Field of Science


The Faithfulness of the Coyote (and Other Urban Animals)

Greeting card companies are scrambling, no doubt, to fire entire departments of artists who draw lovebirds in cages and replace them with artists who draw scrappy wild dogs. That's because the new face of fidelity is the urban coyote, an animal that was until now better known for snatching untended Pomeranians from backyards. Hey, sometimes you have to feed your family.

Among mammals, monogamy is not a popular lifestyle. It's been estimated that five percent or fewer of mammal species opt to pair off exclusively. The practice is more common among dog relatives, which may need both parents to successfully raise a litter of puppies. But even when animals appear to be loyal to one partner, they may be sneaking around with other mates on the side. That's what researchers have observed in various fox, wolf, and wild dog species they've studied in the past—in fact, "extra-pair copulation" has turned up in every genetic study of canids. Evolution should favor animals that can have more offspring (or more-diverse offspring) without added effort.

Ohio State University graduate student Cecilia Hennessy* and other researchers set out to see what kind of mating system coyotes living in the greater Chicago area use. This included four counties in northeastern Illinois where coyotes are prevalent.

Coyotes seem monogamous, staying in pairs for years while they raise young and defend their territory together. But the researchers expected genetic sampling to show that these apparently loyal partners were really sneaking around. Coyotes in this area have plenty of resources available; previous studies have found that when conditions are good, canids are more likely to stray from their mates. And the coyotes in this region live close together in packs, which means more opportunities for cheating.

City rats are the opposite of monogamous. They live in big groups and mate all the time, with everybody.

The researchers captured coyotes over six years, trapping and tranquilizing adults and borrowing pups from dens. The animals were tagged and sometimes radio-collared, and had blood drawn before being released again. (The researchers also took samples "opportunistically" from roadkill. Out of the coyote deaths they observed, 62% were from cars. "Urban coyotes get hit by cars a lot," Hennessy says.)

In total, they managed to get samples from 236 coyotes, including 96 puppies. Hennessy explains that they used the blood samples from the roaming adults to try to identify the parents for each den of puppies. They found at least one parent for most of the dens. But in all puppy litters, even those with unknown parents, the researchers could deduce from the young coyotes' genes whether they were full siblings—or half siblings whose parents were sneaking around.

For the 18 litters of coyote puppies they studied, the scientists found no evidence of polygamy. As they report in the Journal of Mammalogy, the coyote pairs in the study stayed totally faithful to each other.

Pigeons are said to mate for life, though this describes their behavior and not the genes of their young. They may not guard each other as carefully as coyotes do.

From the radio collars they'd put on the trapped coyotes, the researchers could track the movements of their subjects. This included seven mated pairs of coyotes, which "we could track and figure out how much territory they share with each other and time they spend together," Hennessy says. (Seven pairs may not sound like many, but Hennessy points out that trapping adult coyotes in urban areas is not easy. Actually, she says it's "really, really, really hard.")

Three of the mate pairs in the study ended with the death of the male. Two of those females disappeared from the area after the death of their mates; Hennessy says this is common though it's not known why. It may be too difficult for one coyote to defend her territory on her own while searching for a new mate. The third female, though, held her ground and found a new mate the next year. Two of the original mate pairs had been together for at least eight years by the time the paper was written.

It's possible that urban coyotes are more monogamous than their rural relatives, although Hennessy says no one has studied the question. It's also possible that she happened to find the dens belonging to the most faithful coyote pairs out there, and there are philandering coyotes she just didn't find. "But to investigate 18 litters, several of which were whelped by the same mated pair in consecutive years, and to find no polygamy makes a pretty strong case that it doesn't occur in this population," she says.

Human mating habits vary. An extensive literature on the monogamy or polygamy of high-profile humans can be found in journals such as Us Weekly.

Scientists still don't know exactly why urban coyotes find monogamy the best policy. Hennessy says females may not have a choice in the matter, because males guard them carefully while they're fertile. And since males can be confident that they've really fathered the puppies in their dens, they can invest more resources in feeding those puppies. In packs, older siblings may also help care for the new young; if their parents are monogamous, then the siblings are related enough to make this worthwhile.

