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Ewen Callaway Our ancestors were not a picky bunch. Overwhelming genetic evidence shows that Homo sapiens had sex with Neanderthals, Denisovans and other archaic relatives. Now researchers are using large genomics studies to unravel the decidedly mixed contributions that these ancient romps made to human biology — from the ability of H. sapiens to cope with environments outside Africa, to the tendency of modern humans to get asthma, skin diseases and maybe even depression. The proportion of the human genome that comes from archaic relatives is small. The genomes of most Europeans and Asians are 2–4% Neanderthal1, with Denisovan DNA making up about 5% of the genomes of Melanesians2 and Aboriginal Australians3. DNA slivers from other distant relatives probably pepper a variety of human genomes4. But these sequences may have had an outsize effect on human biology. In some cases, they are very different from the corresponding H. sapiens DNA, notes population geneticist David Reich of Harvard Medical School in Boston, Massachusetts — which makes it more likely that they could introduce useful traits. “Even though it’s only a couple or a few per cent of ancestry, that ancestry was sufficiently distant that it punched above its weight,” he says. Last year, Reich co-led one of two teams that catalogued the Neanderthal DNA living on in modern-day humans5, 6. The studies hinted that Neanderthal versions of some genes may have helped Eurasians to reduce heat loss or grow thicker hair. But the evidence that these genes were beneficial was fairly weak. To get a better handle on how Neanderthal DNA shapes human biology, Corinne Simonti and Tony Capra, evolutionary geneticists at Vanderbilt University in Nashville, Tennessee, turned to genome-wide association studies (GWAS) that had already compared thousands of DNA variants in people with and without a certain disease or condition. © 2015 Nature Publishing Group,
Link ID: 21240 - Posted: 07.30.2015
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
By Katie Free Shouting during a nightmare. Struggling to balance a checkbook. A weakened sense of smell. Hallucinations. Chronic constipation. This bizarre mix of symptoms often stumps doctors, but they are some of the telltale signs of Lewy body dementia—the second most common type (after Alzheimer's disease), affecting an estimated 1.4 million Americans. Lewy bodies are protein clumps that kill neurons. Depending on where they cluster in the brain, they can cause either Parkinson's disease or Lewy body dementia, although the two conditions tend to overlap as they progress. Lewy body dementia is more difficult to diagnose and treat, in part because the earliest warning signs have remained unknown. Now a new study finds that certain sensory and motor symptoms can help predict who will acquire the disease, paving the way for targeted studies. Researchers at the Center for Advanced Research in Sleep Medicine (which is associated with the University of Montreal) and at McGill University followed 89 patients with a history of acting out their dreams—not sleepwalking but moving or vocalizing in bed during rapid eye movement (REM) sleep. The failure to suppress such nighttime activity can be an early sign that something is going wrong in the brain; past studies have shown that up to 80 percent of patients who act out their dreams will eventually develop some form of neurodegeneration. Over 10 years the McGill researchers carefully tracked the patients' other potential symptoms of neural disease, such as mild cognitive impairment, depression and movement problems. They found a cluster of symptoms—abnormal color vision, loss of smell and motor dysfunction—that doubled the chance that a person with the REM sleep disorder would develop Parkinson's or Lewy body dementia within three years, according to the study published in February in Neurology. © 2015 Scientific American
Link ID: 21237 - Posted: 07.30.2015
