1. Most mammals hae just two kinds of photopigment in their retinas : one is encoded in the X chromosome and the other in an autosomal (non-sex) chromosome.

2. But was an extra photopigment all that was needed to evolve trichromatic vision? Or does seeing the world in all its colourful splendour require extra brain power too?

3. But was an extra photopigment all that was needed to evolve trichromatic vision?

4. But many primates, including humans, have a third photopigment, encoded by a second gene on the X chromosome.

4. try its best to collect and build good sentences.

5. Most mammals have just two kinds of photopigment in their retinas: one is encoded in the X chromosome and the other in an autosomal (non-sex) chromosome.

6. It's plausible that millions of years ago a single mutation resulted in two different versions of the photopigment gene becoming located on the same X chromosome.

7. The result also hints that perhaps the right kind of photopigment is all that's needed for humans to get owl-like night vision, or to see ultraviolet colours.

8. Is Photosensitive Epilepsy Less Common in Males Due to Variation in X Chromosome Photopigment Genes?

9. Twenty weeks later up to one third of the M-type cones in the animals' retinas had begun to express the L-type photopigment.

10. But many primates , including humans, hae a third photopigment, encoded by a second gene on the X chromosome.