Why’d the zebra evolve its stripes? Perhaps because stripes seem to keep off horseflies, a new study suggests. There’s good evolutionary reason to escape the ravages of horseflies, at least for horses and their relatives; though flies are just annoying pests from the human perspective, horsefly-bitten horses can grow skinny and have trouble producing milk for their young. And as soon as baby-making is affected by something in the environment, adaptation isn’t far behind.
Other research has shown that horseflies prefer to land on black horses instead of white, which got Gabor Horvath, author of the recent study, thinking about how they’d react to black-and-white specimens, such as zebras. Of course, actual zebras can be hard to experiment on, as The Economist notes in an article on the research:
[Real zebras] insist on moving around and swishing their tails. The team therefore conducted their study using inanimate objects. Some were painted uniformly dark or uniformly light, and some had stripes of various widths. Some were plastic trays filled with salad oil (to trap any insect that landed). Some were glue-covered boards. And some were actual models of zebra. They put these objects in a field infested with horseflies and counted the number of insects they trapped.
The strangest thing about this Chinese boy’s light blue eyes is not their color. It’s the purported fact that he can see in the dark. His eyes are just like cat eyes, glowing blue-green when you shine a light in them, says this clip from China’s state-run English TV channel. The boy can catch crickets in the dark without a flashlight and even completes a writing test in a pitch-black stairwell. True, or too good to be?
Natalie Wolchover at Life’s Little Mysteries has rounded up some experts and their collective reaction seems to be, “Hmm…” (It doesn’t help that this video has been posted on YouTube under the name, “Alien Hybrid or Starchild Discovered in China? 2012.”) One possibility they consider is whether the boy has a mutation that produced something like a tapetum lucidum, an extra layer of tissue that helps cats see in the dark. James Reynolds, a pediatric ophthalmologist at State University of New York in Buffalo, puts a stop to that idea:
Bionic contact lenses—which would display navigation data, personal emails, or any other sort of info superimposed on the world before your eyes—have long been mainstays of science fiction. Over the past several years, researchers have been working to make the tech real-world ready, striving to find solutions to the energy, size, safety, and image-quality problems that come up when you’re trying to fit a tiny integrated circuit into something transparent that sits on an eyeball.
Now, University of Washington researchers and their Finnish colleagues have made the first functioning bionic lens: a prototype with a single LED pixel, which could be safely worn by rabbits in the lab. (The image at right shows a rabbit wearing an earlier version of the lens, which contained a circuit but no light-emitting components.) Radio frequency energy emitted from a nearby transmitter and picked up by a circular antenna a fifth of an inch in diameter, printed on the lens, powered the electronics. The transmitter supplied adequate energy from three feet away when the lens was sitting in a dish, but had to be less than an inch away when the lens was placed on a rabbit’s eye, since tissues and fluids in the body interfered with reception. Since light from such a lens would be too close for the human eye to focus, the researchers made a separate contact composed of an array of smaller, flatter lenses, which would sit on top of the bionic contact and focus the light.
The colors that letters and numbers appear to a synesthete
What’s the News: For most of us, our senses stay relatively separate: that is, we hear what we hear and see what we see. People with synesthesia, however, actually see words as colors, taste a particular flavor when they hear a familiar song, or experience other strong, automatic linkages between senses. The neurological underpinnings of the condition—how the brain connects two usually distinct senses—have remained a mystery. But researchers have now found a possible cause, they reported yesterday: neurons in the area responsible for the second sensation, such as the color that goes with the word, may be unusually excitable.
What’s the news: In a study published last week, researchers showed they could reconstruct video clips by watching viewers’ brain activity. The video of the study’s results, below, is pretty amazing, showing the original clips and their reconstructions side by side. How does it work, and does it mean mind-reading is on its way in?
What’s the News: Humans are eerily good at sifting the visual wheat from the chaff—just think of our penchant for word searches, Easter egg hunts, and lushly animated first-person shooters.
But how good are we really? To test the limits of these abilities, in a recent study neuroscientists gave subjects extremely difficult, high-speed Where’s Waldo-type search tasks studded with red herrings. But again and again, subjects found what they were looking for, leading the team to report that humans operate at a near-optimal level when it comes to visual searches—a skill that likely came in handy in our evolutionary history.