By Sophia Kercher As Kathleen Emmets was undergoing cancer treatment in New York over the past few years, her weight began to drop. Even though she was often nauseated and paralyzed by chemotherapy-induced neuropathy, she joked that thinness was the “bonus of cancer,” and found herself looking in the mirror and admiring her deep and hollow collarbone. Ms. Emmets, now 39, filled her closet with extra-small size clothes. At night she pressed her fingers against her protruding bones, saying to herself, “I’m finally skinny.” But it was only when her cancer treatment changed that it became clear that the body-image issues she had been grappling with since her early 20s — when she would eat next to nothing and walk for six hours a day to deal with stress — had begun to resurface. When the new treatment didn’t make her sick, her appetite returned, and she began to gain weight. But instead of celebrating this sign of improving health, Ms. Emmets says she missed her size 2 jeans and was appalled by her round belly and full breasts. Her husband watched with concern as her body appeared stronger but she began imposing her own food restrictions and started shrinking again. “During your cancer treatment, you have no control over your body — you give up your body to your doctor,” said Ms. Emmets, who wrote about her experiences on the website The Manifest-Station. “You are willing to do it because you want to live. Food restriction is the one thing that you can do to have some sense of control when everything is chaotic.” While it isn’t known how often cancer triggers or reawakens an eating disorder, doctors and nutrition experts who work with cancer patients share anecdotal reports of patients who emerge from a difficult round of cancer treatment and weight loss only to begin struggling with a serious eating disorder that threatens their postcancer health. © 2015 The New York Times Company
Keyword: Anorexia & Bulimia
Link ID: 21236 - Posted: 07.30.2015
by Anil Ananthaswamy Science journalist Anil Ananthaswamy thinks a lot about "self" — not necessarily himself, but the role the brain plays in our notions of self and existence. In his new book, The Man Who Wasn't There, Ananthaswamy examines the ways people think of themselves and how those perceptions can be distorted by brain conditions, such as Alzheimer's disease, Cotard's syndrome and body integrity identity disorder, or BIID, a psychological condition in which a patient perceives that a body part is not his own. Ananthaswamy tells Fresh Air's Terry Gross about a patient with BIID who became so convinced that a healthy leg wasn't his own that he eventually underwent an amputation of the limb. "Within 12 hours, this patient that I saw, he was sitting up and there was no regret. He really seemed fine with having given up his leg," Ananthaswamy says. Ultimately, Ananthaswamy says, our sense of self is a layered one, which pulls information from varying parts of the brain to create a sense of narrative self, bodily self and spiritual self: "What it comes down to is this sense we have of being someone or something to which things are happening. It's there when we wake up in the morning, it kind of disappears when we go to sleep, it reappears in our dreams, and it's also this sense we have of being an entity that spans time." Interview Highlights On how to define "self" When you ask someone, "Who are you?" you're most likely to get a kind of narrative answer, "I am so-and-so, I'm a father, I'm son." They are going to tell you a kind of story they have in their heads about themselves, the story that they tell to themselves and to others, and in some sense that's what can be called the narrative self. ... © 2015 NPR
Link ID: 21235 - Posted: 07.29.2015
By Emily Underwood My childhood hamster, Hamlet, seemed pretty depressed. He didn’t seem to enjoy his colorful cage, complete with a tunnel, wheel, and ramp. The only thing he did with zest was gnaw at the plastic, trying to escape, which he eventually did. A few days later, my mother found him lying on the bathroom floor, dead. I have wondered ever since: Was Hamlet suicidal? Or was he simply displaying normal hamster behavior? Now, a new study suggests a scientific method for gauging hamsters’ emotional states. Hamster emotions don’t just baffle pet owners; they also bedevil scientists who use the fluffballs as subjects in their experiments. One of the most frustrating things about trying to study animal emotion in general is that you can’t take behaviors at face value. If a hamster runs madly on its wheel all night, for example, how do you know if it is running out of joy, or boredom? (Or just for the heck of it.) To bypass that problem, the researchers decided to measure something called judgment bias—essentially, the way that mood affects behavior and decision-making. As humans, our decisions are influenced by our emotions all the time—witness stress-eating, or revenge-shopping. Similar biases have been found in primates, rats, mice, and many other animals, but never before in hamsters. In the experiment, researchers split 30 Syrian hamsters into two groups. One group lived the high life, in cages bedecked with extra toys, ramps, bedding, and hammocks. The second group had the minimum in hamster hospitality, with some light bedding and a wheel. © 2015 American Association for the Advancement of Science.
