Chapter 19. Language and Hemispheric Asymmetry
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Rachel Martin The National Football League held its annual hall of fame induction ceremony Saturday night, in Canton, Ohio. Eight players were given football's highest honor, including a posthumous induction for Junior Seau, the former linebacker for the San Diego Chargers who killed himself in 2012. After his death, Seau's brain showed signs of chronic damage — the same kind of damage that has been found in dozens of other former NFL players. Scientific studies have shown that the kind of repeated hits NFL players take is linked to chronic traumatic encephalopathy, or CTE, a degenerative brain disease. CTE is associated with memory loss, impulse control problems, depression and eventually dementia. Some players are rethinking their careers — like up-and-coming linebacker Chris Borland, who quit after his first season with the 49ers a few months ago — for fear of head injuries. Parents are weighing the risks as well. So when someone like Chicago Bears coach Mike Ditka talks, they listen. When host Bryant Gumbel asked Ditka on HBO's Real Sports earlier this year whether, if he had an 8-year-old now, he would want him to play football. "No," he answered. "That's sad. I wouldn't, and my whole life was football. I think the risk is worse than the reward." Tregg Duerson's father, Dave Duerson, a defensive back who played most of his pro football career with the Chicago Bears, killed himself in 2011 in his Miami home. Duerson was part of the legendary '85 team that won the Superbowl, and five years later helped the New York Giants win their own championship. © 2015 NPR
Keyword: Brain Injury/Concussion
Link ID: 21281 - Posted: 08.10.2015
A dipstick inserted into the brain can check its energy levels, just like checking oil levels in a car. The dipstick is already available and can save lives, according to some neuroscientists. “The goal is to save brain tissue,” says Elham Rostami of the Karolinska Institute in Stockholm, Sweden. Last month, Rostami and 47 others published guidelines about how and when to use the technique, known as brain microdialysis, in the hope of encouraging more hospitals to adopt it. The approach involves inserting a slim, 1-centimetre-long probe directly into the brain. It measures levels of chemicals in the fluid that bathes brain cells, including glucose, the brain’s main energy source. When used to monitor the brains of people in intensive care after a stroke or head injury, it warns doctors if glucose starts to dip – which can cause brain damage. The probe can theoretically monitor almost any molecule, but Rostami says the most useful parameters are glucose, which shows if there is a good blood supply, and lactate and pyruvate, two metabolites that indicate if brain cells are using the glucose to release energy. Although widely available, the device has so far mainly been used as a research tool rather than to guide treatment. Rostami believes her use of the probe helped save a woman’s life last year. The woman was in intensive care after a stroke involving bleeding on the surface of her brain. The probe revealed that although the bleeding had stopped, the woman’s brain glucose levels had fallen, probably caused by other blood vessels constricting. © Copyright Reed Business Information Ltd.
// by Richard Farrell Bonobos have a capacity to do something human infants have been shown to do: use a single sound whose meaning varies based on context, a form of "flexible" communication previously thought specific to humans. The finding was made by researchers from the University of Birmingham and the University of Neuchatel, in a paper just published in the journal Peer J. The newly identified bonobo call is a short, high-pitched "peep," made with a closed mouth. The scientists studied the call's acoustic structure and observed that it did not change between what they termed "neutral" and "positive" circumstances (for example, between activities such as feeding or resting), suggesting that other bonobos receiving the call would need to weigh contextual information to discern its meaning. Human babies do something similarly flexible, using sounds called protophones -- different from highly specific sounds such as crying or laughter -- that are made independent of how they are feeling emotionally. The appearance of this capability in the first year of life is "a critical step in the development of vocal language and may have been a critical step in the evolution of human language," an earlier study on infant vocalization noted. The find challenges the idea that calls from primates such as bonobos -- which, along with chimpanzees, are our closest relatives -- are strictly matched with specific contexts and emotions, whether those sounds are territorial barks or shrieks of alarm. © 2015 Discovery Communications, LLC.
