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Like the clever and many-armed cephalopod, Inkfish reaches into all areas of science and brings you interpretations of the newest stories.
"Simple" is often a compliment in the human world, used to describe low-fuss dinners or closet solutions. When scientists use "simple" to describe an animal, they mean something more like, "That sac of goo has no business acting clever." An especially simple creature—a sea slug—recently demonstrated that despite its humble resources, it can learn from experience and form new hunting strategies. Smaller goo sacs, beware.
Despite its squishy stature, the sea slug Pleurobranchaea californica is a killer. It roams the sea and swallows whatever appealing morsels are in its way. Being blind, it can't tell how tasty its prey looks—or doesn't.
It can't see, for example, the flashy coloration of the "Spanish shawl" nudibranch (Flabellina iodinea). If it could, it might guess that those bright pink and orange hues are a warning: Flabellina is not nice to eat. It steals stinging cells from its own prey (such as corals and anemones) and stores those stingers in its bristles.
Rhanor Gillette, a neuroscientist at the University of Illinois, Urbana-Champaign, observed that not only do Pleurobranchaea slugs spit out Spanish shawls, but they seem to remember and avoid the animals in the future. To study how well the predatory sea slugs learn their lesson after tasting Flabellina, he and graduate student Vanessa Noboa set up a meet-and-greet between the two species.
In tanks, the large, hungry sea slugs encountered the smaller nudibranchs. Researchers recorded how long it took for Pleurobranchaea to take a taste, then waited for the slugs to change their minds and turn away from their potential prey. (Here's a great video of a Pleurobranchaea attempting to Hoover up a Flabellina, then spitting the animal back out. While the big slug pivots away in disgust, the little one does its "Don't eat me" dance like nobody's watching, which is true.)
On the first day, this interaction happened five times. By the end, most of the Pleurobranchaea slugs were much slower to take a taste of the Spanish shawls, or were ignoring them altogether. Twenty-four hours later, the sea slugs were still reluctant to approach Flabellina. Even after 72 hours, they remembered what they'd learned. Gillette and Noboa report their results in the Journal of Experimental Biology.
Since the predatory slugs seem to sniff something in the water that makes them turn away, the researchers think the noxious Spanish shawls give off a distinctive warning odor.
Gillette says the sea slugs have a decent memory, considering their elementary nervous system. "In these experiments their memory is strong at 48 hours," he says, "and in unpublished work we've seen savings up to a week, so it's not bad." (Oddly, some slugs had to be removed from the experiment because they didn't mind the taste of the stinging Flabellina at all. They sucked it up just like any other food.)
Learning from an unpleasant taste experience, then using that memory to change one's hunting strategy, is "a real cognitive trait," Gillette says—in other words, a "goal-directed use of knowledge." The Pleurobranchaea slugs learned to avoid the smell of Flabellina, although they continued to eat a related, non-stinging species without hesitation.
Being able to change their feeding strategy is a good thing, since these slugs are generalists. Everything in the path of their oozing is a potential meal. "More specialized animals, say sea-slugs that may munch on a particular kind of sponge, may not need to employ such learning abilities," Gillette says. For a hunter like Pleurobranchaea, the decisions aren't so simple.
Noboa, V., & Gillette, R. (2013). Selective prey avoidance learning in the predatory sea-slug Pleurobranchaea californica Journal of Experimental Biology DOI: 10.1242/jeb.079384
Image: Rhanor Gillette.
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Noboa, V., & Gillette, R. (2013) Selective prey avoidance learning in the predatory sea-slug Pleurobranchaea californica. Journal of Experimental Biology. DOI: 10.1242/jeb.079384
All it takes is an antenna on a headband. If you've got a breathless video report on the dangers of wireless internet connections, that will help your case. It doesn't take much, though, to turn an ominous hint into a real headache.
Some people consider themselves sensitive to electromagnetic fields. They report symptoms such as burning skin, tingling, nausea, dizziness, or chest pain, and they blame their malaise on nearby power lines, cell phones, or WiFi networks. A recent Slate article described such people moving to a remote West Virginia town where radio-frequency signals are banned. (The town is within the U.S. National Radio Quiet Zone, an area that's enforced to keep signals from interfering with radio telescopes there—telescopes that work because they receive the radio-frequency signals constantly hitting our planet from space.)
There's no known scientific reason why a wireless signal might cause physical harm. And studies have found that even people who claim to be sensitive to electromagnetic fields can't actually sense them. Their symptoms are more likely due to nocebo, the evil twin of the placebo effect. The power of our expectation can cause real physical illness. In clinical drug trials, for example, subjects who take sugar pills report side effects ranging from an upset stomach to sexual dysfunction.
Psychologists Michael Witthöft and G. James Rubin of King's College London explored whether frightening TV reports can encourage a nocebo effect. They recruited a group of subjects and showed half of them a clip from a BBC documentary about the potential dangers of wireless internet. (The BBC later acknowledged that the 2007 program was "misleading.") The remaining subjects watched a video about the security of data transmissions over mobile phones.
After watching the videos, subjects put on headband-mounted antennas. They were told that the researchers were testing a "new kind of WiFi," and that once the signal started they should carefully monitor any symptoms in their bodies. Then the researchers left the room. For 15 minutes, the subjects watched a WiFi symbol flash on a laptop screen.
In reality, there was no WiFi switched on during the experiment, and the headband antenna was a sham. Yet 82 of the 147 subjects—more than half—reported symptoms. Two even asked for the experiment to be stopped early because the effects were too severe to stand.
Witthöft says he expected to see a greater effect in people who had watched the frightening documentary. This wasn't the case overall. Instead, the movie mainly increased symptoms in subjects who described themselves beforehand as more anxious.
"It suggests that sensational media reports especially in combination with personality factors (in this case anxiety) increase the likelihood for symptom reports," Witthöft says.
Plenty of symptoms were reported without the sensationalist TV show, though. The antenna on the head, the researchers' allusion to a "new kind of WiFi," and the instructions to monitor their bodies closely were enough to trigger symptoms in many people who watched the other video.
Witthöft points out that his study would have been stronger if there were a third group of subjects who didn't wear the "WiFi" headband at all, but were simply told to pay attention to their bodies for 15 minutes. This kind of attentiveness might trigger symptoms on its own.
Still, Witthöft says, "I think the high percentage of symptom reports nicely shows how powerful nocebo effects are."
Though the researchers set out to show how irresponsible reports in the media can trigger a nocebo effect, they ended up showing how easy it is to make a person feel sick with just a a prop and a few choice words. Even a National Radio Quiet Zone can't protect against that.
Witthöft, M., & Rubin, G. (2013). Are media warnings about the adverse health effects of modern life self-fulfilling? An experimental study on idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) Journal of Psychosomatic Research, 74 (3), 206-212 DOI: 10.1016/j.jpsychores.2012.12.002
Image: Scott Beale/Laughing Squid (via Flickr)
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Witthöft, M., & Rubin, G. (2013) Are media warnings about the adverse health effects of modern life self-fulfilling? An experimental study on idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF). Journal of Psychosomatic Research, 74(3), 206-212. DOI: 10.1016/j.jpsychores.2012.12.002
If cartoonists ever pause in their sketching to ponder human evolution, they must feel grateful to the forces that shaped our fear expression. All it takes is a pair of extra-wide eyes to show that a character is freaking out. There may be a point to this expression beyond making artists' lives easier: widening our eyes expands our peripheral vision, and might even help other people spot the cause of our alarm.
"Our lab is interested in the evolutionary origins of emotional expressions," says Daniel Lee, a graduate student in psychology at the University of Toronto—in other words, "why they look the way they do." When we feel afraid, for example, is there a point to stretching out our eyelids and raising our eyebrows to the ceiling?
To explore this question, Lee and his coauthors first asked whether widening our eyes helps us see better. They had 28 volunteers look at a fixed spot on a computer screen while holding their eyes in a neutral expression, an expression of fear, or one of disgust. (Subjects acted out these expressions rather than, say, having a chair pulled out from under them before each trial. Lee points out that emotions themselves may also change our perception, but he wanted to study the effects of widened eyes separate from any psychological effects of fear on the brain. "We coached each participant on how to make fear and disgust expressions based on the Facial Action Coding System," he says.)
Subjects were tested with flashing images on the screen in their peripheral vision. Lee found that people making a disgusted expression—with the eyelids narrowed as in "Ew, get that out of my face"—scored the worst. People making a wide-eyed fear expression scored the best, with a useful field of vision 9% larger than that of people with a neutral expression.
Being afraid, then, may help us gather more visual information about whatever's threatening us in our environment. But does it also help us communicate that threat to our companions?
