Is 'Red' The Same To All Creatures?
By Elizabeth Landau
http://www.cnn.com/2010/HEALTH/06/24/color.vision.evolution/Violets are blue and roses are red, but maybe those colors are all in your head.
What does it mean for an object to be "red"? Is the way you perceive blueness the same as your neighbor? Your cousin? What about your dog?
Many scientists believe that humans have color vision that is generally consistent across populations and cultures, and that there are evolutionary reasons behind that constancy.
"Color vision is all about emotions and moods, and it has much deeper and richer connections to the rest of our perceptual worlds," said Mark Changizi, a cognitive scientist at Rensselaer Polytechnic Institute in Troy, New York.
Color vision in humans and animals
But some people really don't see the color red in the way that most do. About 8 percent of men have trouble differentiating between certain colors; less than 0.5 percent of women have this problem, according to the American Academy of Ophthalmology.
Color vision is based on photoreceptors in the eye called cones, of which there are about 6 million to 7 million in the human retina. Humans normally have three types of cones, corresponding to short, medium and long wavelengths of light. Purplish blues are at the short end, and reds are at the long end. They eye also has about 120 million rods, which detect light but not color.
According to some estimates, the human eye can distinguish about 1 million to 10 million different colors. A small minority of women actually have four kinds of cones in their eyes -- meaning they could theoretically see even more colors -- but only a genetic test can determine who has extra cones, and it's unclear exactly how differently they may see.
In most cases of colorblindness, the cone systems for either medium or long wavelengths do not work properly, resulting in reds, greens and perhaps yellows appearing very similar. But different people experience this to varying degrees. In rarer cases, people have trouble telling blue and yellow apart; the rarest of all make people see the world in grayscale.
Dogs and cats are generally colorblind, somewhat like humans who have trouble with reds and greens, but only see pale shades of color. On the other hand, they see better at night and have better peripheral vision. Insects see through photoreceptor units numbering in the hundreds or the thousands, almost like viewing the world as a mosaic. Some animals actually have better color vision than humans. Pigeons and goldfish, for example, can see ultraviolet light, which is invisible to people.
"We're great for mammals but pretty mediocre by broader standards," said David Hilbert, associate professor of philosophy at the University of Illinois at Chicago.
Biologists believe that animals' visual systems have evolved over millions of years and that the particular structures around today have persisted because they carried some survival benefit to the animals.
Why, then, do humans see in color?
One idea about the origin of the color vision of humans is that it helped early human ancestors spot red berries among green foliage in the wild.
More generally, color vision helps distinguish objects and their spatial structures from one another, said Stephen Palmer, professor of cognitive science at the University of California, Berkeley.
Changizi has a different idea. According to his research, the cones in our eyes are optimized to detect changes in hemoglobin as blood varies in oxygenation. In other words, what happens physiologically when you blush with embarrassment or turn pale with fear, we can better see with the full human color spectrum.
Across primates, those with furry faces tend to have more primitive visual systems -- with blue-yellow and grayscale perception -- and those with human-like visual systems, such as gorillas, chimpanzees, baboons and macaques, have bare faces. This is because, Changizi argues, the color vision allows bare-faced primates to detect changes in emotion and health according to very subtle changes in reds, yellows, greens and blues in the face.
To take advantage of that ability to detect health signals through skin color changes, Changizi recommends that hospitals adopt gowns that would approximate a variety of natural human skin tones. That would allow doctors to better perceive color changes in the skin than the currently available blue and white gowns, he said. More practically, perhaps, hospitals could have a catalog of hundreds of different skin tone tabs, to help the doctor's eye detect subtle tone changes.
So do most people have the same "red"?
For Changizi, this research on primates and color vision suggests that people's perception of colors must be consistent, given the way the eye's cones detect these specific subtle shifts in skin tone.
But other research suggests that seeing color can be something like tasting foods -- a pleasant flavor for one person may be too bitter or salty for another, just like a single shade of yellow could be seen as pretty or putrid by different people. This argument about color preferences is what Palmer studies in the Berkeley Color Project.
Generally, people naturally dislike tastes of foods that are molding or contain toxic substances. This aversion is evolutionarily beneficial because they are less likely to eat them and get sick.
