If you throw a mouse from a skyscraper onto something soft, let’s say – a stack of mattresses, the mouse would land and be stunned for a moment but probably survive. But, if you throw a dog and an elephant, the dog would break all of its bones and die in an unspectacular way, and the elephant would explode into a red puddle of bones and insides. Why would the mouse survive the fall, but the dog and elephant wouldn’t?

The answer is size. Size is the most underappreciated regulator of living things, explains Kurzgesagt in the video. Size determines everything about our biology, and it does so because the physical laws are different for different sized animals. The mouse would survive the fall because of how scaling size changes everything. He explains that very small things are practically immune to falling from great heights because the smaller the thing is, the less the effect of gravity is.

Moreover, the volume determines the mass of the animal. The more mass the animal has, the higher the kinetic energy before it hits the ground and the greater the impact shock. So in case of elephant, it’s so big that it has extremely little surface area in ratio to its volume. So a lot of kinetic energy gets distributed over a small space and the air doesn’t slow it down much at all. That’s why it gets completely destroyed at the moment of impact with the ground.