Charles DarwinTheory of Evolution

Charles Darwin was a young man who set sail from England in 1831 on a five year trip around the world.

He was known as the ship’s naturalist – a person who studies the natural world.

On his voyage Darwin observed many different plants and animals. He was amazed by the

diversity of living things.

Today scientists have identified over 1.7 million species of organisms on

Earth.

Darwin saw the fossil bones of animals that died long ago.

These bones resembled the bones of living animals, only they

were much larger.

Darwin wondered what had happened to the giant creatures from the past.

Fossils: preserved remains or traces of organisms that lived

in the past.

In 1835, the HMS Beagle reached the Galapagos Islands.

Comparisons Among OrganismsSouth America

Iguanas: small claws for climbing trees

to eat leaves

Galapagos IslandsIguanas: large claws

to grip slippery rocks and eat

seaweed

Darwin made these drawings of four species of Galapagos finches. The structure of each bird’s beak is an adaptation related to the type of food the bird eats.

Can you guess what each bird may have eaten?

Darwin reasoned that animals that arrived on Galapagos faced conditions that were different from those on the mainland. Thus, he hypothesized that

as the species gradually changed over many generations they became better adapted to the new

conditions.

Evolution: the gradual change in a species over time

Just as dog breeders might choose offspring with desirable traits to mate, Darwin thought that a process similar to selective breeding might happen in nature.