"The idea is that the same thing is true for colors, that there are certain kinds of colors that are characteristic of stuff that's good for us as a species -- clear sky, clear water -- and stuff that's bad for us, like rotting foods, biological waste products," he said.
Blue may be a common favorite color because it signals such positive things as clear skies, he says. Yellow-green tends to be generally disliked, perhaps because it signals toxicity. A recent study from Palmer's lab that appeared in the Proceedings of the National Academy of Sciences found that participants' color preferences nearly perfectly corresponded with how much they liked objects of the same color.
Feelings about colors can change dramatically in response to a person's environment, and over the course of a lifetime, Palmer said. Institutional affiliation is also a factor -- a study from his lab found that Berkeley students tended to like their school colors, blue and gold, more than their rival school Stanford's colors, red and white.
"I don't think that we have a pure sensory experience of the color. I think it's overlaid with how much we like things," he said.
But most scientists still maintain that your "red" is probably the same as "red" for everyone else (who's not colorblind) in terms of what you see, the University of Illinois' Hilbert said.
"I think colors are out there in the world, and we see them more or less accurately, just like we do shapes and sizes," he said. "I don't think that makes them any less interesting or cool. In fact, I think it makes them more interesting."
10 Technologies We Stole From the Animal Kingdom
People have been lifting ideas from Mother Nature for decades. Velcro was inspired by the hooked barbs of thistle, and the first highway reflectors were made to mimic cat eyes. But today, the science of copying nature, a field known as biomimetics, is a billion-dollar industry. Here are some of our favorite technologies that came in from the wild
By David Goldenberg and Eric Vance
http://blogs.static.mentalfloss.com/blogs/archives/33696.html1. Sharkskin—The Latest Craze in Catheters
Hospitals are constantly worried about germs. No matter how often doctors and nurses wash their hands, they inadvertently spread bacteria and viruses from one patient to the next. In fact, as many as 100,000 Americans die each year from infections they pick up in hospitals. Sharks, however, have managed to stay squeaky clean for more than 100 million years. And now, thanks to them, infections may go the way of the dinosaur.
Unlike other large marine creatures, sharks don’t collect slime, algae, or barnacles on their bodies. That phenomenon intrigued engineer Tony Brennan, who was trying to design a better barnacle-preventative coating for Navy ships when he learned about it in 2003. Investigating the skin further, he discovered that a shark’s entire body is covered in miniature, bumpy scales, like a carpet of tiny teeth. Algae and barnacles can’t grasp hold, and for that matter, neither can troublesome bacteria such as E. coli and Staphylococcus aureus.
Brennan’s research inspired a company called Sharklet, which began exploring how to use the sharkshin concept to make a coating that repels germs. Today, the firm produces a sharkskin-inspired plastic wrap that’s currently being tested on hospital surfaces that get touched the most (light switches, monitors, handles). So far, it seems to be successfully fending off germs. The company already has even bigger plans; Sharklet’s next project is to create a plastic wrap that covers another common source of infections—the catheter.
2. Holy Bat Cane!
It sounds like the beginning of a bad joke: A brain expert, a bat biologist, and an engineer walk into a cafeteria. But that’s exactly what happened when a casual meeting of the minds at England’s Leeds University led to the invention of the Ultracane, a walking stick for the blind that vibrates as it approaches objects.
The cane works using echolocation, the same sensory system that bats use to map out their environments. It lets off 60,000 ultrasonic pulses per second and then listens for them to bounce back. When some return faster than others, that indicates a nearby object, which causes the cane’s handle to vibrate. Using this technique, the cane not only “sees” objects on the ground, such as trash cans and fire hydrants, but also senses things above, such as low-hanging signs and tree branches. And because the cane’s output and feedback are silent, people using it can still hear everything going on around them. Although the Ultracane hasn’t experienced ultra-stellar sales, several companies in the United States and New Zealand are currently trying to figure out how to market similar gadgets using the same bat-inspired technology.
3. Trains Get a Nose Job for the Birds
When the first Japanese Shinkansen Bullet Train was built in 1964, it could zip along at 120 mph. But going that fast had an annoying side effect. Whenever the train exited a tunnel, there was a loud boom, and the passengers would complain of a vague feeling that the train was squeezing together.