Link ID: 21234 - Posted: 07.29.2015
By JULIE SCELFO Kathryn DeWitt conquered high school like a gold-medal decathlete. She ran track, represented her school at a statewide girls’ leadership program and took eight Advanced Placement tests, including one for which she independently prepared, forgoing the class. Expectations were high. Every day at 5 p.m. test scores and updated grades were posted online. Her mother would be the first to comment should her grade go down. “I would get home from track and she would say, ‘I see your grade dropped.’ I would say, ‘Mom, I think it’s a mistake.’ And she would say, ‘That’s what I thought.’ ” (The reason turned out to be typing errors. Ms. DeWitt graduated with straight A’s.) In her first two weeks on the University of Pennsylvania campus, she hustled. She joined a coed fraternity, signed up to tutor elementary school students and joined the same Christian group her parents had joined at their alma mater, Stanford. But having gained admittance off the wait list and surrounded by people with seemingly greater drive and ability, she had her first taste of self-doubt. “One friend was a world-class figure skater. Another was a winner of the Intel science competition. Everyone around me was so spectacular and so amazing and I wanted to be just as amazing as they are.” Classmates seemed to have it all together. Every morning, the administration sent out an email blast highlighting faculty and student accomplishments. Some women attended class wearing full makeup. Ms. DeWitt had acne. They talked about their fantastic internships. She was still focused on the week’s homework. Friends’ lives, as told through selfies, showed them having more fun, making more friends and going to better parties. Even the meals they posted to Instagram looked more delicious. Her confidence took another hit when she glanced at the cellphone screen of a male student sitting next to her who was texting that he would “rather jump out of a plane” than talk to his seatmate. © 2015 The New York Times Company
Steve Connor Anxiety and depression could be linked to the presence of bacteria in the intestines, scientists have found. A study on laboratory mice has shown that anxious and depressive behaviour brought on by exposure to stress in early life appears only to be triggered if microbes are present in the gut. The study, published in Nature Communications, demonstrates a clear link between gut microbiota – the microbes living naturally in the intestines – and the triggering of the behavioural signs of stress. “We have shown for the first time in an established mouse model of anxiety and depression that bacteria play a crucial role in inducing this abnormal behaviour,” said Premysl Bercik of McMaster University in Hamilton, Canada, the lead author of the study. The scientists called for further research to see if the conclusions applied to humans, and whether therapies that that target intestinal microbes can benefit patients with psychiatric disorders. Previous research on mice has indicated that gut microbes play an important role in behaviour. For instance, mice with no gut bacteria – called “germ-free” mice – are less likely to show anxiety-like behaviour than normal mice. The latest study looked at mice that had been exposed to a stressful experience in early life, such as being separated from their mothers. When these mice grow up they display anxiety and depression-like behaviour and have abnormal levels of the stress hormone corticosterone in their blood, as well as suffering from gut dysfunction based on the release of the neurotransmitter acetylcholine.
Link ID: 21232 - Posted: 07.29.2015
By Ariana Eunjung Cha The Defense Advanced Research Projects Agency funds a lot of weird stuff, and in recent years more and more of it has been about the brain. Its signature work in this field is in brain-computer interfaces and goes back several decades to its Biocybernetics program, which sought to enable direct communication between humans and machines. In 2013, DARPA made headlines when it announced that it intended to spend more than $70 million over five years to take its research to the next level by developing an implant that could help restore function or memory in people with neuropsychiatric issues. Less known is DARPA's Narrative Networks (or N2) project which aims to better understand how stories — or narratives — influence human behavior and to develop a set of tools that can help facilitate faster and better communication of information. "Narratives exert a powerful influence on human thoughts, emotions and behavior and can be particularly important in security contexts," DARPA researchers explained in a paper published in the Journal of Neuroscience Methods in April. They added that "in conflict resolution and counterterrorism scenarios, detecting the neural response underlying empathy induced by stories is of critical importance." This is where the work on the Hitchcock movies comes in. Researchers at the Georgia Institute of Technology recruited undergraduates to be hooked up to MRI machines and watch movie clips that were roughly three minutes long. The excerpts all featured a character facing a potential negative outcome and were taken from suspenseful movies, including three Alfred Hitchcock flicks as well as "Alien," "Misery," "Munich" and "Cliffhanger," among others.