The researchers next used pictures of models' eyes expressing different emotions to create simplified, graphic eye images. (They didn't use real eyes because those might have conveyed extra emotional information, instead of only varying in wideness.) Subjects saw these eye images flash briefly on a screen, looking toward the right or left by varying degrees. Lee found that when the eyes were wider, subjects had an easier time telling which way they were looking. The results are reported in Psychological Science.
"We believe the widening eyes of fear...[are] a functional response for vigilance toward threat," Lee says. When we're scared, he thinks, widening our eyes helps us to see threats and to communicate their location to our group.
The researchers point out that human eyes are uniquely suited for this kind of communication: we're the only primate with a white sclera (the area outside the iris). In other apes and monkeys, this part of the eye is dark. It's yet another factor that cartoonists, no doubt, appreciate.
Lee, D., Susskind, J., & Anderson, A. (2013). Social Transmission of the Sensory Benefits of Eye Widening in Fear Expressions Psychological Science DOI: 10.1177/0956797612464500
Image: by Tom Check (via Flickr)
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Lee, D., Susskind, J., & Anderson, A. (2013) Social Transmission of the Sensory Benefits of Eye Widening in Fear Expressions. Psychological Science. DOI: 10.1177/0956797612464500
While male birds are singing elaborate arias and flashing their feathers, it's easy to imagine their female counterparts are unimportant actors. Duller and quieter, all a lady bird has to do is hold still and let one of these frantic performers mate with her. Yet in brown-headed cowbirds, at least, the quiet female keeps the whole society in order. Scientists discovered this by targeting a tiny portion of the female brain and frying it.
Males of the species Molothrus ater use their songs to compete with each other and to woo females. Once a a mating pair forms, they stay faithful to each other for the whole mating season, the male guarding his partner from rivals.
Near the top of the bird brain, a region called nucleus HVC controls females' choosiness toward their potential mates. Scientists at the University of Pennsylvania and Wilfrid Laurier University performed brain surgery on female cowbirds, carefully destroying only this region. Then they put their lobotomized females back into the dating arena to see what would happen.
First, the ladies listened to recordings of male songs. The researchers played tunes sung by a variety of males and observed the females' responses. (When they like what they hear, female cowbirds show it by crouching down in a copulation-ready pose.)
Normal females were choosy, only responding to the highest-quality male songs. Females who'd had brain surgery, though, responded positively to every song.
The researchers wanted to see what effect the females' new, lax attitude would have in cowbird society. So they put post-surgery females, normal females, and males in one big group together. Then they watched.
At first, it looked like nothing was different. Females missing their HVC seemed to act the same as females with intact brains; once they were all together in the aviary, there was no clear difference in how often females approached male birds or in how they "chattered" back at males to encourage their singing.
Nevertheless, something had changed. The other birds in the aviary treated post-surgery females differently. For one thing, females missing their HVC were serenaded by a greater variety of males, even once they'd chosen a mate. Normally, a female who's bonded with a male hears his song almost exclusively. This is a measure of how strong the bond between partners is, says study author David White. Now, with more males bending a female's ear, her pair bond was weaker.
There were other changes too. With the altered females introduced into the group, female birds competed more for mates. And the whole hierarchy of male birds, which is established before the breeding season starts, was disrupted. Male cowbirds sing at each other to show who's dominant. After the HVC-less females came to live with them, the rules about which males were dominant singers shifted significantly.
"The result in this paper turned everything around for us," White says.
Previously, it had seemed to be the male cowbird's responsibility to create a strong bond with his partner. Females appeared to be passive agents in the group. "They don't sing, they don't fight," White says. "They don't, to our eye, do much of anything." Yet when the choosiness was erased from females' brains, the whole group dynamic changed. "Now we could see that it was the female that was playing a much more active role in pair-bonding, and in all sorts of other roles within the social network," White says. Everything depended on her song preferences.
Incidentally, it's not clear why female cowbirds bond with males at all.
Females have likely evolved to pick mates whose songs demonstrate—somehow—that they have the best genes. Then the males keep singing to the females throughout the breeding season, strengthening the bond between them.
Usually, White says, bird couples only form strong bonds when both parents will need to care for the young. But cowbirds "are very bad parents overall" who abandon their eggs in the nests of other birds. The powerful bond between cowbird partners "really makes no sense," White says.
Yet once they're bonded, males direct almost all their singing to their partner and never try to mate with other birds. "They follow each other around, they eat together, he comes when she calls him," White says. If a female dies or disappears, he adds, "her pairmate just becomes a wreck. We call it the widowed male phenomenon."
After the loss of his mate, the male gives up for the season. "He flies around looking for her," White says. To him, at least, the quiet female never seemed unimportant.
Maguire, S., Schmidt, M., & White, D. (2013). Social Brains in Context: Lesions Targeted to the Song Control System in Female Cowbirds Affect Their Social Network PLoS ONE, 8 (5) DOI: 10.1371/journal.pone.0063239
Image: female brown-headed cowbird by JanetandPhil (via Flickr)
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Maguire, S., Schmidt, M., & White, D. (2013) Social Brains in Context: Lesions Targeted to the Song Control System in Female Cowbirds Affect Their Social Network. PLoS ONE, 8(5). DOI: 10.1371/journal.pone.0063239
We can knit sweaters for oiled penguins, but it's harder to protect whales and dolphins from the harm of having us as neighbors. Loud underwater sounds from activities like sonar and drilling may damage these animals' hearing and even lead to mass strandings. Though we can't chase cetaceans around with homemade earmuffs, we might be able to teach them to tune us out.
Like squinting or letting one's pupil shrink in bright light, some animals can adjust how sensitive their ears are. When we're making loud noises, humans reflexively squeeze the muscles of the middle ear to dampen our hearing. Some bats do the same thing while echolocating.
"Generally speaking, mammals have evolved mechanisms to protect their auditory systems from self-produced intense sounds," write Paul Nachtigall of the University of Hawaii and Alexander Supin of the Russian Academy of Sciences. In 2008, the pair showed that a false killer whale (Pseudorca crassidens) could adjust its hearing while it echolocated. So they set out to see whether the species could also dial down its hearing in response to sounds made by someone else.
They taught their whale (a female, originally caught in the wild and now thought to be 30 or 40 years old) that hearing a quiet warning sound meant a louder sound was coming soon. The subject wore suction-cup electrodes on her head during the experiment. Waiting at an underwater listening station, she first heard a series of tones while the electrodes measured which ones her ears responded to. Then, a variable amount of time later, she heard a sudden loud sound (170 decibels).
Over hundreds of trials,* the researchers saw that the whale learned to anticipate the loud sound. If it came within 35 seconds of the warning sound starting, the whale was able to desensitize her ears before it played. (With a longer delay, her response wasn't as strong.) The authors report their results in the Journal of Experimental Biology.
Nachtigall can't say how a whale turns down its hearing. "No one knows for sure how the cetacean middle ear works," he says. Whales don't have eardrums like humans or other land animals, he says, because the sounds they hear must travel through tissue instead of air. So his whale subject probably doesn't squeeze her ear muscles to dampen sound, as a human or bat would. He speculates that it's more likely a top-down control from the brain.
However she does it, the whale can make her ears less sensitive when she knows a loud sound is coming soon. The biggest decrease in her hearing sensitivity was about 13 decibels. That's "about what your hearing changes if you stick your fingers in your ears," Nachtigall says. If you—or the whale—are trying to protect your hearing from a loud noise, he says, "That helps. This would help."
When humans must make a racket underwater, it's possible that we could help whales and other animals by making quieter warning sounds beforehand. This could teach the animals to anticipate the sound and "plug" their ears.
Since he's only studied one animal so far, Nachtigall doesn't know how the abilities of other marine mammals to desensitize their ears compare. "To ask whether [warning sounds] would prevent whale hearing damage is sort of like asking whether ear plugs would prevent deafness in people who work next to jet engines," he says. "I believe the possibility is great, but there are more questions to be answered."
Image: by MichiKimmig (Flickr)
Nachtigall, P., & Supin, A. (2013). A false killer whale reduces its hearing sensitivity when a loud sound is preceded by a warning Journal of Experimental Biology DOI: 10.1242/jeb.085068
*If you're wondering how one convinces a whale to participate in so many trials, the answer is "fish reinforcement."
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Nachtigall, P., & Supin, A. (2013) A false killer whale reduces its hearing sensitivity when a loud sound is preceded by a warning. Journal of Experimental Biology. DOI: 10.1242/jeb.085068
The Shambulance is an occasional series in which I try to find the truth about bogus or overhyped health products. Helping me keep the Shambulance on course are Steven Swoap and Daniel Lynch, both biology professors at Williams College.
