Most Recent Links

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 21 - 40 of 19333

By Smitha Mundasad Health reporter, BBC News Scientists have discovered a central hub of brain cells that may put the brakes on a desire to eat, a study in mice shows. And switching on these neurons can stop feeding immediately, according to the Nature Neurosciences report. Researchers say the findings may one day contribute to therapies for obesity and anorexia. Experts say this sheds light on the many complex nerve circuits involved in appetite control. Scientists from the California Institute of Technology suggest the nerve cells act as a central switchboard, combining and relaying many different messages in the brain to help reduce food intake. Using laser beams they were able to stimulate the neurons - leading to a complete and immediate stop to food consumption. Prof David Anderson, lead author of the study told the BBC: "It was incredibly surprising. "It was like you could just flick a switch and prevent the animals from feeding." Researchers then used chemicals to mimic a variety of scenarios - including feelings of satiety, malaise, nausea and a bitter taste. They found the neurons were active in all situations, suggesting they may be integral in the response to many diverse stimuli. BBC © 2014

Keyword: Obesity
Link ID: 19887 - Posted: 07.28.2014

|By James Phillips Our inner ear is a marvel. The labyrinthine vestibular system within it is a delicate, byzantine structure made up of tiny canals, crystals and pouches. When healthy, this system enables us to keep our balance and orient ourselves. Unfortunately, a study in the Archives of Internal Medicine found that 35 percent of adults over age 40 suffer from vestibular dysfunction. A number of treatments are available for vestibular problems. During an acute attack of vertigo, vestibular suppressants and antinausea medications can reduce the sensation of motion as well as nausea and vomiting. Sedatives can help patients sleep and rest. Anti-inflammatory drugs can reduce any damage from acute inflammation and antibiotics can treat an infection. If a structural change in the inner ear has loosened some of its particulate matter—for instance, if otolith (calcareous) crystals, which are normally in tilt-sensitive sacs, end up in the semicircular canals, making the canals tilt-sensitive—simple repositioning exercises in the clinic can shake the loose material, returning it where it belongs. After a successful round of therapy, patients no longer sense that they are tilting whenever they turn their heads. If vertigo is a recurrent problem, injecting certain medications can reduce or eliminate the fluctuating function in the affected ear. As a last resort, a surgeon can effectively destroy the inner ear—either by directly damaging the end organs or by cutting the eighth cranial nerve fibers, which carry vestibular information to the brain. The latter surgery involves removing a portion of the skull and shifting the brain sideways, so it is not for the faint of heart. © 2014 Scientific American

Keyword: Hearing
Link ID: 19886 - Posted: 07.28.2014

By PAUL VITELLO The conventional wisdom among animal scientists in the 1950s was that birds were genetically programmed to sing, that monkeys made noise to vent their emotions, and that animal communication, in general, was less like human conversation than like a bodily function. Then Peter Marler, a British-born animal behaviorist, showed that certain songbirds not only learned their songs, but also learned to sing in a dialect peculiar to the region in which they were born. And that a vervet monkey made one noise to warn its troop of an approaching leopard, another to report the sighting of an eagle, and a third to alert the group to a python on the forest floor. These and other discoveries by Dr. Marler, who died July 5 in Winters, Calif., at 86, heralded a sea change in the study of animal intelligence. At a time when animal behavior was seen as a set of instinctive, almost robotic responses to environmental stimuli, he was one of the first scientists to embrace the possibility that some animals, like humans, were capable of learning and transmitting their knowledge to other members of their species. His hypothesis attracted a legion of new researchers in ethology, as animal behavior research is also known, and continues to influence thinking about cognition. Dr. Marler, who made his most enduring contributions in the field of birdsong, wrote more than a hundred papers during a long career that began at Cambridge University, where he received his Ph.D. in zoology in 1954 (the second of his two Ph.D.s.), and that took him around the world conducting field research while teaching at a succession of American universities. Dr. Marler taught at the University of California, Berkeley, from 1957 to 1966; at Rockefeller University in New York from 1966 to 1989; and at the University of California, Davis, where he led animal behavior research, from 1989 to 1994. He was an emeritus professor there at his death. © 2014 The New York Times Company

