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Early Hominins: The First Steps

9 min read 5 practice questions
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On this page 9 sections
  1. In 30 seconds
  2. Why this matters
  3. The college version
  4. Eli explains
  5. Worked example
  6. Key takeaway
  7. Quick check
  8. Study tools
  9. Sources & references

In 30 seconds

Early hominins are the species on the human side of the split from the other great apes. Their signature trait is , walking upright on two legs, with the oldest evidence reaching back about 6 million years. The names to know are Sahelanthropus, , and , each known from fragments. Stone tools appear by about 3.3 million years ago, though who made the earliest ones is debated. The record is fragmentary, but it supports a clear story: these were our deep ancestors.

Why this matters

Every human being walks upright, and that habit is one of the oldest and most distinctive features of our lineage. Understanding early hominins shows where the habit came from and why the human branch of the family tree looks the way it does. The topic also demonstrates how science works on thin evidence: researchers build careful claims from a skull here and a thigh bone there, and they say plainly what they do not know. And it puts our own species in context. Compared with the millions of years of history before them, Homo sapiens is a recent arrival, and the first chapters of the story belong to the upright walkers who came first.

The college version

What an early hominin is

In everyday speech, "early human" sounds like a smaller, hairier version of us. In paleoanthropology it means something more precise. A hominin is any species that the evidence places on the human side of the split from the other great apes, the branch of the family tree that leads to Homo sapiens rather than the branch that leads to chimpanzees and gorillas. The Smithsonian's Human Origins Program notes that humans and the African great apes share a common ancestor that lived between 8 and 6 million years ago. Everything on the human side of that split, from the oldest upright walkers to us, is a hominin. The definition is a working one: a new fossil is placed on the tree by its features, such as teeth, skull, hip, and thigh bone, and researchers do not always agree on the placement.

Bipedalism: the signature trait

Walking upright on two legs is called bipedalism, and it is the signature trait of the hominin branch. The Smithsonian calls it one of the earliest defining human traits, with the oldest evidence for upright walking coming from fossils of the earliest known humans, by about 6 million years ago, and full commitment to two-legged walking in place with Australopithecus by about 4 million years ago. Large brains came much later, mostly after 2 million years ago. The trait is easy to recognize because you do it constantly: standing to reach a high shelf, carrying groceries in both arms, and striding across a parking lot are all things no other living primate does as its usual way of moving. The honest note: why bipedalism evolved is debated. Paleoanthropologist Carol Ward, interviewed in SAPIENS, says scientists still know little about the circumstances that led to the trait's emergence, and the fossil record from the critical 7-to-4-million-year window is thin. Several explanations are on the table; none is settled.

Three names to know

Three names carry the early story, each stated here in one factual line. lived between 7 and 6 million years ago in what is now Chad, West-Central Africa, and is one of the oldest known species in the human family tree; the position of the opening at the base of its skull suggests it may have walked upright. Australopithecus is the genus of "Lucy": Australopithecus afarensis lived between about 3.85 and 2.95 million years ago in eastern Africa, walked upright, and left the oldest documented bipedal footprint trails at Laetoli. Paranthropus lived in eastern and southern Africa from about 2.7 to 1.2 million years ago and had skulls specialized for heavy chewing. These are names, not biographies: each species is known from a limited set of fossils, and researchers continue to sort out how they relate to one another.

The tools idea

Stone tools appear early in the record, and the fact is stated plainly: by 2.6 million years ago, early humans in East Africa were striking hammerstones against stone cores to produce sharp flakes for cutting, pounding, and accessing new foods, and older finds push toolmaking back to 3.3-million-year-old tools from Lomekwi, Kenya. The honest note concerns who made them. For decades the answer seemed to be early Homo, since Homo habilis, "handy man," was named partly as the maker of such tools. But the Lomekwi tools predate the oldest known Homo fossils by roughly half a million years, so paleoanthropologists now describe the identity of the earliest toolmakers as genuinely debated, with Australopithecus among the candidates.

The environments

Early hominins did not live in one kind of place. The Smithsonian describes the earliest upright walkers as getting around in diverse habitats, including forests and grasslands, and Sahelanthropus is specifically associated with both. East African environments fluctuated widely between moist and dry over the past 6 million years, and hominins evolved amid that instability rather than in a single steady landscape. If early hominins moved through a patchwork of forests, woodlands, and grasslands, then a flexible way of moving that worked in all of them is exactly what the record shows.

