Chapter 16. None

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Scientists say they have found a gene that causes a rare but inherited form of multiple sclerosis. It affects about one in every thousand MS patients and, according to the Canadian researchers, is proof that the disease is passed down generations. Experts have long suspected there's a genetic element to MS, but had thought there would be lots of genes involved, as well as environmental factors. The finding offers hope of targeted screening and therapy, Neuron reports. The University of British Columbia studied the DNA of hundreds of families affected by MS to hunt for a culprit gene. They found it in two sets of families containing several members with a rapidly progressive type of MS. In these families, 70% of the people with the mutation developed the disease. Although other factors may still be important and necessary to trigger the disease process, the gene itself is a substantial causative risk factor that is passed down from parents to their children, say the researchers. The mutation is in a gene called NR1H3, which makes a protein that acts as a switch controlling inflammation. In MS the body's immune system mistakenly attacks the protective layer of myelin that surrounds nerve fibres in the brain and spinal cord, leading to muscle weakness and other symptoms. Studies in mice show that knocking out the function of the same gene leads to neurological problems and decreased myelin production. © 2016 BBC.

Keyword: Multiple Sclerosis; Genes & Behavior
Link ID: 22278 - Posted: 06.02.2016

By Simon Makin Other species are capable of displaying dazzling feats of intelligence. Crows can solve multistep problems. Apes display numerical skills and empathy. Yet, neither species has the capacity to conduct scientific investigations into other species' cognitive abilities. This type of behavior provides solid evidence that humans are by far the smartest species on the planet. Besides just elevated IQs, however, humans set themselves apart in another way: Their offspring are among the most helpless of any species. A new study, published recently in Proceedings of the National Academy of Sciences (PNAS), draws a link between human smarts and an infant’s dependency, suggesting one thing led to the other in a spiraling evolutionary feedback loop. The study, from psychologists Celeste Kidd and Steven Piantadosi at the University of Rochester, represents a new theory about how humans came to possess such extraordinary smarts. Like a lot of evolutionary theories, this one can be couched in the form of a story—and like a lot of evolutionary stories, this one is contested by some scientists. Kidd and Piantadosi note that, according to a previous theory, early humans faced selection pressures for both large brains and the capacity to walk upright as they moved from forest to grassland. Larger brains require a wider pelvis to give birth whereas being bipedal limits the size of the pelvis. These opposing pressures—biological anthropologists call them the “obstetric dilemma”—could have led to giving birth earlier when infants’ skulls were still small. Thus, newborns arrive more immature and helpless than those of most other species. Kidd and Piantadosi propose that, as a consequence, the cognitive demands of child care increased and created evolutionary pressure to develop higher intelligence. © 2016 Scientific American

Keyword: Development of the Brain; Evolution
Link ID: 22277 - Posted: 06.02.2016

Amanda Aronczyk At first Giselle wasn't sure what to put on her medical school application. She wanted to be a doctor, but she also wanted people to know about her own health: years of depression, anxiety and a suicide attempt. (We're using only her first name in this story, out of concern for her future career.) "A lot of people were like, you don't say that at all," she said. "Do not mention that you have any kind of weakness." Giselle remembers having her first intense suicidal thoughts when she was 10 years old. Her parents had split up and she had moved from the coast of Colombia to Chicago. She started having extreme mood swings and fighting with her mom. And then, when she was 16 years old, she tried to kill herself. "Yeah, lots of pills." After her suicide attempt she began therapy and eventually started taking antidepressants. That worked extremely well. After finishing high school, she took an unconventional route. She went to Brazil to work with a women's community health group, worked as a research assistant for a doctor, and trained as a doula to assist women in labor. It was while working as a doula and witnessing what she saw as insensitive behavior from a doctor that she resolved her own career indecision: She would become a different kind of doctor. When she applied to medical school, she told them this whole story in her application. In the fall of 2014, she started at the University of Wisconsin School of Medicine and Public Health. © 2016 npr

