Seeing Red

From Scientific American:

Thanks to a genetic manipulation, three color-blind mice recently gained the ability to see the world in the same hues as humans do.

Mice and nonprimate mammals—much like color-blind people—see relatively few hues, because their retinas contain photoreceptors (cells with a light-sensing protein pigment) that only absorb blue (short) and green (medium) wavelengths of light. Scientists say that most primates, including humans, have a third receptor that also absorbs red, or long wavelengths, thanks to a primate ancestor who passed along a gene mutation for it an estimated 40 million years ago. [...]

Would merely adding the new photoreceptor be enough to enable an animal to process new hues or is some brain rewiring—which would take several successive generations to develop—also be needed? The finding, published in this week's Science: new sensory input is all it takes to enhance vision from, say, a box of 16 to a box of 128 colors of crayons.

Jacobs points out that not all of the mutant mice were able to successfully complete the color discrimination test, which he says could indicate how species deal with newly introduced abilities during evolution. He adds that the next step will be to determine how the brain incorporates the new color signals and makes the comparisons necessary to distinguish between different shades. "What this shows is that not only can you expand the range in which animals can sense stimuli," he asserts," but they can derive a new dimension of sensory experience."