That’s when engineer and bird enthusiast Eiji Nakatsu stepped in. He discovered that the train was pushing air in front of it, forming a wall of wind. When this wall crashed against the air outside the tunnel, the collision created a loud sound and placed an immense amount of pressure on the train. In analyzing the problem, Nakatsu reasoned that the train needed to slice through the tunnel like an Olympic diver slicing through the water. For inspiration, he turned to a diver bird, the kingfisher. Living on branches high above lakes and rivers, kingfishers plunge into the water below to catch fish. Their bills, which are shaped like knives, cut through the air and barely make a ripple when they penetrate the water.
Nakatsu experimented with different shapes for the front of the train, but he discovered that the best, by far, was nearly identical to the kingfisher’s bill. Nowadays, Japan’s high-speed trains have long, beak-like noses that help them exit quietly out of tunnels. In fact, the refitted trains are 10 percent faster and 15 percent more fuel-efficient than their predecessors.
4. The Secret Power of Flippers
One scientist thinks he’s found part of the solution to our energy crisis deep in the ocean. Frank Fish, a fluid dynamics expert and marine biologist at Pennsylvania’s West Chester University, noticed something that seemed impossible about the flippers of humpback whales. Humpbacks have softball-size bumps on the forward edge of their limbs, which cut through the water and allow whales to glide through the ocean with great ease. But according to the rules of hydrodynamics, these bumps should put drag on the flippers, ruining the way they work.
Professor Fish decided to investigate. He put a 12-foot model of a flipper in a wind tunnel and witnessed it defy our understanding of physics.
The bumps, called tubercles, made the flipper even more aerodynamic. It turns out that they were positioned in such a way that they actually broke the air passing over the flipper into pieces, like the bristles of a brush running through hair. Fish’s discovery, now called the “tubercle effect,” not only applies to fins and flippers in the water, but also to wings and fan blades in the air.
Based on his research, Fish designed bumpy-edge blades for fans, which cut through air about 20 percent more efficiently than standard ones. He launched a company called Whalepower to manufacture them and will soon begin licensing its energy-efficient technology to improve fans in industrial plants and office buildings around the world. But Fish’s big fish is wind energy. He believes that adding just a few bumps to the blades of wind turbines will revolutionize the industry, making wind more valuable than ever.
5. What Would Robotic Jesus Christ Lizard Do?
There’s a reason the basilisk lizard is often referred to as the Jesus Christ lizard: It walks on water. More accurately, it runs. Many insects perform a similar trick, but they do it by being light enough not to break the surface tension of the water. The much larger basilisk lizard stays afloat by bicycling its feet at just the right angle so that its body rises out of the water and rushes forward.
In 2003, Carnegie Mellon robotics professor Metin Sitti was teaching an undergraduate robotics class that focused on studying the mechanics present in the natural world. When he used the lizard as an example of strange biomechanics, he was suddenly inspired to see if he could build a robot to perform the same trick.
It wasn’t easy. Not only would the motors have to be extremely light, but the legs would have to touch down on the water perfectly each time, over and over again. After months of work, Sitti and his students were able to create the first robot that could walk on water.
Sitti’s design needs some work, though. The mechanical miracle still rolls over and sinks occasionally. But once he irons out the kinks, there could be a bright future ahead for a machine that runs on land and sea. It could be used to monitor the quality of water in reservoirs or even help rescue people during floods.
6. Puff the Magic Sea Sponge
The orange puffball sponge isn’t much to look at; it’s basically a Nerf ball resting on the ocean floor. It has no appendages, no organs, no digestive system, and no circulatory system. It just sits all day, filtering water. And yet, this unassuming creature might be the catalyst for the next technological revolution.
The “skeleton” of the puffball sponge is a series of calcium and silicon lattices. Actually, it’s similar to the material we use to make solar panels, microchips, and batteries—except that when humans make them, we use tons of energy and all manner of toxic chemicals. Sponges do it better. They simply release special enzymes into the water that pull out the calcium and silicon and then arrange the chemicals into precise shapes.
