Curvis Bickham spent eight months in prison for a triple-homicide because a police dog confused his scent with that of the killer. Now Bickham and others who spent months in jail after dogs linked their scents to evidence from crimes they did not commit are filing a lawsuit claiming Texas authorities falsely arrested and imprisoned them, their attorney said Tuesday [AP]. In a scent lineup, dogs sniff items found at a crime scene, and then sniff jars swabbed with the suspects’ scents and the scents of others not involved in the crime. When the dogs link crime scene and suspect, that evidence is often relied on heavily in court by the prosecution. Alaska, Florida, New York and Texas all use scent lineups to link suspects to crimes.
Dogs are used all the time to fight crime—from sniffing out bombs and drugs to locating dead bodies. However, scent lineups have critics barking. They say the lineups are poorly controlled, and argue that avoiding cross-contamination is basically impossible. The main target of the current lawsuit is Fort Bend County Deputy Keith Pikett—whose home-trained bloodhounds identified the suspects. A 2004 F.B.I. report warned that dog scent work “should not be used as primary evidence,” but only to corroborate other evidence. In several of the cases that were based on Deputy Pikett’s dogs, however, the scent lineups appear to have provided the primary evidence, even when contradictory evidence was readily available [The New York Times]. Deputy Pikett, by his own estimation, has conducted thousands of scent lineups.
The three men who filed the lawsuit against Deputy Pickett were all eventually set free after contradictory evidence proved their innocence. The Innocence Project of Texas, a legal defense organization … released a report last month that excoriated dog scent lineups as a “junk science injustice” [The New York Times]. Dog scent lineups bring to mind another high profile forensic science debate in Texas that many believe led to the execution of an innocent man. Now that the science behind dog scent lineups is coming under the same scrutiny, one can’t help but wonder if scent lineups might have led to a similar outcome.
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Image: flickr / contadini
Some migratory birds that have to navigate across continents have an extremely useful tool at their disposal–an internal compass that points unerringly towards magnetic north. Researchers already knew that some birds possess these biological compasses, but their mechanism has been unclear. “This is basically the sixth sense of biology, but no one knows how it works…. The magnetic sense is by far the least understood sense in the natural world,” [Science News], says study coauthor Henrik Mouritsen.
Now, researchers have determined that light-sensing cells in the eye convey the crucial message to a special visual center of a robin’s brain, called cluster N. Special proteins called cryptochromes in the birds’ eyes may mediate this light-dependent magnetic sensing, Mouritsen says. Light hitting the proteins produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have a property called spin which may be sensitive to Earth’s magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, ultimately telling the birds where north is [Science News].
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Phantom limb syndrome is an eerie condition, in which amputees have the physically painful sensation that their missing limbs are still present. Now, a small new study has shown that people can twist those ghostly limbs in anatomically impossible ways, while still feeling that the limb is real and present. In essence, each amputee’s brain reshaped his understanding of where his body was. The findings show that the brain can alter how we perceive our bodies all by itself, without input from our senses [Reuters].
Researchers had patients with “vivid phantoms” try to move their wrists in a physically impossible way—a 360 degree spin of the wrist around the long axis of the forearm—and found that 4 of the 7 patients could move their wrists this way. Some patients that were able to move their wrists later reported that their phantom hands were now more difficult to move from side to side because of changes in their phantom arms’ shapes.
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A new discovery about how mantis shrimp process light could give rise to new and more powerful consumer electronics, according to a new study. Mantis shrimp possess the animal kingdom’s most complicated eyes, capable of distinguishing between 100,000 colors — 10 times as many as humans — and seeing circular polarized light, or CPL, which can’t be detected by any other creature [Wired.com]. Circular polarized light is one of two forms of polarized light, or light waves that travel in a specific plane.
The specialized CPL detecting cells in shrimp eye are similar to the optical detectors found in DVD players; each can convert polarized light into other forms so it can be stored or processed. However, shrimp eyes can do this with all colors of circular polarized light across the spectrum, according to the study in Nature Photonics. The detectors in DVD and CD players can only recognize circular polarized light in a few colors. The research team thinks that in the future, optics devices might be beefed up by chemically engineered crystals that could mimic the light polarizing cells of the mantis shrimp eye.
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Snooty wine pairing rules, such as the edict that one must only drink white wine with fish, now have a little data behind them, according to a new study. Researchers found a correlation between the high iron content of red wine and a nasty, fishy aftertaste when the reds are sipped with seafood. In the experiment, tasters ate a bit of scallop, tasted some wine and evaluated the aftertaste on a scale of 1 to 4. The diners found the unpleasant aftertaste was more intense with wines that had a higher iron content, the researchers say [Los Angeles Times]. The researchers were able to block the aftertaste by adding a compound that masks the iron.
