Chapter 16. None

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By John Pavlus The “brain in a vat” has long been a staple of philosophical thought experiments and science fiction. Now scientists are one step closer to creating the real thing, which could enable groundbreaking experiments of a much more empirical kind. Research teams at Stanford University and the RIKEN Center for Developmental Biology in Japan have each discovered methods for coaxing human stem cells to form three-dimensional neural structures that display activity associated with that of an adult brain. By applying a variety of chemical growth factors, the RIKEN researchers transformed human embryonic stem cells into neurons that self-organized in patterns unique to the cerebellum, a region of the brain that coordinates movement. The Stanford team worked with induced pluripotent stem cells derived from skin cells and chemically nudged them to become neurons that spontaneously wired up into networks of 3-D circuits, much like the ones found in the cerebral cortex—the wrinkled gray matter of the brain that supports attention, memory and self-awareness in humans. “For years people have used mouse embryonic stem cells to generate teratomas—things that look like they could be organs,” says David Panchision, a neuroscientist at the National Institutes of Health, which supported the Stanford research. “But it's not organized and systematic, the way a developing brain needs to be to function.” In contrast, the Stanford team's neural structures not only self-assembled as cortexlike tissue, the neurons also sent signals to one another in coordinated patterns—just as they would in a brain. The cerebellar tissue generated by the Japanese scientists did, too. © 2015 Scientific American

Keyword: Development of the Brain
Link ID: 21427 - Posted: 09.21.2015

By MATTHEW HUTSON ANGER is a primal and destructive emotion, disrupting rational discourse and inflaming illogical passions — or so it often seems. Then again, anger also has its upsides. Expressing anger, for example, is known to be a useful tool in negotiations. Indeed, in the past few years, researchers have been learning more about when and how to deploy anger productively. Consider a forthcoming paper in the November issue of the Journal of Experimental Social Psychology. Researchers tested the effectiveness of expressing anger in three types of negotiations: those that are chiefly cooperative (say, starting a business with a partner), chiefly competitive (dissolving a shared business) or balanced between the two (selling a business to a buyer). In two experiments, negotiators made greater concessions to those who expressed anger — but only in balanced situations. When cooperating, hostility seems inappropriate, and when competing, additional heat only flares tempers. But in between, anger appears to send a strategically useful signal. What does that signal communicate? According to a 2009 paper in Proceedings of the National Academy of Sciences, anger evolved to help us express that we feel undervalued. Showing anger signals to others that if we don’t get our due, we’ll exert harm or withhold benefits. As they anticipated, the researchers found that strong men and attractive women — those who have historically had the most leverage in threatening harm and conferring benefits, respectively — were most prone to anger. The usefulness of anger in extracting better treatment from others seems to be something we all implicitly understand. A 2013 paper in the journal Cognition and Emotion found that when people were preparing to enter a confrontational negotiation, as opposed to a cooperative one, they took steps to induce anger in themselves (choosing to listen to aggressive versus happy music, for example). © 2015 The New York Times Company

Keyword: Emotions
Link ID: 21426 - Posted: 09.21.2015

William Sutcliffe Most epidemics are the result of a contagious disease. ADHD – Attention Deficit Hyperactivity Disorder – is not contagious, and it may not even be a genuine malady, but it has acquired the characteristics of an epidemic. New data has revealed that UK prescriptions for Ritalin and other similar ADHD medications have more than doubled in the last decade, from 359,100 in 2004 to 922,200 last year. In America, the disorder is now the second most frequent long-term diagnosis made in children, narrowly trailing asthma. It generates pharmaceutical sales worth $9bn (£5.7bn) per year. Yet clinical proof of ADHD as a genuine illness has never been found. Sami Timimi, consultant child psychiatrist at Lincolnshire NHS Trust and visiting professor of child psychiatry, is a vocal critic of the Ritalin-friendly orthodoxy within the NHS. While he is at pains to stress that he is “not saying those who have the diagnosis don’t have any problem”, he is adamant that “there is no robust evidence to demonstrate that what we call ADHD correlates with any known biological or neurological abnormality”. The hyperactivity, inattentiveness and lack of impulse control that are at the heart of an ADHD diagnosis are, according to Timimi, simply “a collection of behaviours”. Any psychiatrist who claims that a behaviour is being caused by ADHD is perpetrating a “philosophical tautology” – he is doing nothing more than telling you that hyperactivity is caused by an alternative name for hyperactivity. There is still no diagnostic test – no marker in the body – that can identify a person with ADHD. The results of more than 40 brain scan studies are described by Timimi as “consistently inconsistent”. No conclusive pattern in brain activity had been found to explain or identify ADHD. ©

