Seeing red

摘要

Andre A. Fernandez and Molly R. Morris have revisited a question that evolutionary biologists just can't let go of. Many species of primate have trichromatic colour vision. But what factors drove its evolution? The authors have tested the 'preexisting-bias hypothesis' (Am. Nat. doi:10.1086/518566; 2007). This holds that the evolution of a trait such as colour vision might have evolved to meet one particular need, but was subsequently favoured by selection for another.