By Tina Hesman Saey About 10 percent of people prefer using their left hand. That ratio is found in every population in the world and scientists have long suspected that genetics controls hand preference. But finding the genes has been no simple task, says Chris McManus, a neuropsychologist at University College London who studies handedness but was not involved in the new research. “There’s no single gene for the direction of handedness. That’s clear,” McManus says. Dozens of genes are probably involved, he says, which means that one person’s left-handedness might be caused by a variant in one gene, while another lefty might carry variants in an entirely different gene. To find handedness genes, William Brandler, a geneticist at the University of Oxford, and colleagues conducted a statistical sweep of DNA from 3,394 people. Statistical searches such as this are known as genome-wide association studies; scientists often do such studies to uncover genes that contribute to complex diseases or traits such as diabetes and height. The people in this study had taken tests involving moving pegs on a board. The difference in the amount of time they took with one hand versus the other reflected how strongly left- or right-handed they were. A variant in a gene called PCSK6 was most tightly linked with strong hand preference, the researchers report in the Sept. 12 PLOS Genetics.. The gene has been implicated in handedness before, including in a 2011 study by the same research group. PCSK6 is involved in the asymmetrical positioning of internal organs in organisms from snails to vertebrates. © Society for Science & the Public 2000 - 2013

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 18647 - Posted: 09.14.2013

By Scott Barry Kaufman So yea, you know how the left brain is really realistic, analytical, practical, organized, and logical, and the right brain is so darn creative, passionate, sensual, tasteful, colorful, vivid, and poetic? No. Just no. Stop it. Please. Thoughtful cognitive neuroscientists such as Rex Jung, Darya Zabelina, Andreas Fink, John Kounios, Mark Beeman, Kalina Christoff, Oshin Vartanian, Jeremy Gray, Hikaru Takeuchi and others are on the forefront of investigating what actually happens in the brain during the creative process. And their findings are overturning conventional notions surrounding the neuroscience of creativity. The latest findings from the real neuroscience of creativity suggest that the right brain/left brain distinction is not the right one when it comes to understanding how creativity is implemented in the brain. Creativity does not involve a single brain region or single side of the brain. Instead, the entire creative process– from the initial burst of inspiration to the final polished product– consists of many interacting cognitive processes and emotions. Depending on the stage of the creative process, and what you’re actually attempting to create, different brain regions are recruited to handle the task. Importantly, many of these brain regions work as a team to get the job done, and many recruit structures from both the left and right side of the brain. In recent years, evidence has accumulated suggesting that “cognition results from the dynamic interactions of distributed brain areas operating in large-scale networks.” © 2013 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 14: Attention and Higher Cognition
Link ID: 18528 - Posted: 08.20.2013

by Andrew Porterfield Honey bees may have only a fraction of our neurons—just under a million versus our tens of billions—but our brains aren't so different. Take sidedness. The human brain is divided into right and left sides—our right brain controls the left side of our body and vice versa. New research reveals that something similar happens in bees. When scientists removed the right or left antenna of honey bees, those insects with intact right antennae more quickly recognized bees from the same hive, stuck out their tongues (showing willingness to feed), and fended off invaders. Bees with just their left antennae took longer to recognize bees, didn't want to feed, and mistook familiar bees for foreign ones. This suggests, the team concludes today in Scientific Reports, that bee brains have a sidedness just like ours do. The researchers also think that right antennae might control other bee behavior, like their sophisticated, mysterious "waggle dance" to indicate food. But there's no buzz for the left-antennaed. © 2010 American Association for the Advancement of Science

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 18320 - Posted: 06.29.2013

By Felicity Muth I recently came across an article entitled ‘Advantages in exploring a new environment with the left eye in lizards’ and I couldn’t help but read more. In this study, conducted in Italy, scientists caught 44 wall lizards and glued eye patches on to them (using a paper glue that is harmless to the lizards as they can shed and renew their skin). Half the lizards had their left eye covered, and half had their right eye covered. The lizards were then let into a maze for 20 minutes to see how they fared with turning left and right. The ones that were allowed to use just their left eye were much faster than those that could just use their right eye at turning both left and right. In addition to this, they made fewer stops, seeming to be less hesitant and indecisive than the right-eyed individuals. However, this was only the case when the lizard had to make a choice between turning left or right, not when they only had the choice to turn one way. Why might this be the case? Well, like a lot of vertebrates, lizards have lateralized brains. This means that the brain is divided in two halves, and some functions are specialized to one half. The classic example of this in humans is Broca’s area (associated with speech), which is found in the left hemisphere of the brain in 95% of us. Similar to how humans on the whole prefer to use their right hand, it seems that lizards generally prefer to use their left eye. As with humans, lizard optic nerve fibres are crossed over, meaning that control of the left eye comes from the right hemisphere of the brain and vice versa. As these lizards predominantly use their left eye, this indicates that in this species, something in the right side of their brain is specialised in attending to spatial cues. © 2013 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 7: Vision: From Eye to Brain
Link ID: 18261 - Posted: 06.12.2013