Hennessy suggests an even simpler way of understanding urban coyotes. "I think it's just too much work for one male to get enough food for himself and two females," she says. "And if he doesn't help a female with pups, the pups will likely die." So, she explains, "Cheating without follow-up is just pointless." I can already see that on next year's Valentine's Day cards.

Cecilia A. Hennessy, Jean Dubach, & Stanley D. Gehrt (2012). Long-term pair bonding and genetic evidence for monogamy among urban coyotes (Canis latrans). Journal of Mammalogy DOI: 10.1644/11-MAMM-A-184.1

Image: Coyotes by Bill Weaver (Flickr); rat by Cloveapple (Wikimedia Commons); pigeons by Ingrid Taylar (Flickr); humans by Lili Vieira de Carvalho (Flickr).

*Cecilia Hennessy is now a PhD student at Purdue University.

The Case of the Hollering Koala

During mating season, a sound like an asthmatic pig on a trampoline echoes from the canopy of the eucalyptus forest. It's the mysterious koala bellow, a sound that (when it comes from males) may mean "Come and get me, ladies!" or "Don't start a fight with this guy if you know what's good for you"—or something else entirely. Scientists aren't sure. But they've come a step closer to deciphering this marsupial's dialect by finding out how far its messages can travel through the trees.

Here, have a listen:

In earlier studies, researchers have discovered that both male and female koalas can recognize males by their bellows. They've also found that koalas can perceive the difference between bellows from large and small males. Since the normally quiet koalas save their hollering for the breeding season—in fact, males often bellow right after an attempt at copulation, whether or not it's successful— researchers think the signals help koalas coordinate their mating. For example, females might use the noises they overhear to locate their preferred mates, as in a very adult game of Marco Polo.

But the information carried in a koala's bellow is only as useful as the distance it can travel to other koalas. So researchers led by Benjamin Charlton at the University of Vienna lugged their sound equipment into the eucalyptus forest to find out what that distance was.

The researchers first recorded the bellows of ten male koalas at a koala sanctuary in Brisbane, Australia.  They chose five recordings for each male, giving them 50 total bellows.

In a eucalyptus plantation, the researchers set up speakers at a typical koala-in-a-tree height of 4 meters. They performed their experiments between 3:00 and 5:00 in the morning, a typical time for hollering by  the nocturnal animals. With a speaker broadcasting a bellow, they set up a recorder some distance away to represent the ears of a listening koala. The recorder started out just 1 meter away from the speaker, then moved to 25, 50, 100, and 150 meters distant.

Then the team trained a computer program to recognize the calls of each of the 10 individuals they'd recorded, just as a real koala would be able to recognize them, using the recording taken from 1 meter away. At 25 meters away, with the sound becoming distorted by its passage through the air and trees, the program could identify the right koala only half the time. At 50 meters that number was down to 30 percent, and at 100 meters the software could no longer tell which koala was which.

Because the computer program identified individual koalas using the same sound components that (according to previous studies) the koalas themselves seem to use, the results are probably similar to what a koala's ears would perceive. In other words, as the authors report in PLOS ONE, koalas won't have much luck identifying males by sound from farther than 50 meters.

However, the specific components of the koala bellow that correspond to the animal's size stayed relatively stable over the whole 150 meters. This suggests that even from 150 meters away, koalas can gauge each other's size (and decide whether they want to get any closer).

Knowing how far koala signals travel tells scientists a little bit more about what purpose those signals might serve. But there are still plenty of unknowns, including why female koalas bellow at all. The authors point out that sound recorders could be used to monitor koala populations; as long as the devices were spaced out by 50 meters or less, they could identify and track individual koalas by their bellows. That would help koala researchers keep tabs on their hard-to-spot subjects—even if they never do figure out what the koalas are saying.

Benjamin D. Charlton, David Reby, William A. H. Ellis, Jacqui Brumm, & W. Tecumseh Fitch (2012). Estimating the Active Space of Male Koala Bellows: Propagation of Cues to Size and Identity in a Eucalyptus Forest PLOS ONE : 10.1371/journal.pone.0045420

Image: Cody Pope (Wikimedia Commons). Sound clip: Posted to SoundCloud by NewScientist to accompany this 2011 story.

