Field of Science


12 Days of Inkfish, Day 7: Yearbook

With the year drawing to a close, Inkfish's class officers have chosen superlatives to bestow on the posts of 2012. Please note that a prom king and prom queen were not elected this year because everyone was too busy cheering on the mathletes. (Hey, wildfires in the Cretaceous won Most Popular. Anything's possible.)

Most Popular

Cutest Couple

Class Clown

Worst Hygiene

Most Talkative

Most Athletic

Class Goth

Most Likely to Attend Culinary School*
*This post was also nominated for Most Disgusting Use of an Innocent French-Toast Photo.

Most Likely to Join AA

Best Mustache 

Thanks for taking a minute to reflect on 2012 with me; I'll see you next year. Have a great summer!

Image credits can be found at their respective posts.

12 Days of Inkfish, Day 6: Zion Canyon

Stories about earth science have all the transformations and power struggles of a fairy tale. When I asked my friend Tyler Auer—a photography blogger who studied geoscience in college—to tell me the story behind a favorite photo, he sent me a tale that’s part Princess and the Pea and part Jurassic Park.

Tyler took this picture at Zion Canyon, one of the many national park areas (including the Grand Canyon) within the 130,000-square-mile formation known as the Colorado Plateau.

“Around the time the dinosaurs roamed the western US, the Colorado plateau was a giant sea of sand dunes,” Tyler says. Over millions of years, these sand dunes kept forming on top of one another and compressing into layered sandstone. You can see the outlines of the ancient dunes, like so many stacked mattresses, in the striations of the canyon walls.

While the sand dunes were turning to rock, they were also being pushed upward by tectonic activity. Cracks formed in the ground like the crust of a bread loaf in the oven. Zion Canyon began as one of these cracks. But “sandstone is really soft, as far as rocks go,” Tyler says, “and running water carves through it quickly.” Rainwater and the flow of the Virgin River gradually deepened this split into a half-mile chasm with almost vertical walls.

Since the Colorado Plateau may be the thickest sandstone layer that’s ever formed, it's provided nature with a deep toolkit. “The Colorado Plateau is magnificent example of the slow but beautiful work nature can do,” Tyler says. You can find more fairy-tale pictures at his blog.

Image: Virgin River Narrows north of Zion Canyon, by Tyler Auer

12 Days of Inkfish, Day 5: Running on Water

Human courtship rituals—if you believe television commercials, anyway—are lame. The guy who kneels down right at the jewelry store counter ("It fits perfectly!" "Well honey, that's because I already had it sized") has nothing on birds who walk on water for each other.

Grebes are diving waterbirds that live in the Americas and Eurasia. To pair off, they follow an elaborate courtship choreography that includes trading bits of food and mimicking each other's motions. In the ritual's conclusion, both birds suddenly haul their ungainly bodies out of the water and run together on its surface. The grace of the birds and the physics of the maneuver both seem impossible.

You can see a pair of Clark's grebes do their courtship dance in this incredible video from the BBC. Jewelry companies, take note: there's no prelude to romance quite like swallowing a live fish.

Image: screen grab from BBC Life: Birds: Partners for Life

12 Days of Inkfish, Day 4: Help Desk

When you use website analytics, you quickly learn that there are a lot of people out there Googling things like "how do i make robot" and "which is best medicine for make baby." This year I've seen many visitors whose search queries were probably not answered here. To make things up to them, I'll try to address a few of those questions now.

orangutan stop following me
Unless you live in Borneo or Sumatra and spend a lot of time in rainforest trees, it's very unlikely that you're being followed by an orangutan. Are you sure it isn't a very hairy human or a large orange dog? If an orangutan is, in fact, following you, don't worry—they mostly eat plants.

can you use ab toning belt on butt for bigger muscles
Ab toning belts will not make your muscles stronger (they only stimulate the surface of the muscle) or more toned (because the contractions are involuntary). But if you're really attached to the idea, don't bother strapping the belt around your rear: they sell toning shorts too.

what pills can make a man's hair fall out in clumps
I don't know the answer to that but it sounds like you're working on a super hilarious prank.

toilet training pigeon
Here's a website with some advice on potty-training pet birds. Consistency is key! But if I had a pigeon I'd skip the toilet training and teach it to carry messages, or to find its home from hundreds of miles away. Or to take pictures, like those cool pigeons in World War I.

is science harmful or useful
Did you not just see that pigeon with a camera strapped its chest?

giant barbies on the loose
Please send a picture so I can better assess the problem. Maybe you and the person with the orangutan problem should coordinate.

that story about the monkeys in the room
Your faith in organic search is touching. I don't know what you're looking for, but here's a story about rhesus macaques raised by water bottles instead of mothers.

if you swap brains will you still have the knowledge inside?
Even if this question is only research for a science-fiction story, I really think you should reconsider.

unnecessary otter

sex robot sperm go?
Since you clearly know search terms don't have to be in the form of a coherent sentence, I'm confused about why you think they still need a question mark at the end. On the off-chance you're wondering what the similarities are between a sperm cell and a Roomba, here are some.

why is sperm brown
Wow, please see a doctor. Why are all the sperm people coming here?

i have to pee
No one is stopping you. 

what company makes placebo
Okay, I quit.