Keyword: ADHD
Link ID: 21425 - Posted: 09.21.2015

By Michael Balter Are some animals smarter than others? It’s hard to say, because you can’t sit a chimpanzee or a mouse down at a table for an IQ test. But a new study, in which scientists tested wild robins on a variety of skills, concludes that they do differ in the kind of “general intelligence” that IQ tests are supposed to measure. General intelligence is usually defined as the ability to do well on multiple cognitive tasks, from math skills to problem solving. For years, researchers have questioned whether measurable differences exist in humans and nonhumans alike. In humans, factors like education and socioeconomic status can affect performance. When it comes to animals, the problem is compounded for two main reasons: First, it is very difficult to design and administer tests that pick up on overall smarts instead of specific skills, such as the keen memories of food-hoarding birds or the fine motor skills of chimpanzees that make tools for finding insects in trees. Second, differences in animal test scores can depend on how motivated they are to perform. Because most experiments award would-be test-takers with food, an empty (or a full) stomach might be all it takes to skew the results. Thus, even studies that suggest variations in intelligence among mice, birds, and apes all carry the caveat that alternative explanations could be at play. To get around some of these limitations, a team led by Rachael Shaw, an animal behavior researcher at Victoria University of Wellington, turned to a population of New Zealand North Island robins for a new round of experiments. The robins live at the Zealandia wildlife sanctuary, a 225-hectare nature paradise in Wellington where more than 700 of the birds live wild and protected from predators in the middle of the city. © 2015 American Association for the Advancement of Science.

Keyword: Intelligence; Evolution
Link ID: 21424 - Posted: 09.20.2015

Mo Costandi The human brain is often said to be the most complex object in the known universe, and there’s good reason to believe that this old cliché is true. Even the apparently simple task of compiling a census of the different types of cells it contains has proven to be extremely difficult. Researchers still can’t agree on the best way to classify the numerous sub-types of neurons, and different methods produce different results, so estimates range from several hundred to over a thousand. Basket cells illustrate this neuronal identity crisis perfectly. They are currently sub-divided into multiple different types, according to their shape, electrical properties, and molecular profiles. After nearly ten years of detective work, researchers at King’s College London now reveal them to be masters of disguise. In a surprising new study, they show that these cells can dynamically switch from one identity to another in response to neuronal network activity. Basket cells are a type of interneuron, which are found scattered throughout the cerebral cortex, hippocampus, and cerebellum, and make up about 5% of the total number of cells in these brain regions. They form local circuits with each other and with pyramidal neurons, the much larger and more numerous cells that transmit information to distant parts of the brain, and synthesize the inhibitory neurotransmitter GABA, which dampens pyramidal cell activity when released. These enigmatic cells are thought to exist in more than twenty different types, the best known being the fast-spiking ones, which respond rapidly to incoming signals, and slower ones, which respond after a delay. During brain development, immature forms of all types of basket cells are created in a structure called the medial ganglionic eminence, along with various other types of brain cells. They then migrate into the developing cerebral cortex, before going on to form synaptic connections with other cells. © 2015 Guardian News and Media Limited

