Island Tribes Develop Superior Underwater Vision

Artifice_Eternity writes "I found this Washington Post article fascinating. A tribe of skilled divers known as "sea gypsies" have developed a previously unknown physiological adaptation that gives them better vision underwater. Most humans see poorly underwater, because water has a similar refractive index to the fluid inside the eye, making it difficult to focus incoming light. But children of the Moken tribe compensate by shrinking their pupils (the same way photographers reduce a camera's aperture size to increase sharpness). Their underwater visual acuity is more than double that previously thought possible in humans. The article also describes other adaptations discovered in recent years that challenge our understanding of what the human body and brain can do." (Painless non-registration demographic click-through required.)

Comments

'Physiological Adaptation'

[Hellraisr]

This is more of a "training your eyes" by changing the pupils. I wouldn't call it a major breakthrough or anything of that nature, as I imagine anyone could do it after years of practice like these tribesman have had.

To me this sounds like learning to play a musical instrument or learning a new skill.

Re:Learned?

[Sherloqq]

...could we create superhumans by rigorously teaching children all these different tricks...

Reminds me of an older martial arts movie in which a teacher plants a small tree, then tells a small child to jump over it day in, day out, and as the tree and the child grow, the child is able to jump really high into the air.

Nice theory, but... no.

[Peter T Ermit]

I did a quick back-of-the-envelope calculation last month when I saw a piece about this in Science. There's no way that a mere 22% change in dilation can't double your acuity; the pinhole effect isn't *that* strong. So I'd bet that most of the improvement has to come from "accommodation" or some other effect.

(Not just 22%) and Better Vision Without Glasses

[obtuse]

I think you used the wrong data for your calculation. 22% is only the difference between the underwater dilation of the Sea Gypsies and the normal European minimum. But the article also mentions that most people's pupils dilate when they go underwater, so other people's eyes aren't anywhere near their minimum. The difference is much larger than 22%. Besides, they aren't acheiving perfect focus, only better focus.

A 2mm pinhole seems big, but it is enough to make a significant difference in acuity. I'm pretty blind without my glasses, but I can significantly improve my resolution by making a crude pinhole lens by circling my index finger to a near pinhole of a few millimeters. Try it, if you wear glasses. It's surprising how well it works, especially considering how large the aperture is, and how far it is from circular. Looking through my imaginary monocle also makes me look extra strange.

I wonder if this explains some of the believers in the Bates Method of vision improvement. They believe that you can learn to see better without your glasses, although Bates' original model of the eye is mechanically wrong. Perhaps they aren't completely wrong. They also recommend gazing at the sun as sunbathing for the eyes. That could initiate the dilation. Unfortunately, UV exposure also causes cataracts.

I'm curious as to whether this phenomenon appears anywhere else. It seems to me that families of pearl divers or people who dive for food in other parts of the world should display this too. If not, I'd wonder why.