Images: Help desk by Aryc Ogre; war pigeon via Wikimedia Commons 

12 Days of Inkfish, Day 3: Reverse Sun

"Astronomy! People go crazy studying that!" a Christmas tree farmer said this week after asking my younger sister her college major. He made a head-exploding gesture to illustrate his point.

That farmer might have been distressed by this image. Despite its similarity to sperm tackling an egg, it's really a color-inverted picture of our sun. The background is a field of stars, also with its colors reversed.

Turning the colors around lets us see features on the sun's surface we might not otherwise. The little bumps and crinkles are called granules; they're where hot gas is rising to the outside of the sun before cooling and sinking again. According to a textbook of my sister's, these bumps are "typically the size of Texas."

The image comes from NASA's Astronomy Picture of the Day, which provides new head-explosions every 24 hours.

Image: Jim Lafferty

12 Days of Inkfish, Day 2: Upside-Down Jelly

Cassiopea jellyfish spend much of their adult lives lying on their backs. Or maybe their heads. However you look at it, they're upside-down: they rest in warm, shallow waters, holding their branching arms up toward the sun. Inside those tentacles are single-celled algae, which photosynthesize and provide food for their jelly farmers.

Cassiopeia, the jellyfish's differently spelled namesake, was a queen in Greek mythology. After bragging that she was even more beautiful than sea nymphs called the Nereiads, the queen was punished by having her constellation placed where it sometimes appears upside-down as it rotates in the sky.

The jellyfish are passive but have a mild sting. Some crabs hoist Cassiopea jellyfish onto their backs for self-protection, carrying them around gardens and all.

Image: Cassiopea jellyfish at Shedd Aquarium, taken by me. If you like seeing bizarre animals up close (or adults with their faces pressed up to glass like kids), go see this exhibit.

12 Days of Inkfish, Day 1: Gifts

Consider this a big, many-tentacled squeeze from me to you.

This year, I've expanded into new habitats, learned new tricks (like driving the Shambulance), and seen lots of new readers swimming by. I'm grateful to every person who visits and shares these pages. You've given me a reason to learn about wine-making wasps and anti-placebos, to taste no-calorie noodles and verbally abuse sheep. Say hello in the comments!

For each of the 12 days of Christmas I'll be leaving a little something here to unwrap. The first is a video of an octopus receiving a live crab in a jar. After menacing the crustacean briefly, it unscrews the jar's lid and squeezes its whole body inside to devour its prey. Talk about a stocking stuffer.

Video from CBCtv.

Fossil Scan Reveals Ghost of Lizard Past

Peering into the past life of this fossil took an x-ray scanner powered by a particle accelerator. What scientists saw there was mysterious: an ancient lizard had left behind its skin and teeth, but none of its bones. To tell the ghost's tale, they relied on some very modern equipment.

At Stanford University, an accelerator called a synchrotron sends electrons zipping around a track fast enough that x-rays spin off of them. These x-rays are collected into an extremely bright x-ray beam that scientists can use for various projects. One application, x-ray fluorescence, lets researchers map the actual chemical elements inside on object.

Other methods of analyzing an item's chemical makeup require scientists to focus on tiny slices, destroy their samples entirely, or creep along at a rate of one square centimeter a day. But the setup at Stanford lets scientists look quickly and thoroughly at larger objects while keeping them in one piece. The synchrotron has previously been used to reveal writings of Archimedes that were scraped away and painted over, and to deduce the pattern on the feathers of the 120-million-year-old Confuciusornis.

University of Manchester paleobiologist Phillip Manning and his colleagues, who had worked on scanning Confuciusornis and other fossils, now turned the synchrotron's powerful x-ray beam onto an unusual fossil. The 50-million-year-old lizard specimen comes from Colorado. What's unusual is that the animal's skin is beautifully preserved, right down to the scales—but the skeleton is gone.

Scanning the fossil for sulfur (in the photo above) or copper produced ghostly silhouettes of the lizard's whole body, since these elements are naturally present in trace amounts throughout an organism. Tuning their scans for phosphorous brought a surprise: dots popped out of the lizard's ghostly head in the shape of a jaw.

In the image above, green is a map of sulfur in the head and neck (check out the scales!). Phosphorous and magnesium are overlaid in red and blue. The authors write that this chemistry is "typical for biomineralized structures." A close look revealed two overlapping bites: a full set of lizard teeth.

Before the synchrotron scanning, researchers thought the unusual Colorado fossil was a 50-million-year-old molted lizard skin. But even animals that shed their skin don't tend to leave behind their entire jaws when they do so. This animal died in one piece.

Although bones and teeth have similar ingredients, the authors write that the structure of teeth makes them more resistant to dissolving. But how did the delicate skin stay intact? "If the acidity of the ground waters are high, bone would be vulnerable," Manning says. "However, high acidity is often helpful in 'tanning' skin to preserve [it]. Think bog bodies from northern Europe."