by Helen Thomson "I was sitting on the toilet. I suddenly felt an explosion in the left side of my head and ended up on the floor. I think the only thing that kept me conscious was that I didn't want to be found with my pants down. Then the other side of my head went bang! I woke up in hospital and looked out of the window to see the tree was sprouting numbers. 3, 6, 9. Then I started talking in rhyme…" Ten days after having a subarachnoid haemorrhage – a stroke caused by bleeding in and around the brain – Tommy McHugh, an ex-con who'd been in his fair share of scraps, became a new man, with a personality that nobody recognised. When he was a young man, Tommy did time in prison. But after his stroke at age 51, everything changed. "I could taste the femininity inside of myself," he said. "My head was full of rhymes and images and pictures." Not only did he feel a sudden urge to write poetry, but he also began to paint and draw obsessively for up to 19 hours a day. He was never artistic before – in fact, he joked that he'd never even been in an art gallery "except to maybe steal something". Desperate to find out what was going on, Tommy wrote to several neuroscientists and end up working closely with Alice Flaherty at Harvard Medical School and Mark Lythgoe at University College London. © Copyright Reed Business Information Ltd.

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 18142 - Posted: 05.11.2013

By Lucy Wallis BBC News Abby and Brittany Hensel are conjoined twins determined to live the normal, active life of outgoing 20-somethings anywhere. They have been to university, they travel, they have jobs. But how easy is it for two people to inhabit one body? Like most 23-year-olds Abby and Brittany Hensel love spending time with their friends, going on holiday, driving, playing sport such as volleyball and living life to the full. The identical, conjoined twins from Minnesota, in the United States, have graduated from Bethel University and are setting out on their career as primary school teachers with an emphasis on maths. Although they have two teaching licences, there is one practical difference when it comes to the finances. "Obviously right away we understand that we are going to get one salary because we're doing the job of one person," says Abby. "As maybe experience comes in we'd like to negotiate a little bit, considering we have two degrees and because we are able to give two different perspectives or teach in two different ways." "One can be teaching and one can be monitoring and answering questions," says Brittany. "So in that sense we can do more than one person." Their friend Cari Jo Hohncke has always admired the sisters' teamwork. "They are two different girls, but yet they are able to work together to do the basic functions that I do every day that I take for granted," says Hohncke. BBC © 2013

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 18072 - Posted: 04.25.2013

Michael Corballis, professor of cognitive neuroscience and psychology at the University of Auckland in New Zealand, responds: Although teaching people to become ambidextrous has been popular for centuries, this practice does not appear to improve brain function, and it may even harm our neural development. Calls for ambidexterity were especially prominent in the late 19th and early 20th centuries. For instance, in the early 20th century English propagandist John Jackson established the Ambidextral Culture Society in pursuit of universal ambidexterity and “two-brainedness” for the betterment of society. This hype died down in the mid-20th century as benefits of being ambidextrous failed to materialize. Given that handedness is apparent early in life and the vast majority of people are right-handed, we are almost certainly dextral by nature. Recent evidence even associated being ambidextrous from birth with developmental problems, including reading disability and stuttering. A study of 11-year-olds in England showed that those who are naturally ambidextrous are slightly more prone to academic difficulties than either left- or right-handers. Research in Sweden found ambidextrous children to be at a greater risk for developmental conditions such as attention-deficit hyperactivity disorder. Another study, which my colleagues and I conducted, revealed that ambidextrous children and adults both performed worse than left- or right-handers on a range of skills, especially in math, memory retrieval and logical reasoning. © 2013 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 13: Memory and Learning
Link ID: 17941 - Posted: 03.25.2013