Keyword: Depression
Link ID: 22276 - Posted: 06.02.2016

By Mark Gollom, Anti-smoking advocates who support the Liberal government's proposal to require plain packaging on tobacco products argue that Australia's implementation of similar regulations has had a significant effect on smoking rates in that country. "Australia has seen the biggest decline in smoking prevalence that they've ever recorded after plain packing [was introduced]," said David Hammond, an associate professor of public health and health systems at the University of Waterloo. "All the data we have suggest that plain packing has reduced smoking in Australia." Rob Cunningham, senior policy analyst for the Canadian Cancer Society, agrees and says research supports the effectiveness of plain packaging. "If it wasn't effective, the tobacco companies wouldn't be so strongly opposed," he said. "And it's precisely because it's going to have an effect on sales that they are going to lobby hard against it, threaten legal cases." But not everyone believes that Australia's policy of imposing bland tobacco branding has done much to deter smoking, which has been steadily declining for decades, according to Julian Morris, vice-president of research at the libertarian think tank the Reason Foundation. "The decline in smoking seems to have been continuous and not dramatically effected, one way or the other, by the introduction of plain packaging," he said. ©2016 CBC/Radio-Canada.

Keyword: Drug Abuse
Link ID: 22274 - Posted: 06.02.2016

By Ann Lukits Teens who baby-sit may not only gain confidence in caring for young children, they may also alter their brain chemistry in a way that could make them better parents, suggests an animal study in Developmental Psychobiology. Young female rats housed with various groups of unrelated rat pups had fully developed mothering skills as adults, compared with control rats without caregiving, or alloparenting, experience. The early caregivers had significantly higher concentrations of tryptophan hydroxylase-2 (TPH2) in the brain, an enzyme associated with increased production of serotonin, a chemical involved in mood and social behavior. Previous research has associated baby-sitting experience in humans with greater confidence in new mothers, researchers said. Experiments at Michigan State University involved two groups of juvenile or adolescent female rats from 16 litters. In one group, 24 rats were housed in separate cages with a different group of week-old pups each day. A second group of 24 controls were given pink pup-size pencil erasers. The experiments continued for 14 days. Eight mature rats from both groups were subsequently exposed to new groups of pups. Six rats with alloparenting experience acted maternally toward the pups, whereas none of the control rats exhibited maternal behavior. Rats with alloparenting experience also displayed less anxiety during behavioral testing. The animals were euthanized after testing and TPH2 levels measured in a section of the brain called the dorsal raphe nucleus. ©2016 Dow Jones & Company, Inc

Keyword: Sexual Behavior
Link ID: 22273 - Posted: 06.01.2016

By David Z. Hambrick If you’re a true dog lover, you take it as one of life’s simple truths that all dogs are good, and you have no patience for scientific debate over whether dogs really love people. Of course they do. What else could explain the fact that your dog runs wildly in circles when you get home from work, and, as your neighbors report, howls inconsolably for hours on end when you leave? What else could explain the fact that your dog insists on sleeping in your bed, under the covers—in between you and your partner? At the same time, there’s no denying that some dogs are smarter than others. Not all dogs can, like a border collie mix named Jumpy, do a back flip, ride a skateboard, and weave through pylons on his front legs. A study published in the journal Intelligence by British psychologists Rosalind Arden and Mark Adams confirms as much. Consistent with over a century of research on human intelligence, Arden and Adams found that a dog that excels in one test of cognitive ability will likely excel in other tests of cognitive ability. In more technical terms, the study reveals that there is a general factor of intelligence in dogs—a canine “g” factor. For their study, Arden and Adams devised a battery of canine cognitive ability tests. All of the tests revolved around—you guessed it—getting a treat. In the detour test, the dog’s objective was to navigate around barriers arranged in different configurations to get to a treat. In the point-following test, a researcher pointed to one of two inverted beakers concealing a treat, and recorded whether the dog went to that beaker or the other one. Finally, the quantity discrimination test required the dog to choose between a small treat (a glob of peanut butter) and a larger one (the “correct” answer). Arden and Adams administered the battery to 68 border collies from Wales; all had been bred and trained to do herding work on a farm, and thus had similar backgrounds. © 2016 Scientific American