As researchers continue to peer into the past with the synchrotron, Manning is narrating their progress at his blog. He doesn't anticipate running out of subjects. "We have a few million life forms to wade through," he says. In other words, there are plenty of ghosts of fossils yet to come.

Edwards, N., Wogelius, R., Bergmann, U., Larson, P., Sellers, W., & Manning, P. (2012). Mapping prehistoric ghosts in the synchrotron Applied Physics A DOI: 10.1007/s00339-012-7484-3

Images: Edwards et al.

Are You Healthy Enough to Be a Space Tourist?

Space travel for regular folks is almost here. But before jumping on board the nearest spacecraft, amateur astronauts and their doctors might want to consider the health risks. Although standard air travel is more boring than spaceflight, it's also less likely to shrink your bones or deform your eyeballs.

"Practically only the healthiest people have flown in space so far," says Marlene Grenon, a vascular surgeon at UCSF who researches the effects of microgravity on the body. Government astronauts go through extensive medical testing and training. But even these extra-fit fliers have suffered ailments ranging from cardiac dysrhythmia to good old-fashioned vomiting. What's in store for the rest of us?

Grenon is the lead author of a paper in BMJ asking that question. The researchers say that doctors will have plenty to consider before sending their patients to boldly go where no civilian has gone before.

"Space motion sickness would be expected to be the most common" medical problem, Grenon says, "particularly for short-duration flights." If your inner ear is easily confused by sitting still in a moving vehicle, just imagine what happens when that vehicle has no up or down.* NASA's parabolic flights—trips on aircraft that fly in steep up-and-down waves, simulating weightlessness for astronauts in training and scientists researching low gravity—have earned the nickname "vomit comets" for a reason.

Life without gravity is hard on the bones and muscles as well as the barf reflex. NASA astronauts onboard the space station exercise for two hours every day to counteract bone loss, muscle atrophy, and a decrease in cardiovascular fitness. Grenon says she doesn't yet know how weightlessness might act on people who are less fit to begin with, or overweight.

Exercise may prevent muscle atrophy but it doesn't do much for squished eyeballs. A study last year found that after a six-month space mission, astronauts were likely to have "flattened globes" and other eye problems. The shifting of fluids inside the head, free to bounce off the walls just like the astronauts themselves, might be to blame. Even after shorter trips, many astronauts reported worsened eyesight.

The authors of the new paper name several medical conditions that might worsen in microgravity. For people with diseases of the blood vessels, fluids drifting around might be dangerous. Aneurysms could rupture during takeoff. Bone loss in space could be especially bad for people who already have osteoporosis. Acid reflux could worsen when the esophagus no longer knows which way is up. And don't forget radiation exposure.

But the most ordinary complaint that might ground you is an infection. Grenon writes that even people with simple ear or skin infections should consider postponing trips to space.

That's because the immune system changes during spaceflight, Grenon says. Although these changes are not well understood, they "could place the spaceflight participants at higher risk of infection." Additionally, she says, "Some research has also hinted [at] the fact that bacteria grow stronger in microgravity." And radiation might make people more susceptible to infection—or make bacteria mutate more quickly. Overall, the changes in space favor bacteria over your immune system. These risks would be greater on longer flights.

Still want to fly? Virgin Galactic is accepting reservations. If you're willing to put down $200,000 up front, you can still get a spot on their first round of flights. For a cool million you can reserve a private trip for yourself and five friends—that's a buy-five-spaceflights, get-one-free deal. Make sure you pack enough barf bags.

Grenon, S., Saary, J., Gray, G., Vanderploeg, J., & Hughes-Fulford, M. (2012). Can I take a space flight? Considerations for doctors BMJ, 345 (dec13 8) DOI: 10.1136/bmj.e8124

Image: U.S. Air Force

*For an exceedingly thorough discussion of space barfing, as well as other bodily functions performed in microgravity, I recommend Mary Roach's book Packing for Mars.

Malaria Makes Its Victims More Tempting to Mosquitos

Think mosquitos have a special fondness for you? Do they choose to target you over adjacent humans? No matter how badly you have it, things might be worse if you were infected with malaria. New research in birds shows that malaria parasites somehow make their victims more attractive to mosquitos. After all, the parasite needs a lift to its next destination—so it forces its sick host to flag down a ride.

Malaria, one of the top killers worldwide among infectious diseases, isn't caused by a virus or a bacterium. The culprit is a one-celled protozoan, called Plasmodium, that comes in a couple hundred disease-causing flavors. Plasmodium falciparum is the species that causes most malaria deaths in humans.

Various other Plasmodium species infect birds, reptiles, and mammals ranging from apes to anteaters. Whichever animal it prefers, the parasite needs to travel to new hosts via the belly of a mosquito. If possible, Plasmodium shouldn't just rely on chance—it should encourage mosquitos to bite its host.