Keyword: Language; Aggression
Link ID: 19885 - Posted: 07.28.2014

By KATE MURPHY ONE of the biggest complaints in modern society is being overscheduled, overcommitted and overextended. Ask people at a social gathering how they are and the stock answer is “super busy,” “crazy busy” or “insanely busy.” Nobody is just “fine” anymore. When people aren’t super busy at work, they are crazy busy exercising, entertaining or taking their kids to Chinese lessons. Or maybe they are insanely busy playing fantasy football, tracing their genealogy or churning their own butter. And if there is ever a still moment for reflective thought — say, while waiting in line at the grocery store or sitting in traffic — out comes the mobile device. So it’s worth noting a study published last month in the journal Science, which shows how far people will go to avoid introspection. “We had noted how wedded to our devices we all seem to be and that people seem to find any excuse they can to keep busy,” said Timothy Wilson, a psychology professor at the University of Virginia and lead author of the study. “No one had done a simple study letting people go off on their own and think.” The results surprised him and have created a stir in the psychology and neuroscience communities. In 11 experiments involving more than 700 people, the majority of participants reported that they found it unpleasant to be alone in a room with their thoughts for just 6 to 15 minutes. Moreover, in one experiment, 64 percent of men and 15 percent of women began self-administering electric shocks when left alone to think. These same people, by the way, had previously said they would pay money to avoid receiving the painful jolt. It didn’t matter if the subjects engaged in the contemplative exercise at home or in the laboratory, or if they were given suggestions of what to think about, like a coming vacation; they just didn’t like being in their own heads. © 2014 The New York Times Company

Keyword: Consciousness; Aggression
Link ID: 19884 - Posted: 07.26.2014

By Michael Brooks Occasionally, scientific research comes up with banal findings that should nonetheless stop us in our tracks. For example, researchers recently published a study showing that a father’s brain will change its hormonal outputs and neural activity depending on his parenting duties. The conclusion of the research is, in essence, that men make good parents, too. Surely this is not news. Yet it does provide evidence that is sadly still useful. Those involved with issues of adoption, fathers’ rights, gay rights, child custody, and religion-fuelled bigotry will all benefit from understanding what we now know about what makes a good parent. The biggest enemy of progress has been the natural world, or at least our view of it. Females are the primary caregivers in 95 percent of mammal species. That is mainly because of lactation. Infants are nourished by their mothers’ milk, so it makes sense for most early caring to be done by females. Human beings, however, have developed more sophisticated means of nourishing and raising our offspring. Should the circumstances require a different set-up, we have ways to cope. It turns out that this is not just in terms of formula milk, nannies or day care: We also have a flexible brain. The new study, published in Proceedings of the National Academy of Sciences, scanned the brains of parents while they watched videos of their interactions with their children. The researchers found that this stimulated activity in two systems of the brain. One is an emotional network that deals with social bonding, ensures vigilance and coordinates responses to distress, providing chemical rewards for behaviours that maintain the child’s well-being. The other network is concerned with mental processing. It monitors the child’s likely state of mind, emotional condition, and future needs, allowing for planning. 2014 © The New Republic.

Keyword: Sexual Behavior
Link ID: 19883 - Posted: 07.26.2014

By MICHAEL INZLICHT and SUKHVINDER OBHI I FEEL your pain. These words are famously associated with Bill Clinton, who as a politician seemed to ooze empathy. A skeptic might wonder, though, whether he truly was personally distressed by the suffering of average Americans. Can people in high positions of power — presidents, bosses, celebrities, even dominant spouses — easily empathize with those beneath them? Psychological research suggests the answer is no. Studies have repeatedly shown that participants who are in high positions of power (or who are temporarily induced to feel powerful) are less able to adopt the visual, cognitive or emotional perspective of other people, compared to participants who are powerless (or are made to feel so). For example, Michael Kraus, a psychologist now at the University of Illinois at Urbana-Champaign, and two colleagues found that among full-time employees of a public university, those who were higher in social class (as determined by level of education) were less able to accurately identify emotions in photographs of human faces than were co-workers who were lower in social class. (While social class and social power are admittedly not the same, they are strongly related.) Why does power leave people seemingly coldhearted? Some, like the Princeton psychologist Susan Fiske, have suggested that powerful people don’t attend well to others around them because they don’t need them in order to access important resources; as powerful people, they already have plentiful access to those. We suggest a different, albeit complementary, reason from cognitive neuroscience. On the basis of a study we recently published with the researcher Jeremy Hogeveen, in the Journal of Experimental Psychology: General, we contend that when people experience power, their brains fundamentally change how sensitive they are to the actions of others. © 2014 The New York Times Company