The iron content of a wine depends on the composition of the soil in which the grapes were grown, the dust on the berry, contamination during harvesting, transportation, and crushing, and the conditions during fermentation [Telegraph]. The new research, published in Journal of Agricultural and Food Chemistry, suggests that some low-iron red wines are OK to drink with fish. While red wines tend to have more iron than whites, it varies according to the type of grape, country of origin, and vintage.
But the iron is only half the story. The researchers report that they haven’t yet isolated the compound in the scallops that reacts with the wine, but they suspect it’s an unsaturated fatty acid, which could be breaking down rapidly and releasing the decaying fish smell when exposed to iron [ScienceNOW Daily News].
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Image: flickr / yashima
Cracking open a cold can of Coke and taking a bubbling swig will have your taste buds dancing—and now scientists know why. A new study shows that cells in taste buds that respond to sour stimuli also seem to be the ones responsible for tasting the carbonation’s fizz [NPR].The fact that we can taste the carbon dioxide in a fizzing soda has previously puzzled scientists, since the human tongue is usually thought to only sense five flavors—bitter, sweet, salty, sour, and umami (also called savory). However, the new study, published in Science, shows that the sour taste buds have an enzyme that interacts with carbon dioxide, so it’s not the bursting bubbles that you taste, it’s the C02 itself.
The researchers discovered this tricky bit of chemistry by studying mice. They gave the animals sips of club soda or a little buzz of carbon dioxide gas and recorded how the tongue signaled the sensation to the brain. Both soda and the gas produced similar sensations. But when they tested mice bred to have no sour taste buds, the brain never got its sensory alert. Further probing uncovered the enzyme responsible [AP]. The mechanism should be the same in humans, according to the scientists.
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Inside the brain of someone who’s learning to juggle, some interesting changes take place. Researchers used MRI scans to study the brains of people before and after a six-week training course in juggling, and say they saw a 5% increase in white matter – the cabling network of the brain [BBC News].
The study, published in Nature Neuroscience, follows up on previous work that found changes in the more famous gray matter of the brain, which consists of the cell bodies of the neurons where processing and computation take place. The white matter, which consists mostly of the axons that stretch away from the cell bodies, can be thought of as the brain’s wiring, and researchers say this is the first time that changes have been observed in the white matter of a healthy adult.
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Scientists have found another reason why the fizz in a glass of champagne is so important: Besides tickling the tongue and pleasing the eye, the bubbles also release aromatic compounds that they’ve dragged up from the liquid in the glass. A new study found that concentrations of certain chemical compounds are higher in the air just above the glass than in the actual champagne.
Wine expert Jamie Goode comments: “In the past, we thought that the carbon dioxide in the bubbles just gave the wine an acidic bite and a little tingle on the tongue, but this study shows that it is much more than this” [BBC News]. Smelling the chemical compounds enhances the overall flavor of the champagne, researchers say.
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For two squirrel monkeys nicknamed Dalton and Sam, life has gotten a lot more colorful. Researchers used gene therapy to correct the color blindness of the two adult monkeys, giving them the ability to distinguish between red and green for the first time. The fascinating accomplishment suggests that scientists may someday be able to cure other kinds of blindness in humans. And because the treated monkeys were “middle aged”, it challenges the assumption that gene therapies cannot work in adults because their brain connections are too set in their ways to change beneficially [New Scientist].
The field of gene therapy, in which a malfunctioning gene in a patient’s body is replaced with a functional one, fell into disarray one decade ago following the death of an 18-year-old in a clinical trial. But since then scientists have regrouped, using animal studies to probe the technique’s safety. Last year, researchers progressed to the point of safety trials in humans for the treatment of one rare eye condition called Leber congenital amaurosis, and were able to dramatically improve the patients’ sight. Those results were stunning, but they were also achieved in children, whose still-growing brains can rewire themselves on the fly in response to new sources of visual stimuli [Wired.com].
In the new study, published in Nature, the researchers used a type of squirrel monkey in which the males lack a visual pigment called L-opsin. Its absence renders the monkeys color-blind, unable to distinguish reds and green. Most of the females, on the other hand, see in full color. So the scientists got to wondering: what would happen if they gave a boy squirrel monkey the same opsin that girls have [Scientific American]. They used a harmless virus to ferry in the gene that makes opsin, injecting the virus behind the monkeys’ retinas.
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A person can witness an event in real life, see a doctored video of the same event, and then convince themselves that what they saw on the video is what actually happened, according to a recent study that casts doubt on the reliability of eyewitness testimony.