Sticking a Q-tip up one’s nose is not the source of many great insights. Yet it’s how an American doctor in the early 20th century developed the theory that became modern reflexology. He would be proud—though maybe a little confused—to see people today flocking to reflexology spas, where practitioners treat all their problems via the soles of their feet.
The American doctor in question was William H. Fitzgerald, an ear, nose and throat specialist. In a 1917 book, he explained the genesis of his big idea:
Six years ago I accidentally discovered that pressure with a cotton tipped probe on the muco-cutinous margin (where the skin joins the mucous membrane) of the nose gave an anesthetic result as though a cocaine solution had been applied . . . Also, that pressure exerted over any bony eminence of the hands, feet or over the joints, produces the same characteristic results in pain relief . . . This led to my ‘mapping out’ these various areas and their associated connections and also to noting the conditions influenced through them. This science I have named "Zone Therapy."
Chapter titles from Zone Therapy include "Zone Therapy for Women" (tongue depressor into the back of the throat for menstrual cramps), "Painless Childbirth" (rubber bands around the toes, among other interventions) and "Curing Lumbago with a Comb."
A nurse and physical therapist named Eunice D. Ingham extended the idea of zone therapy in the 1930s and 1940s, eventually mapping the entire body onto the soles of the feet. She called each important point on the foot a “reflex” because it reflected back to a certain organ or body part. Ingham wrote two books on the subject, now called reflexology: Stories the Feet Can Tell and Stories the Feet Have Told.
Today, the International Institute of Reflexology describes its practice as as “a science which deals with the principle that there are reflex areas in the feet and hands which correspond to all of the glands, organs and parts of the body.” Stimulating these points “can help many health problems in a natural way.” The site insists, “Reflexology…should not be confused with massage.”
There has been some confusion and blending, though, between Western reflexology and traditional Chinese medicine. Ingham and Fitzgerald's idea of "zones" is similar to the Chinese principle of "meridians." In traditional Chinese medicine, meridians are paths that carry qi through the body and connect the acupuncture points. Reflexology groups like to say that Fitzgerald "rediscovered" the science from more ancient roots. They even claim that ancient Egyptians practiced it, based on tomb paintings showing people holding each other's feet.
Whoever thought it up first, the idea that the soles of your feet hold a miniature map of the entire rest of your body defies a scientific explanation.
“The problem is communication,” says physiologist Steven Swoap. “How does the foot talk to the pancreas?”
The foot is full of sensory nerves, Swoap explains. These can detect temperature, pain or position and send that information to the spinal cord. If the signal is something urgent—say, you stepped on a nail—the spinal cord will send a quick command back to the foot (“STOP!”). If the signal from the foot is a non-painful one (“Hey, I’m walking on grass”), it will travel all the way up the spinal cord to the brain.
“But in no instance do those sensory nerves bypass either the spinal cord or the brain and go directly to the liver, or the kidney, or the colon,” Swoap says. This means your foot can’t communicate directly with any other body part except your spinal cord or brain. Whatever stories the feet have told, they’ve had a limited audience.
Daniel Lynch, a biochemist, points out that sex organs are missing from some reflexology maps. “Why aren’t the gonads on there?” he asks. Other maps label a "testes and ovaries" region around the middle of the heel, but there's variation from one chart to the next.
Setting aside the map itself, Lynch says, “Where is the evidence that it actually works?”
The evidence is slimmer than a stiletto heel. In a 2011 review paper, complementary medicine researchers at the Universities of Exeter and Plymouth dug up every scientific study of reflexology they could find. Out of 23 randomized clinical trials, only 8 “suggested positive effects.”
The quality of the studies was “variable,” the authors write, “but, in most cases, it was poor.” Only four studies that found a positive effect used a placebo control—that is, did massaging the feet without regard to “zones” give patients the same symptom relief? In general, studies tended to use small groups of subjects and not to be replicated by other researchers.
Reflexology has been tested on conditions including asthma, premenstrual syndrome, irritable bowel syndrome, multiple sclerosis, and back pain. If reflexology does have a benefit, “The most promising evidence seems to be in the realm of cancer palliation,” or making patients more comfortable, the authors write. Overall, though, they found no convincing evidence that reflexology has power beyond the placebo.
Not that we should thumb our Q-tip-free noses at the placebo effect. The body has an impressive power to make itself feel better based on our expectations. A foot rub from a professional may very well ease a person’s pain. If that professional says anything about zones, though, it’s only a story.
Image: Foot reflexology chart by Stacy Simone (Wikipedia)
Ernst, E., Posadzki, P., & Lee, M. (2011). Reflexology: An update of a systematic review of randomised clinical trials Maturitas, 68 (2), 116-120 DOI: 10.1016/j.maturitas.2010.10.011
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Ernst, E., Posadzki, P., & Lee, M. (2011) Reflexology: An update of a systematic review of randomised clinical trials. Maturitas, 68(2), 116-120. DOI: 10.1016/j.maturitas.2010.10.011
She's apparently a picky mater but not a picky eater. The female of a certain fly species, after mating with a male, dumps his ejaculate back out of her body and onto the ground. Then she gobbles it up. Despite new hints that this behavior may help the female choose which partner fertilizes her eggs, or keep her healthy in times of famine, scientists are still a little perplexed by it.
Various female insects, spiders, and birds are known to expel the male ejaculate from their bodies after the deed is done. In some cases, it seems to let them decide which male's sperm reaches their eggs. Females don't always choose who mates with them, but that doesn't mean they have no choice in their progeny's fatherhood. (This kind of female choosiness about sperm can lead to evolutionary arms races between males and females. The "copulatory plug" is a popular tool among male insects, spiders, reptiles, and even some mammals.)
Eating the ejaculate, as Euxesta bilimeki does, is less popular. This fly lives on agave plants and mates pretty much all the time. "Females can be observed escaping male advances in chases that can last more than an hour," write Christian Luis Rodriguez-Enriquez and his coauthors from the Instituto de Ecología in Veracruz, Mexico. Using videocameras and careful meal planning, they tried to divine a reason for the female flies' behavior.
Out of 74 females that the researchers recorded mating, every one expelled and ate the ejaculate afterward. The researchers then killed the females and pulled them apart with tweezers to look for sperm inside their various storage locations. They found that three-quarters of the females had kept some sperm from their male partner, while one-quarter had expelled it all.
There was no obvious rule to which sperm the females kept. There were some patterns, though. For example, females that mated with larger males, then waited longer before expelling the sperm, were more likely to keep some. Since the female's behavior doesn't seem random—and since it's possible for her to keep no sperm at all—the authors think she may be choosing between mates after the fact.
This could explain why the female expels the sperm, but not why she eats it. In another experiment, researchers fed female flies various diets and measured whether supplementing those diets with ejaculate made them healthier. When female flies were starved entirely, the extra snack did help them live longer—but under normal circumstances there was no difference. The authors report their results in Behavioral Ecology and Sociobiology.
"Our study appears to have raised more questions than provided answers," the authors admit. They expected there would be some clear nutritional benefit to justify the females' tastes.
Rodriguez-Enriquez and his coauthors speculate that the ejaculate-as-meal habit may have evolved as a "nuptial gift." This is an edible present that male insects sometimes give to females as part of their courtship. Usually it's nutritious—a nicely wrapped dead bug, say—but in some cases it's just an empty sac. The ejaculate may be, like these gifts, just an edible empty gesture.
(The above is a video of Euxesta bilimeki flies mating. It doesn't look any different from what you're imagining, but the soundtrack is a nice twist.)
Rodriguez-Enriquez, C., Tadeo, E., & Rull, J. (2013). Elucidating the function of ejaculate expulsion and consumption after copulation by female Euxesta bilimeki Behavioral Ecology and Sociobiology DOI: 10.1007/s00265-013-1518-5
Image and video: Rodriguez-Enriquez et al.
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Rodriguez-Enriquez, C., Tadeo, E., & Rull, J. (2013) Elucidating the function of ejaculate expulsion and consumption after copulation by female Euxesta bilimeki. Behavioral Ecology and Sociobiology. DOI: 10.1007/s00265-013-1518-5
Shakespeare wasn't kidding about the "winter of our discontent." In the colder and darker months, people do more internet searches for mental health terms, from anxiety and ADHD all the way to suicide. Search patterns also promise that like a refreshed browser window, better times are due to arrive soon.