Daniel Morse, a professor of biotechnology at the University of California, Santa Barbara, studied the sponge’s enzyme technique and successfully copied it in 2006. He’s already made a number of electrodes using clean, efficient sponge technology. And now, several companies are forming a multimillion-dollar alliance to commercialize similar products. In a few years, when solar panels are suddenly on every rooftop in America and microchips are sold for a pittance, don’t forget to thank the little orange puffballs that started it all.
7. Wasps—They Know the Drill
Don’t be scared of the two giant, whip-like needles on the end of a horntail wasp. They’re not stingers; they’re drill bits. Horntails use these needles (which can be longer than their entire bodies!) to drill into trees, where they deposit their young.
For years, biologists couldn’t understand how the horntail drill worked. Unlike traditional drills, which require additional force (think of a construction worker bearing down on a jackhammer), the horntail can drill from any angle with little effort and little body weight. After years of studying the tiny insects, scientists finally figured out that the two needles inch their way into wood, pushing off and reinforcing each other like a zipper.
Astronomers at the University of Bath in England think the wasp’s drill will come in handy in space. Scientists have long known that in order to find life on Mars, they might have to dig for it. But without much gravity, they weren’t sure how they’d find the pressure to drill down on the planet’s hard surface. Inspired by the insects, researchers have designed a saw with extra blades at the end that push against each other like the needles of the wasp. Theoretically, the device could even work on the surface of a meteor, where there’s no gravity at all.
8. Consider the Lobster Eye
There’s a reason X-ray machines are large and clunky. Unlike visible light, X-rays don’t like to bend, so they’re difficult to manipulate. The only way we can scan bags at airports and people at the doctor’s office is by bombarding the subjects with a torrent of radiation all at once—which requires a huge device.
But lobsters, living in murky water 300 feet below the surface of the ocean, have “X-ray vision” far better than any of our machines. Unlike the human eye, which views refracted images that have to be interpreted by the brain, lobsters see direct reflections that can be focused to a single point, where they are gathered together to form an image. Scientists have figured out how to copy this trick to make new X-ray machines.
The Lobster Eye X-ray Imaging Device (LEXID) is a handheld “flashlight” that can see through 3-inch-thick steel walls.
The device shoots a small stream of low-power X-rays through an object, and a few come bouncing back off whatever is on the other side. Just as in the lobster eye, the returning signals are funneled through tiny tubes to create an image. The Department of Homeland Security has already invested $1 million in LEXID designs, which it hopes will be useful in finding contraband.
9. Playing Dead, Saving Lives
When the going gets tough, the tough play dead. That’s the motto of two of nature’s most durable creatures—the resurrection plant and the water bear. Together, their amazing biochemical tricks may show scientists how to save millions of lives in the developing world.
Resurrection plants refer to a group of desert mosses that shrivel up during dry spells and appear dead for years, or even decades. But once it rains, the plants become lush and green again, as if nothing happened. The water bear has a similar trick for playing dead. The microscopic animal can essentially shut down and, during that time, endure some of the most brutal environments known to man. It can survive temperatures near absolute zero and above 300˚F, go a decade without water, withstand 1,000 times more radiation than any other animal on Earth, and even stay alive in the vacuum of space. Under normal circumstances, the water bear looks like a sleeping bag with chubby legs, but when it encounters extreme conditions, the bag shrivels up. If conditions go back to normal, the little fellow only needs a little water to become itself again.
The secret to the survival of both organisms is intense hibernation. They replace all of the water in their bodies with a sugar that hardens into glass. The result is a state of suspended animation. And while the process won’t work to preserve people (replacing the water in our blood with sugar would kill us), it does work to preserve vaccines.
The World Health Organization estimates that 2 million children die each year from vaccine-preventable diseases such as diphtheria, tetanus, and whooping cough. Because vaccines hold living materials that die quickly in tropical heat, transporting them safely to those in need can be difficult. That’s why a British company has taken a page from water bears and resurrection plants. They’ve created a sugar preservative that hardens the living material inside vaccines into microscopic glass beads, allowing the vaccines to last for more than a week in sweltering climates.