In a 2005 study, researchers found hints that mosquitos are more attracted to the smell of a malarial child than a healthy one. (This was only true once the parasite had reached the right life-cycle stage for spreading to other people.) Giving malaria to kids is hard to justify ethically, though, even if you then treat them with antimalarials as those researchers did.

To pursue the question without leaving behind a trail of sick children, researchers in France turned to birds. Author Stéphane Cornet, of the Centre d'Ecologie Fonctionnelle et Evolutive, says the avian malaria parasite the team used infects more than 30 bird species around the world. For their experiments, they used canaries.

Mosquitos could prefer sick animals simply because they're easy targets. "Infection often renders hosts lethargic, as we are when we feel sick," Cornet says, "so that they are less able to defend themsleves against [mosquito] attacks." But he and his coauthors were more interested in whether malaria changes the particular bouquet of an animal to tempt to passing mosquitos. So they placed all their canaries inside PVC tubes with only their legs sticking out. This way, the birds' behavior and appearance wouldn't matter.

Fifty canaries were divided into pairs. Then the researchers released 70 hungry female mosquitos into a cage with each pair of birds (or, from the mosquitos' perspective, a cage holding four bird legs). After the mosquitos had feasted, the authors checked the DNA of the blood in their bellies to find out which bird each mosquito had chosen. Every mosquito choice test was repeated three times.

After testing mosquitos on healthy birds, the researchers infected one bird in each pair with avian malaria and repeated the tests 10-13 days later, when the birds were sickest. Two weeks after that, they tested the mosquitos and birds a final time. By then, 9 birds had died. But the surviving infected birds had entered the "chronic" stage of infection, when the parasite lies low and the victim isn't as sick.

Mosquitos weren't any more interested in acutely ill birds than in healthy birds, the researchers found. This might have been because the malaria had driven down their red blood cell counts, making their blood less delicious to mosquitos. But once the canaries entered the chronic stage of malaria, mosquitos clearly preferred to feed on the infected birds. The authors report their findings in Ecology Letters.

Cornet believes malarial birds give off some signal to attract mosquitos, such as extra carbon dioxide or a specific odor. What exactly that signal is, and how the Plasmodium parasite manipulates its host into sending the signal, remains a mystery.

A canary is of course not a person, and their malaria parasites are different from ours as well. But there are similarities in how the two parasites act on their hosts, Cornet says. Humans, like birds, might give off some mosquito-enticing perfume when infected with malaria. Finding this perfume could help prevent malaria transmission in the future. And even before that happens, Cornet says, it's useful for people who model the spread of malaria to know that mosquitos aren't choosing their victims randomly.

If you're still feeling resentful toward mosquitos, it may help to know that the malaria "perfume" is really a trap. Mosquitos that carry Plasmodium parasites are about a third less fertile than they would be otherwise, another study this year found. Drinking from infected hosts is bad for mosquitos just like it's bad for the next animal they bite. But, like us, they're helpless to Plasmodium's wiles.

Cornet, S., Nicot, A., Rivero, A., & Gandon, S. (2012). Malaria infection increases bird attractiveness to uninfected mosquitoes Ecology Letters DOI: 10.1111/ele.12041

Image: Travis S. (Flickr)

Ancient Insect Carried Built-In Trash Basket for Camouflage

Covering yourself with garbage is a great way to look less delicious to predators. More than a hundred million years ago, one insect species took this strategy to the extreme by growing a kind of giant trash can on its back. Scientists could identify the new species thanks to a remarkable specimen that was preserved—along with an informative topping of trash—in amber.

The insect that kindly died in a blob of tree resin in early-Cretaceous Spain was a young green lacewing. Modern-day green lacewings are predatory insects common in North American and Europe. Before they develop their lacy adult wings, the larvae of some species protect themselves by carrying trash around. They collect plant material, insect carcasses, and other debris in their jaws, then twist their heads around to tangle the material into short appendages growing out of their backs. The trash camouflages them and provides a physical, untasty shield when predators (which can include ants, wasps, and cannibalistic green lacewings) attack.

But the Cretaceous lacewing was so wildly different from its modern-day relatives that scientists named it Hallucinochrysa—that is, an insect bizarre enough to seem like a hallucination. (For its second name they chose diogenesi in honor of Diogenes syndrome, a trash-hoarding disorder in humans. The disorder, in turn, is named after a Greek philosopher who lived in a tub.)

University of Kansas entomologist Michael Engel, one of the authors of the new paper in PNAS, describes the ancient lacewing's trash-carrying apparatus as "dramatic and unique." Unlike the short appendages on modern green lacewings, the old insects grew a thicket of extremely long, hairy tubes from their backs (illustrated above).

Coauthor Ricardo Pérez-de la Fuente, of the University of Barcelona, points out another unusual feature of the trash basket: the tiny hairs growing out of the tubes have "trumpet-shaped endings," which he says would have helped anchor the trash in the basket. Once the refuse was in place, it stayed there.

Almost as exciting as the hallucination-worthy insect was the collection of trash preserved with it. "What attracted our attention since the very beginning was the high density and intricacy of the trash packet," Pérez-de la Fuerte says. Peering into the amber with a microscope, the researchers identified the thread-like plant parts trapped on the insect's back as bits of ferns.