John Ayers, of the Center for Behavioral Epidemiology and Community Health in San Diego, and other researchers dove into Google Trends to explore whether certain searches vary by season. "Seasonal affective disorder is one of the most studied phenomena in mental health," Ayers says, "with many individuals suffering mood changes from summer to winter due to changes in solar intensity." He wanted to find out whether any other mental health complaints changed with the seasons, as some studies had hinted.
Since Google Trends breaks down searches by category, the researchers started in the "mental health" section. Looking at all mental health searches in the United States between 2006 and 2011, they saw a consistent cycle with peaks in the winter and troughs in the summer. (If you do this search yourself, you'll see that there's also a dip around the December holidays—but the curve reliably bottoms out in July of each year.)
The team did some statistical smoothing and found that mental health searches overall were about 14% higher in the winter than in the summer. To confirm that the difference was due to the season, they ran the same analysis on data from Australia. Searches cycled in the same way—about 11% higher in winter than summer—but the peaks in the southern-hemisphere country were almost exactly 6 months out of sync with the United States.
When the scientists broke down searches by specific symptoms or illnesses, the seasonal cycle remained—and in some cases got much stronger. "We were very surprised" to see this, Ayers says. Searches including the terms ADHD, anxiety, bipolar, depression, anorexia or bulimia, OCD, schizophrenia, and suicide all rose in the winter and fell in the summer.
One of the most dramatically cycling search terms was schizophrenia, at 37% higher in the winter. Eating disorder terms varied just as strongly. (The smallest seasonal difference was for anxiety, which was just 7% higher in the winter in the United States, and 15% in Australia.)
Some of this seasonality might be due to the schedule of the school year, Ayers points out. Referrals for kids with ADHD and eating disorders may come from their schools.
Other explanations involve winter itself. The effect of shorter days on our circadian rhythms and hormone levels might be a factor, the authors write, as in seasonal affective disorder. They speculate that a lack of vitamin D (which we make using sunlight) in the winter might contribute. Even omega 3 fatty acids might matter: we consume less of them in winter, and omega 3 deficiency has been linked to some mental illnesses.
There's also the question of what we're doing all season. People hunkered indoors during the colder months may have fewer chances for socializing, which is "a well-known health emollient," the authors write. The same goes for physical activity.
"There is a lot more we need to learn about mental health and seasonality," Ayers says. "For instance, is there a universal mechanism that impacts our mental health?"
Of course, sometimes our malaise isn't about the season.
Whatever portion of mental health is predictable, though, doctors would love to know about it and use that information to help.
This study doesn't give reveal much about low-income or elderly populations who aren't online. And knowing what people are searching for isn't exactly the same as knowing what symptoms they're experiencing. "We are actively working to address these limitations," Ayers says. Working with Google.org, the charitable branch of Google, he hopes to develop systems similar to Google Flu Trends that can track a population's mental health.
"Intuition suggests that these results are reflective of an important link between the seasons and mental health," Ayers says. For now, we have the reassurance of computer algorithms that skies will be clearer soon.
Ayers, J., Althouse, B., Allem, J., Rosenquist, J., & Ford, D. (2013). Seasonality in Seeking Mental Health Information on Google American Journal of Preventive Medicine, 44 (5), 520-525 DOI: 10.1016/j.amepre.2013.01.012
Image: Skaneateles, NY, by me.
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Ayers, J., Althouse, B., Allem, J., Rosenquist, J., & Ford, D. (2013) Seasonality in Seeking Mental Health Information on Google. American Journal of Preventive Medicine, 44(5), 520-525. DOI: 10.1016/j.amepre.2013.01.012
A young homing pigeon must learn quickly how to find its way home from the strange neighborhoods where humans insist on leaving it. At first the bird does this by relying on its crudest instincts, returning to its roost along a route full of youthful zigzags. Over time, though, it refines its methods. A mature pigeon takes a much simpler route, because it has drawn itself a more complex map.
Homing pigeons have been subjected to all kinds of research. The latest study used GPS devices, which the birds carried in little Teflon backpacks. Ingo Schiffner of the Queensland Brain Institute and Roswitha Wiltschko of Goethe-Universität Frankfurt studied pigeons at three different ages: juveniles (6 to 7 months old), yearlings (the same pigeons in their second year of life, after going through a training program), and older trained birds (at least two years of age).
Wearing their tracking harnesses, the birds were released from various sites that ranged from 3.2 to 23.5 kilometers away from their home loft in Frankfurt, Germany. Here are the routes some of the birds took when returning to their home (the square) from a release site 6.8 kilometers away (the triangle):
You'll notice that some pigeons traveled by more, shall we say, scenic routes than others. The researchers calculated each bird's "efficiency" and found that the youngest group of pigeons were the least direct fliers. On average, they traveled more than three times the distance of a straight-line trip between the two points. (The pigeon researchers, in a bit of a mixed-species metapor, refer to this ideal trip as a "beeline.")
The two older groups of birds were much more efficient, flying no more than 25 percent farther than they needed to. Since their youthful zigzagging days, they had gone through a training program that had them practicing as far as 40 kilometers from their home roost. Now more familiar with the features of the landscape around their home, they could navigate it easily.
But that didn't mean the pigeons stopped refining their internal maps after their first year. Schiffner and Wiltschko also calculated something called the "correlational dimension," which is the number of factors that seem to be contributing to a system—in this case, pigeon navigation.
Previous research has suggested that homing pigeons have multiple tools in their navigational toolkit. In various experiments, "pigeons have been deprived of visual cues, magnetic cues, olfactory cues, infrasound cues, and their gravitational sense," Schiffner says, "yet pigeons are still able to find their way home." Rather than relying on just one tool at a time, they seem to use several.
The correlation dimension is meant to count how many tools each pigeon uses to complete a trip. The youngest pigeons usually hovered close to 2. But year-old pigeons had a somewhat higher score, and the oldest pigeons were closer to 3. In his previous research, Schiffner says, pigeons have seemed to use as many as 4 types of navigational cues simultaneously.
This suggests that pigeons keep refining their mental maps as they age, adding new elements—visual landmarks, say, or the smell of a local factory—to others such as sunlight and magnetic fields. "I cannot say yet which factors pigeons are using," Schiffner says, but he believes the factors add up with age. He and Wiltschko report their results in the Journal of Experimental Biology. Schiffner adds, "I assume that pigeons continue to learn and integrate new information into their navigational map as they grow older."
Attaching GPS devices to animals is currently trendy; there's a whole new journal dedicated to the subject. But humans have a long history of rigging our technologies to pigeons. At the start of the 20th century, German apothecary Julius Neubronner designed and patented a little camera on a harness for homing pigeons to carry (he had previously used the birds to ferry prescriptions and drugs for his patients).
The German military toyed with using Neubronner's pigeon-camera technology for reconnaissance during World War I. With the cameras hooked to timers, the birds could take pictures above enemy lines and carry them back home. These days we're attaching our instruments to the accommodating birds not for the sake of spying on our enemies, but to decode the secrets of the pigeons themselves.
Schiffner, I., & Wiltschko, R. (2013). Development of the navigational system in homing pigeons: increase in complexity of the navigational map Journal of Experimental Biology DOI: 10.1242/jeb.085662
Images: Homing pigeons by Amanda Dague (via Flickr); figure from Schiffner and Wiltschko; pigeon cameras by Julius Neubronner (via Wikimedia Commons).
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Schiffner, I., & Wiltschko, R. (2013) Development of the navigational system in homing pigeons: increase in complexity of the navigational map. Journal of Experimental Biology. DOI: 10.1242/jeb.085662
Close your eyes. Do you know where all your fingers and toes are? Can you pinpoint the exact edges of your body in space?
You may think your knowledge of your body is unshakeable, but a simple trick with a rubber limb can sway you. In kids, the effect is even more extreme—a finding that gives intriguing hints about how our body sense develops.
The new research relies on the "rubber hand illusion," first published in 1998. To produce this illusion, an experimenter sits across a table from a subject. The subject rests one hand, let's say the left, flat on the table and keeps the other hand in his lap. A little wall blocks the left hand from the subject's sight. But the subject can see a rubber hand, also a left hand, sitting on the table just inside the wall.
Actually, hold on, I'll draw you a picture.
OK. The experimenter (or, oval with glasses) holds two paintbrushes and uses them to stroke the backs of the real hand and the rubber one simultaneously. The subject watches these paintbrush strokes that seem to match the ones he's feeling, and eventually the brain takes a shortcut: it decides the seen hand and the felt hand are one and the same. This gives the subject the eerie impression that the rubber hand is part of his body. (I wrote about trying the rubber hand experiment for my eighth-grade science fair—and someone else's kooky version of the illusion that uses entire bodies instead of hands—here.)
