Scientists reconstructed 500 million years of evolutionary history to reveal which came first: colorful signals or the color vision needed to see them. Introduction The natural world is awash with color, and many of these vibrant hues are meant to be seen. Apples blush red to coax animals to spread their seeds, lavender blooms are violet to lure in pollinating bees, and male peacocks trailed by flashy blue trains more successfully attract mates. However, the world is colorful only for some of us...