You can actually see it in modern times. The Himba tribe in Africa doesn’t have a concept of the colour blue. There’s not even a word for it, as far as they’re concerned blue is just a shade of green. To us it seems obvious, the sky is blue and the plants are green but to them it’s all different shades of green. It’s not a genetic thing, they’re seeing the exact same colours as anybody else, their culture just doesn’t distinguish between the two colours.