system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are beavers hardwired to build dams?

I just saw a video of a beaver in rehab building a dam at the front door of a house. What is it about their instincts/psyche that makes them want to build dams of all things?
gpt
Beavers like to build nests/lodges in relatively still bodies of water. It looks basically like an dome made of sticks, and the entrance is from underwater. Very good for staying in and not getting eaten by a wolf. It also ends up being a good place for some of the food they like to eat to grow.

If there's no body of water they end up building a dam to -make- a body of water from damming up a river.

So the instinct is just part of the same evolutionary development that drives animals to do stuff like birds building nests, or squirrels burying nuts.