University of London psychologist Dorothy Cowie and her colleagues tested the rubber hand illusion on kids of varying ages to see how their response compared to adults. Like researchers before them, they measured the effect in two ways. The first was a questionnaire about whether the rubber hand felt like the subject's own (for kids, the scale went from "definitely not" to "lots and lots").
For the second measurement, subjects closed their eyes and slid the index finger of their right hand under the edge of the table until they believed it was aligned with the index finger of their left hand. After experiencing this illusion, subjects tend to get skewed in the direction of the rubber hand.
The researchers tested adults as well as 90 kids between the ages of 4 and 9. They saw that in the sliding-finger measurement, kids in all age groups drifted farther toward the rubber hand than adults did. The results are reported in Psychological Science.
To explain this, Cowie suggests that people rely on two different methods to figure out where their body parts are. One combines vision and touch: do the cues I'm feeling match what I see? The illusion worked best for adults when the paintbrush strokes on both hands were perfectly in sync.
But for kids, the illusion stayed strong even when the paintbrush strokes they saw were out of sync with the ones they felt. This suggests that a second system of perception simply asks whether something that looks like our arm appears in roughly the place we expect it. Kids overuse this system, Cowie says. "Seeing a 'hand-like thing' in front of them on the table was enough to sway their perception of where their own hands were." By adulthood, Cowie thinks, we learn to pay more attention to tactical cues. "Adults rely less on the visual stuff than kids."The fact that the illusion works at all demonstrates that "we don't just rely on muscle info to tell us where our body is," Cowie says, whether we're kids or adults. "In fact vision is really important!" Her research group is conducting further studies to find out how perception changes with age. "The results are absolutely always that kids are more susceptible than adults" to the illusion, she says.
If you're feeling worried that you don't know your body very well, consider taking on a more childlike attitude. Cowie says the kids in her experiment enjoyed being tricked by the illusion. One kid reacted with "You seem to have painted my hand!" They were eager to check where their hands really were when the test was over.
"Kids are actually open to weird stuff more than adults are," she says.
Cowie, D., Makin, T., & Bremner, A. (2013). Children's Responses to the Rubber-Hand Illusion Reveal Dissociable Pathways in Body Representation Psychological Science DOI: 10.1177/0956797612462902
Images: St0rmz (via Flickr); me (via Post-It note).
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Cowie, D., Makin, T., & Bremner, A. (2013) Children's Responses to the Rubber-Hand Illusion Reveal Dissociable Pathways in Body Representation. Psychological Science. DOI: 10.1177/0956797612462902
At nightfall, the Hawaiian bobtail squid digs itself out of the sand and rises into the ocean water like a spaceship taking off. It switches on its cloaking device: glowing bacteria inside its body light up, disguising the squid's silhouette against the moonlight for any predators swimming below. As sleek a vehicle as it appears, though, the bobtail may not totally outrank its microscopic crewmembers. The bacteria seem to power a clock inside the squid's body that can't function without them.
Hiding during the day and hunting at night in shallow Pacific waters, Euprymna scolopes clearly has a working circadian clock. Researchers had noticed, though, that the squid's light organ—the specialized pocket inside its body that houses its bacterial helpers—seemed to have a rhythm of its own. The Vibrio fischeri bacteria give off fluctuating amounts of light throughout the day, for one thing. And the bacteria have their own daily rhythm of gene expression (when various genes are turned on or off), explains Margaret McFall-Ngai, a microbiologist at the University of Wisconsin, Madison.
McFall-Ngai and her coauthors looked for genes linked to circadian rhythms within the squid. They found two types of "cry" genes, which are known to control internal clocks throughout the animal and plant kingdoms. One gene had a daily cycle of activity in the squid's head—which is what you'd expect, since animals' main circadian clocks are in our brains. Other clocks can be elsewhere in the body, though, and this is what researchers found with the second cry gene. It was cycling only within the light organ.
Baby squid, which hadn't yet collected bacterial friends in their light organs, didn't show the same cycling. So it seemed that the bacteria themselves were driving the daily rhythms in the light organ. When the researchers let squid fill their light organs with defective, non-glowing bacteria, the cry gene still didn't cycle properly. This suggested that the glow of the bacteria was the crucial ingredient.
To test this idea, the scientists shone a blue light on the squid holding defective bacteria. Now they expressed just as much cry as the original squid.
McFall-Ngai explains that cryptochromes, the proteins made by cry genes, respond to blue light. Based on the light signals the cryptochromes receive, they turn other genes on or off. Cryptochromes in the squid's head respond to light from the sun to drive its daily rhythms, as in other animals and plants. Those in its light organ, though, respond to the light of its glowing bacterial companions.
The role of the bacterial clock isn't clear yet. "We don't know if the light organ rhythms control any other rhythms in the body," says McFall-Ngai. "But they certainly seem to be involved in controlling the rhythms of the organ itself." The squid controls the daily schedule of the bacteria, too: it jettisons most of its bacteria in the morning, and seems to keep them dimmed during the day by restricting their oxygen supply. At night, it gives the bacteria enough resources to glow at full strength—and that glow drives the clock within the light organ. "There seems to be a tit for tat," McFall-Ngai says. "The host and symbiont 'talk' to one another, controlling one another's biology."
The idea that bacteria can drive circadian rhythms inside their hosts is exciting to humans because we, too, are animals packed full of bacteria. Ours don't glow, but they do line our guts and participate in digesting our food. McFall-Ngai points out that scientists have found "profound circadian rhythms" within our gut tissues, both in their activity and in what genes they express.
Even though we're land-bound, non-glowing vertebrates, our bacteria could be powering circadian rhythms within our bodies just like the squid's. "We think it might be a very general phenomenon," McFall-Ngai says. Our microscopic passengers, that is, might be helping to steer the spaceship.
Heath-Heckman, E., Peyer, S., Whistler, C., Apicella, M., Goldman, W., & McFall-Ngai, M. (2013). Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis mBio, 4 (2) DOI: 10.1128/mBio.00167-13
Image: Margaret McFall-Ngai
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Heath-Heckman, E., Peyer, S., Whistler, C., Apicella, M., Goldman, W., & McFall-Ngai, M. (2013) Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis. mBio, 4(2). DOI: 10.1128/mBio.00167-13
Christmas arrived early this year for people who love animals carrying transmitters around. A new open-access journal called Animal Biotelemetry launched this week, and it promises to bring new tales of mind-blowing bird migrations and seals that study climate change (without exactly having volunteered for the job). Also, sharks.
Published by BioMed Central, the journal will include all kinds of research having to do with biological data gathered by instruments attached to animals. This is a field that's been expanding as the technologies themselves shrink. A few decades ago, scientists were limited to studying the movements of giant land animals such as bears or elk—because transmitters and battery packs were too bulky to comfortably attach to other creatures. Now, miniaturized electronics (aided by GPS satellites) mean that even lightweight birds can carry tracking devices.
Editor A. Peter Klimley describes the history of the field in an introduction to the journal. Klimley himself is a professor and shark guy at the University of California, Davis. His biography claims that he "is known to have held his breath while diving up to 100m deep in order to hand-tag hammerhead sharks with a dart gun." In case "biotelemetry" didn't sound exciting to you.
To mark the occasion, here are some earlier posts involving animals carrying transmitters around, since I am one of the aforementioned people who love them.
Monitoring from Space Shows Even This Giant Crab Can Navigate Better than You
Climate-Studying Seals Bring Back Happy News
This Penguin: An Unexpected Journey
Klimley, A. (2013). Why publish Animal Biotelemetry? Animal Biotelemetry, 1 (1) DOI: 10.1186/2050-3385-1-1
Image: by MEOP Norway North
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Maybe it's no mistake that we talk about "grasping" new ideas. When we find our hands moving wildly as we try to explain something, maybe we shouldn't feel ridiculous. Research in math classrooms has found that kids learned better when a teacher used gestures—and their grip on the new material improved even more after the lesson ended.
Teachers who gesture more or less while they speak can have other differences too, of course: they might use different intonation or vocabulary, or have more or less energy. University of Iowa psychologist Susan Wagner Cook and her coauthors, though, were only interested in the effect of teachers' hand motions. To isolate this factor, they created a series of videos.
In the videos, aimed at elementary schoolers, a teacher taught a single scripted lesson. The subject of the lesson was equivalence, the idea that what's on one side of an "=" must be equal to the other side.
In one set of videos, the teacher used her hand to indicate "one side" and "the other side" of an equation. A second set of videos showed the same teacher reading the same script, but she kept her hands at her sides. The researchers made several recordings and chose the ones in which the teacher's intonation was the most consistent, ensuring that the only difference between the lessons was her hands.