10. Picking Up the Bill
The bill of the toucan is so large and thick that it should weigh the bird down. But as any Froot Loops aficionado can tell you, Toucan Sam gets around. That’s because his bill is a marvel of engineering. It’s hard enough to chew through the toughest fruit shells and sturdy enough to be a weapon against other birds, and yet, the toucan bill is only as dense as a Styrofoam cup.
Marc Meyers, a professor of engineering at the University of California at San Diego, has started to understand how the bill can be so light. At first glance, it appears to be foam surrounded by a hard shell, kind of like a bike helmet. But Meyers discovered that the foam is actually a complicated network of tiny scaffolds and thin membranes. The scaffolds themselves are made of heavy bone, but they are spaced apart in such a way that the entire bill is only one-tenth the density of water. Meyers thinks that by copying the toucan bill, we can create car panels that are stronger, lighter, and safer. Toucan Sam was right; today we’re all following his nose.
South African Doctor Invents Female Condoms With 'Teeth' To Fight Rape
By Faith Karimi
http://edition.cnn.com/2010/WORLD/africa/06/20/south.africa.female.condom/index.html?iref=NS1South African Dr. Sonnet Ehlers was on call one night four decades ago when a devastated rape victim walked in. Her eyes were lifeless; she was like a breathing corpse.
"She looked at me and said, 'If only I had teeth down there,'" recalled Ehlers, who was a 20-year-old medical researcher at the time. "I promised her I'd do something to help people like her one day."
Forty years later, Rape-aXe was born.
Ehlers is distributing the female condoms in the various South African cities where the World Cup soccer games are taking place.
The woman inserts the latex condom like a tampon. Jagged rows of teeth-like hooks line its inside and attach on a man's penis during penetration, Ehlers said.
Once it lodges, only a doctor can remove it -- a procedure Ehlers hopes will be done with authorities on standby to make an arrest.
"It hurts, he cannot pee and walk when it's on," she said. "If he tries to remove it, it will clasp even tighter... however, it doesn't break the skin, and there's no danger of fluid exposure."
Ehlers said she sold her house and car to launch the project, and she planned to distribute 30,000 free devices under supervision during the World Cup period.
"I consulted engineers, gynecologists and psychologists to help in the design and make sure it was safe," she said.
After the trial period, they'll be available for about $2 a piece. She hopes the women will report back to her.
"The ideal situation would be for a woman to wear this when she's going out on some kind of blind date ... or to an area she's not comfortable with," she said.
The mother of two daughters said she visited prisons and talked to convicted rapists to find out whether such a device would have made them rethink their actions.
Some said it would have, Ehlers said.
Critics say the female condom is not a long-term solution and makes women vulnerable to more violence from men trapped by the device.
It's also a form of "enslavement," said Victoria Kajja, a fellow for the Centers for Disease Control and Prevention in the east African country of Uganda. "The fears surrounding the victim, the act of wearing the condom in anticipation of being assaulted all represent enslavement that no woman should be subjected to."
Kajja said the device constantly reminds women of their vulnerability.
"It not only presents the victim with a false sense of security, but psychological trauma," she added. "It also does not help with the psychological problems that manifest after assaults."
However, its one advantage is it allows justice to be served, she said.
Various rights organizations that work in South Africa declined to comment, including Human Rights Watch and Care International.
South Africa has one of the highest rape rates in the world, Human Rights Watch says on its website. A 2009 report by the nation's Medical Research Council found that 28 percent of men surveyed had raped a woman or girl, with one in 20 saying they had raped in the past year, according to Human Rights Watch.
In most African countries, rape convictions are not common. Affected women don't get immediate access to medical care, and DNA tests to provide evidence are unaffordable.
"Women and girls who experience these violations are denied justice, factors that contribute to the normalization of rape and violence in South African society," Human Rights Watch says.
Women take drastic measures to prevent rape in South Africa, Ehlers said, with some wearing extra tight biker shorts and others inserting razor blades wrapped in sponges in their private parts.
Critics have accused her of developing a medieval device to fight rape.
"Yes, my device may be a medieval, but it's for a medieval deed that has been around for decades," she said. "I believe something's got to be done ... and this will make some men rethink before they assault a woman."
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