By C. CLAIBORNE RAY Q. Are men more likely to be claustrophobic than women? A. The opposite seems to be true, as is the case in almost all anxiety disorders, large epidemiological studies have found. The reasons for such a gender difference are not clear, and claustrophobia, the feeling of extreme panic when faced with being in a confined or enclosed space, is not as well studied as some other phobias. One situation that has been comparatively well researched is what happens when people need magnetic resonance imaging, which often involves a prolonged period of confinement in a small enclosure, the perfect storm of claustrophobia triggers. A recent study found that certain factors seem to correlate with an increase in claustrophobic reactions, including being female, going into the scanner head first and having a previous negative experience with the test. Another large study involving scanners with a shorter chamber and noise reduction found a significant reduction in claustrophobic reactions, but being female and middle-aged were still associated with a higher rate of claustrophobia. It has often been assumed that claustrophobia develops as a response to a traumatic experience, like being trapped in a closet as a child, but newer research suggests a genetic component. In one study in mice, a single defective gene was associated with claustrophobia. email@example.com © 2015 The New York Times Company
Victoria E Brings & Mark J Zylka A study finds that pain hypersensitivity in male and female mice is differentially dependent on microglia and T cells, and describes a sex-specific response to microglia-targeted pain treatments. This sex difference will be important to consider when developing treatments for pain and other neurological disorders involving microglia and immune cells. Animal studies1, 2 have spawned great interest in using microglial inhibitors such as minocycline to treat pain in humans. However, these studies were conducted largely on male rodents. Now, Sorge et al.3 have evaluated several microglial inhibitors in nerve-injured mice of both sexes. The study—led by Jeffrey Mogil, who has championed the testing of males and females in pain studies4—found that microglial inhibitors did reduce allodynia, a form of pain hypersensitivity to touch, in males. Surprisingly, however, these inhibitors were ineffective in female mice, despite a robust activation of spinal microglia (Fig. 1). The authors instead found that cells of the adaptive immune system promote pain hypersensitivity in females. Although focused on pain, these findings could have implications for other neurological disorders that disproportionately affect one sex, such as autism and neurodegeneration, and in which microglia and immune cells are implicated5, 6. Figure 1: Pain mechanisms differ in male and female mice. Pain mechanisms differ in male and female mice. Nerve injury activates microglial cells in the spinal cord of male and female mice, but microglial inhibitors only block allodynia in males. P2RX4 is upregulated in males only. Female mice have about twice as many T cells as males. Testosterone increases PPARα and decreases PPARγ gene expression in T cells. Compounds that activate PPARα inhibit mechanical pain hypersensitivity (allodynia) in males, whereas those that activate PPARγ inhibit allodynia in females. © 2015 Macmillan Publishers Limited
By Roni Caryn Rabin “Fat” cartoon characters may lead children to eat more junk food, new research suggests, but there are ways to counter this effect. The findings underscore how cartoon characters, ubiquitous in children’s books, movies, television, video games, fast-food menus and graphic novels, may influence children’s behavior in unforeseen ways, especially when it comes to eating. Researchers first randomly showed 60 eighth graders a svelte jelly-bean-like cartoon character or a similar rotund character and asked them to comment on the images. Then they thanked them and gestured toward bowls of Starburst candies and Hershey’s Kisses, saying, “You can take some candy.” Children who had seen the rotund cartoon character helped themselves to more than double the number of candies as children shown the lean character, taking 3.8 candies on average, compared with 1.7 taken by children shown the lean bean character. (Children in a comparison group shown an image of a coffee mug took 1.5 candies on average.) But activating children’s existing health knowledge can counter these effects, the researchers discovered. In a separate experiment, they showed 167 elementary school children two red Gumby-like cartoon characters, one fat and one thin, and then asked them to “taste test” some cookies. But they also asked the children to “think about things that make you healthy,” such as getting enough sleep versus watching TV, or drinking soda versus milk. Some children were asked the health questions before being given the cookie taste test, while others were asked the questions after the taste test. Remarkably, the children who were asked about healthy habits before doing the taste test ate fewer cookies — even if they had first been exposed to the rotund cartoon character. Those who were shown the rotund figure ate 4.2 cookies on average if they were asked about healthy habits after eating the cookies, compared to three cookies if they were asked about healthy habits before doing the taste test. Children who saw the normal weight character and who were asked about healthy habits after the taste test also ate about three cookies. © 2015 The New York Times Company
By Neuroskeptic According to British biochemist Donald R. Forsdyke in a new paper in Biological Theory, the existence of people who seem to be missing most of their brain tissue calls into question some of the “cherished assumptions” of neuroscience. I’m not so sure. Forsdyke discusses the disease called hydrocephalus (‘water on the brain’). Some people who suffer from this condition as children are cured thanks to prompt treatment. Remarkably, in some cases, these post-hydrocephalics turn out to have grossly abnormal brain structure: huge swathes of their brain tissue are missing, replaced by fluid. Even more remarkably, in some cases, these people have normal intelligence and display no obvious symptoms, despite their brains being mostly water. This phenomenon was first noted by a British pediatrician called John Lorber. Lorber never published his observations in a scientific journal, although a documentary was made about them. However, his work was famously discussed in Science in 1980 by Lewin in an article called “Is Your Brain Really Necessary?“. There have been a number of other more recent published cases. Forsdyke argues that such cases pose a problem for mainstream neuroscience. If a post-hydrocephalic brain can store the same amount of information as a normal brain, he says, then “brain size does not scale with information quantity”, therefore, “it would seem timely to look anew at possible ways our brains might store their information.”
