[Λευκός Λύκος]

Κάτι βρήκα με αφορμή το ποστ του Bernie Rico Jr. Φαίνεται πως έχει σχέση με την εξέλιξη των ματιών. Δυστυχώς είναι στα αγγλικά.

"Sometimes it does U-turns. Eyes are as complex as their owners need them to be, and if those needs diminish, so do the eyes. Most birds and reptiles see color with four types of cone photoreceptors, each carrying an opsin that’s tuned to a different color. But mammals evolved from a nocturnal ancestor that had lost two of these cones, presumably because color vision is less important at night and because cones are most effective in bright daylight.

Most mammals are still saddled with these losses, and see the world through a limited palette. Dogs have just two cones, one tuned to blue and the other to red. But Old World primates partly reversed this loss by re-evolving a red-sensitive cone. That opened our ancestors’ eyes to a previously invisible world of reds and oranges and may have helped them discriminate between ripe and unripe fruit. Marine mammals went the other way, dispensing with the blue cone when they became aquatic. Many whales lost the red cone too. They have only rod photoreceptors—excellent for seeing in the deep ocean darkness but useless for seeing color."

Πηγή: