The peacock's color secrets.

• Position: Science

What do human fingernails have in common with a peacock's feathers? Scientists in China, delving into how peacocks produce such colorful displays, report that slight variations in the arrangement of keratin and melanin are responsible for the palette of colors found in the eye of a peacock's tail feather. Keratin is also found in human fingernails, and melanin is the substance that darkens human skin. "It's an ingenious and simple way to diversify colors," says researcher Jian Zi. Most colors in nature are caused by...