Until now it was considered that the red coloration of the hair or the feathers was too "expensive" for vertebrates from a biological point of view. And all because pheomelanin , the pigment responsible for reddish hair and freckles in humans, as well as the orange colors that other animals wear, increases the risk of skin cancer or melanoma when present in large quantities. What's more, part of the glutathione reserves, which is a beneficial oxidant, is used up to make the pigment. So why are there redheads?
A study published by French scientists in the journal Physiological and Biochemical Zoology seems to have identified that pheomelanin from redheads also has advantages. By studying birds in Europe and America with red and orange feathers, researchers have found that their survival increases when a certain amount of the carmine pigment is produced because it "sequesters" a toxic substance . It is cysteine , an amino acid ingested through the diet that can be harmful over a certain amount.
