ELI5: evolution

// eli5

What is evolution?

Evolution is how animals and plants slowly change over many, many years to become better at surviving [1]. Imagine if all the tall giraffes had babies, and their babies were also tall—over thousands of years, giraffes would get taller and taller because the short ones couldn't reach the leaves they needed to eat [1].

Why does it happen?

Living things have babies that are a little bit different from their parents [1]. The ones that are best at surviving in their world have more babies, so their special traits get passed down to lots of kids [1].

What does it feel like to evolve?

It's not something one animal notices—it takes hundreds of thousands of years [1]. Your great-great-great grandparents looked a tiny bit different from you, but the change is so slow that nobody sees it happening [1].

How do scientists know it's real?

Scientists look at fossils (old animal bones in rocks) and see how animals slowly changed shape over time [1]. They also see that all living things share similar body parts, which shows they had common ancestors long ago [1].