Why are there redheads? Birds might hold the clues

January 28, 2013

Red coloration—historically seen as costly in vertebrates—historically seen as costly in vertebrates—might represent some physiological benefit after all, according to research published in the journal Physiological and Biochemical Zoology.

Pheomelanin, which is responsible for red hair and freckles in humans and orange and chestnut coloration in other animals, is known to increase the damage to and melanoma risk when present in large amounts. Furthermore, its creation involves the consumption of glutathione, a beneficial antioxidant.

In an attempt to unearth the factors favoring the evolution of pheomelanin in spite of its costs, Ismael Galván and Anders P. Møller of the University of Paris-Sud examined the survival from one breeding season to the next of a wild of barn swallows, as well as the annual of 58 species of American birds.

A recent hypothesis claims that the consumption of cysteine (a component of glutathione) that occurs when pheomelanin is produced can be beneficial under conditions of low stress. Cysteine, which is mainly acquired through diet, can be toxic at high levels, so the production of pheomelanin may help to sequester excess quantities of this amino acid.

Galván and Møller measured birds' blood levels of uric acid and analyzed the coloration of their chestnut throat feathers (an indication of pheomelanin content). When they compared birds that had similar uric acid levels (and therefore similar capacities to excrete excess ), they found that both the European and the American birds with larger amounts of pheomelanin in their feathers survived better.

This study is the first to propose that the costs/benefits of pheomelanin may depend on prevailing environmental conditions, and its results suggest that the production of this pigment may even be beneficial in some circumstances. Given that all higher vertebrates, including humans, present pheomelanin in skin, pelage, and plumage, Galván and Møller's findings increase the scant current knowledge on the physiological consequences of pheomelanin and open new avenues for research that will help us understand the evolution of pigmentation.

Explore further: Brightly colored birds most affected by Chernobyl radiation

More information: Ismael Galván and Anders P. Møller, "Pheomelanin-Based Plumage Coloration Predicts Survival Rates in Birds." Physiological and Biochemical Zoology 86:2 (March/April 2013). Available ahead of print at www.jstor.org/stable/10.1086/668871

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2.3 / 5 (3) Jan 29, 2013
Why are there redheads?

Because God knows a good thing when he sees one.

Purple hair is nice too.


1.7 / 5 (6) Jan 29, 2013
Kind of begs the question: "why are there blondes?"
not rated yet Jan 29, 2013
If Neanderthal population had a great number of redheads this could originate in an evolutionary improvement to survive conditions of scarce sunlight ( less risk of cancer) and only huge amounts of meat to eat, nearly no vegetables. So at the end Neanderthals would be the ancestors of human redheads in their 5% mixed genome ... Auge Aabye
not rated yet Jan 29, 2013
Ought to be pleased to have some Neanderthal ancestors since as well as ginger hair and freckles they also had much bigger brains and were highly skilled. Hope this all got passed down with the nice hair colour.
1 / 5 (8) Jan 29, 2013
The 'Coward Herr Vendicar' has childishly changed his personal login profile, slightly to avoid people following his name back through past comments..... Anyone interested in his cowardly death threats towards posters in the past comments section, follow them through the link below. http://phys.org/p...ndicarD/
1 / 5 (8) Jan 29, 2013
Link fixed....just check out the 'Green Murder Porn' this guy wanks to....


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