Chickens 'One-Up' Humans in Ability to See Color

Researchers at Washington University School of Medicine in St. Louis mapped five types of light receptors in the chicken's eye. Scientists discovers the receptors were laid out in interwoven mosaics that maximized the chicken's ability to see many colors in any given part of the retina, the light-sensing structure at the back of the eye

"Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision," says Joseph C. Corbo, M.D., Ph.D. "Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas."

Corbo plans follow-up studies of how this organization is established. He says such insights could eventually help scientists seeking to use stem cells and other new techniques to treat the nearly 200 genetic disorders that can cause various forms of blindness.

Birds likely owe their superior color vision to not having spent a period of evolutionary history in the dark, according to Corbo. Birds, reptiles and mammals are all descended from a common ancestor, but during the age of the dinosaurs, most mammals became nocturnal for millions of years.

"The human retina has cones sensitive to red, blue and green wavelengths," Corbo explains. "Avian retinas also have a cone that can detect violet wavelengths, including some ultraviolet, and a specialized receptor called a double cone that we believe helps them detect motion."

http://www.sciencedaily.com/releases/2010/02/100216101159.htm