system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do animals like to be pet by humans?
gpt
Many mammals, especially the kind we interact with, are social creatures - the evolved to work in small family units to share in responsibilities like hunting, care for young, protection, and health.

Part of health is grooming; keeping each other clean and free of disease. Petting is a form of grooming. Animals evolved to seek out grooming, as it is a social behavior beneficial to the survival of these animals.