The plants seem to match a tropical group of ferns that, these days, move into areas swept clean by wildfire or lava. Since ancient wildfires also encouraged amber to form, and this particular sample was part of an abundant amber cache, it seems likely that the area had experienced fire. At least one trash-toting insect had filled its basket with bits of the ferns that sprouted afterward. Then this insect carried its garbage collection up into a tree and died.

Since the ferns lived on the forest floor, their remains would have been "extremely unlikely to be found otherwise," says Pérez-de la Fuerta. The day this little trash hoarder walked into a sticky tree was a bad one for the insect, but a very lucky one for scientists.

Ricardo Pérez-de la Fuente, Xavier Delclòs, Enrique Peñalver, Mariela Speranza, Jacek Wierzchos, Carmen Ascaso, & Michael S. Engel (2012). Early evolution and ecology of camouflage in insects PNAS : 10.1073/pnas.1213775110

Image: J. A. Peñas

Cold and Hungry? Scientists Suggest Remembering Soup

Regrettably, and despite what the Breatharians will tell you, a person can't live on a diet of air. But you can keep hunger pangs at bay, scientists say, simply with the power of memory. And feelings of nostalgia can help you withstand cold, according to another group of scientists. Now that winter is settling in, it might be a good time for all of us to start collecting some really good soup experiences.

Researchers studied the effect of nostalgia on body temperature in a series of experiments reported in the journal Emotion. People may describe their fond thoughts of the past as "warm feelings," but do they really mean it?

In one experiment, 64 subjects individually sat in a room kept at a cool 16 degrees C (60 F). They were asked to recall either a memory that made them nostalgic or an "ordinary autobiographical event." After taking some time to reflect on the memory and record their feelings, subjects estimated the temperature of the room. The ordinary-memory people guessed about 17 C (63 F). But the nostalgic ones put the temperature higher, at around 20 C (a comfortable 68 F).

Another group of 80 volunteers reflected on a nostalgic or non-nostalgic memory, like the earlier group had. Afterward, they had to plunge one hand into a bowl of ice-cold water and hold it there for as long as they could. The non-nostalgic subjects lasted about 20 seconds before yanking their hands out of the bowl. Those fortified by warm, nostalgic memories, though, stuck it out for an average of 26 seconds.

A separate study, published this week in PLOS ONE, looked at how memory affects hunger. Patients with severe memory problems, the authors note, sometimes eat one full meal right after another—without recalling what they've eaten, they apparently don't feel full. For people with intact memories, does hunger also depend on our memory of our last meal?

To find out, researchers at the University of Bristol relied on a trick soup bowl. A hidden pump in the bowl's base, connected to a tube under the table, let scientists sneakily refill or drain the bowl while subjects were eating (surely this is the plot of a Greek myth I'm forgetting).

Researchers gave 100 subjects a bowl of "creamed tomato" soup that initially held either 500 ml (about 2 cups) or 300 ml (1 1/4 cups). Half the subjects were allowed to eat their soup with no funny business. A quarter of them saw a bowl holding the larger amount of soup but only ate the smaller amount as their bowls were secretly drained. And the final group saw a small bowl of soup but ate a larger portion as it refilled.

Over the next three hours, subjects rated how hungry they felt. By the end, people who had seen a small portion of soup felt significantly hungrier than those who had seen a large portion—regardless of the amount they'd actually eaten.

This suggests, the authors write, that appetite is closely tied to our memory of what we've eaten recently. We take visual hints from our food about how full it will make us feel, and those hints can override the information coming from our stomachs.

If you don't have a magic soup bowl, you might still be able to use your memory to your advantage by paying attention to what you eat. Previous research has shown that watching TV, or otherwise distracting ourselves during meals, can make us hungrier later on. Taking in all the visual information from our plates, so we remember it later, can keep us feeling fuller. And, of course, recalling fond memories might make us warmer. Maybe all that time Eliza Doolittle spent standing on the street and singing about "warm face, warm 'ands, warm feet!" would have been better spent looking to the past.

Zhou, X., Wildschut, T., Sedikides, C., Chen, X., & Vingerhoets, A. (2012). Heartwarming memories: Nostalgia maintains physiological comfort. Emotion, 12 (4), 678-684 DOI: 10.1037/a0027236

Brunstrom, J., Burn, J., Sell, N., Collingwood, J., Rogers, P., Wilkinson, L., Hinton, E., Maynard, O., & Ferriday, D. (2012). Episodic Memory and Appetite Regulation in Humans PLoS ONE, 7 (12) DOI: 10.1371/journal.pone.0050707

Image: Maria Pontikis (Flickr)

Fishing Yanks the Best Parents from the (Gene) Pool

A fishing rod and reel aren't just gear for human recreation: they're the tools of evolution. The difference between fish we pull out of lakes or commercial fisheries by their lips and those we leave behind can drive change in entire fish populations. And that change may be for the worse. In at least some species, the fittest fish are the ones that end up on our hooks.

