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Thanks, Moneesha, i thought it was too!! Rayilyn Brown Director AZNPF Arizona Chapter National Parkinson Foundation [log in to unmask] ----- Original Message ----- From: "Moneesha Sharma" <[log in to unmask]> To: <[log in to unmask]> Sent: Sunday, August 31, 2008 3:00 AM Subject: Re: Eyes evolved for x-ray vision > Most fascinating. Thanks, Ray > Moneesha > > > > 2008/8/31 rayilynlee <[log in to unmask]> > >> Study says eyes evolved for X-Ray vision >> August 29, 2008 >> >> Troy, N.Y. - The advantage of using two eyes to see the world around us >> has >> long been associated solely with our capacity to see in 3-D. Now, a new >> study from a scientist at Rensselaer Polytechnic Institute has uncovered >> a >> truly eye-opening advantage to binocular vision: our ability to see >> through >> things. >> >> Most animals - fish, insects, reptiles, birds, rabbits, and horses, for >> example - exist in non-cluttered environments like fields or plains, and >> they have eyes located on either side of their head. These >> sideways-facing >> eyes allow an animal to see in front of and behind itself, an ability >> also >> known as panoramic vision. >> >> Humans and other large mammals - primates and large carnivores like >> tigers, >> for example - exist in cluttered environments like forests or jungles, >> and >> their eyes have evolved to point in the same direction. While animals >> with >> forward-facing eyes lose the ability to see what's behind them, they gain >> X-ray vision, according to Mark Changizi, assistant professor of >> cognitive >> science at Rensselaer, who says eyes facing the same direction have been >> selected for maximizing our ability to see in leafy environments like >> forests. >> >> All animals have a binocular region - parts of the world that both eyes >> can >> see simultaneously - which allows for X-ray vision and grows as eyes >> become >> more forward facing. >> >> Demonstrating our X-ray ability is fairly simple: hold a pen vertically >> and >> look at something far beyond it. If you first close one eye, and then the >> other, you'll see that in each case the pen blocks your view. If you open >> both eyes, however, you can see through the pen to the world behind it. >> >> To demonstrate how our eyes allow us to see through clutter, hold up all >> of >> your fingers in random directions, and note how much of the world you can >> see beyond them when only one eye is open compared to both. You miss out >> on >> a lot with only one eye open, but can see nearly everything behind the >> clutter with both. >> >> "Our binocular region is a kind of 'spotlight' shining through the >> clutter, >> allowing us to visually sweep out a cluttered region to recognize the >> objects beyond it," says Changizi, who is principal investigator on the >> project. "As long as the separation between our eyes is wider than the >> width >> of the objects causing clutter - as is the case with our fingers, or >> would >> be the case with the leaves in the forest - then we can tend to see >> through >> it." >> >> To identify which animals have this impressive power, Changizi studied >> 319 >> species across 17 mammalian orders and discovered that eye position >> depends >> on two variables: the clutter, or lack thereof in an animal's >> environment, >> and the animal's body size relative to the objects creating the clutter. >> >> Changizi discovered that animals in non-cluttered environments - which he >> described as either "non-leafy surroundings, or surroundings where the >> cluttering objects are bigger in size than the separation between the >> animal's eyes" (think a tiny mouse trying to see through 6-inch wide >> leaves >> in the forest) - tended to have sideways-facing eyes. >> >> "Animals outside of leafy environments do not have to deal with clutter >> no >> matter how big or small they are, so there is never any X-ray advantage >> to >> forward-facing eyes for them," says Changizi. "Because binocular vision >> does >> not help them see any better than monocular vision, they are able to >> survey >> a much greater region with sideways-facing eyes." >> >> However, in cluttered environments - which Changizi defined as leafy >> surroundings where the cluttering objects are smaller than the separation >> between an animal's eyes - animals tend to have a wide field of binocular >> vision, and thus forward-facing eyes, in order to see past leaf walls. >> >> "This X-ray vision makes it possible for animals with forward-facing eyes >> to visually survey a much greater region around themselves than >> sideways-facing eyes would allow," says Changizi. "Additionally, the >> larger >> the animal in a cluttered environment, the more forward facing its eyes >> will >> be to allow for the greatest X-ray vision possible, in order to aid in >> hunting, running from predators, and maneuvering through dense forest or >> jungle." >> >> Changizi says human eyes have evolved to be forward facing, but that we >> now >> live in a non-cluttered environment where we might actually benefit more >> from sideways-facing eyes. >> >> "In today's world, humans have more in common visually with tiny mice in >> a >> forest than with a large animal in the jungle. We aren't faced with a >> great >> deal of small clutter, and the things that do clutter our visual field - >> cars and skyscrapers - are much wider than the separation between our >> eyes, >> so we can't use our X-ray power to see through them," Changizi says. "If >> we >> froze ourselves today and woke up a million years from now, it's possible >> that it might be difficult for us to look the new human population in the >> eyes, because by then they might be facing sideways." >> >> Rensselaer Polytechnic Institute >> >> >> Rayilyn Brown >> Director AZNPF >> Arizona Chapter National Parkinson Foundation >> [log in to unmask] >> ---------------------------------------------------------------------- >> To sign-off Parkinsn send a message to: mailto: >> [log in to unmask] >> In the body of the message put: signoff parkinsn >> > > ---------------------------------------------------------------------- > To sign-off Parkinsn send a message to: > mailto:[log in to unmask] > In the body of the message put: signoff parkinsn ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn