system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why do so many juvenile animals, including juvenile people, experience so much hyperactivity?
gpt
All animals must learn to survive as rapidly as possible. One way this happens is through mechanisms in the brain that reward curiosity and learning. When an animal makes new discoveries, it gets a powerful sense of reward. 

Over time, animals also learn about dangerous things. That generates fear, and fear tempers curiosity. As a result, animals that live in very safe environments will tend to be very curious. Animals that live in extreme fear will stop being curious.

Babies with protective parents will feel safe and display a lot curious, stimulation-seeking behavior.