Keyword: Emotions; Aggression
Link ID: 19882 - Posted: 07.26.2014

By James Gallagher Health editor, BBC News website Even low levels of light in bedrooms may stop breast cancer drugs from working, US researchers have warned. Animal tests showed light, equivalent to that from street lamps, could lead to tumours becoming resistant to the widely used drug Tamoxifen. The study, published in the journal Cancer Research, showed the light affected sleep hormones, which in turn altered cancer cell function. UK experts said it was an intriguing finding, but not proven in people. Tamoxifen has transformed the treatment of breast cancer by extending lives and increasing survival times. It stops the female hormone oestrogen fuelling the growth of tumours although the cancerous cells may eventually become resistant to the drug. Light Researchers at the Tulane University School of Medicine investigated the role of the body clock in Tamoxifen resistance. They focused their research on the sleep-promoting hormone melatonin, which normally begins to rise in the evening and continues through the night, before falling away as dawn approaches. However, light in the evening - such as from a smartphone, tablet or artificial lights - can lower melatonin levels. Rats, with human breast cancer and treated with Tamoxifen, were left to sleep in a completely dark cage or one that had dim light. The scientists showed that in dim light, melatonin levels were lower, the tumours were bigger and were resistant to Tamoxifen. A second set of tests showed that giving those mice melatonin supplements kept Tamoxifen working and resulted in smaller tumours. BBC © 2014

Keyword: Biological Rhythms
Link ID: 19881 - Posted: 07.26.2014

by Claudia Caruana GOT that ringing in your ears? Tinnitus, the debilitating condition that plagued Beethoven and Darwin, affects roughly 10 per cent of the world's population, including 30 million people in the US alone. Now, a device based on vagus nerve stimulation promises to eliminate the sounds for good by retraining the brain. At the moment, many chronic sufferers turn to state of the art hearing aids configured to play specific tones meant to cancel out the tinnitus. But these do not always work because they just mask the noise. The new device, developed by MicroTransponder in Dallas, Texas, works in an entirely different way. The Serenity System uses a transmitter connected to the vagus nerve in the neck – the vagus nerve connects the brain to many of the body's organs. The thinking goes that most cases of chronic tinnitus result from changes in the signals sent from the ear to neurons in the brain's auditory cortex. This device is meant to retrain those neurons to forget the annoying noise. To use the system, a person wears headphones and listens to computer-generated sounds. First, they listen to tones that trigger the tinnitus before being played different frequencies close to the problematic one. Meanwhile, the implant stimulates the vagus nerve with small pulses. The pulses trigger the release of chemicals that increase the brain's ability to reconfigure itself. The process has already worked in rats (Nature, doi.org/b63kt9) and in a small human trial this year, where it helped around half of the participants. "Vagus nerve stimulation takes advantage of the brain's neuroplasticity – the ability to reconfigure itself," says Michael Kilgard at the University of Texas at Dallas, and a consultant to MicroTransponder. © Copyright Reed Business Information Ltd.