What’s the News: Neuroscientists have found a preliminary answer to a question that has puzzled philosophers for centuries: If someone who has always been blind is one day able to see, can they recognize by sight objects they already know by touch? In a new study published online by Nature Neuroscience, patients who had been blind since birth underwent sight-restoring surgeries as children or adolescent. In the day or two following surgery, patients seemed unable to match what they felt with their hands with what they saw, the researchers found, but a week later, they could.
This results suggests that the brain doesn’t have the innate ability (or maybe has limited innate ability) to tie input from different senses to the same concept—but that it can learn, and pretty fast. Just how fast, the researchers wrote, suggests that the neuronal machinery needed to bring together visual and tactile information may already be there; it just has to be started up.
What’s the News: The reproductive life of a cuckoo is both easy—it lays its eggs in others birds’ nests, and lets them feed the young—and difficult: cuckoos are involved in an “evolutionary arms race” with other birds, finds a new study. Even as cuckoos improve their counterfeiting skills—producing eggs that look more like others birds’—the host birds get better and better at identifying the forged eggs.
How the Heck:
Knowing that birds have four types of color-sensitive cone cells in their eyes, allowing them to see ultraviolet wavelengths, researchers used a spectroscope to measure the amount of light reflected from hundreds of cuckoo and host-bird eggs. They then fed this data into models to produce images showing how birds see the different types of eggs.
They discovered that while cuckoo and redstart eggs have a high degree of color overlap, cuckoo eggs targeted for dunnock nests did not.
Here’s the kicker: Redstarts and dunnocks don’t spot forgeries equally. Redstarts are more discerning of foreign eggs and readily kick out cuckoo forgeries, while the dumb dunnocks accept even the most mismatched eggs. So these findings suggest that cuckoos targeting redstarts evolved the ability to create better forgeries because the redstart has such a good eye. With dunnocks, that evolutionary force wasn’t at play because the birds are so accepting of forgeries; why bother?
What’s the Context:
What sets this research apart from previous work is how the researchers used UV-sensing equipment to mimic bird vision. (Past research relied merely on human inspection.)
The Future Holds: Scientists still aren’t sure why some hosts, like the dunnock, are so accepting of cuckoo eggs. Some scientists argue that this is because the risk in mistakenly rejecting a real egg outweighs the cost of raising a cuckoo egg. The jury’s still out.
Reference: “AVIAN VISION AND THE EVOLUTION OF EGG COLOR MIMICRY IN THE COMMON CUCKOO” Mary Caswell Stoddard and Martin Stevens. DOI: 10.1111/j.1558-5646.2011.01262.x
When you’re nature’s ideal killing machine, perhaps color vision is merely an unnecessary affection. New research argues that sharks could be completely colorblind.
An Australian team led by Nathan Scott Hart investigated 17 shark species, peeking at the structure of their rod and cone photoreceptor cells in the retina. Human eyes come with red, green, and blue cone variations, allowing us to see in color. But not shark eyes. They appear to have just one kind of cone.
“Our study shows that contrast against the background, rather than color per se, may be more important for object detection by sharks,” Hart said. [CNN]
That, Hart says, may explain the common wisdom that sharks love yellow (and therefore you ought to avoid sunny swimsuits). It may be the reflective quality of yellow that catches a shark’s eye, not the hue itself.
“Bright yellow is supposed to be attractive to some sharks, presumably because it appears to the sharks as a very bright target against the water,” said Dr Hart. “So perhaps it is best to avoid those fluoro-yellow shorts next time you are in the surf.” [BBC News]
Embryonic stem cell treatments are edging closer to mainstream medicine. An experimental treatment just approved for clinical trials may provide hope to the 10 to 15 million elderly patients in the United States who suffer from a common form of macular degeneration, which causes gradual blindness.
The biotech company behind the treatment, Advanced Cell Technology, Inc., previously won FDA approval to try an embryonic stem cell treatment on patients with a rare, juvenile form of macular degeneration. The new FDA-approved trial will use similar techniques, but targets a much broader patient base.
“ACT is now the first company to receive FDA clearance for two hESC (human embryonic stem cell) trials, and is now a true translational leader in the field of regenerative medicine,” said chief executive Gary Rabin. “It marks a major step forward, not just within the stem cell sector, but, potentially for modern healthcare techniques.” [AFP]
Embryonic stem cell treatments are finally breaking out of the lab and arriving in the clinic. In October, the first federally approved trial of a treatment derived from these controversial cells got underway in patients with spinal cord injuries. Now, the FDA has approved a second trial, this one to test a treatment for a rare disease that causes serious vision loss or blindness.