By Michael Balter Have you ever wondered why you say “The boy is playing Frisbee with his dog” instead of “The boy dog his is Frisbee playing with”? You may be trying to give your brain a break, according to a new study. An analysis of 37 widely varying tongues finds that, despite the apparent great differences among them, they share what might be a universal feature of human language: All of them have evolved to make communication as efficient as possible. Earth is a veritable Tower of Babel: Up to 7000 languages are still spoken across the globe, belonging to roughly 150 language families. And they vary widely in the way they put sentences together. For example, the three major building blocks of a sentence, subject (S), verb (V), and object (O), can come in three different orders. English and French are SVO languages, whereas German and Japanese are SOV languages; a much smaller number, such as Arabic and Hebrew, use the VSO order. (No well-documented languages start sentences or clauses with the object, although some linguists have jokingly suggested that Klingon might do so.) Yet despite these different ways of structuring sentences, previous studies of a limited number of languages have shown that they tend to limit the distance between words that depend on each other for their meaning. Such “dependency” is key if sentences are to make sense. For example, in the sentence “Jane threw out the trash,” the word “Jane” is dependent on “threw”—it modifies the verb by telling us who was doing the throwing, just as we need “trash” to know what was thrown, and “out” to know where the trash went. Although “threw” and “trash” are three words away from each other, we can still understand the sentence easily. © 2015 American Association for the Advancement of Science.
A protein previously linked to acute symptoms following a traumatic brain injury (TBI), may also be responsible for long-term complications that can result from TBI, according to research from the National Institute of Nursing Research (NINR), a component of the National Institutes of Health. Using an ultra-sensitive technology, researchers — led by NIH Lasker Clinical Research Scholar and Chief of NINR’s Brain Injury Unit, Tissue Injury Branch Jessica Gill, Ph.D., R.N., — were able to measure levels of the protein, tau, in the blood months and years after individuals (in this case, military personnel) had experienced TBI. They found that these elevated levels of tau — a protein known to have a role in the development of Alzheimer’s disease and Parkinson’s disease — are associated with chronic neurological symptoms, including post-concussive disorder (PCD), during which an individual has symptoms such as headache and dizziness in the weeks and months after injury. These chronic neurological symptoms have been linked to chronic traumatic encephalopathy (CTE) — progressive brain degeneration that leads to dementia following repetitive TBIs — independent of other factors such as depression and post-traumatic stress disorder (PTSD). The study and an accompanying editorial appear in the August 3 issue of JAMA Neurology. “Our study was limited to identifying the effects of tau accumulation in military personnel who experienced long-term neurological symptoms after a TBI. With further study, our findings may provide a framework for identifying patients who are most at risk for experiencing chronic symptoms related to TBI. Identifying those at risk early in the progression of the disease provides the best opportunity for therapies that can lessen the cognitive declines that may result from these long-term effects,” said Dr. Gill, the study’s lead author.
Keyword: Brain Injury/Concussion
Link ID: 21259 - Posted: 08.04.2015
By Ariana Eunjung Cha Children who suffer an injury to the brain -- even a minor one -- are more likely to experience attention issues, according to a study published Monday in the journal Pediatrics. The effects may not be immediate and could occur long after the incident. Study author Marsh Konigs, a doctoral candidate at VU University Amsterdam, described the impact as "very short lapses in focus, causing children to be slower." Researchers looked at 113 children, ages six to 13, who suffered from traumatic brain injuries (TBIs) ranging from a concussion that gave them a headache or caused them to vomit, to losing consciousness for more than 30 minutes, and compared them with a group of 53 children who experienced a trauma that was not head-related. About 18 months after the children's accidents, parents and teachers were asked to rate their attention and other indicators of their health. They found that those with TBI had more lapses in attention and other issues, such as anxiety, a tendency to internalize their problems and slower processing speed. Based on studies of adults who experienced attention issues after suffering from a brain injury, doctors have theorized for years that head injuries in children might be followed by a "secondary attention deficit hyperactivity disorder." This study appears to confirm that association.
By Ariana Eunjung Cha Think you have your hands full making sure your baby is fed and clean and gets enough sleep? Here's another thing for the list: developing your child's social skills by the way you talk. People used to think that social skills were something kids were born with, not taught. But a growing body of research shows that the environment a child grows up in as an infant and toddler can have a major impact on how they interact with others as they get older. And it turns out that a key factor may be the type of language they hear around them, even at an age when all they can do is babble. Psychologists at the University of York observed 40 mothers and their babies at 10, 12, 16 and 20 months and logged the kind of language mothers used during play. They were especially interested in "mind-related comments," which include inferences about what someone is thinking when a behavior or action happens. Elizabeth Kirk, a lecturer at the university who is the lead author of the study, published in the British Journal of Developmental Psychology on Monday, gave this as an example: If an infant has difficulty opening a door on a toy, the parent might comment that the child appears "frustrated." Then researchers revisited the children when they were 5 or 6 years of age and assessed their socio-cognitive ability. The test involved reading a story and having the children answer comprehension questions that show whether they understood the social concept -- persuasion, joke, misunderstanding, white lies, lies, and so forth -- that was represented.