The Shambulance: Infrared Body Wraps

(The Shambulance is an occasional series in which I try to find out the truth about bogus or overhyped health products. Having recovered from my taste of no-calorie noodles, I'm back this week with Shambulance first officers Steven Swoap and Daniel Lynch.)

Sometimes it's for the best when product claims turn out to be blatant lies. If purveyors of infrared body wraps, for example, were telling the truth, clients would walk out of their spas dripping grease from their skin—and that wouldn't even be their biggest concern, next to the heart attacks.

All body wraps are not created equal. There are slimming volcanic ash wraps, herbal wraps, mud wraps, and even chocolate wraps. Some are only meant to be relaxing skin treatments. Others involve swaddling clients mummy-style in bandages and plastic wrap, then leaving them for an hour or so to stew in their own sweat.

These kinds of body wraps often promise weight loss or overall slimming. In reality, how much weight you lose will depend on how much water your body sweats out in a frantic effort to cool down. Additional svelte-ness might come from the squishing action of the tight bandages. Both effects will be temporary. 

As another benefit, spas that offer body wraps unfailingly promise "detox." This isn't the first time the d-word has come up here. Suffice it to say that unwanted molecules are filtered from our blood and sent out of our bodies by the liver and kidneys—not sucked from us forcefully by mud wraps, juice diets, or ionic foot baths.

But the most amazing promises of all come from the infrared body wrap. Unlike some of the body wrap's other incarnations, this treatment doesn't require you to strip down, be slathered in goo, and get bandaged head to toe. Instead, clients lie on a bed with their clothes on while several infrared-generating silicone pads are strapped around them. Then they're left under a heated blanket for a while.

So far, it sounds like nothing more than a toasty nap. But spas say that you'll leave an infrared wrap session skinnier and healthier, with better circulation, a faster metabolism, clearer skin, and less cellulite. How?

The pads give off long and short infrared waves that penetrate deep into your fat layers, websites claim, increasing your body temperature, metabolism, and blood circulation. The heat "break[s] down fats into a liquid form, allowing secretion of body water, toxins and fat as you perspire," according to one Chicago spa.

All that formerly stored fat, once liquefied by the infrared waves, is obviously eager to escape your body through the nearest exit. But don't worry if the fat gets stuck inside you—you'll burn it anyway. "You can burn 900 to 1,400 calories or more in just one 50 minute session," another Chicago site proclaims.

After studying this calorie chart, I'm thinking I've been wasting my time by walking to work. What I should really do is buy some of these silicone pads, strap them on, and see if I can get someone to roll me there.

This is "completely insane," says Williams College physiologist Steven Swoap. "How are they allowed to write this stuff?"

For one thing, "Fats simply don't come out of sweat glands," he says. Though if they did, you would definitely have to throw away your spa outfit after soaking it with grease from the inside.

Infrared radiation, Swoap explains, isn't a magical cellulite-blasting weapon. In fact, people naturally give off long infrared waves as body heat. "Instead of wrapping yourself with this stuff, maybe a good long hug with your significant other would work too," Swoap says. Or, if you're looking for shorter infrared waves, "You could take your TV zapper and shoot it at yourself all day long."

Daniel Lynch, a Williams College biochemist, says that heating parts of your body could certainly increase your water loss. But your fat isn't budging. "To get rid of the fat, it must be metabolized," he says, "and that is not going to be enhanced by lying on a bed with silicone wraps on your legs."

Furthermore, Lynch speculates, if your fat deposits really did get broken down and sent back into your blood—and you were, say, lying on a table instead of using those fat molecules for fuel—"You could actually have dangerous levels of fatty acids circulating in your blood. That's good for a heart attack!"

If you're looking for an exercise-free way to burn fat, Swoap suggests hanging out in a cold room rather than under a warm blanket. Being in the cold will raise your metabolism as your body tries to replace the heat you're losing. If you're still hankering after the spa experience, you could always wait until winter, wrap up in a scarf, and have someone log-roll you down the sidewalk.

Images: Top, Leah Chavie Skincare Boutique; middle, Formostar Infrared Body Wrap System; calorie chart, Formostar Infrared Body Wrap System.