Keyword: Development of the Brain
Link ID: 21423 - Posted: 09.20.2015

We all have our favourite movie moments, ones we love to watch again from time to time. Now it seems chimpanzees and bonobos, too, have the nous to recall thrilling scenes in movies they have previously seen and anticipate when they are about to come up. The results suggest apes can readily recall and anticipate significant recent events, just by watching those events once. Rather than use hidden food as a memory test, Japanese researchers made short movies and showed them to apes on two consecutive days. “We showed a movie instead, and asked whether they remember it when they only watch an event once, and an event totally new to them,” says Fumihiro Kano of Kyoto University in Japan. “Their anticipatory glances told us that they did.” Plot moment Kano and his colleague Satoshi Hirata made and starred in two short films. Another of the characters was a human dressed up as an ape in a King Kong costume who carried out attacks on people, providing the key plot moment in the first movie (see video). Both films were designed to contain memorable dramatic events, and the researchers deployed laser eye-tracking technology to see if the animals preferentially noticed and remembered these moments. © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory
Link ID: 21421 - Posted: 09.20.2015

By C. CLAIBORNE RAY A. Wild canines that rely on strenuous hunting to survive may sleep or rest as much as, or even more than, indolent human-created breeds that rely on a can or a bag of kibble. Domestic dogs, with their great range of body types and personalities, show a tremendous variety of sleep patterns, often including relatively brief periods of deep sleep spread out over several hours. A half-century-long study of wolves and their interaction with their prey on Isle Royale, a wilderness island in Lake Superior, found that in winter the wolves would feed for hours on a fresh kill, then sprawl out or curl up in the snow and rest or sleep about 30 percent of the time. “Wolves have plenty of reason to rest,” the study’s researchers wrote. “When wolves are active, they are really active. On a daily basis, wolves burn about 70 percent more calories compared to typical animals of similar size.” The researchers note that while hunting, wolves may burn calories at 10 to 20 times the rate they do while resting. “When food is plentiful, wolves spend a substantial amount of time simply resting, because they can,” the study said. “When food is scarce, wolves spend much time resting because they need to.” Wolves may eat only once every five to 10 days, the researchers said, losing as much as 8 to 10 percent of body weight, but regaining all the lost weight in just two days of eating and resting. © 2015 The New York Times Company

Keyword: Sleep
Link ID: 21419 - Posted: 09.20.2015

By David Grimm The journal Nature is revising its policy on publishing animal experiments after a study it ran in 2011 received criticism because the authors allowed tumors to grow excessively large in mice. The paper reported that a compound isolated from a pepper plant killed cancer cells without harming healthy cells. Yesterday, the journal published a correction to the study (the paper’s second), which noted that “some tumors on some of the animals exceeded the maximum size … permitted by the Institutional Animal Care and Use Committee.” The tumors were only supposed to grow to a maximum of 1.5 cubic centimeters, but some reached 7 cubic centimeters, according to David Vaux, a cell biologist at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, who first raised concerns about the paper in 2012. (Vaux spoke to Retraction Watch, which first reported the correction.) In an editorial published yesterday, Nature calls the large tumors “a breach of experimental protocol,” one that could have caused the mice to “have experienced more pain and suffering than originally allowed for.” The journal also noted the lapse could have implications beyond the one study, saying that “cases such as this could provoke a justifiable backlash against animal research.” Nature says it will now require authors to include the maximum tumor size allowed by its institutional animal-use committee, and to state that this size was not exceeded during the experiments. The journal does say, however, that it is not retracting the paper, and that the study remains “valid and useful.”

Keyword: Animal Rights
Link ID: 21418 - Posted: 09.20.2015

By JAMES GORMAN Among the deep and intriguing phenomena that attract intense scientific interest are the birth and death of the universe, the intricacies of the human brain and the way dogs look at humans. That gaze — interpreted as loving or slavish, inquisitive or dumb — can cause dog lovers to melt, cat lovers to snicker, and researchers in animal cognition to put sausage into containers and see what wolves and dogs will do to get at it. More than one experiment has made some things pretty clear. Dogs look at humans much more than wolves do. Wolves tend to put their nose to the Tupperware and keep at it. This evidence has led to the unsurprising conclusion that dogs are more socially connected to humans and wolves more self-reliant. Once you get beyond the basics, however, agreement is elusive. In order to assess the latest bit of research, published in Biology Letters Tuesday by Monique Udell at Oregon State University, some context can be drawn from an earlier experiment that got a lot of attention more than a decade ago. In a much publicized paper in 2003, Adam Miklosi, now director of the Family Dog Project, at Eotvos Lorand University in Budapest, described work in which dogs and wolves who were raised by humans learned to open a container to get food. Then they were presented with the same container, modified so that it could not be opened. Wolves persisted, trying to solve the unsolvable problem, while dogs looked back at nearby humans. At first glance it might seem to a dog lover that the dogs were brilliant, saying, in essence, “Can I get some help here? You closed it; you open it.” But Dr. Miklosi didn’t say that. He concluded that dogs have a genetic predisposition to look at humans, which could have been the basis for the intense but often imperfect communication that dogs and people engage in. © 2015 The New York Times Company

