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5 December 2013 11:26 am ,
Vol. 342 ,
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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ScienceShot: It's a Dark World Out There
20 September 2010 3:01 pm
Earth's creatures have eyes so they can see the light—at least that's been the thinking for several millennia. But new research suggests that our eyes are actually geared to pick out darkness. Animal eyes have two ways of processing light-dark contrasts. "On" cells pick out bright spots on dark backgrounds (left image), and "off" cells pick out dark spots on bright backgrounds (right image). Our eyes have almost twice as many "off" cells as "on" cells. University of Pennsylvania researchers wanted to find out if our environment could explain the discrepancy. After analyzing 50 photos ranging from downtown Philadelphia to the plains of Botswana, they discovered that in natural and human-made settings the "off" contrasts (dark on light) outnumber the "on" contrasts (light on dark) by 10% to 20%. A bit of mathematics showed that the ideal ratio of "off" to "on" cells to take in these contrasts is roughly what's seen in our eyes, the researchers report online today in Proceedings of the National Academy of Sciences.
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