By Dwayne Godwin and Jorge Cham Dwayne Godwin is a neuroscientist at the Wake Forest University School of Medicine. Jorge Cham draws the comic strip Piled Higher and Deeper at www.phdcomics.com. © 2013 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 17898 - Posted: 03.13.2013

By Daisy Yuhas At least 1 in 4000 infants is born without a corpus callosum. This powerful body of connective white matter serves as the primary bridge between the brain’s hemispheres, allowing us to rapidly integrate complex information. “It’s a hidden disability,” says University of California Institute of Technology psychologist Lynn Paul. Many born without this structure go undiagnosed for years—only neuroimaging can confirm the agenesis, or failed development, of this brain area. Instead people are diagnosed with disorders such as autism, depression, or ADHD. People born without a corpus callosum face many challenges. Some have other brain malformations as well—and as a result individuals can exhibit a range of behavioral and cognitive outcomes, from severe cognitive deficits to mild learning delays. Paul is also the founding president of the National Organization of Disorders of the Corpus Callosum, a non-profit that offers resources and support to those affected and their families. She believes psychologists and neuroscientists can learn much from this disorder, including how varied biological problems can result in the same behavioral outcomes. But what may be most remarkable is how the acallosal brain adapts to its limitations and finds new connective routes. Precisely how the brain does this is a biological mystery, but there are several possible routes of compensation, which effectively re-route the brain’s connections in novel ways. Similarly, each individual born with this condition must find his or her own way to overcome unique challenges. As is clear from their stories, individuals often find strength in one another and in sharing their experiences. © 2012 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 17625 - Posted: 12.21.2012

By Susan Milius A patch over a male Gouldian finch’s right eye works like beer goggles, though the bird doesn’t need booze to flirt unwisely. If limited to using his left eye when checking out possible mates, he risks making really stupid choices. Gouldian finches have caps of black, red or yellow feathers on their heads. In nature, the birds prefer to mate with partners with the same cap color. Yet black-headed males rendered temporarily left-eyed by a tiny removable eye patch flirted as readily with red-heads as with black-heads, says cognitive ecologist Jennifer Templeton of Knox College in Galesburg, Ill. That’s not smart because daughters typically fail to survive when Gouldian finches mate outside their cap color. Also the male himself “becomes less attractive,” Templeton says. When the bird’s right eye was covered, he sang, bowed and posed less during his attempts at courtship. Some left-eyed males didn’t manage to make up their minds at all, but “just hopped around randomly,” Templeton says. Moving the eye patch to the right eye, however, restored male Gouldian finches to their senses. Males then spent more time perching near same-cap-color females and flirting with them. “Beauty is in the right eye of the beholder,” Templeton and her colleagues conclude online October 3 in Biology Letters. Birds make fine subjects for comparing eye biases because many species’ eyes sit on opposite sides of their skulls with very different fields of view. A bird’s right eye connects to the left hemisphere of its brain, and the left eye to the right hemisphere. Unlike mammals, birds don’t have a high-speed connection between hemispheres. © Society for Science & the Public 2000 - 2012

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 15: Language and Lateralization
Link ID: 17330 - Posted: 10.04.2012

Chris McManus, professor of psychology and medical education at University College London, responds: if by intelligent you mean someone who performs better on IQ tests, the simple answer is no. Studies in the U.K., U.S. and Australia have revealed that left-handed people differ from right-handers by only one IQ point, which is not noteworthy. If by intelligent you mean someone who performs better on IQ tests, the simple answer is no. Studies in the U.K., U.S. and Australia have revealed that left-handed people differ from right-handers by only one IQ point, which is not noteworthy. Left-handedness is, however, much more common among individuals with severe learning difficulties, such as mental retardation. A slightly higher proportion of left-handers have dyslexia or a stutter. Other problems, such as a higher rate of accidents reported in left-handers, mostly result from a world designed for the convenience of right-handers, with many tools not made for left-handed use. Although some people claim that a higher percentage of left-handers are exceptionally bright, large research studies do not support this idea. If by smarter you mean more talented in certain areas, left-handers may have an advantage. Left-handers’ brains are structured differently from right-handers’ in ways that can allow them to process language, spatial relations and emotions in more diverse and potentially creative ways. Also, a slightly larger number of left-handers than right-handers are especially gifted in music and math. A study of musicians in professional orchestras found a significantly greater proportion of talented left-handers, even among those who played instruments that seem designed for right-handers, such as violins. Similarly, studies of adolescents who took tests to assess mathematical giftedness found many more left-handers in the population. The fact that mathematicians are often musical may not be a coincidence. © 2012 Scientific American,

