Theory of Evolution by Natural Selection

Hello. Have you ever wondered why a giraffe has such a long neck to munch on tall trees, or why a polar bear's fur is white just like the snow? That’s me at work. I am a very, very slow story of change. I don't use a magic wand; I just take a lot of time—millions and millions of years. I help living things, from the tiniest bug to the biggest blue whale, fit perfectly into their homes in the world. I am the reason there are so many different and amazing plants and animals all around us. I am the secret story of how life changes to become stronger. My name is Evolution.

For a long, long time, people didn't know I was real. Then, a curious man named Charles Darwin got on a big ship called the HMS Beagle in the year 1831. He wanted to explore the world. He traveled for five whole years, looking very closely at all the plants and animals he found. On a group of special islands called the Galápagos, he saw something amazing about some little birds called finches. The finches on one island had strong, thick beaks that were perfect for cracking open hard nuts. But on another island, the finches had thin, pointy beaks that were just right for catching tiny insects. Charles realized that the birds’ beaks had slowly changed over a very long time to match the food on their island. This helped them survive and have babies. At the same time, another smart scientist named Alfred Russel Wallace was having the very same idea while studying animals in faraway lands. They both understood that I was the secret behind how all living things change. In the year 1859, Charles Darwin wrote a very important book called 'On the Origin of Species' to share this big idea with everyone.

My work is never finished. I am still happening all around you, every single day, just so slowly that you can’t see me with your eyes. I am in the flowers that have the brightest colors to call the bees over for a visit. I am in the cheetahs who have strong legs to run super fast and catch their dinner. Understanding me helps scientists figure out how to protect animals that are in danger. It helps doctors understand how tiny germs change so they can keep us healthy, and it helps farmers grow bigger and stronger food. I am the amazing, true story of how life adapts. I show everyone that all living things on Earth are connected, like one giant family tree. And that story is always, always growing.