By inserting a human gene into mice, neuroscientist Gerald H. Jacobs of the University of California, Santa Barbara, and colleagues have created mice that can see a broader range of color (Science 2007, 315, 1723). This work sheds some light on the evolutionary process of color vision and potentially other sensory systems. Humans have three kinds of photopigment cone cells in the retina, and the brain notes which cones respond in perceiving color. Mouse eyes naturally contain only blue and green photopigment cells. Jacobs and colleagues essentially replicated the evolution of primate trichromacy by inserting the human gene for red photopigment into female mice. The researchers wondered if just adding the gene would change mouse vision immediately or if additional nervous system changes were needed. They got their answer when the genetically altered mice approached three panels, of which two were the same color and one was a different color (shown). The trained mice picked the odd-colored panel in 80% of the trials, a success rate that would be highly improbable without the genetic enhancement.