Eli5 Why does fire burn in a visual spectrum for humans

Question

Basically the above. Building a great fire and the thought came up.

In: 2

Answer 1

Eyesight evolved as a way of perceiving relevant immediate threats within the relevant spectrum of light. Since fire is a relevant threat, our evolutionary ancestors who could perceive it many hundreds of millions of years ago were the ones to continue their lineage. If other immediate physical threats reflected light outside of our visible spectrum, the surviving evolutionary ancestors whose eyesight was their predominant characteristic of survival would have been capable of perceiving that light. UV radiation was not so important to perceive for survival because, 1: our ozone was still intact during that stage of evolution; and 2: its effects take longer to affect survivability than it takes to pass on our genes to the next generation.