I've always thought, that were it possible for biology to harnessionizing radiation for energy, some organism would already have doneso. We'd just have to find it. For example we already know about theD. Radiodurans bacteria which survives immense gamma-ray doses, butdoesn't harvest the photons as far as anyone knows. The Earthcontains vast fungal and bacterial communities subject to billions ofyears of evolutionary forces, and also contains "light sources" in theform of uranium ore deposits.Well, it looks like my suspicions were correct: Inside the Chernobyl reactor: fungus feeds on radiation But there's more... Apparently the fungus uses an unsuspectedphotosynthetic molecule: melanin. It's not green like light-lovingplants, instead it's brown and eats gamma rays. This is new, so thedetails are yet unknown.What other organism deals with hard radiation and employs the melaninmolecule? People?Expose caucasian skin to ionizing radiation (hard UV sunlight) and itramps up melanin production. Melanin absorbs UV and acts as ashield. "Getting a sun tan." Or be of non-European ancestry andyou're already shielded.But wait a minute. What if human skin was bright green. Would youthink to yourself "ah, our skin contains a dye molecule which shieldsagainst visible light?" Or instead would you think "ah, our skincontains an energy-harvesting molecule which employs visible light tosynthesize it's own fuel?"In other words... if I have a dark tan, and I go sit in summersunlight without eating, will avoid starvation longer than if I stayedindoors without eating? Maybe vitamin-D isn't the only thing made byhuman skin in sunlight.Just out of curiousity, I wonder if human melanin production respondsto ALL ionizing radiation? If I stick my hand under a high-powergamma ray source for a few minutes per day, will I receive a nice darktan? (I'd be sure to start slowly so I don't get a bone-deep sunburnat the start.)And just how effective is melanin as a shielding...

Thanks. That's interesting!Pete

Could human skin be photosynthetic?

Oct 05, 2007 23 Replies

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John Larkin 18 years ago

Cancer cells, not stem cells.

John

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John O'Flaherty 18 years ago

Or cancerous stem cells, creating all different types of cancer in the body simultaneously.

John

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Willie.Mookie 18 years ago

haha.. OR he's been reading too much of me.

Fact is, photosynthesis as it now occurs in nature is very inefficient. Does anyone who knows, know what the energy efficiency of photosynthesis is? Its well below 5% isn't it? So, you'd need some sort of super efficient light machine made with nano-tech to drive animals around. That's why plants stay rooted in one place - less energy.

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JosephKK 18 years ago

Bill Beaty snipped-for-privacy@eskimo.com posted to sci.electronics.design:

Well slap yourself on the forehead. Revisit the distribution of skin color vs protective clothing.

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