The Secret History of Life on Our Planet

Life on Earth started a very long time ago in the deep oceans.

At first, only tiny single-celled organisms lived in the water.

Over millions of years, these small things began to change and grow.

Eventually, more complex plants and animals appeared in the sea.

Some fish developed the ability to breathe air and move onto land.

This was a major step because it opened up many new environments.

Giant reptiles like dinosaurs ruled the planet for many millions of years.

During this time, small mammals were also starting to live and hunt.

After the dinosaurs disappeared, mammals had more space to grow and evolve.

Different species adapted to their surroundings to find food and survive.

Some animals grew thick fur for the cold, while others learned to fly.

Evolution is a very slow process that happens over many generations.

Much later, early humans began to walk on two legs and use tools.

Today, scientists study fossils to learn about the history of all living things.

Earth is still home to millions of different species that continue to change.