system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why has evolution favored external testicles for temperature regulation of sperm rather than just favoring sperm that flourishes in any body temperature?

I would imagine that the natural selection process would originally just favor the sperm that's able to survive in harsher environments rather than developing a whole dangling contraption that's prone to injury and environmental influence.
gpt
Because the natural selection process does not necessarily favor the *best*; it favors what works *well enough*.

Having a dangling contraption may be an inelegant, imperfect solution, but it worked well enough to keep us around.