> we can assume our eyes evolved to the spectrum best suited for our environment and survival Sadly, no. Fish, reptiles, dinosaurs and birds have four colour

> we can assume our eyes evolved to the spectrum best suited for our environment and survival Sadly, no. Fish, reptiles, dinosaurs and birds have four colour receptors, so they would need four primary colours in their monitors (and would consider us colour-blind). Back when they competed with dinosaurs, mammals were nocturnal, so colour-vision de-evolved and most mammals today only have two receptors (so humans would would consider them colour-blind). The fact that humans have three receptors is a recent development, it is only present in primates. It comes from a mutation which split a single receptor type into red and green ones. They are still not optimal---because they diverged recently, the sensitivity curves overlap more than would be ideal.