Psychologists set up an experiment where they filmed two people sitting side by side–one experimental subject and one researcher pretending to be a participant–playing a gambling game where they bet phony money on whether or not they could answer multiple choice questions correctly. They were told that the person with the most money at the end would win a prize.
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Meat may be tasty, but many people object to way that chickens, cows, and other animals are treated at so-called “factory farms,” which produce massive amounts of edible flesh. So could animals that have been genetically engineered to not feel pain (or at least not be bothered by the sensation) offer a solution to an ethical dilemma posed by these meat factories?
That’s what one philosopher asked in a paper published in the journal Neuroethics, concluding that we have an ethical duty to consider the option. “If we can’t do away with factory farming, we should at least take steps to minimise the amount of suffering that is caused” [New Scientist] by practices such as de-beaking chickens without anesthesia, says author Adam Shriver. But because pain serves as an important warning sign, these so-called “pain-free” animals would still be able to sense pain–they just wouldn’t be bothered by it. Researchers seek ways to eliminate the suffering caused by pain without tampering with the physical sensation [New Scientist].
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It’s a movie cliche: the moment when the lost traveler intersects a set of footprints, only to realize that the prints where made by his very own boot soles. The hero then realizes, with plunging heart, that he’s been walking in circles while trying to walk a straight course through the featureless expanse. Now a small study has shown that the cliche is true. Without the sun, a compass or a landmark, people trying to follow a straight course through a forest or a desert ended up back where they started [HealthDay News].
In the first experiment, six participants tried to follow a straight course through a forest in Germany, in an area where the land is flat and the trees quickly begin to look alike. The two subjects who walked on a sunny day stayed on a fairly straight course (as tracked by a GPS device), except for the first 15 minutes when the sun was behind the clouds. But the four who walked on an overcast day repeatedly traveled in circles, sometimes crossing their own paths after only 10 minutes. Says lead researcher Jan Souman: “They didn’t really believe when we showed them afterwards…. I think that’s certainly a point to take away, people may feel very confident about the direction where they’re going but it’s not certain” [ABC News].
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Scientists seem to have finally put to rest a longstanding debate over itchiness: Is the urge to itch a sensation that is simply another interpretation of pain, or a separate feeling altogether? It turns out the two stem from different cells and neural pathways, according to a new study in Science.
To find out whether pain and itchiness are separate sensations, scientists injected mice with a neurotoxin. This toxin homed in on and killed cells that contained active versions of GRPR, a gene that is involved in the sensation of itchiness. (The same research group discovered this itch gene in 2007.) Afterward, the mice could no longer respond to any itchy stimuli. They didn’t flinch. They made no effort to scratch. But they did respond to pain just like other mice do [TIME], showing that the gene needed to be active to transmit itchiness, but not pain. It’s just one study, but it provides strong evidence that itchiness and pain are processed by separate neural pathways.
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Wind power may prove to be a promising source of clean energy, but it can also be deadly to bats. Not only can the animals be sliced by the blades of wind turbines, but the sudden drop in air pressure around the turbines can also cause bats’ lungs to explode. An electromagnetic field emitted near the turbines, however, may help bats steer clear of them, according to a new study published in the Public Library of Science One.
Bat casualties near wind turbines have proven to be significant: In 2004, over the course of six weeks, roughly 1,764 and 2,900 bats were killed at two wind farms in Pennsylvania and West Virginia, respectively [LiveScience]. If wind power continues to become increasingly prevalent, so too might the turbines become a growing threat to bat populations. “Given the growing number of wind turbines worldwide, this is going to be an increasing problem, no question about that,” said [co-author] Paul Racey [LiveScience].
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Bats may have a clever way of catching prey, but it turns out the tiger moth has some tricks of its own to avoid becoming a bat’s next meal. According to a study published in Science, the tiger moth disrupts the sound waves the bat uses home in on prey by emitting its own ultrasound blasts.
Researchers knew that the tiger moth emitted ultrasound waves, but they weren’t sure why. Previous studies indicated the moth’s sounds might serve to startle the bats, or warn them that the insects were unpalatable. The new research, however, tested both of these theories. The scientists had so-called big brown bats hunt tiger moths in a chamber fitted with ultrasonic recording equipment and high-speed infrared video. If the moth sound is used to startle bats, then in the chamber the bats should be disrupted on first attack, then learn to ignore the ultrasonic click, the team figured. That didn’t happen. If the moths’ clicks are warnings that the insects taste bad, then the bats should hear the click, bite the moth—and never do so again whenever they hear the sound. That didn’t happen either [National Geographic News].
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