Rate-of-living theory

Okay kiddo, so you know how we need food and water to survive and grow big and strong, right? Well, everything in nature needs energy to live and grow too!

Scientists have a theory called the rate-of-living theory, which says that the faster something uses up its energy, the shorter its lifespan will be. It's like if we ate cookies all day every day, we might get sick and not live as long as if we ate lots of fruits and veggies that give us lots of nutrients and help us use our energy better.

So, animals that have faster heartbeats and use up their energy faster often have shorter lifespans than animals that live more slowly and use their energy more efficiently. For example, a mouse has a much faster heartbeat than an elephant, and it typically only lives for a few years, while an elephant can live for several decades!

But there are some exceptions to this theory. Some animals, like birds and bats, have very fast metabolisms and still live long lives. And some animals like turtles, who use their energy slowly, can live for over a century!

So that's the rate-of-living theory - the faster something uses up its energy, the shorter its lifespan will be (but there are some exceptions!).