Today is special day here at the Fort!

We’re having a birthday party! We're celebrating one of the world’s most famous scientists, a man named Charles Darwin.

Charles Darwin was the kind of scientist we call a naturalist. A naturalist is someone who studies plants and animals as they live in nature. Naturalists don’t usually do experiments like other kinds of other scientists do.

Instead, they simply observe — or use their eyes — to look around them to learn about the natural world! A naturalist might try to find out where snow geese like to build their nests, or they might write down what time of year a wildflower blooms, and they might ask big questions like, "Why are there so many different kinds of living things?" In fact, that’s a big question that Darwin himself asked. And the answer to that question, along with the rest of Darwin’s work, helps us understand how the plants and animals on Earth today are different from those that were on Earth a long time ago.

So, let’s find out some more about Darwin, and what he learned! Charles Darwin was born in England over two hundred years ago. When he was a young man, he studied to be a doctor.

But while he was at school, he became fascinated with the natural world, and he decided that he wanted to study nature. One of Darwin’s friends suggested that a good way to learn about different kinds of plants and animals was to go on a special adventure, and that’s exactly what Darwin did! He set off with a ship called the HMS Beagle.

And this was no ordinary boat trip — Darwin and his shipmates sailed all over the world, for five years! The Beagle left England in December of 1831. It sailed all the way around the tip of South America to some islands in the Pacific Ocean, past the continent of Australia, around the southernmost point of Africa, and arrived back to England in October of 1836.

And during this trip, Darwin’s job was to study nature at every place where the ship stopped. So Darwin took lots of notes on the rocks, trees, and animals he found all over the world. One of the most important stops on this trip was in a place called the Galapagos Islands, which are here... located next to South America, quite close to the Equator.

These islands were formed by volcanoes deep beneath the ocean. They're are special for another reason, too. There are kinds of animals found here that aren’t found anywhere else on Earth, like a penguin that likes warm water, a special kind of sea lion, and a giant tortoise.

What Darwin learned on the Galapagos Islands was that the living things that fit into their environment, that is, the place they live, have a better chance to stay alive than ones that don’t fit quite as well. But what’s that mean? Well, say there’s a bird that eats insects, and it’s looking for a tasty snack.

And in the place where this bird lives, there’s a group of insects — some that are green, and some that are bright pink. The bird is more likely to see a bright pink insect sitting on a green leaf than a green insect sitting on a green leaf. The insect’s green color helps it hide, while the pink insect sort of, well — stands out!

So, you might say that the green insect fits better into its environment, because it blends in better, so it has a better chance of not getting eaten than the pink insect. And if fewer green insects get eaten than pink ones, that means that more green ones will go on to lay their eggs and have baby insects. Which means, after a while, there will be even more greenies! And if this keeps happening over a long time, then eventually all of the insects that hatch in that area will be green, because that’s what works best there!

And this same idea is true for other animals, and plants, too — not just bugs and what color they are. For example, birds who happen to be born with bigger, stronger beaks might be able to crack open seeds that birds with smaller beaks can’t. And if those birds with bigger beaks get more food, and have more babies, then over time we’ll see more of those birds with bigger beaks than smaller ones!

Or, picture tortoises living in a place where plants grow tall, and their leaves are pretty far off the ground. In a place like that, tortoises that happen to be born with longer necks will have an easier time reaching the leaves that they need to eat. So they’ll be healthier, and have more babies, and eventually, the long-necked tortoises will take over.

Darwin believed that, over long periods of time, living things change to help them fit — and thrive — in the places where they live. Darwin wrote this idea about change over time, as well as a lot of other ideas in a book. And what a book!

People made a lot of fuss about it. They talked about it and even argued about it. We’re still talking about it today, and scientists still use his ideas to learn more about how living things change over time.

So, Happy Birthday, Charles Darwin! And thank you for all of your hard work.

Now let’s have some cake! And thank you for joining us here on SciShow Kids! If you have a question about something, grab a grownup and ask them to help you leave a comment down below. Or send us an email to kids@scishow.com. Thanks! We'll see you next time here at the Fort!