In Adolescence, Fears Are Harder to Forget

When it comes to fear, unlearning is as crucial as learning. Our growing brains learn to be afraid of scalding pans, oncoming traffic, and our parents calling us by our full names. But if we can't unlearn a fearful reaction, we may live our whole lives paralyzed by dentists' offices or barking chihuahuas. The ease of this unlearning may depend on our age: new research suggests that in both mice and humans, fears are hardest to dislodge in adolescence.

People suffering from PTSD or phobias are often un-taught their fears through "exposure therapy." By repeatedly facing the things that scare them while in a safe, controlled environment, they dilute the strength of the fearful association. This washing away of old associations is a classic psychological trick called extinction. But it doesn't always work.

Researchers at Cornell and New York University, reporting this week in PNAS, used human volunteers and mouse "volunteers" to assess how easy fear extinction is at different stages of development.

The mice were 23, 29, or 70 days old—representing childhood, adolescence, and adulthood. On the first day of the study, mice were put into a box where they repeatedly heard a long tone that was followed by an electric shock from the floor. A day later, the mice found themselves in a different box where they again heard the threatening tones, but received no shocks to the paws. These sessions went on for four days.

On the first day after their fearful experience in the shock chamber, mice demonstrated fear by freezing whenever they heard the tone. By the fourth day of their "therapy," this reaction was much weaker in both young and adult mice. But adolescent mice still reacted almost as fearfully as they had on the first day.

Human subjects were also split into groups based on their age: 30 kids (age 5-11), 28 adolescents (age 12-17), and 25 adults (age 18-28). On the first day, all the subjects completed a task that involved pressing computer keys while watching colored squares go by on a screen. Really, they were being taught to associate one color of square with a very loud and unpleasant noise that was sometimes blasted into their headphones.

On the second day, subjects again saw a sequence of colored squares, but this time were spared the loud noises. Meanwhile, researchers monitored their subjects' skin conductance. (This isn't exactly a measure of fear, but of general "arousal" or excitement. Or, really, sweatiness. It's the same factor measured in a lie detector test.)

Children and adults showed lower skin conductance, meaning they were less on edge, as the experiment went on and they learned not to expect loud noises anymore. But adolescents remained on edge, barely lessening their learned response to the colored squares.

To find out in more detail what was happening in the brains of their mouse subjects, the researchers dove right in. (Human volunteers were allowed to keep their brains.) They focused on an area of the prefrontal cortex that was already known to be involved in fear extinction, called the vmPFC (short for ventromedial prefrontal cortex, which is neuroscience-speak for "smack in the middle of the forehead").

Author B.J. Casey says that for the first time, her study showed that this brain region's role in fear extinction happens at the level of the connections between neurons. In young mice or adult mice, slices of fear-extinguished brains had more-active neurons in a subsection of this brain region, compared to slices of fearful brains. But adolescent brains all looked the same, whether they had undergone the fear-extinction training or not. The diminished activity in adolescent neurons, Casey says, matches adolescents' diminished ability to unlearn a fearful reaction. This region of the adolescent mouse brain—not unlike some adolescents—is relatively inactive and set in its ways.

Casey says her group's research might help explain teenage emotions in general. "Our findings are consistent with exaggerated emotional reactivity during adolescence in humans and rodents," she says, as well as "diminished ability to regulate these emotions."

In all mammals, adolescence—whether it happens at 29 days or 16 years—is a time to learn what threats you're facing and how to live independently. Holding on to learned fears more stubbornly might be helpful for an adolescent in evolutionary terms. But if the trait makes it harder for teens to get past crippling phobias and anxieties, therapists may need to learn a different way to talk to teenage patients and their stubbornly fearful brains.

Siobhan S. Pattwell, Stéphanie Duhoux, Catherine A. Hartley, David C. Johnson, Deqiang Jing, Mark D. Elliott, Erika J. Ruberry, Alisa Powers, Natasha Mehta, Rui R. Yang, Fatima Soliman, Charles E. Glatt, B. J. Casey, Ipe Ninan, & Francis S. Lee (2012). Altered fear learning across development in both mouse and human. PNAS : 10.1073/pnas.1206834109

Image: Drew Herron/Flickr

Sex Makes Everything Less Disgusting

Our biological drive to do it conflicts pretty directly with our biological drive not to get involved with other people's bodily fluids. How do we ignore the obvious grossness of sex for long enough to propagate the species? Maybe, researchers say, by turning off our disgust reflex whenever we get turned on.