Keyword: Hearing; Aggression
Link ID: 19880 - Posted: 07.26.2014

By Helen Briggs Health editor, BBC News website The timing of when a girl reaches puberty is controlled by hundreds of genes, say scientists. And age at first period may vary in daughters from the same family because of genetic factors, research shows. The findings, published in Nature, could give clues to why early puberty may be linked to an increased risk of health conditions. Scientists at 166 institutions analysed the DNA of more than 180,000 women in one of the largest studies of its kind. They found that hundreds of genes were involved in the timing of puberty. Unusually, a girl's first period was also influenced by imprinted genes - a rare event where genes from either the mother of father are silenced. "Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent," said lead researcher Dr John Perry of the University of Cambridge. He said the biological complexity revealed in the study was "amazing". "We identified more than 100 regions of the genome associated with puberty timing, but our analysis suggests there are likely to be thousands," he told BBC News. Lifestyle BBC © 2014

Keyword: Hormones & Behavior; Aggression
Link ID: 19879 - Posted: 07.26.2014

Posted by Katie Langin In a battle of wits, could a bird outsmart a kindergartner? Don’t be too quick to say no: One clever young bird solved a problem that has stumped 5-year-old children, according to a new study. The bird—a New Caledonian crow named Kitty—figured out that dropping rocks in one water-filled tube was the key to raising the water level in another, seemingly unconnected tube, giving her access to a floating morsel of meat. To solve this problem, Kitty needed to decipher a confusing cause-and-effect relationship, basically akin to figuring out that if you flip a switch on the wall, a ceiling light will turn on. This mental ability was once thought to be restricted to humans, but causal reasoning—the ability to understand cause and effect—has now been identified in a handful of animals, from chimpanzees to rats. Crows are the Einsteins of the bird world, renowned for their ability to make tools and solve complex puzzles. (Watch a video of a New Caledonian crow solving problems.) Their impressive mental capacity was even apparent to the ancient Greeks. In one of Aesop’s fables, a thirsty crow is presented with a dilemma when he cannot reach the water at the bottom of a pitcher. He figures out that the water level rises when he drops pebbles into the pitcher, and many pebbles later he is rewarded with a drink. As it turns out, there’s some truth to this fictional story. A study published earlier this year reported that New Caledonian crows will place rocks in water-filled tubes if they can’t reach a piece of meat that is attached to a floating cork. © 1996-2013 National Geographic Society.

Keyword: Intelligence; Aggression
Link ID: 19878 - Posted: 07.26.2014

by Douglas Heaven Hijacking how neurons of nematode worms are wired is the first step in an approach that could revolutionise our understanding of brains and consciousness CALL it the first brain hack. The humble nematode worm has had its neural connections hot-wired, changing the way it responds to salt and smells. As well as offering a way to create souped-up organisms, changing neural connectivity could one day allow us to treat brain damage in people by rerouting signals around damaged neurons. What's more, it offers a different approach to probing brain mysteries such as how consciousness arises from wiring patterns – much like exploring the function of an electronic circuit by plugging and unplugging cables. In our attempts to understand the brain, a lot of attention is given to neurons. A technique known as optogenetics, for example, lets researchers study the function of individual neurons by genetically altering them so they can be turned on and off by a light switch. But looking at the brain's connections is as important as watching the activity of neurons. Higher cognitive functions, such as an awareness of our place in the world, do not spring from a specific area, says Fani Deligianni at University College London. Deligianni and her colleagues are developing imaging techniques to map the brain's connections, as are other groups around the world (see "Start with a worm..."). "From this we can begin to answer some of the big questions about the workings of the brain and consciousness which seem to depend on connectivity," she says. Tracing how the brain is wired is a great first step but to find out how this linking pattern produces a particular behaviour we need to be able to see how changing these links affects brain function. This is what a team led by William Schafer at the MRC Laboratory of Molecular Biology in Cambridge, UK, is attempting. © Copyright Reed Business Information Ltd.