The kids who watched the videos were 184 boys and girls from 22 classrooms in central Michigan schools. Most were in second or third grade, and a few were in fourth. The kids had taken a pretest to make sure they weren't already familiar with this mathematical idea.
Each classroom watched a videotaped lesson, either the one with hand gestures or the one without. Immediately afterward, they took a test with questions such as:
7 + 2 + 4 = 7 + __
Kids who had understood the lesson would answer "6."
A day later, the kids had a second set of test questions spring on them. First they answered the same type of questions that they had the day before. Then they saw a second set of questions designed to make them "transfer" the rules they'd learned to new situations. For second graders, this meant trickier addition problems such as:
6 + 4 + 2 = __ + 3
in which none of the numbers on the right side matched the left. Third and fourth graders had to transfer their new skills to multiplication problems such as:
5 x 2 x 3 = __ x 3
Kids who had seen the lesson with gestures did significantly better than the no-gesture kids on the first test. A day later, they again outperformed the hands-free group—and beat their own test scores from the day before. Their understanding of the lesson seemed to have gotten even better in the 24 intervening hours. (This wasn't true of kids who watched the hands-free lesson.) Finally, the gesture group did better on the test of transferred skills.
A couple factors could explain why students learned better from a gesturing teacher, the authors write. Hand movements might help them pay better attention to the teacher, for example. And seeing a repeated hand motion across different problems might reinforce how those problems are similar.
That doesn't answer the question of why students continued to improve over the next 24 hours. Susan Wagner Cook explains that shortly after we form new memories, those memories are stabilized or "consolidated" in our minds. Consolidation can make new memories even stronger.
"We do know that motor memory is often consolidated during sleep," Cook says. Seeing another person's hands moving may have built motor (movement) memories in kids' minds, as if they were pointing and waving their own hands. "One possibility is that memories encoded with gesture are more likely to be consolidated during sleep," Cook says. "We are trying to figure this out!"
Although being able to point to the two sides of an equation seems like a clear advantage in this particular lesson, Cook says the benefit of gesturing goes beyond arithmetic—or even math. Other studies have shown that hand motions help kids learn in a wide range of subjects.
What's new is the idea that gestures help in the future, not only the present. Cook points out that even though some kids learned the lesson just fine without gestures, they didn't show the same improvement over time that the other kids did. Instead of only clarifying, gestures may help kids grasp their new knowledge more tightly. (Please imagine a fist-closing gesture to drive home this idea.)
Image: sleepinyourhat (via Flickr)
Cook, S., Duffy, R., & Fenn, K. (2013). Consolidation and Transfer of Learning After Observing Hand Gesture Child Development DOI: 10.1111/cdev.12097
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Cook, S., Duffy, R., & Fenn, K. (2013) Consolidation and Transfer of Learning After Observing Hand Gesture. Child Development. DOI: 10.1111/cdev.12097
A fish swims along a sandy lake bottom, carrying one of its babies in its mouth. It approaches the nesting cave of another family of fish. With a furtive "ptooey," it leaves the baby behind for adoption. For certain fish, this seems to be a common scene: giving up your young and taking on others' may be the best way to ensure your offspring grow past snack size.
The fish in question is Neolamprologus caudopunctatus, a type of cichlid (pronounced like a compliment for someone's hat).* Just a couple of inches long, the diminutive fish lives only in East Africa's Lake Tanganyika. Males and females form monogamous pairs. They raise their young in burrows under rocks; carrying sand in their mouths, they pile it up around the rocks to build narrow entrances.
For the first 40 days or so in the lives of the young fish (called fry), both parents work to protect them from predators. They guard the nest and attack any other fish that come by looking for a meal. Cichlids can also protect their young by carrying them inside their mouths.
As the fry grow older and start swimming on their own, they may wander away from their parents' nests and into nearby ones. However, cichlids have also been spotted carrying young in their mouths and leaving them at other nests. Scientists at the Konrad Lorenz Institute of Ethology in Vienna set out to see how much of the baby swapping among N. caudopunctatus is intentional.
Researchers scuba dived down to the home of the cichlids, mapped the locations of their nests, and collected DNA samples. Back on land, like the crew of a daytime talk show for African lake bottoms, they analyzed the DNA to find out just how these fish were related.
Out of 32 nests, more than half held adopted fry, the authors report in Behavioral Ecology. Within nests that housed adopted fish, those outsiders made up anywhere from 10% to 77% of the nest.
The researchers took their DNA analysis a step further for a dozen adopted fry, hunting down their biological parents. They found that while some fry had been adopted from nearby nests, others were a very long way from home—as far as 40 meters or more. "It is virtually inconceivable that they swam there alone," says senior author Richard Wagner. The lake is packed with hungry predators. It would be, he says, "like a toddler walking across a busy city without mishap." It's more likely that parents deliberately carried these young fish in their mouths from one nest to the other.
There was another piece of evidence that adoptions happened on purpose. Adopted fish were on average larger (which is to say older) than non-adopted fish across the whole sample. But within each nest, the size difference wasn't significant. This suggests that when cichlid parents give up their young, they select nests with fry that are close in size to their own. Such a strategy might make the adopted fish less conspicuous to predators.
Parents who leave their fry at other nests may be hedging their bets, making sure that at least some of their offspring survive if their own nest is wiped out by a predator. As for adoptive parents, they could just kick out the freeloading fry. But keeping adopted fish around means that when predators attack, there's a smaller chance of your own offspring ending up in another fish's mouth.
"Our paper adds evidence that adoption is an adaptive strategy," Wagner says, rather than simply the result of wandering babies. We humans aren't the only animals that regularly choose to raise others' young. One hopes, though, that human foster parents aren't in it for the reduced predation.
Schaedelin, F., van Dongen, W., & Wagner, R. (2012). Nonrandom brood mixing suggests adoption in a colonial cichlid Behavioral Ecology, 24 (2), 540-546 DOI: 10.1093/beheco/ars195
Image: N. caudopunctatus by Varmer (via Flickr)
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Schaedelin, F., van Dongen, W., & Wagner, R. (2012) Nonrandom brood mixing suggests adoption in a colonial cichlid. Behavioral Ecology, 24(2), 540-546. DOI: 10.1093/beheco/ars195
Too many mouths to feed? Just make your babies fight each other to the death! That's a strategy some bird parents have been using since even before The Hunger Games was popular. It means the strongest chicks get stronger while the weakest ones conveniently stop showing up to the table.
One type of bird takes this family drama a step further: after letting the biggest chicks bully their siblings for a while, parents suddenly decide the runts are their favorites and begin beating up the older chicks themselves. Authors looking for the next dystopian mega-hit, take note.
"Many species of birds show 'hatching asynchrony,'" says Daizaburo Shizuka of the University of Nebraska, Lincoln. This means they stagger the hatching of the eggs within a nest. When some chicks emerge from their eggs days later than others, the younger birds are doomed to be outweighed and outcompeted by their older siblings. Blue-footed boobies, for example, produce two mismatched chicks; one may peck the other to death or shove it out of the nest. (If you think that's horrifying, you haven't heard about sand tiger sharks, which eat each other inside their mother's womb.)
The polite way to say "letting half your babies die" is "brood reduction." Why hatch a runty egg at all? Parents may allow more siblings to live if food is plentiful. Or a second egg might be a kind of insurance in case the first doesn't hatch.
American coots are waterbirds that lay large clutches of eggs and may space out their hatching over a week or more. This means some siblings end up much heftier than others. At first, young coots follow their parents around, relying on their parents to feed them insects and plant material they find by diving. Siblings don't physically attack each other, but older birds easily out-jostle smaller ones for food. Half of all chicks die of starvation.
Over several years, Shizuka and Bruce Lyon, an ecologist at the University of California, Santa Cruz, monitored 75 American coot families on a lake in British Columbia. They snuck every new chick away as it hatched to give it a color-coded tag. Spying on these families while their chicks ate or starved, the researchers discovered a highly unusual system at work.
During the first 10 days after hatching, younger coot chicks often died of starvation. But any runty chicks who survived this period saw their luck turn around. Parents suddenly started playing favorites. Each coot parent picked one preferred chick out of those who'd hatched last, and gave that chick the most food. Heightening the drama, moms and dads each chose a different favorite.
To discourage bigger siblings from asking for so much food, the parents spent more time "tousling" these birds. In humans this means "affectionately messing up someone's hair," but in birds it means "grabbing your baby by the head and shaking it." As you might imagine, it's pretty convincing. The beefy siblings backed off.
Once parents switched to spoiling the runts and beating up the bigger kids, late hatchers became just as likely to survive as their siblings. The youngest chicks even grew slightly larger than their older brothers and sisters.