Tara Haelle To tell if a baby has been injured or killed by being shaken, the courts use three hallmark symptoms: Bleeding and swelling in the brain and retinal bleeding in the eyes. Along with other evidence, those standards are used to convict caregivers of abusive head trauma, both intentional and unintentional, that can result in blindness, seizures, severe brain damage or death. But in recent years a small cadre of experts testifying for the defense in cases across the country has called into question whether those symptoms actually indicate abuse. Though they are in the minority – disputing the consensus of child abuse experts, pediatricians and an extensive evidence base – they have gained traction in the media and in courtrooms by suggesting that shaking a child cannot cause these injuries. Instead, they argue that undiagnosed medical conditions, falls or other accidents are the cause. So researchers have developed and validated a tool doctors can use to distinguish between head injuries resulting from abuse and those from accidents or medical conditions. The method, described in the journal Pediatrics Monday, asks doctors to check for six other injuries, each of which increases the likelihood that a head injury resulted from severe shaking, blunt force or both. "It is vitally important that abuse head trauma is diagnosed accurately so that the team looking after the child can ensure that they receive appropriate support and are protected from further harm," lead study author Laura Elizabeth Cowley, a PhD student at the Cardiff University School of Medicine in the U.K., said in an email. "However, it is also important that accidental head injury cases are not wrongly diagnosed as abusive," she continues, "because this can have devastating consequences for the families involved." © 2015 NPR
A panel of independent experts has decided that a clot-busting drug often used to treat strokes is "safe and effective". The UK medicines watchdog wanted the benefits and risks of alteplase to be analysed after concerns were raised about its safety. The panel concluded that the best time to use the drug is up to four and a half hours after the start of symptoms. But some other doctors are still not convinced by the evidence. Most strokes are caused by a clot blocking the flow of blood to the brain. Many patients are given the drug alteplase to break down and disperse the clot - a treatment known as thrombolysis. The independent expert panel, chaired by Prof Sir Ian Weller, said it had looked at all available data on alteplase and decided that the earlier the drug was given to patients, the greater the chance of a good outcome. Used up to four and a half hours after the onset of symptoms, the benefits of the drug were found to outweigh the risks. But it added that the benefits of using alteplase to treat strokes were "highly time-dependent" and, in a small number of people, there was a risk of haemorrhage. Prof Weller explained: "The evidence shows that for every 100 patients treated with alteplase, whilst there is an early risk of a fatal bleed in two patients, after three to six months, around 10 more in every 100 are disability-free when treated within three hours." © 2015 BBC.
Link ID: 21218 - Posted: 07.25.2015
Carl Zimmer An ant colony is an insect fortress: When enemies invade, soldier ants quickly detect the incursion and rip their foes apart with their oversize mandibles. But some invaders manage to slip in with ease, none more mystifyingly than the ant nest beetle. Adult beetles stride into an ant colony in search of a mate, without being harassed. They lay eggs, from which larva hatch. As far as scientists can tell, workers feed the young beetles as if they were ants. When the beetles grow into adults, the ants swarm around them, grooming their bodies. In exchange for this hospitality, the beetles sink their jaws into ant larvae and freshly moulted adults in order to drink their body fluids. “They’re like vampire beetles wandering in the ant nests,” said Andrea Di Giulio, an entomologist at Roma Tre University in Rome. Dr. Di Giulio and his colleagues have now uncovered a remarkable trick that the beetles use to fool their hosts. It turns out they can perform uncanny impressions, mimicking a range of ant calls. Dr. Di Giulio and his colleagues study a species of ant nest beetle called Paussus favieri, which lives in the Atlas Mountains of Morocco, where it infiltrates the nests of Moroccan ants, known as Pheidole pallidula. Like many ant species, Pheidole pallidula makes noises by rubbing its legs against ridges on its body. The meanings of these signals vary from species to species; leaf-cutting ants summon bodyguards for the march back to the nest; in other species, a queen trills to her workers to attend to her. Scientists have found that Pheidole pallidula ants make three distinct sounds, each produced by a different caste: soldiers, workers and the queen. © 2015 The New York Times Company
