(Get a brief overview of human genetics.)
The new, long-wavelength receptors immediately opened up a new visual realm to mice, the researchers say.
The study results also show that mammals' nervous systems are remarkably adaptable.
"We think this has implications not just for the evolution of visual systems but for sensory systems in general," Jacobs added.
In other words, animals' brains may be primed to process new sights, smells, tastes, or sounds just as soon as their bodies evolve the abilities to detect "new" phenomena.
Daniel Osorio is a neuroscientist at the University of Sussex in Britain.
He said the discovery that simply giving mice a new type of photoreceptor allows full-color vision "is quite surprising."
"This ability allows mice to cope with new types of visual environment and hence contributes to their adaptability as a species," Osorio said.
He added that the study debunks a common explanation about why only primates are able to see in trichromatic vision: because they're the only ones with the brains to handle it.
"It is evident," he said, "that mice could do what primates did."
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