Keyword: Animal Communication; Language
Link ID: 21416 - Posted: 09.16.2015

For primary school children in China, spending an extra 45 minutes per day outside in a school activity class may reduce the risk of nearsightedness, or "myopia," according to a new study. In some parts of China, 90 per cent of high school graduates have nearsightedness, and rates are lower but increasing in Europe and the Middle East, the authors write. "There were some studies suggesting the protective effect of outdoor time in the development of myopia, but most of this evidence is from cross-sectional studies [survey] data that suggest 'association' instead of causality," said lead author Dr. Mingguang He of Sun Yat-sen University in Guangzhou. "Our study, as a randomized trial, is able to prove causality and also provide the high level of evidence to inform public policy." Intense levels of schooling and little time spent outdoors may have contributed to the epidemic rise of nearsightedness in China, he told Reuters Health by email. The researchers divided 12 primary schools in China into two groups: six schools continued their existing class schedule, while six were assigned to include an additional 40 minutes of outdoor activity at the end of each school day. Parents of children in the second group were also encouraged to engage their children in outdoor activities on the weekends. In total, almost 2,000 first-graders, with an average age of almost seven years old, were included. After three years, 30 per cent of the outdoor activity group had developed nearsightedness, compared to almost 40 per cent of kids in the control group, according to the results in JAMA. ©2015 CBC/Radio-Canada.

Keyword: Vision
Link ID: 21413 - Posted: 09.16.2015

By Emily DeMarco When it comes to finding a mate in the animal kingdom, females tend to gravitate toward males who appear strong and healthy. But a new study in zebra finches reveals that the small, gray-striped birds prefer mates with similar interests, such as a penchant for exploring the world. The drive for this compatibility is so strong that when scientists forced the females to mate up with males not of their choosing, the birds were more likely to cheat and shirk their parental duties, leading to more deaths among their chicks. The research “suggests that having a mate you’re behaviorally compatible with is very important from an evolutionary perspective for zebra finches,” says behavioral ecologist Sasha Dall of the University of Exeter, Cornwall, in the United Kingdom, who wasn’t involved in the study. Scientists have long been puzzled by female zebra finches. As opposed to females of other bird species, which tend to prefer males with brighter plumage or longer tails (traits that suggest that the males have good, healthy genes), female zebra finches seem to choose mates for some mysterious reason known only to each lady bird. Sometimes one will go for the guy with the bright red beak, sometimes the male with the thrilling song, sometimes neither. So what’s really driving this mate choice? In the past, scientists have speculated that a desire for compatibility might be the answer. But they have disagreed over whether the birds are on the lookout for males with the right genes (genetic compatibility between the partners might help lower the high rates of embryonic mortality seen in the species) or the right behaviors. © 2015 American Association for the Advancement of Science