Earlier studies have asked this question in a variety of ways. For example, by asking men to "self-stimulate" and then quizzing them on what sex acts or partners they'd be open to. Or by showing men erotic slideshows and then having them stick their hands into cold pea soup or buckets of condoms. Psychology researchers Charmaine Borg and Peter J. de Jong at the University of Groningen in the Netherlands—perhaps feeling less pessimistic than others about their ability to arouse a group of female subjects—decided to study the question in women instead.

The researchers gathered 90 female university students. Rather than just answering questions about distasteful things, these subjects were going to be challenged with some actual gross tasks to see how many they would do.

But first the researchers had to turn their subjects on. Well, a third of them, anyway. One group of women watched a film described as "female friendly erotica." A second group watched a movie that was meant to be non-sexually arousing—that is, heart-pounding but not steamy. These women saw footage of sky diving and mountain climbing. The third group saw a movie about a train ride, meant to not cause any feelings at all. The movies had been previously tested with a separate group to make sure they elicited the right emotions.

As the women watched their steamy, exciting, or boring movies, they were periodically interrupted by an experimenter who showed up and gave them disgusting tasks to do. There were a total of 16 challenges, ranging from picking up apparently soiled toilet paper to sticking a needle in a cow eye. The subjects didn't have to go through with any task they didn't want to, but they did have to rate how disgusting they found each one.

Out of the 16 gross-out tasks, 5 were classified as sex-related. These included touching some "used" condoms, handling "used" women's underwear, and reading aloud a sexual phrase about, um, a dog. (The researchers made liberal use of Halloween-style tools and props, including blood-colored ink, fake feces, coconut milk in the underwear, and one plastic bug. And one real worm, which they rereleased outside when the study was over.)

The groups who watched the train movie and the sky-diving movie didn't differ in their willingness to do the gross tasks, or in how disgusting they rated those tasks. But the women who watched the erotic film rated the sex-related tasks as significantly less disgusting than the other groups. They seemed to find the rest of the tasks less gross too, though the result wasn't quite significant. And overall, the erotica group completed more challenges of both kinds. The turned-on subjects completed 85% of the non-sexy tasks, for example, compared to about 66% in the other two groups.

Charmaine Borg says she was surprised to see that sexual arousal, but not general arousal (the sky-diving kind), "makes us approach stimuli that are in general so disgusting." The way subjects perceived disgusting things seemed to change when they were sexually aroused.

The study focused on a small group of young, heterosexual, dysfunction-free women. It was limited to one method of turning those subjects on (the erotic film) and an odd handful of gross, somewhat sex-related tasks. And the study relied on subjects' own ratings of their arousal and repulsion. But if it proves to be generally true that sexual arousal squelches disgust, it would explain how we manage to reproduce despite our usual instincts—which presumably evolved to keep us safe from disease-carrying stuff.

Borg is more interested, though, in women whose bodies don't let them have sex. She wonders if sexual disorders such as dyspareunia (painful intercourse) or vaginismus (involuntary clenching of the muscles around the vagina, making intercourse difficult or impossible) are rooted in problems overcoming disgust.

"Studies from our lab with women afflicted with vaginismus have shown that they experience disgust responses towards erotic stimulation," Borg says. "Sex-related stimuli appeared to elicit disgust rather than arousal." Since our usual response to disgust is to keep far away from what's causing it, she says the problem could be self-perpetuating as women start avoiding sex altogether.

Borg says her results so far are "very exciting." By carrying on her experiments in the condom-filled, fake-blood-soaked laboratory, she helps to hope women overcome their difficulties and get down to whatever business they want.

Charmaine Borg, & Peter J. de Jong (2012). Feelings of Disgust and Disgust-Induced Avoidance Weaken following Induced Sexual Arousal in Women. PLOS ONE : 10.1371/journal.pone.0044111

Image: Feggy Art/Flickr (Related note: I cannot BELIEVE I lived this long without knowing that England has both a name for making horrible faces—"gurning"—and competitions for it.)