This system may be a way "for parents to try to get the best of both worlds," Shizuka says. First, coot parents allow brood reduction to happen, watching their chicks compete to the death. Once the family reaches its optimal size, he says, "parents can take matters into their own hands to make sure that the youngest chicks that are still surviving end up getting enough."
Don't throw out your parenting books yet. Although this method seems to work for the coots, scientists still aren't sure why so many birds have evolved elaborate strategies that require siblings to murder each other—or why chicks go along with it. Shizuka says, "It's safe to say the matter is not resolved."
Shizuka, D., & Lyon, B. (2013). Family dynamics through time: brood reduction followed by parental compensation with aggression and favouritism Ecology Letters, 16 (3), 315-322 DOI: 10.1111/ele.12040
Image: Bruce E. Lyon
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Shizuka, D., & Lyon, B. (2013) Family dynamics through time: brood reduction followed by parental compensation with aggression and favouritism. Ecology Letters, 16(3), 315-322. DOI: 10.1111/ele.12040
Forget a needle in a haystack. For that search you'd be allowed light and air—and when you held the needle in your hand at last, it wouldn't be unrecognizably coated in bone-eating worms. Looking for whale skeletons on the ocean floor is such an impossible task that no one sets out to do it on purpose. The most recent find, lying near Antarctica and crawling with previously unseen species, was a very happy accident.
A dead whale that sinks all the way to the ocean floor is called a "whale fall," kind of like "windfall," which it is. The corpse is a massive sack of food dropped from above into a barren landscape. It feeds generation upon generation of life: first the scavengers that pick it clean, then other creatures that chew the bones into scaffolding and bacteria that churn out sulfides, and then a host of animals that feed on these chemicals directly or indirectly.
The same types of animals live at hydrothermal vents and cold seeps, where they consume sulfides and other chemicals seeping out of the earth. Whale falls may act as stepping stones for these species to migrate from one undersea chimney to the next. Even though they haven't seen many sunken skeletons up close, scientists have deduced this with the help of experiments such as dropping wood piles into the ocean and leaving them there.
When the members of a UK-funded research expedition came across the latest whale fall, they were piloting a remotely operated vehicle (ROV) more than 1,440 meters under the sea. "We were at the end of a very long ROV survey," says graduate student Diva Amon, "and had already gone an hour over our allocated time on the seafloor." Then, she says, "we spotted a row of curious white blocks in the distance."
Investigating more closely, the team realized that the blocks were spine bones. They were looking at a whale skeleton covered in deep-sea animals. "We all realized that this was only the sixth natural whale fall to be seen, and the first in the Antarctic," Amon says. "Everyone was thrilled."
In this video, you can watch from the eyes of the ROV as it pans across the find. The camera moves from the whale's skull to its vertebrae, which are lined up like a string of enormous marshmallows. Then it zooms in to see the lush jungle of life sprouting from each bone. Around 50 seconds in, you'll get a cephalopod surprise (is there a better kind?).
The fronds you see waving from the vertebrae are the tail ends of bone-eating worms called Osedax, which Amon calls "remarkable." Tucked in between them are the shells of limpets. When the camera pans down to a fellow who looks like a rubbery sock (a sipunculan worm), you might spot tiny crustaceans scurrying across the bone in the background. Did you see the worm whisk itself into hiding when the squid jetted by? You should probably watch again to be sure.
If the pale denizens of this skeleton look weird to you, they were weird to the scientists back at sea level too. The creatures at the whale fall included nine species that had never been seen before. "Every time one explores the deep sea, there is a very large chance of finding a new species," Amon says.
DNA analysis showed that the skeleton, nearly 11 meters long, once belonged to a minke whale. The types of creatures now living on it were similar to those at other whale falls. Based on these life forms and the state of the bones, scientists could tell that the whale fall has become a sulfur-rich environment. It houses the same animals that inhabit deep-sea vents and cold seeps, and it may be helping those creatures migrate across the ocean floor. "One species of limpet that was found on the whale bones was also found on nearby hydrothermal vents," Amon says.
The researchers couldn't tell whether the skeleton had been in its resting place for a few years or for several decades. Either way, they left this rare needle right where they found it.
Amon, D., Glover, A., Wiklund, H., Marsh, L., Linse, K., Rogers, A., & Copley, J. (2013). The discovery of a natural whale fall in the Antarctic deep sea Deep Sea Research Part II: Topical Studies in Oceanography DOI: 10.1016/j.dsr2.2013.01.028
Images: Whale vertebrae photo and video (c) UK Natural Environment Research Council ChEsSo Consortium; deep-sea creatures (c) Natural History Museum.
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Amon, D., Glover, A., Wiklund, H., Marsh, L., Linse, K., Rogers, A., & Copley, J. (2013) The discovery of a natural whale fall in the Antarctic deep sea. Deep Sea Research Part II: Topical Studies in Oceanography. DOI: 10.1016/j.dsr2.2013.01.028
"The connection with the sun coming up is a misconception," asserts an article in the rural lifestyle magazine Grit. "Roosters crow all the time." Some roosters in Japan would like to loudly disagree. They've shown scientists that their crowing has everything to do with what time of day it is—something they don't even need the sun to know.
Tsuyoshi Shimmura and Takashi Yoshimura, both of Nagoya University in Japan, investigated whether a rooster's crowing is tied to its circadian clock. That is, does the bird's internal sense of night and day determine when it's noisiest? Or do roosters crow at random hours—"morning, noon and night, not to mention afternoon, evening and the parts of the day that don’t have names," according to a disgruntled neighbor-to-roosters quoted in the Grit story?
Like any scientists studying how animals follow the sun's rhythms, the researchers began by shutting their subjects indoors. In a controlled environment, they kept the roosters on a strict schedule of 12 hours in the light and 12 hours in the dark.
Recordings showed that the roosters did not crow at random. A sudden burst of crowing came two hours before the artificial dawn, and the birds gave another "cock-a-doodle-doo" immediately after the lights came on. (Though in their country, the authors point out, it's "ko-ke-kok-koh.")
Then the scientists turned the lights out entirely, keeping the birds in a permanent night. The roosters at first continued to follow crowing cycles of roughly 24 hours, with only their internal clocks keeping them on schedule. Over the course of two lightless weeks, this rhythm gradually wound down.
In the barnyard, though roosters need their circadian alarm clocks for any pre-dawn crows, they can rely on other cues to trigger their crowing at sunrise—say, the sun. So Shimmura and Yoshimura next checked whether light itself causes crowing.
Starting with roosters that were living in permanent night, they tried exposing the birds to a little bit of light at the dawn hour. A few of the roosters crowed. When the researchers used brighter and brighter light, more and more of the birds crowed in response, as if recognizing the sun. A sound recording of other roosters crowing also worked to set their birds off.
Yet just flipping on the lights wasn't enough to make a benighted bird start crowing. When the light and sound signals came at "dawn," the roosters readily responded. When researchers used the same signals later in the "day," their birds didn't respond as strongly. And when they tried the signals at "night," the roosters didn't crow at all.
Even though they were living in permanent dark, roosters weren't fooled by seeing a fake sun at any old time. To get them crowing in earnest, the signals of sunrise had to come at the same time that the birds' bodily alarm clocks rang.
Roosters seem to be expert timekeepers. This knowledge, though, may not make come as much consolation to their neighbors.
Shimmura, T., & Yoshimura, T. (2013). Circadian clock determines the timing of rooster crowing Current Biology, 23 (6) DOI: 10.1016/j.cub.2013.02.015
Image: by -JvL- (Flickr)
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Shimmura, T., & Yoshimura, T. (2013) Circadian clock determines the timing of rooster crowing. Current Biology, 23(6). DOI: 10.1016/j.cub.2013.02.015
If it were urgent, maybe we could be more forgiving. But the subject of that phone call one table away at Starbucks never seems to be vital. A bathroom renovation, maybe. Or a phrase-by-phrase recounting of a text message dialogue with an ex. If you suspect overheard phone conversations are inherently more awful than people talking face to face, you're right: research shows that these conversations reach across our espresso cups, grab our attention, and don't let go.
Psychologist Veronica Galván studied this problem recently at the University of San Diego. To bring the coffee shop into the lab, she started by lying to about 150 undergrads. The students believed themselves to be in an experiment about reading comprehension. When they sat down at a table to solve a worksheet full of anagrams, another student sat down next to them and launched into a seven-minute conversation. This person, of course, was a plant.
