system
Given the following post, respond as if you're commenting on Reddit:
human
Ferrets are classified as being unrelated to mongoose and fossa, which in turn are not closely related to civets. Why do these unrelated animals look so similar?

I get that they most likely evolved to fill the same niche, but they have the same long body, short limbs, and arched spine. Why would they share all of these traits if they evolved independently?
gpt
It's a principle known as convergent evolution. It's why a dolphin looks much more like a tuna than it does a hippo, despite being much more closely related to the hippo.

Animals that live in a very similar way tend to solve the same problems in the same way.