Pigments are largely responsible for the appearance of organisms. Most biological pigments derive from the metabolism of shikimic acid (melanins), mevalonic acid (carotenoids) or levulinic acid...

Colourful plumage is typical of males in species with conventional sex roles, in which females care for offspring and males compete for females, as well as in many monogamous species in which both...

Animals cannot synthesize carotenoid pigments de novo, and must consume them in their diet. Most mammals, including humans, are indiscriminate accumulators of carotenoids but inefficiently...