Keyword: Sexual Behavior
Link ID: 21412 - Posted: 09.15.2015

By Barbara S. Moffet It’s 1 in the morning and I’ve been in bed for a few hours now. Maybe it’s the few drops of caffeine I mistakenly drank earlier in the day. Or perhaps it’s the 26 wires that are attached to my scalp, face, finger and legs and the strap pulled taut around my waist. All I know is I’m not doing what you’re supposed to do in a sleep lab, and if I don’t fall asleep soon, it’ll be time to take off my pajamas and go home. I’m here because my doctor thought it was time to find out what was causing a cluster of possibly sleep-related health issues: snoring, frequent middle-of-the-night waking and some problems with concentrating that I’ve had most of my 63 years. I also have a genetic condition, Ehler-Danlos syndrome, that can cause airways to partially close during sleep. I’ve landed at Sleep Centers of Northern Virginia in Alexandria, one of at least two dozen sleep labs in the area. According to the National Institutes of Health, some 70 million Americans are “poor sleepers,” and the ramifications of inadequate shut-eye can range from grumpiness and lack of focus to heart disease, diabetes, high blood pressure and even a diminished life expectancy. Research published this year in the journal Neurology concluded that people with sleep apnea — a disorder that causes a person to repeatedly stop breathing during the night, rousing them from sleep — developed problems with cognition about 10 years earlier than other people.

Keyword: Sleep
Link ID: 21409 - Posted: 09.15.2015

John Peever, and Brian J. Murray, The function of sleep has mystified scientists for thousands of years, but modern research is providing new clues about what it does for both the mind and body. Sleep serves to reenergize the body's cells, clear waste from the brain, and support learning and memory. It even plays vital roles in regulating mood, appetite and libido. Sleeping is an integral part of our life, and as research shows, it is incredibly complex. The brain generates two distinct types of sleep—slow-wave sleep (SWS), known as deep sleep, and rapid eye movement (REM), also called dreaming sleep. Most of the sleeping we do is of the SWS variety, characterized by large, slow brain waves, relaxed muscles and slow, deep breathing, which may help the brain and body to recuperate after a long day. When we fall asleep, the brain does not merely go offline, as implied by the common phrase “out like a light.” Instead a series of highly orchestrated events puts the brain to sleep in stages. Technically sleep starts in the brain areas that produce SWS. Scientists now have concrete evidence that two groups of cells—the ventrolateral preoptic nucleus in the hypothalamus and the parafacial zone in the brain stem—are involved in prompting SWS. When these cells switch on, it triggers a loss of consciousness. After SWS, REM sleep begins. This mode is bizarre: a dreamer's brain becomes highly active while the body's muscles are paralyzed, and breathing and heart rate become erratic. The purpose of REM sleep remains a biological mystery, despite our growing understanding of its biochemistry and neurobiology. © 2015 Scientific American

Keyword: Sleep
Link ID: 21408 - Posted: 09.15.2015

Patricia Neighmond Are you getting enough sleep, or not enough? If your answer to either of these questions is "yes," you may be at risk of heart disease. Just the right amount of good-quality sleep is key to good heart health, according to researchers at the Center for Cohort Studies at Kangbuk Samsung Hospital and Sungkyunkwan University School of Medicine in Seoul, South Korea. Poor sleep habits may put you at higher risk for early signs of heart disease, even at a relatively young age. The researchers studied more than 47,000 young and middle-aged men and women, average age around 41, who answered questions about how long and how well they slept. Then they had tests to measure their cardiovascular health. Early coronary lesions were detected by measuring the amount of calcium in the arteries of the heart. Stiffness of arteries was measured by the speed of blood coursing through the arteries in the upper arm and ankle. Calcium buildup and arterial stiffness are two important warning signs of oncoming heart disease. Findings showed that adults who slept less than five hours a night had 50 percent more calcium in their coronary arteries than those who slept seven hours. Those who slept nine hours or more a night had even worse outcomes, with 70 percent more coronary calcium compared to those who slept seven hours. © 2015 NPR

Keyword: Sleep
Link ID: 21406 - Posted: 09.14.2015

A study suggests that a chemical in dark chocolate and red wine can slow the progression of Alzheimer’s disease. But how conclusive is the data, and does this mean we should all drink more wine? New Scientist looks at the evidence. What is resveratrol? Found in grapes, red wine and dark chocolate, many claims have been made about resveratrol. It has been touted as a potential panacea for a range of age-related disorders, including cancer, diabetes and neurological problems, but so far most of the data supporting these claims has come from lab studies and work in animals. There have been only a few, small studies in humans. How might resveratrol protect us from age-related illness? Extremely calorie-restricted diets greatly reduce age-related diseases in lab animals. This is thought to happen through the activation of a group of enzymes called sirtuins, which seem to affect gene expression and protect against the effects of stress, including a poor diet. The hope is that resveratrol activates sirtuins to get the same benefits – like preventing the onset of age-related diseases, including Alzheimer’s – without having to stick to such a low-energy diet. But some experiments have suggested slowed ageing from caloric restriction may not be down to sirtuins after all. What does the latest study show? To see if resveratrol could delay the progression of Alzheimer’s disease in people , Scott Turner at Georgetown University Medical Centre in Washington DC and his team gave 119 people with mild to moderate symptoms of the disease either a gram of synthesised resveratrol twice a day in pills for a year, or a placebo. © Copyright Reed Business Information Ltd.