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 1: Introduction: Scope and Outlook
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 20:
Link ID: 16656 - Posted: 04.16.2012

David Wolman In the first months after her surgery, shopping for groceries was infuriating. Standing in the supermarket aisle, Vicki would look at an item on the shelf and know that she wanted to place it in her trolley — but she couldn't. “I'd reach with my right for the thing I wanted, but the left would come in and they'd kind of fight,” she says. “Almost like repelling magnets.” Picking out food for the week was a two-, sometimes three-hour ordeal. Getting dressed posed a similar challenge: Vicki couldn't reconcile what she wanted to put on with what her hands were doing. Sometimes she ended up wearing three outfits at once. “I'd have to dump all the clothes on the bed, catch my breath and start again.” In one crucial way, however, Vicki was better than her pre-surgery self. She was no longer racked by epileptic seizures that were so severe they had made her life close to unbearable. She once collapsed onto the bar of an old-fashioned oven, burning and scarring her back. “I really just couldn't function,” she says. When, in 1978, her neurologist told her about a radical but dangerous surgery that might help, she barely hesitated. If the worst were to happen, she knew that her parents would take care of her young daughter. “But of course I worried,” she says. “When you get your brain split, it doesn't grow back together.” In June 1979, in a procedure that lasted nearly 10 hours, doctors created a firebreak to contain Vicki's seizures by slicing through her corpus callosum, the bundle of neuronal fibres connecting the two sides of her brain. This drastic procedure, called a corpus callosotomy, disconnects the two sides of the neocortex, the home of language, conscious thought and movement control. Vicki's supermarket predicament was the consequence of a brain that behaved in some ways as if it were two separate minds. © 2012 Nature Publishing Group,

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 16513 - Posted: 03.15.2012

By Ferris Jabr As a baby bird develops, its body contorts to fit within the confines of its egg. The bird's neck twists so that one side of its head is tucked against its chest. In this position, the bird's left eye remains nestled among sprouting feathers—where it does not receive much light from the outside world—whereas the right eye is pressed up against the eggshell, glimpsing flickers of light and shadow through a veil of calcium carbonate. Even though this uneven stimulation of the eyes lasts only one or two days before the chick hatches, it seems to be crucial for typical brain development. Pigeons incubated in the dark have a much harder time solving puzzles as adults than pigeons exposed to light before hatching. The reason, some researchers think, is that the brain's two hemispheres cannot properly integrate information if they miss a critical window period of learning in the egg. Martina Manns of Ruhr University Bochum in Germany has been studying pigeon brains for the past 20 years. For a new study published in the February issue of Nature Communications, Manns and her colleague Juliane Römling focused on 14 domestic pigeons raised in normal lighting conditions by local breeders and another eight pigeons raised in dark incubators in their lab. (Scientific American is part of Nature Publishing Group.) Through various memory tests and logic puzzles, Manns and Römling compared the problem-solving abilities of the two groups of birds. One by one, Manns and Römling presented each pigeon with different pairs of plastic cups filled with colorful aquarium gravel, only one of which concealed a kernel of corn. There were four pairings: red and blue, blue/green, green/yellow and yellow/violet. Through trial and error the pigeons learned to prefer one color in each pair, because gravel of that color always contained the tasty snack. Given a choice between blue and green gravel, for instance, blue was always the right answer; green gravel always contained the reward when matched with yellow, etcetera. © 2012 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 16497 - Posted: 03.10.2012

