system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why/how is it that, with all the incredible variety between humans, practically every body has the same healthy body temperature of 98.6° F (or very close to it)?
gpt
Because all of our tissues/proteins/enzymes have very similar structures. Temperatures can drastically affect how a protein works; higher temperatures can render a protein completely non-functional, if not outright destroying the protein.

A narrow temperature range provides the best performance for the body's proteins. This temperature is maintained by the hypothalamus, which tries to keep the body at peak performance: in that narrow temperature range.