by Sarah Zielinski It may not be polite to eavesdrop, but sometimes, listening in on others’ conversations can provide valuable information. And in this way, humans are like most other species in the animal world, where eavesdropping is a common way of gathering information about potential dangers. Because alarm calls can vary from species to species, scientists have assumed that eavesdropping on these calls of “danger!” requires some kind of learning. Evidence of that learning has been scant, though. The only study to look at this topic tested five golden-mantled ground squirrels and found that the animals may have learned to recognize previously unknown alarm calls. But the experiment couldn’t rule out other explanations for the squirrels’ behavior, such as that the animals had simply become more wary in general. So Robert Magrath and colleagues at Australian National University in Canberra turned to small Australian birds called superb fairy-wrens. In the wild, these birds will flee to safety when they hear unfamiliar sounds that sound like their own alarm calls, but not when they hear alarm calls that sound different from their own. There’s an exception, though: They’ll take to cover in response to the alarm calls of other species that are common where they live. That suggests the birds learn to recognize those calls. In the lab, the team played the alarm call from a thornbill or a synthetic alarm call for 10 fairy-wrens. The birds didn’t respond to the noise. Then the birds went through two days of training in which the alarm call was played as a mock predator glided overhead. Another group of birds heard the calls but there was no pretend predator. © Society for Science & the Public 2000 - 2015
By Lauran Neergaard, New research suggests it may be possible to predict which preschoolers will struggle to read — and it has to do with how the brain deciphers speech when it's noisy. Scientists are looking for ways to tell, as young as possible, when children are at risk for later learning difficulties so they can get early interventions. There are some simple pre-reading assessments for preschoolers. But Northwestern University researchers went further and analyzed brain waves of children as young as three. How well youngsters' brains recognize specific sounds — consonants — amid background noise can help identify who is more likely to have trouble with reading development, the team reported Tuesday in the journal PLOS Biology. If the approach pans out, it may provide "a biological looking glass," said study senior author Nina Kraus, director of Northwestern's Auditory Neuroscience Laboratory. "If you know you have a three-year-old at risk, you can as soon as possible begin to enrich their life in sound so that you don't lose those crucial early developmental years." Connecting sound to meaning is a key foundation for reading. For example, preschoolers who can match sounds to letters earlier go on to read more easily. Auditory processing is part of that pre-reading development: If your brain is slower to distinguish a "D" from a "B" sound, for example, then recognizing words and piecing together sentences could be affected, too. What does noise have to do with it? It stresses the system, as the brain has to tune out competing sounds to selectively focus, in just fractions of milliseconds. And consonants are more vulnerable to noise than vowels, which tend to be louder and longer, Kraus explained. ©2015 CBC/Radio-Canada
By Gretchen Reynolds Would soccer be safer if young players were not allowed to head the ball? According to a new study of heading and concussions in youth soccer, the answer to that question is not the simple yes that many of us might have hoped. Soccer parents — and nowadays we are legion — naturally worry about head injuries during soccer, whether our child’s head is hitting the ball or another player. The resounding head-to-head collision between Alexandra Popp of Germany and Morgan Brian of the United States during the recent Women’s World Cup sent shivers down many of our spines. People’s concerns about soccer heading and concussions have grown so insistent in the past year or so that some doctors, parents and former professional players have begun to call for banning the practice outright among younger boys and girls, up to about age 14, and curtailing it at other levels of play. Ridding youth soccer of heading, many of these advocates say, would virtually rid the sport of severe head injuries. But Dawn Comstock, for one, was skeptical when she heard about the campaign. An associate professor of public health at the University of Colorado in Denver and an expert on youth sports injuries, she is also, she said, “a believer in evidence-based decision making.” And she said she wasn’t aware of any studies showing that heading causes the majority of concussions in the youth game. In fact, she and her colleagues could not find any large-scale studies examining the causes of concussions in youth soccer at all. So, for a study being published this week in JAMA Pediatrics, she and her colleagues decided to investigate the issue themselves. © 2015 The New York Times Company
Keyword: Brain Injury/Concussion
Link ID: 21172 - Posted: 07.15.2015