By Jason G. Goldman Which limb do you prefer? If you’re like most members of our species, you prefer your right hand for most tasks. If you’re like a smaller minority of our species, you might prefer your left hand. Very, very few of us are truly ambidextrous. Most of us have at least a minor preference for one hand over the other. So do wallabies. On the one hand (ha!), this shouldn’t be all that surprising. Nervous systems became lateralized quite early in the evolution of vertebrates. For example, there is research showing that fish show a preference for touching the sides of aquariums with one side of their ventral fins or another. And it is not surprising that humans overwhelmingly favor their right hands. When it comes to feeding behaviors, fishes, reptiles, and toads all favor their right eye (and their brain’s left hemisphere). The same is true for birds like chickens, pigeons, quails, and stilts. The right-eye preference can be so strong that one bird – New Zealand wry-billed plover – evolved a beak that slopes slightly to the right. And a study of seventy-five whales showed that sixty of them had abrasions on the right side of their jaws, while the other fifteen had only injured the left side of their jaws. As Peter F. MacNeilage, Lesley J. Rogers and Giorgio Vallortigara pointed out in a 2009 article in Scientific American, the data indicated that whales tended to use one side of the jaw more than the other for gathering food, “and that ‘right-jawedness’ is by far the norm.” On the other hand, we have no real reason to automatically assume that wallabies would show a limb preference, just because a diverse handful of other species do. After all, the vast majority of research on limb preference and of behavioral laterality more generally has focused on primates, mainly because researchers’ main goal has been to discern the evolutionary origins of brain asymmetry and handedness in humans. © 2012 Scientific American

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 16307 - Posted: 01.28.2012

Molly Hennessy-Fiske, Los Angeles Times Dylan Catania is almost 2. He likes pasta with red sauce, playing catch or wrestling with his dad, sitting on slick leather chairs at Starbucks to greet strangers and holding his breath underwater. He does not like baby food, sitting in his car seat or taking naps. When he is really, really happy, Dylan likes to sit on the ground, crack a smile exposing his fledgling teeth and spin like a top. The faint scar on his right temple is invisible under a cap of downy brown hair. He was born with half of his brain enlarged and malformed, a disorder known as hemimegalencephaly that occurs in fewer than two dozen births a year. When he was nearly 3 months old, neurosurgeons at UCLA severed the right hemisphere of Dylan's brain from the left in a seven-hour hour operation, radical surgery to stop him from suffering as many as a hundred seizures each day. Neurologists who see him now, scooting across the floor propelled by his right hand, recognize the telltale "hemi scoot." His family and friends see a determined boy who has grown not only stronger but also more trusting, empathetic and brave. He can say more than two dozen words. He does not cry for his mother at the preschool near his family's home in the Beverly Glen neighborhood of Los Angeles, but if another child wails, he joins in solidarity. He favors classical music and anything Elmo, waving his right hand to the beat, but has been known to watch in awe as his sister and cousins groove along to their Wii. He has yet to make peace with his left side, slightly paralyzed by the surgery, but if his parents ask nicely, he will kiss his left hand, known as "lefty." © 2011 Hearst Communications Inc.

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 4: Development of the Brain
Link ID: 16225 - Posted: 01.07.2012

By Jeannine Stamatakis I met Kim Peek when he gave a presentation at Ohlone College in October 2009, just a few weeks before his passing. During the talk, Peek astonished my students by showcasing his remarkable talent for calendar calculations. Just from knowing my students’ birth dates, Peek was able to determine the day of the week they were born and could recall the front-page news that day. Known as a mega savant or a “Kimputer,” Peek had one of the most impressive memories people have ever seen. Physicians who examined Peek discovered that he had damage to the cerebellum, a brain region that regulates attention and language, as well as emotional reactions, such as pleasure and fear. Perhaps most notably, physicians found that Peek had no corpus callosum, the bundle of nerves that connects the brain’s right and left hemispheres. They speculated that the absence of this critical structure allowed Peek’s neurons to make new and unusual connections between his right and left hemispheres. These novel connections most likely explain his abnormal memory capacity. According to Peek’s father, Peek could memorize every word in the books they read before he was two years old. Peek progressed to reading two pages simultaneously. Although how he did so remains a mystery, some have theorized he read the left page of a book with his left eye and the right page with his right eye. © 2011 Scientific American,

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 13: Memory and Learning
Link ID: 15521 - Posted: 07.02.2011

