OUR ability to see the world in glorious colour comes at a price – a diminished sense of smell. So say biologists who have found that two separate lineages of primates, one of which includes humans, independently evolved colour vision while losing much of their sense of smell.
Humans, other apes and Old World monkeys have trichromatic vision, with eyes containing three colour receptors, sensitive to blue, green and yellow-red. They allow us and our Old World relatives to distinguish around 2.3 million colours. Most other mammals only have receptors for blue and green, and can distinguish far fewer colours.
In…
