All living things, from bunnies to blueberries, evolved, or came from another living thing. In other words, the cute bunny outside your window likely looked very different from her great, great, great grandparents one hundred years ago. It might look like all living things stay pretty much the same, but that isn't true at all. An adaptation is a change that lets a living thing survive better in its home. In fact, all living things actually came from the same ancestor. They all just changed to stay alive in the different homes they live in. Let's look more closely at all the changes different living things have made over time to stay alive. 

Did you ever look at a fish and wonder how they were able to breathe under the water? It's because they have gills, or parts they use to breathe oxygen from water. And fish aren't the only ones with these - amphibians like frogs have them, too. Gills are an adaptation that makes fish able to live in the water. At first look, it might sound crazy to think that fish and people share a common ancestor from long, long ago, but it's true and we can prove it. Mammals, like people, have small bones inside their ears that look exactly like the bones in a fish's mouth. We use these bones to hear. This makes it pretty likely that, over time, the bones inside our ears that help us to hear have been adapted from the bones that hold up a fish's gills. 

Most animals that have backbones also have a skeleton that is made from bone. This includes different animals from fish to cows to people. We can look at how bones are shaped and what they are made out of to learn how animals have changed over time. Let's look at birds. They have a special adaptation that lets them fly. In order to fly, you need to be light. If an animal is large and heavy, it needs to use more strength to fly. In other words, it is easier for lighter birds to fly. To make this possible, over time birds have adapted to weigh less. One way they have done this is with pneumatic bones, which are hollow inside instead of filled with tissue, like in other animals with bones. This makes it so the birds weigh less and can fly more easily.  (Figure 3) 

Plants have many parts that help them stay alive. Did you know that all life started in the water? As plants adapted to dry land and got used to not having water all of the time, they needed new organs and structures. The things that helped the plants lived got passed on to their children, which why plants today look how they do. The first plants grew very close to the ground, which means that they had to fight with other short plants to get a spot in the sun. By developing a shoot and growing taller, plants were able to get more light. When plants were in the water, the water held them up. In order to stay up on land, they needed something to make their stems stronger. In order to that, they developed two important parts. The first one is Xylem, tissues inside plants that move water up from the roots. The second is phloem, tissues inside plants that move food from leaves to the rest of the plants. Roots formed in the ground to take up water from the soil and to hold the tall plant into the ground.