The neighbor had a scripted conversation, either over the phone or with a second actor in the room. (The discussion covered three typically scintillating topics: "a birthday party for dad, shopping for furniture, and meeting a date at the shopping mall.") Meanwhile, subjects tried to ignore the noise and dutifully completed their worksheets.
When subjects filled out questionnaires afterward about how distracting they'd found the conversation in the room, their answers depended on what they'd heard. People who heard the one-sided conversation (a person on a cell phone) found it significantly more noticeable, more distracting, and more annoying than those who heard two people talking.
Even so, all the subjects performed about the same on their anagram-solving test. Galván had expected to see a difference between people who heard a phone conversation and people who didn't, but she says the anagrams may have been too easy to show an effect. Conversely, they may have been too difficult to allow people's attention to wander. Galván hopes her future experiments will reveal what kinds of tasks are most vulnerable to distracting phone conversations.
After their anagram test, subjects took a pop quiz about the conversation they'd just overheard. They saw a series of words and had to decide whether each one had been spoken in the conversation. In this case, the test results were clear. People who'd heard a one-sided conversation remembered it better than people who'd heard a two-sided conversation, Galván reports in PLOS ONE. Additionally, they rated their confidence in their responses higher than people who heard the two-sided conversation.
It's possible people remembered two-sided conversations less clearly because they heard more words overall. But the idea that a one-sided conversation seizes more of our attention agrees with previous research on the subject.
Because we can follow along with a two-sided conversation, its content is more predictable and therefore (the theory goes) easier to ignore. One person yakking away into a phone, however, is unpredictable and confusing. We can't stop our minds from trying to puzzle it out.
The subjects in Galván's study were all undergraduates. "College students are fairly accustomed to overhearing cell phone conversations," she says. "Yet even they reported more annoyance and had better memory for the one-sided conversation." She suspects older adults might find cell phone conversations even more annoying and distracting than college students do.
Until science finds a way to make other people's phone calls less bothersome, you're doomed to catch every word of that half-a-business-meeting being conducted two chairs over. On the bright side, you may remember it well enough to blackmail the guy in the future.
Galván, V., Vessal, R., & Golley, M. (2013). The Effects of Cell Phone Conversations on the Attention and Memory of Bystanders PLoS ONE, 8 (3) DOI: 10.1371/journal.pone.0058579
Image: Ed Yourdon (Flickr)
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Galván, V., Vessal, R., & Golley, M. (2013) The Effects of Cell Phone Conversations on the Attention and Memory of Bystanders. PLoS ONE, 8(3). DOI: 10.1371/journal.pone.0058579
Without plagues, earthquakes, and unhinged criminal masterminds, the residents of Gotham might never need to put up the bat signal. Real bats, of course, are less concerned with responding to emergencies than with eating bugs. But like Batman, they do just fine—if not better than ever—in recently devastated environments. Specifically, forests that have burned down.
For five weeks in the summer of 2002, a wildfire tore through national forests in the Sierra Nevada mountains. The McNally Fire was started by a careless human, and ended with over 150,000 acres burned. A year later, scientists came by to see how the bats were doing.
"Bat ecologists have known for a while now that bats respond favorably to controlled, low intensity fires," says Michael Buchalski of Western Michigan University, one of the study's authors. "We were more interested in the effects of large, natural fires." These blazes can completely destroy the forest canopy, leaving an area unrecognizable.
Researchers visited 14 sites in the woods, half in burned areas and half in areas that were untouched. They left devices that recorded the ultrasonic cries of echolocating bats at night. Since tallying up all the bat activity they heard could be misleading—one flourishing species of bats might mask the disappearance of another—they divided the recordings into groups of similar-sounding calls, representing groups of bat species.
The researchers estimated how plentiful each type of bat was based on how often they heard its calls. Comparing burned and unburned areas, they found that no bat group was bothered by the fire. Instead, every group of bats was at least as plentiful in the fire-scorched areas—and some were doing even better than usual.
Despite the absence of costumed criminals, a few factors might account for bats' increased activity in a scorched landscape. Bats hunt by swooping through the air and searching for insects below. With much of the vegetation cleared out by fire, insects have fewer places to hide, and hunting bats have a clearer view for their echolocation.
Additionally, the first plant regrowth after a fire leads to a boom in insect species. This means there's more prey than ever available for hungry bats. "One-stop shopping!" says coauthor Joseph Fontaine of Murdoch University. Those bats may find new places to roost—or, if you prefer, build their secret lairs—inside dead trees.
Buchalski and Fontaine say bats probably need a mix of landscapes to thrive, including areas that have recently burned. Carefully allowing forests to burn more like they did in the past could lead to "healthier forests and healthier wildlife populations," Buchalski says. "However, this is a very contentious issue within the field of forestry management."
"We have spent the majority of the last century suppressing and excluding fire," Fontaine adds. "More fire right now is probably not a bad thing whatsoever." (For non-human animals, anyway.) With climate change increasing the potential for drought and wildfire, the authors say that understanding how different species deal with fire is becoming more important.
Bats aren't the only animals that appreciate a fire. Fontaine says deer mice and other short-lived rodents respond very well to fire, and deer and elk like to chew on the soft new shrubs that have regrown a few years later. Several types of woodpeckers, he adds, rely on fires. The California spotted owl doesn't mind fire—like a bat, it hunts from above and doesn't need a live tree for its nest.
Although forest fires are a boon for many species, the robin doesn't seem to be among them.
Buchalski, M., Fontaine, J., Heady, P., Hayes, J., & Frick, W. (2013). Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA PLoS ONE, 8 (3) DOI: 10.1371/journal.pone.0057884
Image from public domain files at Wikia.
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Buchalski, M., Fontaine, J., Heady, P., Hayes, J., & Frick, W. (2013) Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA. PLoS ONE, 8(3). DOI: 10.1371/journal.pone.0057884
There's more to a pair of rat noses than meets the eye. Like tiny, leashless dogs, rats like to sniff each other all over when they meet. Yet not all of this sniffing is aimed at gathering scents. Some of it seems to transmit messages such as "I'm in charge" or "Be cool" or "Please don't bite my face."
Rats and other animals give off odors from the "face, flanks, and anogenital region," says neuroscientist Daniel Wesson of Case Western Reserve University. So it's not surprising that these regions are where rats aim their sniffers when they cross paths. To find out whether there might be more going on, though, Wesson outfitted rats with head-mounted devices that measured the speed of their sniffs. Then, after recording videos of these rats encountering each other, he looked at how sniff frequency lined up with different stages of the rodents' interaction.
He saw that all rats sped up their sniffing when their noses were pointed at each other's flanks or rear ends. But when the rats were sniffing each other's faces, their behavior depended on whether they were socially dominant or subordinate. Higher-ranking rats sped up their sniffing as usual. Lower-ranking rats slowed down their own sniffing in response.
This seemed to be an "appeasement signal," akin to climbing into one's own locker when the school bully approaches. Wesson found that when subordinate rats didn't give this signal—when they kept up their sniffing at the usual rate—dominant rats were quicker to pick a fight.
To further test this idea, Wesson treated the insides of the rats' noses with zinc sulfate, making them temporarily lose their sense of smell. Even though they weren't gathering any odors, rats kept on sniffing. And when they were face-to-face, they acted the same as always: dominant rats sniffed faster, while subordinate ones slowed down to avoid trouble. "This sniffing behavior was interestingly resilient," Wesson says.
Sniffing seems to be a form of communication for rats—but only sniffing in the face, not other body parts. Wesson says this may be because face sniffing is an especially vulnerable position for a rat or other animal to be in. When their eyeballs and whiskers and biting parts are all in close proximity, maybe it's a good time for rats to make clear that they don't want a fight.
Alternately, face-to-face might be the only way a rat can detect another rat's sniffing; maybe the signal wouldn't get through if it were aimed at the tail end. "These are different theories we are testing now," Wesson says. There may also be ultrasonic squeaks or other signals invisible to humans that contribute to the conversation between two rats.
If rats use sniffing for communication, and not only for gathering smells, do other social sniffers do the same thing? "I would predict so," Wesson says. "Other rodents likely use this behavior, as could possibly cats and dogs." He points out that neighborhood dogs who meet on a walk will sniff each other, then either part peacefully or start fighting. Some signal in their sniffing behavior may make the difference, though this idea would have to be tested.
That's not to say dogs or rats aren't also gathering actual smells when they sniff. It would be "frankly silly" to discount the importance of smell in an animal's life, Wesson says. It seems there's much more going on, though, when an animal sticks its nose into the world.
Wesson, D. (2013). Sniffing Behavior Communicates Social Hierarchy Current Biology DOI: 10.1016/j.cub.2013.02.012
Image: Daniel Wesson.
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