of dated fossils showing gradually larger brains and more human-like bodies, though the record is patchy.
Debates and open questions
Which species bridged the gap, Homo habilis, Homo rudolfensis or another, and why bodies and brains grew, are actively debated.