The largemouth bass (Micropterus salmoides) lives all over the United States and is a popular target of recreational anglers. You wouldn't guess it from the bug eyes and mailbox mouth, but M. salmoides males are also doting dads. For several days after the female lays her eggs and before they hatch, the male stays close to the nest. He fans the eggs with his tail and chases off any other creatures who come looking for a snack.

The more aggressively a male largemouth bass attacks intruders near his nest, the more of his offspring are likely to survive. But when fending off threats, a bass doesn't necessarily notice the difference between a hungry fish and a dangling lure. So the fish that guard their nests most aggressively might also be the most likely to bite into a fishhook.

David Sutter, a PhD student at the University of Illinois at Urbana-Champaign, and other researchers used specially bred largemouth bass in artificial ponds to investigate this question. Their fish had been bred into two lines: one that's especially likely to attack a fishhook, and one that's especially unlikely.

(Vulnerability to being caught on a rod and line is heritable, Sutter explains—a kind of personality trait for fish. Largemouth bass were first bred this way starting in the late 1970s. Researchers kept the bass in a reservoir where any fish that got caught were marked and rereleased. Eventually researchers drained the reservoir, revealing some fish with multiple marks and others that had never been caught. These extremes were separated into new ponds where the experiment was repeated. After a few generations of this, the researchers had created one line of fish that was consistently catchable and a second line that was consistently hard to catch.)

Sutter and his colleagues put the two kinds of male bigmouth bass together in a pond, along with ordinary females. Once the fish had spawned, snorkelers visited their nests to count their eggs. By spying on the fish remotely, researchers could observe how attentive the fish dads were to their nests—and how aggressive they were to "intruders," which in this case were hookless fishing lures.

The fish bred for catchability, as expected, attacked the fishing lures more often than other fish. In addition to chasing these imaginary predators away from their eggs, they also spent more time hanging out near the nest and fanning their eggs with their tails. By comparison, the fish bred to ignore fishhooks spent more time away from the nest and didn't bother chasing away intruding lures. Overall, as the authors report in PNAS, the easiest-to-catch largemouth bass are also the best dads.

Hooking one of these fish from a body of water obviously removes him—and his good-dad DNA—from that population's gene pool. It also dooms any eggs he was guarding, which carry those same genes, to become food for roving predators.

There's another way fishing fouls up the next generation of fish. The researchers found that females spent more of their eggs on aggressive males, especially large ones. Apparently the female fish can tell which males will guard a nest well. When these sexy bass are removed from a pond, they leave behind more eggs (and more potential young) than a smaller and less aggressive male would.

All this means that humans can drive the evolution of a whole fish population. Thanks to our fishing lines, male largemouth bass (or species with similar behaviors) can become less aggressive, less capable as parents, and less attractive to females. And, of course, less catchable by us. The authors suspect these changes are already happening in popular angling spots, though it hasn't been studied yet.

Sutter says fisheries might be able to prevent the problem by leaving largemouth bass alone during their spawning season. "It would probably be best to allow fish to successfully reproduce and minimize disturbances," he says—by disturbances he means fishhooks—"especially in areas where fish only have limited opportunities to reproduce." Otherwise, the only fish that are left alive may be the deadbeats.

David A. H. Sutter, Cory D. Suski, David P. Philipp, Thomas Klefoth, David H. Wahl, Petra Kersten, Steven J. Cooke, & Robert Arlinghaus (2012). Recreational fishing selectively captures individuals with the highest fitness potential PNAS : 10.1073/pnas.1212536109

Image: (Not a largemouth bass) by Blake Facey (Flickr)

The Shambulance: Copying Roger Clemens Won't Help You Lose Holiday Pounds

The Shambulance is an occasional series in which I try to find the truth about bogus or overhyped health products. With me at the wheel of the Shambulance are Steven Swoap and Daniel Lynch.

The injections he'd been receiving in the buttocks during his major-league baseball career, pitcher Roger Clemens explained to a jury this summer, were not steroids. They were perfectly legal and innocent shots of vitamin B12. The jury acquitted him, lifting the weight of a felony perjury charge from his shoulders. You, too, can use B12 to put some spring back into your step—at least, if you believe the companies that market the injections for weight loss, energy, and general well-being. In reality, this is not a performance enhancer.

B12 is a quirky vitamin that you can't get from plants. It's manufactured by bacteria that provide their services to some animals by living in their guts. Humans mainly get B12 from meat, eggs, and dairy. Of course, this means vegan humans have to find the vitamin elsewhere, such as in fortified breakfast cereals or Flintstones chewables. (They might also ingest B12 from soil bacteria on vegetables that haven't been washed well.)

"Healthy individuals have a six-year supply of B12 stored in their liver," says Daniel Lynch, a biochemist at Williams College. So even a temporary shortage in your diet shouldn't harm you. Long-term vegans, though, can become deficient in B12. Some older adults and gastric-bypass patients who can't absorb enough B12 from their food need to get it from an outside source. And patients who suffer from a disorder called (oddly) "pernicious anemia" need B12 supplements.

