A chimpanzee reflects on lunch.
New research sheds light on how primates, including man, evolved the ability to see red and green.
Scientists believe this more advanced form of colour vision emerged because it helped our ancestors to forage for food. According to a study of chimps and monkeys in the forests of Uganda, red and green vision allows primates to select tasty young red leaves among the green hue of the trees. A few animals can see colour, including man and the other primates, fish, amphibians, and some birds. But most of these animals have a relatively primitive form of colour vision limited to blue and yellow light. It is only a small group of primates, including humans, that can see the full range of colours ranging from red to green as well as blue-yellow.