Gretchen Cuda Kroen When Kate Klein began working as a nurse in the Cleveland Clinic's Neurointensive Care Unit, one of the first things she noticed was that her patients spent a lot of time in bed. She knew patients with other injuries benefitted from getting up and moving early on, and she wondered why not patients with brain injuries. "I asked myself that question. I asked my colleagues that question," Klein says. "Why aren't these patients getting out of bed? Is there something unique about patients with neurologic injury?" Doctors have long encouraged their surgical patients to get out of bed as soon as it's safe to do so. Movement increases circulation, reduces swelling, inflammation and the risk of blood clots, and it speeds healing. But that wasn't the thinking with brain injuries, explains Edward Manno, director of the Neurointensive Care Unit at the Cleveland Clinic and one of the neurologists who works with Klein. "The predominant thinking was that rest was better suited for the brain," Manno says. Often the damaged brain is susceptible to lack of blood flow. Increased activity may make things worse if initiated too quickly, Manno says. "So many of us thought for quite some time that we needed to put the brain to rest after the initial insult of stroke or other neurologic injury." © 2015 NPR
Keyword: Brain Injury/Concussion
Link ID: 21136 - Posted: 07.06.2015
By BARRY MEIER and DANIELLE IVORY In a small brick building across the street from a Taco Bell in Marrero, La., patients enter a clear plastic capsule and breathe pure oxygen. The procedure, known as hyperbaric oxygen therapy, uses a pressurized chamber to help scuba divers overcome the bends and to aid people sickened by toxic gases. But Dr. Paul G. Harch, who operates the clinic there on the outskirts of New Orleans, offers it as a concussion treatment. One patient, Rashada Parks, said that she had struggled with neck pain, mood swings and concentration problems ever since she fell and hit her head more than three years ago. Narcotic painkillers hadn’t helped her, nor had antidepressants. But after 40 hourlong treatments, or dives, in a hyperbaric chamber, her symptoms have subsided. “I have hope now,” Ms. Parks said. “It’s amazing.” Three studies run at a taxpayer cost of about $70 million have all come to a far different conclusion. They found that the benefits of hyperbaric oxygen reported by patients like Ms. Parks may have resulted from a placebolike effect, not the therapy’s supposed ability to repair and regenerate brain cells. But undeterred, advocates of the treatment recently persuaded lawmakers to spend even more public money investigating whether the three studies were flawed. A growing industry has developed around concussions, with entrepreneurs, academic institutions and doctors scrambling to find ways to detect, prevent and treat head injuries. An estimated 1.7 million Americans are treated every year after suffering concussions from falls, car accidents, sports injuries and other causes. While the vast majority quickly recover with rest, a small percentage of patients experience lingering effects a year or longer afterward. Along with memory issues, symptoms can include headaches, dizziness and vision and balance problems. © 2015 The New York Times Company
Keyword: Brain Injury/Concussion
Link ID: 21132 - Posted: 07.04.2015
Henry Nicholls Andy Russell had entered the lecture hall late and stood at the back, listening to the close of a talk by Marta Manser, an evolutionary biologist at the University of Zurich who works on animal communication. Manser was explaining some basic concepts in linguistics to her audience, how humans use meaningless sounds or “phonemes” to generate a vast dictionary of meaningful words. In English, for instance, just 40 different phonemes can be resampled into a rich vocabulary of some 200,000 words. But, explained Manser, this linguistic trick of reorganising the meaningless to create new meaning had not been demonstrated in any non-human animal. This was back in 2012. Russell’s “Holy shit, man” excitement was because he was pretty sure he had evidence for phoneme structuring in the chestnut-crowned babbler, a bird he’s been studying in the semi-arid deserts of south-east Australia for almost a decade. After the talk, Russell (a behavioural ecologist at the University of Exeter) travelled to Zurich to present his evidence to Manser’s colleague Simon Townsend, whose research explores the links between animal communication systems and human language. The fruits of their collaboration are published today in PLoS Biology. One of Russell’s students Jodie Crane had been recording the calls of the chestnut-crowned babbler for her PhD. The PLoS Biology paper focuses on two of these calls, which appear to be made up of two identical elements, just arranged in a different way. © 2015 Guardian News and Media Limited
