Too bad about their brains

Feb 17, 2010 14:43 GMT  ·  By
Chucken see better than we do, on account of their highly-complex retinal arrangements
   Chucken see better than we do, on account of their highly-complex retinal arrangements

In a new scientific study, researchers have learned that farm fowls best humans when it comes to their perception of color. The investigation revealed that, regardless of the actual size of their brains, the animals can perceive a wider and more accurate range of colors than the human eye ever could. The researchers in charge of the new investigation say that the main thing differencing the two species is the fact that chicken have eyes that are considerably better organized than those of humans. The study looked at five types of individual light-detecting cells in the retinas of chicken, LiveScience reports.

The investigation revealed that these cells were disposed in a very interesting pattern on the birds' retinas. They were interwoven, in a mosaic-type pattern that ensured all portions of the retina exhibited about the same color-recognition ability. “Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision. Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas,” says Washington University in St. Louis (WUSL) School of Medicine expert Dr. Joseph C. Corbo, also the author of the new study.

The reason for this high degree of organization can be found in the creatures' evolutionary history, ranging all the way down to the time of the dinosaurs. As we now know, birds and dinosaurs could have had a common ancestor, but the winged animals never experienced an evolutionary stage in which they were nocturnal. While most mammal species learned to hunt and roam at night, thus developing rod cells on their retina (for night-vision), birds seldom went out at night. This means that they had a few extra millions of years to develop more time of cone retinal cells which are used to detect color during daytime. We, as descendants of the common ancestor we share with primates, are subjected to the same limitation as all mammals.

“The human retina has cones sensitive to red, blue and green wavelengths. 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,” Corbo adds. This ability could be essential in mate selection, as some species of birds are renowned for their colorful plumages. Additionally, when eating colorful fruits such as berries, the creatures need to be able to distinguish between poisonous plants and the real deal.