The company behind the trial, Advanced Cell Technology, will test the safety and efficacy of the treatment on 12 patients.
The trial will examine the safety of a therapy for Stargardt’s Macular Degeneration, an inherited juvenile eye disease affecting an estimated 1 in 10,000 young people in the US. As the disease progresses, a layer of the retina called the retinal pigment epithelium (RPE) degenerates, causing vision loss. It’s hoped the new therapy would also work for other types of macular degeneration, a widespread cause of blindness, particularly in the elderly. [Nature blog]
In an exciting pilot study, blind people equipped with microchips in their retinas were able to see again–at least dimly–and were able to make out shapes.
Ed Yong explains how the experiment helped a study participant named Miikka:
In people like Miikka with retinitis pigmentosa, the light-detecting cells of the retina break down with age. Eberhart Zrenner and a team of German scientists have designed a chip that does the same job as these defunct cells. Just a few millimetres across, it contains 1,500 light-detecting diodes that detect light and convert it into a current. The brighter the light that hits the chip, the stronger the current it puts out. The current is delivered directly to the bipolar cells, which would normally transmit the signals from the retina’s actual light detectors.
Find out more about how the technology works and get the full story on Miikka and his fellow experiment subjects at Not Exactly Rocket Science. And check out the videos of Miikka trying out his new eyes below.
Deep in your brain there are probably several thousand neurons that will respond only to the sight of Lady Gaga. Several thousand others probably only crackle to the sight of Justin Bieber. It might be nice to reassign those neurons to loftier thoughts. For now, though, neurology can’t help you. What neurology can do for you (if you’re up for a little invasive brain surgery) is let you use those Gaga and Bieber neurons to control a computer.
A team of researchers has built on the previous discovery that specific neurons respond to the images of specific people–like Lady Gaga, or your grandmother. To harness these neurons, the researchers tried out an ingenious brain-machine interface based on images of celebrities who triggered particularly strong responses in 12 patients.
A patient could bring a digital image of a celebrity (like Marilyn Monroe) into the foreground by consciously focusing on the image, which meant that the celebrity-associated neurons were firing. As they describe in a paper in Nature, the patients quickly got the hang of it, activating patches of neurons at will. This has led researchers to wonder if people could one day control devices simply by visualizing certain people, things, or concepts.
You can get the rest of the story on this fascinating but intrusive technology, and can also see a video that Carl made about the experiments, at The Loom.
A brain is a terrible thing to waste–and your brain knows that. A new study of congenitally deaf cats has shown that some parts of their brains which would typically work on hearing are repurposed, and instead help out with vision. As a result of that clever efficiency, these deaf cats have superior peripheral vision and motion-detection abilities than cats with normal hearing.
Researchers say the human brain may perform the same trick.
For years, researchers have known that deaf people often have superior peripheral vision and motion detection, but just how the brain creates these advantages was unclear. “Over the years, we’ve speculated about how these changes might be taking place,” says neuroscientist Helen Neville of the University of Oregon in Eugene, but a clear cause has been elusive. [Science News]
The genetics behind near-sightedness are coming into focus.
In studies (1, 2) in Nature Genetics that looked at more than 4,000 people, scientists report that variations in a gene called RASGRF1 are partly responsible for whether or not a person develops myopia.
“It is not quite the end of glasses yet but clearly the hope is that we will be able to block the genetic pathways that causes shortsightedness,” said Dr Christopher Hammond at King’s College London, an eye surgeon who led the British research. [The Telegraph]
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
What’s the News: Neuroscientists have found a preliminary answer to a question that has puzzled philosophers for centuries: If someone who has always been blind is one day able to see, can they recognize by sight objects they already know by touch? In a new 
What’s the News: The reproductive life of a cuckoo is both easy—it lays its eggs in others birds’ nests, and lets them feed the young—and difficult: cuckoos are involved in an “
Embryonic stem cell treatments are edging closer to mainstream medicine. An experimental treatment just approved for clinical trials may provide hope to the 10 to 15 million elderly patients in the United States who suffer from a common form of macular degeneration, which causes gradual blindness.
Embryonic stem cell treatments are finally breaking out of the lab and arriving in the clinic. In October, the first federally approved trial of a treatment derived from these controversial cells 
From 
A brain is a terrible thing to waste–and your brain knows that. A new study of congenitally deaf cats has shown that some parts of their brains which would typically work on 
The genetics behind near-sightedness are coming into focus.