Keyword: Intelligence; Evolution
Link ID: 22272 - Posted: 06.01.2016

By Frances Marcellin A shirt and cap that can diagnose epilepsy quickly and easily has been approved for use by European health services, including the UK’s NHS. Epileptic seizures are the result of excessive electrical discharges in the brain. The World Health Organization estimates that over 50 million people worldwide have the condition, including 6 million in Europe, making it one of the world’s most common serious neurological conditions. Brain implants and apps have been developed to warn of oncoming seizures. But to diagnose the condition, someone must typically have a seizure recorded by an EEG machine in a hospital – with sensors and wires attached to the scalp. “An EEG reading is at the heart of a reliable diagnosis,” says Françoise Thomas-Vialettes, president of French epilepsy society EFAPPE. But seizures rarely coincide with hospital appointments. “The diagnosis can take several years and is often imprecise.” Seizures are so difficult to record that 30 per cent of people with epilepsy in Europe are misdiagnosed. In developing countries that lack medical equipment and healthcare the situation is even worse. To make diagnosis easier, French start-up BioSerenity has developed a smart outfit called the Neuronaute that monitors people as they go about their day. The shirt and cap are embedded with biometric sensors that record the electrical activity of the wearer’s brain, heart and muscles. If a seizure occurs, the outfit can send an EEG recording of the brain to doctors via a smartphone. © Copyright Reed Business Information Ltd.

Keyword: Epilepsy
Link ID: 22271 - Posted: 06.01.2016

Amy McDermott Giant pandas have better ears than people — and polar bears. Pandas can hear surprisingly high frequencies, conservation biologist Megan Owen of the San Diego Zoo and colleagues report in the April Global Ecology and Conservation. The scientists played a range of tones for five zoo pandas trained to nose a target in response to sound. Training, which took three to six months for each animal, demanded serious focus and patience, says Owen, who called the effort “a lot to ask of a bear.” Both males and females heard into the range of a “silent” ultrasonic dog whistle. Polar bears, the only other bears scientists have tested, are less sensitive to sounds at or above 14 kilohertz. Researchers still don’t know why pandas have ultrasonic hearing. The bears are a vocal bunch, but their chirps and other calls have never been recorded at ultrasonic levels, Owen says. Great hearing may be a holdover from the bears’ ancient past. Citations M.A. Owen et al. Hearing sensitivity in context: Conservation implications for a highly vocal endangered species. Global Ecology and Conservation. Vol. 6, April 2016, p. 121. doi: 10.1016/j.gecco.2016.02.007. © Society for Science & the Public 2000 - 2016.

Keyword: Hearing
Link ID: 22269 - Posted: 06.01.2016

What do large tables, large breakfasts, and large servers have in common? They all affect how much you eat. This week on Hidden Brain, we look at the hidden forces that drive our diets. First we hear from Adam Brumberg at Cornell University's Food and Brand Lab about how to make healthier choices more easily (hint: good habits and pack your lunch!). Then, Senior (Svelte) Stopwatch Correspondent Daniel Pink returns for another round of Stopwatch Science to tell you about those tables, breakfasts, and servers. If you don't like spoilers, stop reading and go listen to the episode! Here are the studies: You may have heard that smaller portions can help you eat fewer calories. That's true. But what about larger tables? Researchers Brennan Davis, Collin Payne, and My Bui hypothesized that one of the ways smaller food units lead us to eat less is by playing with our perception. They tested this with pizza and found that while study participants tended to eat more small slices, they consumed fewer calories overall because it seemed like they were eating more. The researchers tried to distort people's perception even further by making the smaller slices seem bigger by putting them on a bigger table. What they found is that even hungry college students at fewer calories of (free) pizza when it was chopped into tiny slices and put on a big table. What about who's around that big table? That seems to matter, too. Researchers found both men and women order more food when they eat with women but choose smaller portions when they eat in the company of men. They say breakfast is the most important meal of the day. Well, it may also be the most slimming. When researchers assigned two groups of overweight women to eat a limited number of calories each day, they found those who ate more at breakfast and less at dinner shed about twice as many pounds as the other group. © 2016 npr