B12 deficiency causes weakness and fatigue, and an injection of the vitamin reverses those symptoms. This has apparently led some people to conclude that healthy, non-deficient folks will also get stronger and more energetic by taking B12. Why settle for normal functioning when you could be a vitamin-powered superhuman?

"[Weekly] vitamin B12 injections are intended to crank up the metabolism and boost energy levels to increase daily activity and help weight loss even when the body is at rest," says one Chicago weight-loss center.  An "anti-aging" clinic asserts that "B12 injections effective means of boosting the body's metabolism for those looking to lose weight."

You'll start by shedding weight in the wallet region: a 3-month course of shots from that office will relieve you of nearly $500.

It's true that vitamin B12 is involved in metabolism. However, according to the National Institutes of Health, "Vitamin B12 supplementation appears to have no beneficial effect on performance in the absence of a nutritional deficit."

In other words? "Basically, for any healthy person this is a sham," Lynch says. "Any excess B12 is peed out anyway."

Non-human animals store B12 in the liver, just as humans do. "So you could get the same effect of the injection by munching on liver," says Steven Swoap, a physiologist who's also at Williams College. "This is how they 'cured' vitamin B12 deficiency a hundred years ago."

If you still feel a craving for B12 but don't care for liver sandwiches, you can buy bottles of B12 pills—and they'll run you about five cents a tablet. "It begs the question as to why anyone would stick a needle in themselves when you can buy this stuff as a pill at the local drugstore," Swoap says. Maybe we can find a Hall-of-Fame-nominated baseball player to explain it.

Image: Craig Strachan (Flickr)

Hack Your Wallet: Crisp Bills Are Harder to Spend

Do the strains of Bing Crosby's Christmas standards make you throw cash at salespeople until they give you something you can leave the mall with? Are pricey, between-department-store lattes your early gifts to yourself? Don't panic. Scientists have a way for you to hack your spending this holiday season. 

We consumers, it turns out, are not always rational with our cash. Research in the past has suggested that people are more likely to spend the money they carry if it's in smaller bills. Larger bills seem to have value even in addition to their denomination. A $20 bill, for example, is a little harder to let go of than four $5 bills.

This idea is called the "denomination effect." But it's not the only factor that affects whether we save our cash or spend a little more. Two marketing professors, Fabrizio Di Muro at the University of Winnipeg and Theodore Noseworthy at the University of Guelph, investigated another factor: grubbiness. Do people assign extra value to crisp, clean-seeming bills, regardless of their denomination? And are people eager to get rid of—that is, spend—worn, dirty cash?

Previous research has provided a few reasons why this might be true. One study showed that consumers value an object less after it's been touched by other people. After someone else has had their paws on a product, even if they don't see the touching happening, people aren't willing to pay as much for it. As for currency itself, research has shown that most people think money is dirty—and they're not wrong.

In a series of experiments, Di Muro and Noseworthy tried to sort out consumers' real feelings about their cash. They report in the Journal of Consumer Research that crisp bills are keepers.

Participants in the first experiment tried to solve a series of puzzles and received a $10 bill at the end. Then they were offered the chance to wager their winnings on one final puzzle; if they got it right, they'd receive a $20 bill. Half the subjects started with a worn, crumpled $10 and were shown a crisp new $20 that they could win. Eighty percent of these subjects chose to gamble. The other half of the group had a crisp $10 and were offered a worn $20; less than a quarter of these people chose to gamble. Subjects were much more tempted to gamble their winnings, in other words, when it might have meant upgrading to a nicer-looking bill. (In reality, all the bills in the study were brand-new; the researchers had crumpled some of them until they looked old and worn.)

The researchers also found that the lure of a crisp bill could override the denomination effect. In a second experiment, subjects were given either a $20 bill or four $5 bills to "shop" with (in the lab). When their bills looked old, people with small bills spent more. But subjects with four crisp, new $5 bills spent less than those with a worn $20.

In a third experiment, subjects shopped with a wallet holding an assortment of bills. Most people don't like to break a larger bill if they have the right small bills to pay for what they want. But in this case, people with a larger bill that was old and worn were much more likely to break it unnecessarily. If the larger bill was crisp, almost no one did this.

Based on questionnaires after their experiments, the authors think that two emotions are at play. One is disgust: people think old, crumpled bills are dirty, and like to get rid of them in a hurry. The other is pride: people enjoy owning crisp new bills, and don't want to spend them.

(This sense of pride may be what led to a surprising twist: When the researchers repeated the final experiment but told subjects that they were being videotaped, those people were more likely to break their crisp larger bills. Imagining others' eyes on them apparently made people eager to show off their nice-looking cash.)

Overall, people tended to spend more and get rid of their cash more readily when they had worn, dirty-seeming bills. People with crisp, clean bills spent less and didn't like to break those bills unnecessarily—unless someone else was spying on them.

What does this mean for your wallet? Stocking up on crisp ATM bills, rather than taking cash back at the grocery store, might help you spend less. Keeping large bills instead of small ones will help too.