The honest note: the record is fragmentary

Now the reality check. Fossilization happens only under very specific conditions, so the hominin record is a scattered sample: a skull here, a thigh bone there, a few teeth. For the critical window between 7 and 4 million years ago there are very few sites with fossils at all; Ward describes the gap as largely a matter of geologic happenstance. Because the record is thin, scientists disagree about how some species relate to one another, and the Smithsonian notes that most early human species left no living descendants. None of this makes the record useless. It makes it a record that must be read carefully, with every claim matched to the evidence behind it, and with what is unknown stated as openly as what is known.

The honest framing: deep ancestors, not embarrassment

The second reality check is about attitude. Popular pictures of early hominins often treat them as punch lines, shambling figures that almost made it. The evidence supports a different reading. The Smithsonian's Human Origins Program describes human evolution as the lengthy process by which people originated from apelike ancestors, with the traits shared by all people today accumulating over roughly 6 million years. Bipedalism came first, tools followed, brains grew later. Every upright step you take is a behavior with a deep pedigree. Early hominins are not failed humans; they are the deep ancestors of every person alive, the earliest chapters of a story whose later chapters are us.

Eli, the EliExplains learning guide

Eli explains

The same idea, in plain words

Explain it like I’m 10

Early hominins are the first members of the human branch of the family tree, the species on our side of the split from the other African apes. Their big invention was bipedalism, walking on two legs, a habit that shows up in the fossil record by about 6 million years ago and that every later hominin kept. For most of that time brains stayed small: walking came first, tools came later. By about 3.3 million years ago someone was making stone tools, though we do not know exactly who. The names to know are Sahelanthropus, Australopithecus, and Paranthropus, real species that lived in varied African habitats from forests to grasslands.

Picture it like this

Think of a family photo album from a century ago where only three photos survive, each slightly blurry and each showing a different branch of the family. You can still see that everyone in the photos stands upright, the posture is unmistakable. But you cannot tell from those photos why they started standing that way, what they ate, or who spoke to whom. That is close to the position of scientists studying early hominins: the posture is clear, the details are few.

Where the picture stops working

Photos were left for people to look at; fossils are not messages to us. A photo shows one instant completely, while a fossil is a fragment of one individual, often the only fragment of its entire species. A photo is exact, while a fossil bone supports inference, not certainty, which is why the lesson says "evidence suggests" instead of "we know." The album also suggests one family and one story, but the real hominin tree is bushy, with many branches that died out.

Worked example

Dr. Amara is handed a fossil from Chad dated to about 7 million years ago: a skull, and only a skull. She works through the features one at a time. The brain case is small, smaller than a chimpanzee's, and the face slopes, both ape-like. But the canine teeth are small and flat, more human-like, and the foramen magnum, the opening where the spinal cord leaves the skull, sits underneath the skull rather than at the back, which keeps the head balanced on an upright spine. On those features she assigns the skull to Sahelanthropus tchadensis and records the honest limit: the skeleton beyond the skull is unknown, so statements about how this species moved rest on the skull alone. One skull, one careful claim.

Key takeaway

Early hominins walked upright long before they had big brains, lived in varied African habitats, and left a fragmentary record. Read carefully, those fragments show they are our deep ancestors, not our embarrassment.

Quick check

3 questions here, of 5 in this lesson’s practice set. Answers stay hidden until you check.

Question 1 of 3foundational

In this lesson, the term "hominin" refers to —

Choose an answer, then check it.
Question 2 of 3foundational

Which trait does this lesson name as the signature trait of early hominins, present long before large brains?

Choose an answer, then check it.
Question 3 of 3intermediate

A fossil skull from Chad is dated to between 7 and 6 million years ago. The opening at its base sits underneath the skull, its brain case is small, and it is among the oldest known species in the human family tree. This species is —

Choose an answer, then check it.
Practice all 5

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Practice this lesson
Study tools & related lessonsYou’ll learn to · Common mistakes · Easily confused · Key vocabulary · Related

You’ll learn to

  • Define hominins as the fossil species on the human side of the split from the other great apes, using the attributed working definition.
  • Explain bipedalism as the signature trait of early hominins, giving an original example from daily life.
  • State one factual line about each named genus, Sahelanthropus, Australopithecus, and Paranthropus, with attributed dates.
  • Describe when stone tools appear in the record and explain why the identity of the earliest toolmakers is debated.
  • Summarize the environments of early hominins as varied habitats, with an attributed example.
  • Analyze the two reality checks: the record is fragmentary, and early hominins are our deep ancestors rather than an embarrassment.

