system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why is it that so many animals have their brains in their head, rather than anywhere else in their body?
gpt
Simply, the speed of transmitting information from the senses to the brain and back encourages a central nervous system that is focused on the primary sense gathering organs.  Eyes, Ears, Nose.  

From there it's an evolutionary advantage having those in an optimal position to gather data, or a head.  Different species have different locations of not only their heads, but also their sense organs.  Fish and horses for example have eyes on the sides of their heads, while most mammals have forward facing eyes.  That's a bit of an aside, but it does go to show that their are evolutionary advantages to different configurations.