Key learning points

1. Evidence suggests Earth was formed 4.5 billion years ago (one billion is one thousand million).
2. Evidence suggests the first living organisms (microorganisms) appeared around 3.8 billion years ago.
3. The oldest fossils are around 3.5 billion years old, and the newest fossils are around 10 thousand years old.
4. Evidence suggests the first land plants appeared 500mya, the first mammals 200mya, and modern humans 350k years ago.
5. Scientists divide Earth’s history into eons, periods and epochs to make it easier to understand.

Keywords

• Billion - One billion is one thousand million (1 000 000 000).

• Thousand - One thousand (1000) is equal to 10 × 10 × 10.

• Million - One million is one thousand thousand (1 000 000).

• Evolution - The characteristics of species gradually change over time, sometimes forming new species. This process is called evolution.

• Extinction - Extinction is the permanent loss of a species.

Common misconception