Why do people see in colours when many other animals see in black and white?

Question

Is there a need for us to have colours visible in our sight whilst so many species see in b&w or even ultraviolet(bird & fish)?

Answer 1

Seeing colours is a trade off to acuity. Animals with monochrome vision have it because it gives them better movement sense than animals with colour vision. This means that they are less likely to be taken by surprise and eaten than colour-sighted animals. Anything that hunts them would have to have evolved a mechanism to better sense movement in order to catch them, either monochrome vision, or, as in the case of some birds, vision edging into the infra red or ultraviolet wavelengths.

Answer 2

Just the way things are. A lot of birds also see in colour - especially those that eat fruit. Many fish can also see colour.

From an evolutionary point of view, it is probable that all animals had the facility, but those that didn't need it then lost the ability as it does not disadvantage them.

Answer 3

The number of colors you can perceive depend on the number of different types of photoreceptors you have in your eye. Humans have three photoreceptor types: one type of molecule that's most sensitive to the red wavelength, another that's most sensitive to green, and a third that's sensitive to blue. Real colors are mixtures of wavelengths (from infrared to ultraviolet), and we can distinguish them by how much they activate each type of receptor molecule relative to the others.

Some birds have four photoreceptors and can detect color differences slightly better than humans.

Answer 4

colour pigments