Jon Hamilton Lihong Wang creates the sort of medical technology you'd expect to find on the starship Enterprise. Wang, a professor of biomedical engineering at Washington University in St. Louis, has already helped develop instruments that can detect individual cancer cells in the bloodstream and oxygen consumption deep within the body. He has also created a camera that shoots at 100 billion frames a second, fast enough to freeze an object traveling at the speed of light. "It's really about turning some of these ideas that we thought were science fiction into fact," says Richard Conroy, who directs the Division of Applied Science & Technology at the National Institute of Biomedical Imaging and Bioengineering. Wang's ultimate goal is to use a combination of light and sound to solve the mysteries of the human brain. The brain is a "magical black box we still don't understand," he says. Wang describes himself as a toolmaker. And when President Obama unveiled his BRAIN initiative a couple of years ago to accelerate efforts to understand how we think and learn and remember, Wang realized that brain researchers really needed a tool he'd been working on for years. "We want to conquer the brain," Wang says. "But even for a mouse brain, which is only a few millimeters thick, we really don't have a technique that allows us to see throughout the whole brain." Current brain-imaging techniques such as functional MRI or PET scans all have drawbacks. They're slow, or not sharp enough, or they can only see things near the surface. So Wang has been developing another approach, one he believes will be fast enough to monitor brain activity in real time and sharp enough to reveal an individual brain cell. © 2015 NPR
Keyword: Brain imaging
Link ID: 21226 - Posted: 07.27.2015
The eyes may be windows to the mind, but for children with autism, the body is the better communicator. They are just as good at reading emotions in body language as those without autism. The finding challenges the commonly held notion that children with autism have difficulty reading emotions. This may have arisen from studies focusing on whether people with the condition can interpret emotions from just the face or eyes, says Candida Peterson at the University of Queensland in Australia. “Looking at a face is in itself a problem,” says Peterson. “Autistic children and adults don’t like making eye contact,” she adds, as this requires a close encounter with another person. Reading body language, by contrast, can be done from a distance. In the study, children aged 5 to 12 were shown photos of adults with blurred faces posing in ways to convey happiness, sadness, anger, fear, disgust and surprise. Those with autism were just as good as those without at recognising the emotions. But this is only part of the picture. People with autism also have difficulty changing their behaviour in response to others’ emotions, says Julie Grezes at INSERM’s Laboratory of Cognitive Neurosciences in Paris, France. When most people recognise that someone is experiencing a certain emotion, they are able to put themselves in their place to understand why they might be feeling that way. People with autism are known to struggle with this. Now we know that they can read body language, says Peterson, we can look for ways to help them link certain cues to what the other person might be thinking and feeling. She and her colleagues now plan to test how good children with autism are at reading body language cues in real-life interactions, in particular when they are faced with individuals in extremely emotional states. Journal reference: Journal of Experimental Child Psychology, doi.org/6dp © Copyright Reed Business Information Ltd.
