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:'Physiological Adaptation'

[Anonymous Coward]

True. We Americans have been training ourselves for years to be blind to the damage we are causing the rest of the world, and I must say it is working exceptionally well.

Re:'Physiological Adaptation'

[FroMan]

That suggests the Moken learn the skill in childhood and do not simply inherit it as an inborn reflex.

Not evolution: (from the article) That suggests the Moken learn the skill in childhood and do not simply inherit it as an inborn reflex.

This is a form of adaptation to their environment.

Evolution is a trait that is passed on through genetics from one generation to another.

Personally I see evolution and survival of the fittest as two separate catagories though. Evolution is mutations (which add to the set of genes), where survival of the fittest is removal of the "bad" (genes which leave the carrier at a disadvantage, which can be localized to area though) genes from the gene pool.

Re:'Physiological Adaptation'

[paulthomas]

You are a little off.

Evolution (macroevolution specifically) is the emergence of desirable traits for a specific environment due to differential reproductive success, more commonly known as natural selection.

Natural Selection occurs when any or all of the rules of Hardy-Weinberg Equilibrium are broken.

Essentially, when something is less fit for an environment it is less likely to live long enough to reproduce. What makes up these genetic differences to begin with include Mutations, Genetic Drift, and Migration, among other factors.


Competition for limited resources is the key.

A nice google search for your learning pleasure.

How learning can guide evolution

[Anonymous Cowdog]

There is a widely cited paper on the topic of how learning can guide evolution. Abstract here:

How learning can guide evolution

Can anyone find an online version of the full article?

(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.