Keyword: Obesity
Link ID: 22266 - Posted: 05.31.2016

By Viviane Callier Bees don’t just recognize flowers by their color and scent; they can also pick up on their minute electric fields. Such fields—which form from the imbalance of charge between the ground and the atmosphere—are unique to each species, based on the plant’s distance from the ground and shape. Flowers use them as an additional way to advertise themselves to pollinators, but until now researchers had no idea how bees sensed these fields. In a new study, published online today in the Proceedings of the National Academy of Sciences, researchers used a laser vibrometer—a tiny machine that hits the bee hair with a laser—to measure how the hair on a bee’s body responds to a flower’s tiny electric field. As the hair moves because of the electric field, it changes the frequency of the laser light that hits it, allowing the vibrometer to keep track of the velocity of motion of the hair. When the bees buzzed within 10 centimeters of the flower, the electric field—like static electricity from a balloon—caused the bee’s hair to bend. This bending activates neurons at the base of bee hair sockets, which allows the insects to “sense” the field, the team found. Electric fields can only be sensed from a distance of 10 cm or so, so they’re not very useful for large animals like ourselves. But for small insects, this distance represents several body lengths, a relatively long distance. Because sensing such fields is useful to small animals, the team suspects this ability could be important to other insect species as well. © 2016 American Association for the Advancement of Science.

Keyword: Pain & Touch
Link ID: 22263 - Posted: 05.31.2016

By Jane E. Brody Joanne Reitano is a professor of history at LaGuardia Community College in Long Island City, Queens. She writes wonderful books about the history of the city and state, and has recently been spending many hours — sometimes all day — at her computer to revise her first book, “The Restless City.” But while sitting in front of the screen, she told me, “I developed burning in my eyes that made it very difficult to work.” After resting her eyes for a while, the discomfort abates, but it quickly returns when she goes back to the computer. “If I was playing computer games, I’d turn off the computer, but I need it to work,” the frustrated professor said. Dr. Reitano has a condition called computer vision syndrome. She is hardly alone. It can affect anyone who spends three or more hours a day in front of computer monitors, and the population at risk is potentially huge. Worldwide, up to 70 million workers are at risk for computer vision syndrome, and those numbers are only likely to grow. In a report about the condition written by eye care specialists in Nigeria and Botswana and published in Medical Practice and Reviews, the authors detail an expanding list of professionals at risk — accountants, architects, bankers, engineers, flight controllers, graphic artists, journalists, academicians, secretaries and students — all of whom “cannot work without the help of computer.” And that’s not counting the millions of children and adolescents who spend many hours a day playing computer games. Studies have indicated 70 percent to 90 percent of people who use computers extensively, whether for work or play, have one or more symptoms of computer vision syndrome. The effects of prolonged computer use are not just vision-related. Complaints include neurological symptoms like chronic headaches and musculoskeletal problems like neck and back pain. © 2016 The New York Times Company

Keyword: Vision
Link ID: 22262 - Posted: 05.30.2016

By C. CLAIBORNE RAY Q. Does the size of an animal’s brain really correlate with intelligence on a species-by-species basis? A. “It’s not necessarily brain size but rather the ratio of brain size to body size that really tells the story,” said Rob DeSalle, a curator at the Sackler Institute for Comparative Genomics at the American Museum of Natural History. Looking at this ratio over a large number of vertebrate animals, he said, scientists have found that “brain size increases pretty linearly with body size, except for some critical species like Homo sapiens and some cetaceans,” the order of mammals that includes whales, dolphins and porpoises. “So if there is a deviation from this general ratio, one can predict how smart a vertebrate might be,” Dr. DeSalle continued. Therefore, living vertebrates that deviate so that their brains are inordinately bigger compared with their bodies are for the most part smarter, he said. As for dinosaurs, he said, scientists really can’t tell how smart they may have been. “But the Sarmientosaurus, with its lime-sized brain, was a big animal, so the extrapolation is that it would have been pretty dense,” he said. “On the other hand, Troodon, a human-sized dinosaur, had a huge brain relative to its body size and is widely considered the smartest dinosaur ever found.” © 2016 The New York Times Company