Subliminal Placebo: You Didn't See It, but It's Working

The latest additions to the placebo effect family might be the rudest. First there was placebo, which uses your body's own tools to make you feel better after you try a treatment you imagine will help you. Then there was nocebo, placebo's evil twin: it makes you feel worse only because you think you will. Now researchers have discovered that placebo and nocebo effects can be triggered subliminally, which is like finding out that the good and evil twins have both been living in your basement without you knowing it.

Usually, placebo and nocebo look like cases of our own expectations manipulating us. Someone swallows his favorite headache remedy or visits a doctor, and his body, expecting to feel better, ramps up production of its own pain-relief molecules. Someone else steps onboard a plane and begins to feel nauseous, simply because her body has learned that airplanes mean queasiness. If we were more ignorant of our circumstances, the effects wouldn't be there.

But there seem to be some cues we can take in subliminally, without noticing them. So researchers led by Karin Jensen at Harvard Medical School wondered whether visual signals that are too brief to reach our consciousness—but perhaps not too brief for certain areas of our brains to snag as they pass—can trigger placebo and nocebo effects too.

For their visual signals, the team chose photos of male faces. "We know from previous studies that faces can be detected and processed very quickly in the brain," Jensen says. Their models came from a set of photos created for use in psychology experiments.

The researchers carried out two experiments, the first of which was a classic test of placebo and nocebo. Subjects were shown pictures of two expressionless male faces over and over. Each time they saw face A, they felt a painfully hot sensation on the forearm. Face B was paired with heat that was milder, but still uncomfortable. (The A and B models alternated between different subjects—just in case one man's face really was more painful to look at.) During the conditioning part of the experiment, subjects saw each face 25 times. This taught them to expect higher pain with face A and lower pain with face B.

Then came a second series where subjects saw the same two faces as before, with a few new ones mixed in as controls. With each face they saw, subjects rated the pain they felt from the heat instrument on a 100-point scale. The twist was that in this part of the experiment, the heat level was exactly the same every time. But subjects consistently reported high pain for face A and low pain for face B. When they saw a new face, subjects reported an intermediate level of pain (which corresponded to what they were actually feeling).

This first experiment showed the researchers that pairing faces with painful heat stimuli could create both a placebo effect (when subjects rated moderate heat as less painful because they saw face B) and a nocebo effect (when subjects found moderate heat more painful, thanks to face A). So they moved on to the second experiment. In this round, the visual signals would be "nonconscious,"or subliminal.

A new group of subjects went through the same conditioning sequence as before. Then they were given a testing sequence using face A, face B, and the new (control) faces, all paired with the same moderate heat on the arm. But the faces in this sequence flashed on the screen for just 12 milliseconds, compared to 100 milliseconds in the earlier experiment.

12 milliseconds is fast. Too fast, in fact, for subjects to consciously process the faces zipping by. They reported that they couldn't tell who was who (and a separate experiment confirmed that people can't recognize faces shown this quickly).

But, as the researchers report this week in PNAS, the pain scores still matched the faces subjects said they couldn't see. Face A got significantly higher pain scores than face B, with the control faces scoring in the middle—and don't forget that, once again, subjects were actually feeling the same degree of heat every time.

Even though the pictures flashed too briefly to enter conscious awareness, they seem to have snuck in through the brain's back door. These visual cues made subjects experience more or less pain than they should have, even though they had no idea what they'd seen.

There were only 20 subjects in each experiment; it would take further studies to show how consistent or how powerful the subliminal placebo and nocebo effects are. But the fact that they found an effect at all is exciting news to the researchers. "To the best of my knowledge, there has not been an experiment [previously] where placebo/nocebo effects have been activated by nonconscious cues," Jensen says.

The common assumption, Jensen says, is that placebo and nocebo rely on the signals we're paying attention to (pills, needles, drug commercials) and the results we expect (relief, discomfort, alarming side effects). But this study "proves that we don't need to be aware of the cue to elicit a conditioned response," Jensen says.

Don't expect to start seeing mysterious images flashing at you in the doctor's office. The subjects in Jensen's study had to be trained to associate photos of faces with high or low pain. And even if there were another kind of image that automatically produced a placebo effect in a wide audience (teddy bears? puppies?), our brains might not be able to recognize it as quickly as a human face.