Keyword: Brain imaging; Aggression
Link ID: 19877 - Posted: 07.24.2014

By JAMES GORMAN Any dog owner would testify that dogs are just as prone to jealousy as humans. But can one really compare Othello’s agony to Roscoe’s pique? The answer, according to Christine Harris, a psychologist at the University of California, San Diego, is that if you are petting another dog, Roscoe is going to show something that Dr. Harris thinks is a form of jealousy, even if not as complex and twisted as the adult human form. Other scientists agree there is something going on, but not all are convinced it is jealousy. And Roscoe and the rest of his tribe were, without exception, unavailable for comment. Dr. Harris had been studying human jealousy for years when she took this question on, inspired partly by the antics of her parents’ Border collies. When she petted them, “one would take his head and knock the other’s head away,” she said. It certainly looked like jealousy. But having studied humans, she was aware of different schools of thought about jealousy. Some scientists argue that jealousy requires complex thinking about self and others, which seems beyond dogs’ abilities. Others think that although our descriptions of jealousy are complex, the emotion itself may not be that complex. Dog emotions, as owners perceive them, have been studied before. In one case, Alexandra Horowitz, a cognitive scientist who is an adjunct associate professor at Barnard College and the author of “Inside of a Dog,” found that the so-called guilty look that dogs exhibit seemed to be more related to fear of punishment. Dr. Harris ventured into the tricky turf of dog emotion by devising a test based on work done with infants. © 2014 The New York Times Company

Keyword: Emotions; Aggression
Link ID: 19876 - Posted: 07.24.2014

by Helen Thomson How do you smell after a drink? Quite well, it turns out. A modest amount of alcohol boosts your sense of smell. It is well known that we can improve our sense of smell through practice. But a few people have also experienced a boost after drug use or brain damage. This suggests our sensitivity to smell may be damped by some sort of inhibition in the brain, which can be lifted under some circumstances, says Yaara Endevelt of the Weizmann Institute of Science in Rehovot, Israel. To explore this notion, Endevelt and her colleagues investigated whether drinking alcohol – known to lower inhibitory signals in the brain – affected the sense of smell. In one odour-discrimination test, 20 volunteers were asked to smell three different liquids. Two were a mixture of the same six odours, the third contained a similar mixture with one odour replaced. Each volunteer was given 2 seconds to smell each of the liquids and say which was the odd one out. The test was repeated six times with each of three trios of liquids. They were then given a drink that consisted of 35 millilitres of vodka and sweetened grape juice, or the juice alone, before repeating the experiment with the same set of liquids. In a second experiment with a similar drinking structure, the same volunteers were asked which of three liquids had a rose-like odour. The researchers increased the concentration of the odour until the volunteers got the right answer three times in a row. © Copyright Reed Business Information Ltd.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 19875 - Posted: 07.24.2014

By Phil Plait From the twisted mind of brusspup comes another brain-hurting illusion. This one is really, really convincing, so tell me: When you look at this video, you’re seeing a circle of eight dots rotating as it spins around inside a bigger circle, right? No, you’re not. As brusspup shows, each individual white dot is moving in a straight line! The trick here is two-fold: One is that the dots aren’t moving at constant velocity (you can see that in the video at the 0:44 mark), and that combined their motion mimics what we’d see if a smaller circle is rolling around inside a big one. Try as I may, when I look at this video I can’t make my brain see the dots moving linearly; it looks like a circle rolling. If I focus on one of the dots I can see it moving back and forth along a line, but the others still look like the rim of a circle rolling around. For most illusions there’s a moment when your brain can see what’s going on and the illusion shatters, but not with this one. It’s maddening. When I was a kid, Spirograph was a very popular “game.” It wasn’t really a game, but a set of clear plastic disks with gear teeth around them (or rings with teeth on the inside). They had holes in them; you’d pin a ring down on a piece of paper, then take another disk, place it inside the ring, put your pencil tip in a hole, and roll the inner disk around inside the outer ring. The results were really lovely and graceful interlocking and overlapping curves. If you’re a lot younger than me and missed this craze, here’s a video that’ll help you picture it: © 2014 The Slate Group LLC.

