Animal Eye Close-Ups
By Suren Manvelyan
Jeepers creepers, where’d you get them peepers?
Aren’t eyes just great? It’s amazing to see how evolution has solved a single problem in such a myriad of ways. Actually, to be more accurate, it’s amazing to see that evolution has molded such diverse and intricate machinery from perhaps the same starting point.
That’s right. Although it’s long been thought that animal eyes evolved separately as many as 40 times, eyes most likely owe their varied existence all to one single gene. That gene is named Pax6, and it’s a master control switch for many of the things that end up becoming eyes in jellyfish, flies, snakes and even humans. It doesn’t make eyes on its own, but acts like the conductor during the symphony of development. The protein it makes looks like this:
Now that we are sequencing more and more genomes, and deciphering the precise DNA sequence of Pax6 in all of those diverse creatures, we are able to map out how that gene has changed over time. Like a game of molecular telephone, DNA sequences (usually) get more and more scrambled as they spread into new species. Follow the molecular breadcrumbs back far enough, and you can find out where you came from.
And for all those oodles of eyes, all gorgeous, intricate and exquisite, Pax6 might hold the key to seeing where vision began.