By Bruce Bower Right-handedness reaches back a half million years in the human evolutionary family, at least if scratched-up fossil teeth have anything to say about it. Stone-tool scratches on the front teeth of Neandertals and their presumed European ancestors occur at angles denoting right-handedness in most of these Stone Age hominids, just as in human populations today, say anthropologist David Frayer of the University of Kansas in Lawrence and his colleagues. Scientists have linked prevalent right-handedness in human populations to a left brain hemisphere that controls right-sided body movements and enables critical language functions. Given the new tooth evidence, populations of largely right-handed Neandertals and their predecessors must have possessed a gift for gab, Frayer’s team proposes in a paper published online April 14 in Laterality. “Findings so far suggest that most European hominids were right-handed by at least 500,000 years ago,” Frayer says. “A capacity for language appears to have ancient, not recent, roots.” Along with widespread right-handedness indicating that these ancient hominids possessed language-ready brains, humanlike inner-ear fossils show that Neandertals’ ancestors could hear all the sounds employed in modern tongues, Frayer asserts. Other researchers contend that, based on vocal-tract reconstructions informed by skull and upper-body fossils, Neandertals were physically incapable of articulating some modern speech sounds. In these scientists’ view, language as spoken today originated in Homo sapiens sometime after 200,000 years ago. © Society for Science & the Public 2000 - 2011

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 15273 - Posted: 04.28.2011

By John Roach Lefties were as outnumbered 600,000 years ago as they are today, according to telltale markings on teeth found on Neanderthal and Neanderthal ancestors in Europe. The finding serves as a new technique to determine whether a person was left- or right-handed from limited skeletal remains, and it also suggests that a key piece for the origin of language was in place at least half a million years ago, David Frayer, an anthropologist at the University of Kansas, told me today. But while ancient righties appeared to outnumber lefties nine to one, the findings don't reveal whether some of the ancient lefties dominated in sports, as baseball players do today; and in politics, where being left-handed seems to help open the door to the White House. The telltale tooth markings, based on experiments, appear to result from how these Neanderthals and their relatives processed hides with stone tools, explained Frayer, a co-author of a paper on the findings published this month in the journal Laterality. One of his colleagues in Spain had people wear a mouth guard and then strike a hide as if they were cutting or stretching it with a stone tool. Every now and then, the test subjects were asked to whack their guarded teeth, as the researchers think would have accidentally happened as the ancient humans worked away.

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 15251 - Posted: 04.21.2011

By PERRI KLASS, M.D. Humans are asymmetric animals. Early in our embryonic development, organs turn to one side or the other — heart to the left, liver to the right and so on. In rare cases, an organ may turn up on the “wrong” side with no untoward effects. (I once examined a child with dextrocardia, or heart on the right.) But there is one form of asymmetry that is common and, until quite recently, stigmatized: handedness. Over the centuries, left-handers have been accused of criminality and dealings with the devil, and children have been subjected to “re-education.” In recent years the stigma has largely vanished; among other things, four of our last five presidents — Reagan, the elder Bush, Clinton, Obama — have been left-handed. (Reagan is sometimes cited as ambidextrous.) But the riddle of why about 10 percent of children are born with this essentially human asymmetry remains. “This is really still mysterious,” said Clyde Francks, the lead author of a 2007 study in which Oxford University researchers identified a genetic variant linked to left-handedness. Hand asymmetry (whether left or right) is related to brain asymmetry. And that, Dr. Francks said, “is not at all understood; we’re really at the very beginning of understanding what makes the brain asymmetrical and what goes wrong — we don’t understand that process in the normal case.” © 2011 The New York Times Company

Related chapters from BN: Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 15: Language and Lateralization
Link ID: 15076 - Posted: 03.07.2011

by Ferris Jabr People who are relatively ambivalent about which hand they use may also have moods that are more susceptible to suggestion. So says Ruth Propper at Montclair State University, New Jersey, and colleagues, who discovered that "inconsistent-handers" – those who favour neither their right nor left hand – are more easily persuaded to feel a certain way than consistent right-handers. Almost 90 per cent of the world's population remains loyal to the right hand, whether brushing their teeth, flipping through TV channels or whipping up some brownies. The remaining 10 per cent is divided between people who consistently prefer the left hand and those who switch between right and left. To see whether handedness had any relationship to emotional stability, Propper attempted to influence the moods of inconsistent-handers and right-handed individuals by asking them think happy, sad or anxious thoughts while listening to different kinds of classical music. Inconstant moods Proper found that inconsistent-handers not only reported that as soon as they walked into the lab they had more negative feelings, suggesting their moods were more immediately influenced by their surroundings, but were also far more likely to report slipping into a new mood during the experiment. The right-handers proved more resistant to suggestion, reporting less flux in emotion. © Copyright Reed Business Information Ltd

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 11: Emotions, Aggression, and Stress
Link ID: 15038 - Posted: 02.22.2011