Link ID: 21225 - Posted: 07.27.2015
By Jane E. Brody Barrett Treadway, now 3½, has never been the best of sleepers, but her sleep grew increasingly worse in the last year and a half. She gets up several times a night, often climbs into her parents’ bed and creates havoc with their nights. “We’ve known for a long time that she snores, but until a mother-daughter trip in May when we shared a bed, I didn’t realize that this was not simply snoring,” her mother, Laura, told me. “She repeatedly stopped breathing, then started again with a loud snort that often woke her up and kept me up all night.” Barrett has sleep apnea, a condition most often diagnosed in adults and usually associated with obesity. But neither of those attributes describes Barrett, who is young and lithe, although the condition is somewhat more common in overweight children. In most cases, the problem results when, during sleep, the child’s airway is temporarily obstructed by enlarged tonsils or adenoids or both — lymphoid tissues in the back of the throat — hence the name obstructive sleep apnea. When breathing stops for 10 or more seconds, the rising blood level of carbon dioxide prompts the brain to take over and restart breathing, typically accompanied by a loud snore or snort. Rarely, a child may have what is called central sleep apnea, in which the brain temporarily fails to signal the muscles that control breathing. Experts say that between 1 percent and 3 percent of children have sleep apnea that, if untreated, can disrupt far more than a family’s restful nights. Affected children simply do not get enough restorative sleep to assure normal development. If not corrected, the condition can result in hyperactivity and attention problems in school that are often mistaken for attention deficit hyperactivity disorder (A.D.H.D.) and sometimes mistreated with a stimulant that only makes matters worse. © 2015 The New York Times Company
By Karen Weintraub Can I ever re-pay my sleep debt? (I estimate it at 15 years of poor sleep.) It is unclear whether you can make up a long-term sleep debt, because most studies have looked at the effects of sleep loss and recovery only over a few nights or weeks, said Dr. Matt T. Bianchi, the chief of the division of sleep medicine at Massachusetts General Hospital and an assistant professor of neurology at Harvard Medical School. Simulated driving performance and reaction times are affected by just one sleepless night, research has shown. There’s no doubt that sleeping just four hours a night catches up to people within a few nights, leading to impairments of attention, learning and memory and worse performance in school and at work. And making up for lost sleep over the weekend doesn’t work. Five brief nights quickly add up to a shortfall of 20 hours, but people don’t sleep more than five to 10 extra hours to compensate, Dr. Bianchi said. “The interpretation has been you can’t pay off your sleep debt, you just carry it with you,” though it’s also possible that people don’t sleep an extra 20 hours because they don’t need it, Dr. Bianchi said. He cited research by Jim Horne of Loughborough University in Britain showing that a timely nap of less than 20 minutes can equate to an extra hour of nighttime sleep. Different people need somewhat different amounts of sleep, but anything less than six hours a night is definitely not enough, said Dr. Charles Czeisler, a professor of sleep medicine at Harvard. In one sleep study, people were brought into a lab and required to stay in bed for 14 hours a day. They slept 10 to 12 hours a night at first, Dr. Czeisler said. Then they gradually slept less over the next few weeks until they stabilized at about 8.4 hours per night. © 2015 The New York Times Company
Link ID: 21223 - Posted: 07.27.2015
Alexandra Sims Intelligent people are not only smarter than the average person - it seems they could also live longer as well. A study by the London School of Economics found that smarter siblings are more likely to outlive their less clever brothers and sisters, with genetics accounting for 95 per cent of the connection between intelligence and life span. The scientists examined the differences in longevity between identical twins, who share all of their genes and non-identical twins, who on average share half of their genes. Writing in the International Journal of Epidemiology, scientists noted the difference in intellect between the twins and the age at which they died. Focusing on three different twin studies from Sweden, Denmark and the United States the researchers examined sets of twins for whom both intelligence and age of death had been recorded in pairs where at least one of the twins had died. In both types of twins it was found that the smarter of the two lived longer, but this effect was far more prominent in non-identical twins. Rosalind Arden, a research associate at the LSE, told The Times that "the association between top jobs and longer lifespans is more a result of genes than having a big desk.” She added though that the research does not mean parents can "deduce your child’s likely lifespan from how he or she does in their exams this summer”.
By Claire Asher City folk have a reputation for being less friendly than their rural counterparts, and the same appears to be true for garden birds. Urban song sparrows (Melospiza melodia, pictured) are more aggressive toward their neighbors than are sparrows out in the country, researchers report this month in Behavioral Ecology. But whereras the temperament of human city-dwellers is often attributed to the sheer density of people, this isn’t the case for sparrows. The team measured birds’ responses to recordings of another male’s song, noting how often males approached or attacked the speakers, and found that aggression depended not on the density of sparrows, but on the availability of food in the environment. Counterintuitively, male sparrows responded more aggressively in the city, where there tends to be more food, and rural birds became more aggressive when provided with food supplements. The authors explain that the sparrows defend food-rich, high-quality territories more aggressively, but it isn’t clear whether this is an offensive or a defensive strategy; city birds may be more aggressive because a territory with more food is more valuable to them, or because their abundant resources attract more thieves. © 2015 American Association for the Advancement of Science.
Link ID: 21221 - Posted: 07.27.2015