Keyword: Evolution
Link ID: 22261 - Posted: 05.30.2016

By Roland Pease BBC Radio Science Unit Researchers have invented a DNA "tape recorder" that can trace the family history of every cell in an organism. The technique is being hailed as a breakthrough in understanding how the trillions of complex cells in a body are descended from a single egg. "It has the potential to provide profound insights into how normal, diseased or damaged tissues are constructed and maintained," one UK biologist told the BBC. The work appears in Science journal. The human body has around 40 trillion cells, each with a highly specialised function. Yet each can trace its history back to the same starting point - a fertilised egg. Developmental biology is the business of unravelling how the genetic code unfolds at each cycle of cell division, how the body plan develops, and how tissues become specialised. But much of what it has revealed has depended on inference rather than a complete cell-by-cell history. "I actually started working on this problem as a graduate student in 2000," confessed Jay Shendure, lead researcher on the new scientific paper. "Could we find a way to record these relationships between cells in some compact form we could later read out in adult organisms?" The project failed then because there was no mechanism to record events in a cell's history. That changed with recent developments in so called CRISPR gene editing, a technique that allows researchers to make much more precise alterations to the DNA in living organisms. The molecular tape recorder developed by Prof Shendure's team at the University of Washington in Seattle, US, is a length of DNA inserted into the genome that contains a series of edit points which can be changed throughout an organism's life. © 2016 BBC.

Keyword: Development of the Brain; Neurogenesis
Link ID: 22259 - Posted: 05.28.2016

By BENEDICT CAREY Suzanne Corkin, whose painstaking work with a famous amnesiac known as H.M. helped clarify the biology of memory and its disorders, died on Tuesday in Danvers, Mass. She was 79. Her daughter, Jocelyn Corkin, said the cause was liver cancer. Dr. Corkin met the man who would become a lifelong subject and collaborator in 1964, when she was a graduate student in Montreal at the McGill University laboratory of the neuroscientist Brenda Milner. Henry Molaison — known in published reports as H.M., to protect his privacy — was a modest, middle-aged former motor repairman who had lost the ability to form new memories after having two slivers of his brain removed to treat severe seizures when he was 27. In a series of experiments, Dr. Milner had shown that a part of the brain called the hippocampus was critical to the consolidation of long-term memories. Most scientists had previously thought that memory was not dependent on any one cortical area. Mr. Molaison lived in Hartford, and Dr. Milner had to take the train down to Boston and drive from there to Connecticut to see him. It was a long trip, and transporting him to Montreal proved to be so complicated, largely because of his condition, that Dr. Milner did it just once. Yet rigorous study of H.M., she knew, would require proximity and a devoted facility — with hospital beds — to accommodate extended experiments. The psychology department at the Massachusetts Institute of Technology offered both, and with her mentor’s help, Dr. Corkin landed a position there. Thus began a decades-long collaboration between Dr. Corkin and Mr. Molaison that would extend the work of Dr. Milner, focus intense interest on the hippocampus, and make H.M. the most famous patient in the history of modern brain science. © 2016 The New York Times Company

