I tried the all powerful google to answer this question - but I am not getting the answer I seek. I know we turn darker because the skin produces melanin. The question remains - why darker?

I am a physicist and it would make sense to me that the bodies response would want us to turn whiter- since a higher albedo would reflect more UV radiation. It seems that evolution took the way of absorbing more and more UV radiation by this melanin and then converting it to heat. Which begs the question as well - do black people get hotter than white people given the temperature is constant? Although this a side point to my original question.

What sparked this question was the use of thousand of black balls being dumped into LA's water reservoir in the hopes to reduce evaporation. Again... BLACK balls. This makes no sense to me - why the heck not use white balls to reflect more sunlight?

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    $\begingroup$ biology.stackexchange.com/questions/35713/… $\endgroup$ – Macedon93 Aug 24 '15 at 20:01
  • $\begingroup$ Well if you used white it would reflect most all of the solar energy back at the water and what happens to molecules when the get a bump from a photon? $\endgroup$ – AMR Aug 24 '15 at 20:02
  • $\begingroup$ Interesting question. I don't know the answer, but I am guessing that either no suitable white pigment has evolved, or maybe it's too costly to produce compared to the benefits over black. The extra heat absorbed radiates away quickly in most situations anyway, and even when it doesn't, sunburns are hardly life threatening. $\endgroup$ – Roland Aug 24 '15 at 20:59
  • $\begingroup$ For the concern of the black balls, I googled black balls California and the first link gave me an explanation. Note, btw that the question for the black balls is off-topic here (but this is not your main question in your post)and would be on-topic on Physics.SE. $\endgroup$ – Remi.b Aug 26 '15 at 2:09