Common mistakes

  • All early hominins were direct ancestors of modern humans.

    The hominin tree is bushy, not a single ladder. The Smithsonian notes that most early human species left no living descendants; early hominins are the deep ancestral stock of the human branch, but individual species were often cousins that died out.

  • Big brains came first, and bipedalism followed.

    It is the reverse. Bipedalism is one of the earliest defining human traits, with evidence by about 6 million years ago, while large brains expand mainly after about 2 million years ago.

  • The earliest stone tools were definitely made by early Homo.

    The oldest known tools, at 3.3 million years from Lomekwi, predate the oldest Homo fossils by roughly half a million years. The identity of the earliest toolmakers is debated, with Australopithecus among the candidates.

  • Early hominins lived only on open grasslands, which is why they started walking.

    The record shows varied habitats, including forests and grasslands, with climates fluctuating widely. The "why" of bipedalism is an open question, not a settled grassland story.

  • A fragmentary record means we know almost nothing about early hominins.

    Fragments still support well-attested claims: upright walking by about 6 million years ago, committed bipedalism by about 4 million, and stone tools by about 3.3 million. The honest approach is to state both what the fragments show and what they cannot show.

Easily confused

Hominins vs. Primates

All hominins are primates, but not all primates are hominins. Hominins are the species on the human side of the split from the other great apes; monkeys, lemurs, and the African apes themselves are primates that are not hominins.

Bipedalism in early hominins vs. Occasional upright walking in chimpanzees

Chimpanzees can stand and walk upright for short stretches, but their skeletons are not built for it. Early hominins evolved skeletons that supported regular upright walking, and Australopithecus was fully committed to it.

Australopithecus vs. Paranthropus

Both are bipedal early hominins of Africa. Australopithecus, such as Lucy's species, has modest chewing anatomy; Paranthropus skulls are specialized for heavy chewing, with crests and massive cheek teeth.

Early hominins vs. Homo sapiens

Early hominins lived from about 7 to 1.2 million years ago, walked upright, and had small brains. Our species emerged in Africa much later, with large brains and complex symbolic culture; the full comparison belongs to the Homo sapiens topic.

Key vocabulary

hominin
Humans and all fossil species that the evidence places on the human side of the split from the other great apes, the branch of the family tree leading to us.
bipedalism
Moving on two legs, walking upright, as the usual way of getting around; the signature trait of the hominin branch.
foramen magnum
The opening at the base of the skull where the spinal cord enters; sitting underneath the skull rather than at the back is evidence of upright posture.
fossil
The preserved remains or traces of a once-living organism, usually in rock; the raw material of the hominin record.
Sahelanthropus tchadensis
An early species from Chad, dated to between 7 and 6 million years ago, among the oldest known species in the human family tree.
Australopithecus
A genus of early hominins of eastern and southern Africa, living roughly 4 to 2 million years ago, that walked upright; its best-known member is Au. afarensis, "Lucy's species."
Paranthropus
A genus of early hominins of eastern Africa, living from about 2.3 to 1.2 million years ago, with skulls specialized for heavy chewing.
stone tool
A rock deliberately struck or shaped to cut, pound, or scrape; the oldest known examples are about 3.3 million years old.

Sources & references

  1. Introduction to Human Evolution — Smithsonian Human Origins Program — Smithsonian National Museum of Natural History, Human Origins Program
  2. Walking Upright — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  3. Sahelanthropus tchadensis — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  4. Australopithecus afarensis — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  5. Paranthropus boisei — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  6. Tools & Food — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  7. Climate and Human Evolution — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  8. Dating — The Smithsonian Institution's Human Origins Program — Smithsonian Institution, National Museum of Natural History, Human Origins Program
  9. Unraveling the Mystery of Human Bipedality — SAPIENS (interview with paleoanthropologist Carol Ward) — SAPIENS (Wenner-Gren Foundation)
  10. The First Butchers — SAPIENS (Briana Pobiner) — SAPIENS (Wenner-Gren Foundation)

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Researched 2026-08-22

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