Keyword: Alzheimers
Link ID: 21404 - Posted: 09.14.2015

James Gorman If spiders had nightmares, the larvae of ichneumonid wasps would have to star in them. The wasp lays an egg on the back of an orb weaver spider, where it grows fat and bossy, and occupies itself with turning the spider into a zombie. As Keizo Takasuka and his colleagues point out in The Journal of Experimental Biology, this is a classic case of “host manipulation.” Using more colorful language, he described the larva turning the spider into a “drugged navvy.” The larva forces the spider to turn its efforts away from maintaining a sticky, spiral web to catch prey, and to devote itself to building a safe and sturdy web to serve as a home for the larva’s cocoon, in which it will transform itself into a wasp. This process was well known, but Dr. Takasuka and Kaoru Maeto at Kobe University, working with other Japanese researchers, wanted to explore how the wasp overlords controlled their spiders. They suspected that the larvae were co-opting a natural behavior of the spiders. Turning on a behavior already in the spiders’ repertoire would be much easier than controlling every step of modifying a sticky web. So they compared the cocoon web to one that the spiders themselves build to rest in when they are molting. It’s called a resting web. The similarities were striking. In both the resting and cocoon webs, the sticky, spiraling threads that make the webs of orb weavers so appealing were gone. Instead, the spokes of the web remained, decorated with fibrous spider silk that the researchers found reflected ultraviolet light. That would be a highly useful quality to warn away birds and some large insects from flying into the web because those creatures can see in the ultraviolet spectrum. The strength of the two silk webs was also similar. © 2015 The New York Times Company

Keyword: Miscellaneous; Evolution
Link ID: 21403 - Posted: 09.14.2015

Mo Costandi At some point back in deep time, a group of fish were washed into a limestone cave somewhere in northeastern Mexico. With no way out and little more than bat droppings to eat, the fish began to adapt to their new troglodytic lifestyle. Unable to see other members of their group in the dark, they lost their colourful pigmentation. Then they lost their eyesight, their eyes gradually got smaller, and then disappeared altogether. This was accompanied by a dramatic reduction in the size of the brain’s visual system. Yet, the question of why the blind cave fish lost its eyes and a large part of its brain remains unresolved. Now, biologists in Sweden believe they have found the answer. In new research published today, they report that loss of the visual system saves the fish a substantial amount of energy, and was probably key to their stranded ancestors’ survival. The blind cave fish Astyanax mexicanus is adapted to its subterranean environment in other ways. As its vision regressed, it became more reliant on smell and taste, and its taste buds grew larger and more numerous. They also developed an enhanced ability to detect changes in mechanical pressure, which made them more sensitive to water movements. Last year, Damian Moran of Lund University and his colleagues reported that blind cave fish eliminated the circadian rhythm in their metabolism during their course of evolution, and that this leads to a massive 27% reduction in their energy expenditure. This new study was designed test whether or not they lost their visual system for the same reason. © 2015 Guardian News and Media Limited

