system
Given the following post, respond as if you're commenting on Reddit:
human
Why haven't more animals evolved infrared vision?

It is biologically feasible for animals to have infrared vision, since some insects and snakes (possibly others?) have it. And infrared vision would confer massive advantages to any predator or prey that had it. So, you'd think it might be relatively commonplace in the animal kingdom, and yet it isn't. Why not? Is there some prohibitive functional or biological cost to having infrared vision?
gpt
I've asked the same question before.  The most reasonable answer (edit: that I've gotten) is that there would be too much background coming from yourself, and would swamp out any signal.  Another answer I've heard is that there might not be sufficient energy in an infrared photon to drive structural change in rhodopsins.  The search for evolving one that can has been the focus of many labs (like Gobind Khorana's lab after the genetic code discoveries) with not a tremendous amount of success.