Keyword: Vision
Link ID: 19874 - Posted: 07.24.2014

By Emily Underwood The Broad Institute, a collaborative biomedical research center in Cambridge, Massachusetts, has received a $650 million donation from philanthropist and businessman Ted Stanley to study the biological basis of diseases such as schizophrenia and bipolar disorder. The largest donation ever made to psychiatric research, the gift totals nearly six times the current $110 million annual budget for President Barack Obama’s Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Stanley has already given Broad $175 million, and the $650 million will be provided as an annual cash flow on the order of tens of millions each year, with the remainder to be given after Stanley’s death. The gift accompanies a paper published online today in Nature from researchers at Broad and worldwide, which identifies more than 100 areas of the human genome associated with schizophrenia, based on samples from almost 37,000 people with schizophrenia and about 113,000 without the disease. Researchers are likely to find hundreds of additional genetic variations associated with the disease as the number of patients sampled grows, says psychiatrist Kenneth Kendler of the Virginia Institute for Psychiatric and Behavioral Genetics in Richmond, a co-author on the study. Identifying the variants themselves is unlikely to lead directly to new drug targets, Kendler says. Instead, the hope is that researchers at Broad and elsewhere will be able to use those data to reveal clusters of genetic variation, like placing pins on a map, he says. © 2014 American Association for the Advancement of Science.

Keyword: Schizophrenia; Aggression
Link ID: 19873 - Posted: 07.23.2014

by Bethany Brookshire Even when we love our jobs, we all look forward to some time away. During the week, as stress builds up and deadlines accumulate, Friday looks better and better. Then, with a sigh of relief, the weekend arrives. But come Monday, it seems like the whole weight of responsibility just comes crashing down again. It’s not just you. Rats feel it, too. Rats given a two-day break from a stressful procedure show more signs of strain on “Monday” than rats who never got the weekend, researchers report July 11 in PLOS ONE. The results show that in some cases, an unpredictable getaway can cause more stress than just working through the pressure. Wei Zang, J. Amiel Rosenkranz and colleagues at the Rosalind Franklin University of School of Medicine and Science in Chicago wanted to understand how changes to a stressful situation alter an animal’s response to stress. Normally, when rats are exposed over and over to a stress such as a restraint (in which a rat is placed in a small tube where it can’t turn around or get out), they begin to get used to the stress. Over a few days, rats stop avoiding the tube and stay calmly in the restraint without struggling, until they are set free. Hormones like corticosterone — which spikes in response to stress — go down. This phenomenon is called habituation. Zhang and colleagues wanted to see what happens when this pattern of stress is interrupted. They restrained rats for 20 minutes each for five days. By day five, the animals were hanging out comfortably in the tubes. Then, the scientists introduced an interruption: They gave half of the rats two days off, a science-induced weekend. The scientists continued to restrain the other group of rats daily. © Society for Science & the Public 2000 - 2013

Keyword: Stress
Link ID: 19872 - Posted: 07.23.2014

By Janice Lynch Schuster I have never been one to visit a doctor regularly. Even though I had accumulated my share of problems by age 50— arthritic knees, poor hearing — I considered myself to be among the mostly well. But 19 months ago I developed a perplexing problem that forced me to become not only a regular patient but also one of the millions of Americans with chronic pain who struggle to find relief, in part through treatment with opioids. The trouble began with a terrible and persistent pain in my tongue. It alternately throbbed and burned, and it often hurt to eat or speak. The flesh looked red and irritated, and no amount of Orajel or Sensodyne relieved it. My doctor suggested I see my dentist; my dentist referred me to an oral surgeon. The surgeon thought the problem was caused by my being “tongue-tied,” a typically harmless condition in which the little piece of tissue under the tongue, called the frenulum, is too short. It seems I have always had this condition but had never noticed, because it hadn’t affected my ability to eat or speak. Now things had changed. The doctor recommended a frenectomy, a procedure to remove the frenulum and relieve tension on the tongue. “Just a snip,” he promised. It sounded trivial, and I was eager to be done with it. Although I make a living writing about health care, I didn’t even bother to do a Web search on the procedure. It never occurred to me that “a snip” might entail some risks. I trusted the oral surgeon.

