Most electron transitions take place in the infrared region,The ability to see this part of the electromagnetic spectrum without reliance on sophisticated technology would have tremendous advantages. Is it possible to manipulate human genes to see this part of the spectrum?
Our heads are warm, so the receptors that react to infrared radiation would be set off constantly by ambient radiation, not just radiation that comes in through the eye. Note that the animals that do see infrared are cold blooded.
So it would be a massive genetic engineering project to get working infrared vision, to either make human heads be room temperature, or to thermally insulate eyeballs from the surrounding tissue.