Keyword: Evolution; Vision
Link ID: 21401 - Posted: 09.12.2015

Eating two and a half times more than you should will leave you overweight and prone to type 2 diabetes, although no one is entirely sure why. Now a team that fed volunteers a whopping 6000 calories a day have found some clues. Obesity is only one problem caused by eating too much. An overly large food intake can also increase a person’s risk of diabetes, heart disease and some cancers, but no one is sure why this should be the case. Resistance to the hormone insulin seems to play a role. When a healthy person eats a meal, their blood glucose levels rise, and the body responds by making insulin. This hormone prompts the body to store un-needed glucose, but people who develop insulin resistance are not able to absorb excess glucose in the same way. This means that, after eating, their blood glucose levels remain high, and over time, this can damage the kidneys, nervous system and heart, for example. Guenther Boden and Salim Merali at Temple University, Philadelphia, and their team set out to investigate how overeating might lead to insulin resistance. They fed six healthy male volunteers 6000 calories’ worth of food every day for a week – around two and a half times what they should have been eating. “It was a regular, American diet, composed of pizzas, hamburgers and that sort of thing,” says Merali. Each volunteer stayed at a hospital for the duration of the experiment, where they were bed-bound, carefully monitored and prevented from doing any sort of exercise. © Copyright Reed Business Information Ltd.

Keyword: Obesity
Link ID: 21400 - Posted: 09.12.2015

Ever waited for a bus rather than take the short walk to work? Headed for the escalator instead of the stairs? Humans clearly harbour a deep love of lethargy – and now we know how far people will go to expend less energy. We will change our walking style on the fly when our normal gait becomes even a little more difficult. The finding could have implications for the rehabilitation offered to people with spinal injuries. Jessica Selinger and her colleagues at Simon Fraser University in Burnaby, British Columbia, Canada, strapped volunteers into a lightweight robotic exoskeleton and put them on a treadmill. Initially, the team let the volunteers find their preferred walking rhythm – which turned out to be 1.8 steps per second, on average. Then the researchers switched on the exoskeleton, programming it to make it more difficult for the volunteers to walk at their preferred pace by preventing the knee from bending – and leg swinging – as freely. The exoskeleton didn’t interfere with the human guinea pigs’ ability to walk faster or slower than they preferred. Within minutes the volunteers had found a walking style that the exoskeleton would allow without offering resistance. Remarkably, though, they did so despite the fact that the exoskeleton only ever offered minimal resistance. By using breathing masks to analyse the volunteers’ metabolic activity, Selinger’s team found that subjects would shift to an awkward new gait even if the energy saving was only 5 per cent. “People are able to adapt and fine-tune in order to move in the most energetically optimal way,” says Selinger. “People will change really fundamental characteristics of their gait.” © Copyright Reed Business Information Ltd.

Keyword: Movement Disorders
Link ID: 21398 - Posted: 09.11.2015

By JOHN NOBLE WILFORD Acting on a tip from spelunkers two years ago, scientists in South Africa discovered what the cavers had only dimly glimpsed through a crack in a limestone wall deep in the Rising Star Cave: lots and lots of old bones. The remains covered the earthen floor beyond the narrow opening. This was, the scientists concluded, a large, dark chamber for the dead of a previously unidentified species of the early human lineage — Homo naledi. The new hominin species was announced on Thursday by an international team of more than 60 scientists led by Lee R. Berger, an American paleoanthropologist who is a professor of human evolution studies at the University of the Witwatersrand in Johannesburg. The species name, H. naledi, refers to the cave where the bones lay undisturbed for so long; “naledi” means “star” in the local Sesotho language. In two papers published this week in the open-access journal eLife, the researchers said that the more than 1,550 fossil elements documenting the discovery constituted the largest sample for any hominin species in a single African site, and one of the largest anywhere in the world. Further, the scientists said, that sample is probably a small fraction of the fossils yet to be recovered from the chamber. So far the team has recovered parts of at least 15 individuals. “With almost every bone in the body represented multiple times, Homo naledi is already practically the best-known fossil member of our lineage,” Dr. Berger said. The finding, like so many others in science, was the result of pure luck followed by considerable effort. Two local cavers, Rick Hunter and Steven Tucker, found the narrow entrance to the chamber, measuring no more than seven and a half inches wide. They were skinny enough to squeeze through, and in the light of their headlamps they saw the bones all around them. When they showed the fossil pictures to Pedro Boshoff, a caver who is also a geologist, he alerted Dr. Berger, who organized an investigation. © 2015 The New York Times Company

Keyword: Evolution
Link ID: 21396 - Posted: 09.11.2015