But the idea that placebo and nocebo effects can be triggered by cues patients don't even notice could be important for healthcare, Jensen says. Certain conditions such as asthma, depression, and irritable bowel syndrome are known to respond well to placebos. Maybe doctors' offices and hospitals in the future will tailor everything patients see—from the posters on the wall to the instruments on the counter to the fish swimming in the lobby aquarium—to encourage placebo and avoid nocebo. Or maybe we'll be able to use the same tricks at home to keep ourselves feeling our best. Let's kick those weird placebo relatives out of the basement and put them to work.

Karin B. Jensen, Ted J. Kaptchuk, Irving Kirsch, Jacqueline Raicek, Kara M. Lindstrom, Chantal Berna, Randy L. Gollub, Martin Ingvar, & and Jian Kong (2012). Nonconscious activation of placebo and nocebo pain responses PNAS : 10.1073/pnas.1202056109

Image: freya.gefn/Flickr

Deep-Sea Census Finds Glow-in-the-Dark Bonanza

Sometimes the best way to answer a question like "How many animals on the bottom of the ocean glow?" is to just go down there and poke some sea creatures with a robot arm. That's how researchers found out that the pitch-black seafloor in the Bahamas is alive with bioluminescence. They also found glowing currents full of plankton, a crustacean with the world's slowest vision, and creatures that vomit light when provoked.

In the middle depths of the ocean, making your own light is ordinary. Around 80 percent of fish and crustaceans that live here are bioluminescent, and the skill is also common in squid and other cephalopods. These animals may light up to lure prey, confuse predators, or attract a mate.

Species that live on the bottom of the ocean are less well studied, for the obvious reason that they're on the bottom of the ocean. So researchers led by Sönke Johnsen of Duke University and Tamara Frank of Nova Southeastern University set out to begin a census of bottom-dwellers. They descended in a submersible to the floor of the Bahamas to knock on some doors.

The team made 19 dives to depths between 500 and 1000 meters. Once at the seafloor, they began scooping up samples of all the species they could find, using the submersible's robotic arm. On some of their dives, they turned off the sub's lights and sat in total darkness: they could see life glowing all around them. The researchers tested individual creatures for bioluminescence by gently poking them with the robotic arm. If something glowed in response, they grabbed it or sucked it up for further study.

Bioluminescence, at least in the limited regions the researchers were able to explore in their dives, was rarer than in the middle depths of the ocean. Less than 20 percent of the species they observed could glow. The skill was most common among sea anemones, bamboo corals, and coral relatives called sea pens (so named because some of them look like old quills).

Although the ability to light up was uncommon, the light on the seafloor was abundant, thanks to bioluminescent plankton. Drifts of these tiny animals are carried on the currents and ping with light whenever they collide with another object. "Where there are 'tree-like' animals...that stick up from the bottom," Frank says, "the tiny plankton that flows by in the currents get stuck on it."

The frequent flashing of drifting plankton could be one reason bioluminescence is a less common skill on the seafloor, the authors write. It might not be worthwhile to try to generate bioluminescent signals when the visual noise of plankton is drowning everything else out. Another reason not to bother with bioluminescence on the seafloor could be that the uneven terrain, punctuated by corals and other stationary creatures, blocks signals from traveling far. In the middle of the ocean, light can travel in every direction.

Yet the large eyes on some of the specimens they gathered told the researchers that light was still an important signal for them. When the team brought their subjects back to the surface to photograph them and measure the light they emitted, they found that the stationary animals (such as anemones and corals) gave off a greener light compared to the bluish glow of mid-ocean animals. This might be an adaptation that lets light travel farther through the cloudier water of the ocean floor.

Most of the bioluminescent creatures that Johnsen and Frank observed glowed suddenly when bothered, then faded over the next few seconds. But a few were more creative with their light production: they found a sea pen that pulses with half-second flashes; a bamboo coral made up of polyps that flash individually, creating a twinkling effect; and a shrimp that vomits light in self-defense. ("In the deep dark depth, squirting a blindingly bright fluid into the face of a predator is certainly going to distract it," Frank says, "allowing the spewer to get away.")

