Human Evolution Timeline

One of the First Upright Walkers

Sahelanthropus tchadensis lives in what is now Chad, in central Africa; the position of the hole at the base of its skull suggests it may have walked on two legs.

Why it mattered: It is one of the oldest known members of the human family tree and shows the human story began in Africa, near the time our line split from the chimpanzees'.

Lucy Walks Upright

A small Australopithecus afarensis later nicknamed Lucy lives in Ethiopia; scientists found 40 percent of her skeleton in 1974, and footprints of her species pressed into ash at Laetoli, Tanzania, are about 3.66 million years old.

Why it mattered: Lucy proved our ancestors walked upright long before their brains grew large; her brain was about the size of a chimpanzee's.

Stone Tools Spread

Human ancestors in East Africa make simple Oldowan tools by striking flakes off stones to cut meat and crack bones; even older tools, about 3.3 million years old, have been found in Kenya.

Why it mattered: Tools let our ancestors eat more meat and marrow, a rich food that may have helped later humans grow bigger brains.

Homo habilis, the "Handy Man"

Homo habilis appears in East Africa; it has a larger brain than Lucy's species and is found alongside many stone tools.

Why it mattered: Homo habilis is one of the first members of our own genus, Homo, the group that includes every kind of human.

Homo erectus Leaves Africa

Homo erectus, tall with long legs built for walking and running, appears in Africa; by about 1.8 million years ago its kind had reached Georgia in western Asia, and later China and Java.

Why it mattered: Homo erectus was the first human ancestor known to spread far beyond Africa, and it survived for more than a million years.

Controlling Fire

Burned bones and plant ash in Wonderwerk Cave, South Africa, show human ancestors using fire about a million years ago; by about 400,000 years ago people used fire regularly.

Why it mattered: Fire gave warmth, light and protection from animals, and cooked food is easier to chew and digest.

Neanderthals in Europe

Neanderthals, a stocky, big-brained kind of human suited to cold climates, live in Europe and western Asia; they make fine stone tools, hunt large animals and bury some of their dead.

Why it mattered: Neanderthals were close relatives of ours: modern humans later met them and had children with them, and many people today still carry a little Neanderthal DNA.

Homo sapiens Appears

The oldest known fossils of our species, Homo sapiens, are found at Jebel Irhoud in Morocco and date to about 300,000 years ago.

Why it mattered: Every person alive today belongs to this one species, which began in Africa and is now the only kind of human left.

Out of Africa

Starting between about 70,000 and 50,000 years ago, groups of modern humans move out of Africa into Asia, reaching Australia by about 50,000 years ago and Europe by about 45,000 years ago; Neanderthals die out about 40,000 years ago.

Why it mattered: Within a few tens of thousands of years, Homo sapiens lived on every continent except Antarctica, reaching the Americas by at least 15,000 years ago.

The First Farmers

About 12,000 years ago, at the end of the last Ice Age, people in the Fertile Crescent of the Middle East begin to plant wheat and barley and herd sheep and goats.

Why it mattered: Farming let people stay in one place, store food and grow in number, leading to villages, then cities, writing and the first civilizations.