Keyword: Pain & Touch
Link ID: 19871 - Posted: 07.23.2014

By Sid Perkins Forget the phrase “blind as a bat.” New experiments suggest that members of one species of these furry flyers—Myotis myotis, the greater mouse-eared bat—can do something no other mammal is known to do: They detect and use polarized light to calibrate their long-distance navigation. Previous research hinted that these bats reset their magnetic compass each night based on cues visible at sunset, but the particular cue or cues hadn’t been identified. In the new study, researchers placed bats in boxes in which the polarization of light could be controlled and shifted. After letting the bats experience sundown at a site near their typical roost, the team waited until after midnight (when polarized light was no longer visible in the sky), transported the animals to two sites between 20 and 25 kilometers from the roost, strapped radio tracking devices to them, and then released them. In general, bats whose polarization wasn’t shifted took off for home in the proper direction. But those that had seen polarization shifted 90° at sunset headed off in directions that, on average, pointed 90° away from the true bearing of home, the researchers report online today in Nature Communications. It’s not clear how the bats discern the polarized light, but it may be related to the type or alignment of light-detecting pigments in their retinas, the team suggests. The bats may have evolved to reset their navigation system using polarized light because that cue persists long after sunset and is available even when skies are cloudy. Besides these bats (and it’s not known whether other species of bat can do this, too), researchers have found that certain insects, birds, reptiles, and amphibians can navigate using polarized light. © 2014 American Association for the Advancement of Science

Keyword: Vision; Aggression
Link ID: 19870 - Posted: 07.23.2014

By Katherine Harmon Courage Octopuses do the darndest things. Like kill their mate during mating—by strangling him with three arms, according to new observations from the wild. Enterprising scientists Christine Huffard and Mike Bartick watched wild octopuses in action. They found that, for males, mating can be a dangerous game. Especially when your lady has long limbs. Some of the more dicey encounters are detailed in a new paper, published online July 11 in Molluscan Research. Hold on a second, you say. Strangling octopuses? Octopuses don’t even have necks—or inhale air. So how, exactly, does that work? The strangulation seems to happen when “an octopus wraps at least one arm around the base of the mantle of the competitor” (or mate), Huffard wrote in 2010. This constriction then keeps the octopus from taking in fresh water to run past its gills—starving the animal of its oxygen source. Octopuses are not known to get cuddly with one another on a day-to-day basis. In fact, “octopuses touch each other with their arms primarily in the context of mating and aggression,” the researchers write. And in this case it seems to have been both. Huffard came across a pair of mating day octopuses (Octopus cyanea) near Fiabacet Island in Indonesia. The female, as is often the case in this species, was larger—with a body about seven-and-a-half inches long; the male was closer to six inches long. They were positioned on a reef, outside the female’s den, the male’s mating arm (hectocotylus) inserted into the female’s mantle from a (presumably) safe distance. © 2014 Scientific American

Keyword: Sexual Behavior
Link ID: 19869 - Posted: 07.23.2014

By Virginia Morell Dogs, most of us think, have the best noses on the planet. But a new study reveals that this honor actually goes to elephants. The power of a mammal’s sniffer hinges on the number and type of its olfactory receptor genes. These genes are expressed in sensory cells that line the nasal cavity and are specialized for detecting odor molecules. When triggered, they set off a cascade of signals from the nose to the brain, enabling an animal to identify a particular smell. In the new study, scientists identified and examined olfactory receptor genes from 13 mammalian species. The researchers found that every species has a highly unique variety of such genes: Of the 10,000 functioning olfactory receptor genes the team studied, only three are shared among the 13 species. Perhaps not surprisingly, given the length of its trunk, the African elephant has the largest number of such genes—nearly 2000, the scientists report online today in the Genome Research. In contrast, dogs have only 1000, and humans and chimpanzees, less than 400—possibly because higher primates rely more on their vision and less on their sense of smell. The discovery fits with another recent study showing that Asian elephants are as good as mice (which have nearly 1300 olfactory receptor genes) at discriminating between odors; dogs and elephants have yet to be put to a nose-to-trunk sniffer test. Other research has also shown just how important a superior sense of smell is to the behemoths. A slight whiff is all that’s necessary, for instance, for elephants, such as those in the photo above, to distinguish between two Kenyan ethnic groups—the Maasai, who sometimes spear them, and the Kamba, who rarely pose a threat. They can also recognize as many as 30 different family members from cues in their urine. © 2014 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 19868 - Posted: 07.23.2014