If birds don’t go grey, why do we? Sheffield high-flyers have the answer

Non-fade: A seasonal robin will always have its red breast
Non-fade: A seasonal robin will always have its red breast
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Scientists have worked out why birds do not go grey as they age - a discovery they say could lead to a new generation of fade-proof paint and clothing.

A team from Sheffield University looked at how the colours are created in the blue-and-white feathers of the jay and found that they come from the way they are structured rather than the pigments that colour human hair.

The researchers found that instead of using dyes that would fade over time, the birds use well-controlled changes to the nanostructure to create their vividly coloured feathers, which are possibly used for jays to recognise one another.

The jay is able to pattern these different colours along an individual feather barb - the equivalent of having many different colours along a single human hair.

Andrew Parnell, from the university’s Department of Physics and Astronomy, said: “This discovery means that in the future, we could create long-lasting coloured coatings and materials synthetically. We have discovered it is the way in which it is formed and the control of this evolving nanostructure - by adjusting the size and density of the holes in the sponge-like structure - that determines what colour is reflected.

“Current technology cannot make colour with this level of control and precision - we still use dyes and pigments. Now we’ve learnt how nature accomplishes it, we can start to develop new materials such as clothes or paints using these nanostructuring approaches. It would potentially mean that if we created a red jumper using this method, it would retain its colour and never fade in the wash.”

The jay’s feather, which goes from ultra violet in colour through to blue and into white, is made of a nanostructured spongy keratin material which is the same material human hair and fingernails are made from.

The work, published in Nature Scientific Reports, used feathers from the extensive collection at the Natural History Museum in London.

Adam Washington, also from Sheffield University, said the research also answers the long-standing conundrum of why non-iridescent structural green colours are rare in nature.

He said: “This is because to create the colour green, a very complex and narrow wavelength is needed, something that is hard to produce by manipulating this tuneable spongy structures. As a result, nature’s way to get round this and create the colour green - an obvious camouflage colour - is to mix the structural blue like that of the jay with a yellow pigment that absorbs some of the blue colour.”