Emma Bowman In a small, sparse makeshift lab, Melissa Malzkuhn practices her range of motion in a black, full-body unitard dotted with light-reflecting nodes. She's strapped on a motion capture, or mocap, suit. Infrared cameras that line the room will capture her movement and translate it into a 3-D character, or avatar, on a computer. But she's not making a Disney animated film. Three-dimensional motion capture has developed quickly in the last few years, most notably as a Hollywood production tool for computer animation in films like Planet of the Apes and Avatar. Behind the scenes though, leaders in the deaf community are taking on the technology to create and improve bilingual learning tools in American Sign Language. Malzkuhn has suited up to record a simple nursery rhyme. Being deaf herself, she spoke with NPR through an interpreter. "I know in English there's just a wealth of nursery rhymes available, but we really don't see as much in ASL," she says. "So we're gonna be doing some original work here in developing nursery rhymes." That's because sound-based rhymes don't cross over well into the visual language of ASL. Malzkuhn heads the Motion Light Lab, or ML2. It's the newest hub of the National Science Foundation Science of Learning Center, Visual Language and Visual Learning (VL2) at Gallaudet University, the premier school for deaf and hard of hearing students. © 2015 NPR
Link ID: 21107 - Posted: 06.29.2015
By Sarah C. P. Williams Parrots, like the one in the video above, are masters of mimicry, able to repeat hundreds of unique sounds, including human phrases, with uncanny accuracy. Now, scientists say they have pinpointed the neurons that turn these birds into copycats. The discovery could not only illuminate the origins of bird-speak, but might shed light on how new areas of the brain arise during evolution. Parrots, songbirds, and hummingbirds—which can all chirp different dialects, pick up new songs, and mimic sound—all have a “song nuclei” in their brain: a group of interconnected neurons that synchronizes singing and learning. But the exact boundaries of that region are fuzzy; some researchers define it as larger or smaller than others do, depending on what criteria they use to outline the area. And differences between the song nuclei of parrots—which can better imitate complex sounds—and other birds are hard to pinpoint. Neurobiologist Erich Jarvis of Duke University in Durham, North Carolina, was studying the activation of PVALB—a gene that had been previously found in songbirds—within the brains of parrots when he noticed something strange. Stained sections of deceased parrot brains revealed that the gene was turned on at distinct levels within two distinct areas of what he thought was the song nuclei of the birds’ brains. Sometimes, the gene was activated in a spherical central core of the nuclei. But other times, it was only active in an outer shell of cells surrounding that core. When he and collaborators looked more closely, they found that the inner core and the outer shell—like the chocolate and surrounding candy shell of an M&M—varied in many more ways as well.
by Kate Solomon Jean-Dominique Bauby famously wrote The Diving Bell and The Butterfly by blinking as an assistant read out the alphabet, but locked-in patients could soon have a much easier way to communicate. For the first time, scientists have successfully transcribed brainwaves as text, which could mean that those unable to speak could use the system to "talk" via a computer. Carried out by a group of informatics, neuroscience and medical researchers at Albany Medical Centre, the team managed to identify the brainwaves relating to speech by using electrocorticographic (ECoG) technology to monitor the frontal and temporal lobes of seven epileptic volunteers. This involves using needles to record signals directly from a person's neurons; it's an invasive procedure requiring an incision through the skull. The participants then read aloud from a sample text while machine learning algorithms pulled out the most likely word sequence from the signals recorded by the EcOG. Existing speech-to-text tools then transcribed the continuously spoken speech directly from the brain activity. Error rates were as low as 25 percent during the study, which means the potential for the system is pretty vast. The findings could offer locked-in and mute patients a valuable communication method but it also means humans could one day communicate directly with a computer without needing any intermediary equipment.
by Sarah Zielinski Last year in Australia, I visited Featherdale Wildlife Park where, in a couple of areas, kangaroos and wallabies hop amongst the tourists. For a dollar, you can buy an ice cream cone full of grass for the marsupials to eat. But if you’re not careful, an animal will quickly grab the cone out of your hand and feed itself. Now I’m wishing that I had paid more attention to that grabbing motion. Kangaroos are lefties, scientists report June 18 in Current Biology. And the preference for one hand over the other may be linked to the ability to walk on two legs. Humans show a definite preference for one hand over the other, usually the right. This handedness had been considered a distinctly human trait. But scientists have found more and more evidence that other species have such preferences as well. Female domestic cats, for instance, tend to use their right paws and males their left. Andrey Giljov of Saint Petersburg State University in Russia and colleagues were curious about the evolution of handedness and looked to marsupials, since these animals are an early offshoot of the mammal lineage. They observed four species in the wild — red kangaroos, eastern gray kangaroos, red-necked wallabies and Goodfellow’s tree kangaroos — performing tasks such as grooming and feeding. © Society for Science & the Public 2000 - 2015.
Link ID: 21075 - Posted: 06.20.2015