When the researchers collected crustaceans from the ocean floor using baited traps, they got even more surprises. One was an isopod with the slowest vision ever recorded in a crustacean. The researchers measured the "flicker rate" of the crustaceans' eyes, which is the number of images the eyes send to the brain every second. In humans it's about 60, which means movies shown a little faster than 60 frames per second look seamless to us. In the crustacean Booralana tricarinata, the flicker rate is just 4.

Gathering only four snapshots of the world each second, the isopod is probably unable to follow the motion of even slow-moving prey. It's possible, the researchers say, that the animal instead uses those slow eyes to scavenge. Its long-exposure vision might let it see the subtle glow of bioluminescent bacteria living on its food. In other words, though it can't see motion, the isopod sees a whole glowing ocean-floor world we'll never be able to.

Sönke Johnsen, Tamara M. Frank, Steven H. D. Haddock, Edith A. Widder, & Charles G. Messing (2012). Light and vision in the deep-sea benthos: I. Bioluminescence at 500–1000m depth in the Bahamian Islands The Journal of Experimental Biology DOI: 10.1242/jeb.072009

Tamara M. Frank, Sönke Johnsen, & Thomas W. Cronin (2012). Light and vision in the deep-sea benthos: II. Vision in deep-sea crustaceans The Journal of Experimental Biology DOI: 10.1242/jeb.072033

Image: Bioluminescent plankton by NOAA (via Wikimedia Commons).

Thieving Baby-Killer Bees Welcomed to the Family

Bee-related surprises are rarely good ones. But entomologists were delighted recently to discover five brand-new bee species in Africa. In another happy twist, these bees are thugs that break into other bees' nests, steal their food, and eat their babies.

The new species belong to a group called "cuckoo bees." Don't worry, they don't fly out of clocks (nor is the name in reference to their sanity). Instead, they're named in honor of cuckoo birds, which notoriously sneak their eggs into other birds' nests. After hatching, young cuckoos bully their nest-mates out of food and are doted on by clueless foster mothers.

Cuckoo bees, too, are parasites that prey on other bees' nests. Mothers sneak inside and lay their eggs in the cells a host bee has built for her own young. After the cuckoo bee larva hatches, it eats its foster sibling's food—and then eats the young bee itself. Most cuckoo bees prey on bee species that live alone, but some infiltrate the hives of social bees and may even assassinate their queens.

Jakub Straka of Charles University in Prague went on two expeditions to Cape Verde, an archipelago nation off the coast of Senegal, to see what kinds of bees were living there. Along with University of Kansas entomologist Michael Engel, he then compared the newly collected bees to old samples from private and museum collections. The researchers found that this population—long overlooked by scientists, Straka says—included five entirely new species of cuckoo bee.

When an animal or plant species floats, swims, or flies onto a new island, it may find that there's a lot of room to spread out and evolve into multiple new species. This is why there are 800 or so species of fruit fly on the Hawaiian islands. The Cape Verde cuckoo bees are similar to a species from the Canary Islands, Straka says. A bee that flew over from the Canary Islands in the distant past may have been the ancestor to the whole Cape Verde family tree.*

Another quirk of island living is that tiny-bodies species sometimes grow enormous. It's called island gigantism, and one of the cuckoo bees Straka discovered is an example. At less than half a centimeter in length, Chiasmognathus batelkai isn't much of a giant. But it's still more than twice the size of any of its relatives.

The rest of the new Cape Verde cuckoo bees (all in the genus Thyreus) seem to target a genus of solitary, ground-dwelling bees (Amegilla) for their breaking-and-entering exploits. Straka hopes that further research will reveal how the host and parasite bees have evolved together on these islands. And he plans to use genetics to track exactly where the Cape Verde cuckoos came from.

"We also hope that we discover other interesting new species on this archipelago forgotten by the scientists," Straka says—because who could stop at just five surprise bees?

Jakub Straka, & Michael S. Engel (2012). The apid cuckoo bees of the Cape Verde Islands ZooKeys DOI: 10.3897/zookeys.218.3683

Image: from Straka and Engel, 2012.

*Several other sites have reported that Straka and Engel discovered cuckoo bees as a whole, which is incorrect. The Cape Verde cuckoo bees are just a few of the many thieving, baby-killing bee species in the world.