Keyword: Learning & Memory
Link ID: 22258 - Posted: 05.28.2016

Martha Bebinger Labels for the first long-acting opioid addiction treatment device are rolling off printing machines Friday. Trainings begin Saturday for doctors who want to learn to insert four matchstick-size rods under the skin. They contain the drug buprenorphine, which staves off opioid cravings. The implant, called Probuphine, was approved by the Food and Drug Administration on Thursday, and is expected to be available to patients by the end of June. "This is just the starting point for us to continue to fight for the cause of patients with opioid addiction," said Behshad Sheldon, CEO of Braeburn Pharmaceuticals, which manufactures Probuphine. But debate continues about how effective the implant will be and whether insurers will cover it. Nora Volkow, head of the National Institute on Drug Abuse, calls Probuphine a game changer, saying it will help addiction patients stay on their meds while their brain circuits recover from the ravages of drug use. And addiction experts say it will be much harder for patients prescribed the implant to sell their medication on the street, which can be a problem with addiction patients prescribed pills. "I think it's fantastic news," said Dr. Sarah Wakeman, medical director of the Substance Use Disorder Initiative at Massachusetts General Hospital. "We need as many tools in the toolbox as possible to deal with the opioid epidemic." © 2016 npr

Keyword: Drug Abuse
Link ID: 22256 - Posted: 05.28.2016

By RUSSELL GOLDMAN There’s an elephant at a zoo outside Seoul that speaks Korean. — You mean, it understands some Korean commands, the way a dog can be trained to understand “sit” or “stay”? No, I mean it can actually say Korean words out loud. — Pics or it didn’t happen. Here, watch the video. To be fair, the elephant, a 26-year-old Asian male named Koshik, doesn’t really speak Korean, any more than a parrot can speak Korean (or English or Klingon). But parrots are supposed to, well, parrot — and elephants are not. And Koshik knows how to say at least five Korean words, which are about five more than I do. The really amazing part is how he does it. Koshik places his trunk inside his mouth and uses it to modulate the tone and pitch of the sounds his voice makes, a bit like a person putting his fingers in his mouth to whistle. In this way, Koshik is able to emulate human speech “in such detail that Korean native speakers can readily understand and transcribe the imitations,” according to the journal Current Biology. What’s in his vocabulary? Things he hears all the time from his keepers: the Korean words for hello, sit down, lie down, good and no. Elephant Speaks Korean | Video Video by LiveScienceVideos Lest you think this is just another circus trick that any Jumbo, Dumbo or Babar could pull off, the team of international scientists who wrote the journal article say Koshik’s skills represent “a wholly novel method of vocal production and formant control in this or any other species.” Like many innovations, Koshik’s may have been born of sad necessity. Researchers say he started to imitate his keepers’s sounds only after he was separated from other elephants at the age of 5 — and that his desire to speak like a human arose from sheer loneliness. © 2016 The New York Times Company

Keyword: Language; Animal Communication
Link ID: 22253 - Posted: 05.26.2016

By Teal Burrell In neuroscience, neurons get all the glory. Or rather, they used to. Researchers are beginning to discover the importance of something outside the neurons—a structure called the perineuronal net. This net might reveal how memories are stored and how various diseases ravage the brain. The realization of important roles for structures outside neurons serves as a reminder that the brain is a lot more complicated than we thought. Or, it’s exactly as complicated as neuroscientists thought it was 130 years ago. In 1882, Italian physician and scientist Camillo Golgi described a structure that enveloped cells in the brain in a thin layer. He later named it the pericellular net. His word choice was deliberate; he carefully avoided the word “neuron” since he was engaged in a battle with another neuroscience luminary, Santiago Ramón y Cajal, over whether the nervous system was a continuous meshwork of cells that were fused together—Golgi’s take—or a collection of discrete cells, called neurons—Ramón y Cajal’s view. Ramón y Cajal wasn’t having it. He argued Golgi was wrong about the existence of such a net, blaming the findings on Golgi’s eponymous staining technique, which, incidentally, is still used today. Ramón y Cajal’s influence was enough to shut down the debate. While some Golgi supporters labored in vain to prove the nets existed, their findings never took hold. Instead, over the next century, neuroscientists focused exclusively on neurons, the discrete cells of the nervous system that relay information between one another, giving rise to movements, perceptions, and emotions. (The two adversaries would begrudgingly share a Nobel Prize in 1906 for their work describing the nervous system.) © 1996-2016 WGBH Educational Foundation

