Giant Tortoises and Darwin's Finches

Darwin’s discoveries in the Galápagos continued beyond the iguanas. The islands were named after giant tortoises—huge reptiles so big that two people could ride on them!

As Darwin observed them, he noticed they looked different depending on where they lived.

For example, on islands where food was close to the ground, the tortoises had short necks and rounded shells. However, on islands with tall plants, they developed long necks and curved shells that helped them stretch up to reach food.

In addition to the tortoises, Darwin also studied finches—small birds that lived on the islands. At first, he didn’t realize they were all finches because they looked different on each island. Later, he found that the key difference was their beaks.

For instance, finches that ate large seeds had larger beaks, while those that ate small seeds had smaller beaks. Over time, their beaks adapted to match their food sources, helping them survive.

Based on these observations, Darwin developed the theory of natural selection, which states animals change over generations, passing on traits that help them survive.