Here's a fascination fact to append to this topic.

All old world primates, including humans, share the same colour vision genes. However, whilst colour blindness among our primate cousins is rare - less than 0.1% among macaques, for example - the figure is up to 8% in male Caucasoid humans. This is due to abnormalities in the opsin genes, and indicates a genetic regression among humans due to removal of the selective pressure that still operates in the wild.


"Time is what prevents everything from happening at once" - John Wheeler