Keyword: Glia
Link ID: 22252 - Posted: 05.26.2016

Bradley George All sorts of health information is now a few taps away on your smartphone, from how many steps you take — to how well you sleep at night. But what if you could use your phone and a computer to test your vision? A company is doing just that — and eye care professionals are upset. Some states have even banned it. A Chicago-based company called Opternative offers the test. The site asks some questions about your eyes and overall health; it also wants to know your shoe size to make sure you're the right distance from your computer monitor. You keep your smartphone in your hand and use the Web browser to answer questions about what you see on the computer screen. Like a traditional eye test, there are shapes, lines and letters. It takes about 30 minutes. "We're trying to identify how bad your vision is, so we're kind of testing your vision to failure, is the way I would describe it," says Aaron Dallek, CEO of Opternative. Dallek co-founded the company with an optometrist, who was searching for ways to offer eye exams online. "Me being a lifetime glasses and contact wearer, I was like 'Where do we start?' So, that was about 3 1/2 years ago, and we've been working on it ever since," Dallek says. © 2016 npr

Keyword: ADHD
Link ID: 22250 - Posted: 05.26.2016

Susan Milius Forget it, peacocks. Nice try, elk. Sure, sexy feathers and antlers are showy, but the sperm of a fruit fly could be the most over-the-top, exaggerated male ornamentation of all. In certain fruit fly species, such as Drosophila bifurca, males measuring just a few millimeters produce sperm with a tail as long as 5.8-centimeters, researchers report May 25 in Nature. Adjusted for body size, the disproportionately supersized sperm outdoes such exuberant body parts as pheasant display feathers, deer antlers, scarab beetle horns and the forward-grasping forceps of earwigs. Fruit flies’ giant sperm have been challenging to explain, says study coauthor Scott Pitnick of Syracuse University in New York. Now he and his colleagues propose that a complex interplay of male and female benefits has accelerated sperm length in a runaway-train scenario. Males with longer sperm deliver fewer sperm, bucking a more-is-better trend. Yet, they still manage to transfer a few dozen to a few hundred per mating. And as newly arrived sperm compete to displace those already waiting in a female’s storage organ, longer is better. Fewer sperm per mating means females tend to mate more often, intensifying the sperm-vs.-sperm competition. Females that have the longest storage organs, which favor the longest sperm, benefit too: Males producing megasperm, the researchers found, tend to be the ones with good genes likely to produce robust offspring. “Sex,” says Pitnick, “is a powerful force.” © Society for Science & the Public 2000 - 2016

Keyword: Sexual Behavior; Evolution
Link ID: 22249 - Posted: 05.26.2016

by Helen Thompson In hunting down delicious fish, Flipper may have a secret weapon: snot. Dolphins emit a series of quick, high-frequency sounds — probably by forcing air over tissues in the nasal passage — to find and track potential prey. “It’s kind of like making a raspberry,” says Aaron Thode of the Scripps Institution of Oceanography in San Diego. Thode and colleagues tweaked a human speech modeling technique to reproduce dolphin sounds and discern the intricacies of their unique style of sound production. He presented the results on May 24 in Salt Lake City at the annual meeting of the Acoustical Society of America. Dolphin chirps have two parts: a thump and a ring. Their model worked on the assumption that lumps of tissue bumping together produce the thump, and those tissues pulling apart produce the ring. But to match the high frequencies of live bottlenose dolphins, the researchers had to make the surfaces of those tissues sticky. That suggests that mucus lining the nasal passage tissue is crucial to dolphin sonar. The vocal model also successfully mimicked whistling noises used to communicate with other dolphins and faulty clicks that probably result from inadequate snot. Such techniques could be adapted to study sound production or echolocation in sperm whales and other dolphin relatives. © Society for Science & the Public 2000 - 2016.

Keyword: Hearing
Link ID: 22244 - Posted: 05.25.2016