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Human History and the Global Environment

Modern humans first appeared in Africa about 300,000 years ago. Groups later walked outward in many waves and reached every continent except Antarctica. Ice ages lowered the sea and opened land paths; the warm period that followed melted ice, raised the sea and made farming possible. Climate and people shaped each other.

đŸŽŦ Step-by-step story

  1. This is empty land. The red marker shows where our story starts.
  2. A small group of humans lives here. They hunt animals and gather fruits and roots.
  3. When food or water runs short, groups walk on. Little by little they spread across the land.
  4. A cold age comes. Ice grows and the sea level drops, so a new land path appears.
  5. Then the climate warms. Ice melts, the sea rises, and people begin to farm.
  6. Now you control the climate. Move the slider and watch ice, sea and farms change.

Tip: drag the 3D scene to turn it. Use two fingers to zoom.

🤔 Common doubts, cleared

Where do I see where humans started?

The red marker is the start. Humans began in Africa and moved outwards from there. See how the story begins in one place.

Why did people leave their homes at all?

Food, water and animals moved with the climate. When a place could not feed everyone, some groups walked on. Watch the purple figures spread.

Where does the sea water go in an ice age?

It is stored as ice on land. See the ice cap grow and the sea go down. That lowered sea exposes the land path.

Why did farming start only after the ice age?

A warmer and steadier climate gave plants enough time and water to grow in the same place every year. See the green farms appear when the slider goes warm.

Does a warm climate always mean farming?

No. It makes it possible. People also needed suitable plants and the skills to look after them. Try the slider yourself to see what warm brings.

Where did humans begin?

Scientists study bones, stone tools and ancient DNA. They find that our own species, Homo sapiens, first appeared in Africa about 300,000 years ago. Earlier human relatives had lived in Africa for millions of years, and some had already walked out into Asia and Europe.

Early people were hunter-gatherers. They moved with the seasons, made stone tools, used fire and shared food in small groups.

How did humans spread across the Earth?

Groups of Homo sapiens left Africa in several waves. The big spread came roughly 70,000 to 50,000 years ago. People moved along coasts and river valleys, and over time they reached Asia, Australia, Europe and later the Americas. They moved a few kilometres in a lifetime, not in one long march.

Why did they move? Animals moved, food ran short, climate changed, or a group grew too big. To live in new lands people learned new skills: warm clothes, boats, new ways to hunt and new tools.

Ice ages, sea level and land paths

During an ice age much of Earth's water is locked in huge ice sheets. So the sea level falls (by about 120 metres at the coldest time, roughly 20,000 years ago). Shallow sea floor turns into dry land. These land paths joined places that are islands today, and helped people and animals move.

When the ice melts, the sea rises again and covers the paths. That is why some old human camps now lie under the sea.

Warming, farming and settling down

About 11,700 years ago the climate became warmer and steadier. Ice melted, forests and grasslands grew, and people found plants and animals they could look after. Farming began in several places, including West Asia, China, South Asia and the Americas, over a few thousand years.

Farming made villages possible. Food could be stored, populations grew, and later came towns, trade and states. Climate did not decide everything, but it opened or closed choices for people.

Try it: your climate experiment

In the 3D: first guess, then check. Slide to Cold. Does the sea go up or down? Is the land path there? Slide to Warm. What shows up on the green squares?

At home: fill a glass with ice and water, mark the water level with tape, and let the ice melt. Think about what ice on land would do to the sea. (Careful: floating ice does not change the level much; ice on land does.)

Key formulas and definitions

Worked examples

1. Why could people walk to some islands during the last ice age but cannot do so now?

In the ice age, much water was frozen as ice on land, so the sea was about 120 m lower. Shallow sea floor became dry land and joined places. When the ice melted, the sea rose and covered those land paths.

2. Homo sapiens appeared about 300,000 years ago. Farming began about 10,000 years ago. For about how many years before farming were all humans hunter-gatherers?

300,000 - 10,000 = 290,000 years. So for well over 95 percent of our species' time, people lived by hunting and gathering.

3. A sea-floor ridge is 80 m below today's sea level. At the coldest time, the sea was 120 m lower. Was the ridge dry land then? By how much?

Yes. The sea surface was 120 m below today's level, which is 40 m below the ridge's top level (120 - 80 = 40). So the ridge stood about 40 m above the sea.

4. Give two reasons a group of early humans might move to a new place.

Any two of: food or water ran short; animals they hunted moved; the climate became colder or drier; the group grew too big for the area; they were following a coast or river with more food.

Common mistakes

Practice quiz

1. Where did Homo sapiens first appear?
2. During an ice age the sea level usually:
3. Early humans lived mainly by:
4. Which change helped farming begin about 11,700 years ago?
5. A land bridge is:

Practice: answer these yourself

Type or choose your answer, then press Check. Use a hint if you are stuck; the full solution appears after you answer.

Frequently asked questions

When did humans spread across the world?

Modern humans appeared in Africa about 300,000 years ago. The main spread out of Africa happened roughly 70,000 to 50,000 years ago, and people reached the Americas at least about 20,000 years ago.

How did the ice age help humans move?

Water locked in ice made the sea fall. Shallow sea floor became land, creating paths between places that are now separated by sea.

Did climate change cause farming?

A warm, steady climate made farming possible and rewarding, but people still had to find plants, try seeds and keep animals. So climate opened the door, and people walked through it.

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