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Most primates have excellent colour vision which is why it is so often used in primate communication. Adult Phayre's leaf monkeys, for example, are grey and rather drab, unlike their babies which are born with bright orange fur. The advantage to having such conspicuous colouring is that it makes it easier for their parents to keep an eye on them and it's not just the parents. Close friends and relatives are eager to help too, with the result that a baby is rarely left on its own for long. After a few months, however, when it's more independent, the young one will turn grey and blend in with the rest of the group. But until then, it can't be ignored.