The government might be able to hack its own wallet, though, by following the opposite advice. The Federal Reserve regularly removes beat-up, grubby cash from circulation and replaces it with new bills. If it replaced worn bills less often, leaving everyone stuck with wallets full of grubby cash, maybe we'd all spend a little more money and give the economy a real holiday boost.

Di Muro, F., & Noseworthy, T. (2012). Money Isn’t Everything, but It Helps If It Doesn’t Look Used: How the Physical Appearance of Money Influences Spending Journal of Consumer Research DOI: 10.1086/668406

Image: 401(K) 2012 (Flickr)

Math Shows Penguins Only Care about Themselves

Don't let the adorable mini-orchestra-conductor look fool you: penguins aren't that nice. When emperor penguins huddle together during Antarctic storms, they act like they're all in it together. But a new mathematical model shows just how the clusters of birds keep warm, accounting for everything from their geometry to the speed of the wind. Concern for one's fellow bird, it turns out, isn't a factor.

Regardless of your motivations, huddling together in a group is a great way to wait out a frigid storm. Instead of burning up their own energy reserves trying to warm their bodies, emperor penguins can rely on the warmth of a bunch of big feathery animals pressed together. There may be ten or hundreds of bodies in the huddle. Inside, the temperature is between 20 and 37.5 degrees Celsius (a cozy 68 to 99.5 degrees Fahrenheit). In the chilliest storms, penguins squeeze as tight as 10 birds every square meter.

Those huddles aren't motionless, though. With a continuous slow shuffling, the penguins rotate through the formation. Birds with their backs exposed to the wind creep away from it, up the sides of the huddle, until they find some protection. Meanwhile, birds that were formerly on the warm interior find themselves on the outside.

Three applied mathematicians at the University of California, Merced, set out to create a computer model of penguin huddling. Aaron Waters, François Blanchette, and Arnold Kim wanted to find out how well the birds' strategy works—and whether any penguins are left out in the cold.

To pack their penguin huddle as tightly as possible, the mathematicians imagined the birds on a grid of hexagons. This is the best way for circles to squeeze into a plane (think of a honeycomb), and scientists in the field have observed that real penguins arrange themselves roughly this way. The researchers also assumed that "penguins in this huddle have uniform size and shape."

Next, they added wind to the model, which flowed around the huddle differently depending on its overall shape. Then they calculated the rate at which each computerized penguin was losing body heat. They sent the coldest penguin shuffling around the outside of the huddle until it found the warmest spot it could stand in, then started over with the new coldest penguin.

The simulated penguins constantly shifted positions within the huddle, just as real penguins do. Over time, the model huddle tended to take on the shape of a flat-sided oval and travel slowly downwind (as penguins on the windward side continuously moved away from it).

When they calculated the flock's heat loss, the authors discovered that their model huddle was very fair: every penguin lost approximately the same amount of body heat. But these model penguins were only programmed to maximize their own warmth, not to consider the warmth of other penguins or the group as a whole. This means that even if penguins are only looking out for themselves, the whole huddle stays warm, as the authors report in PLOS ONE.

Just because emperor penguins can be totally selfish doesn't mean they are, the authors point out. It's still possible that penguins are altruists, organizing their huddle by thinking about the group as a whole. But it's not necessary to explain how they behave in the wild.

There's one flaw in the penguins' strategy: the elliptical shape a huddle tends to take on isn't optimal. A less stretched-out formation would help the whole group stay a little warmer. Maybe the emperor penguins should consult with a mathematician.


ADDENDUM: Francois Blanchette, who was traveling when I first contacted him, says that this research was inspired by (what else?) March of the Penguins. While watching the movie, he noticed that factors in the penguins' environment, such as wind flow and heat transfer, were relevant to his own field of fluid dynamics. "I figured there should be a problem I could address that had to do with penguins," he says. "I was looking to do something different than my usual line of research."

With penguins out of the way, Blanchette and his coauthors are now interested in modeling other groups of living things, such as bacterial colonies. "However, not being biologists," he says, "we are not very familiar with other biological systems where such a model could be useful." If you're a biologist with a clump of organisms you'd like to model, let him know.

Image: Emperor penguins, by Mtpaley (Wikimedia Commons)

Waters, A., Blanchette, F., & Kim, A. (2012). Modeling Huddling Penguins PLoS ONE, 7 (11) DOI: 10.1371/journal.pone.0050277

P.S. If you enjoy reading about math and self-interested animals, you may like my earlier post Geometry Proves Sheep Are Selfish Jerks.

Monitoring from Space Shows Even This Giant Crab Can Navigate Better than You

It was crabnapping for a just cause. But the crustaceans that found themselves suddenly plucked from their burrows, stuffed into opaque sacks, and carried off through the forest couldn't know that. When the scientists freed their captives, they waited to see whether the crabs would find their way home or be stranded forever. They'd be watching—from space.

The best way to find out exactly where and how far an animal travels is to tag it with a GPS tracker. But if you're interested in invertebrates, most of your subjects are too small or squishable to carry around such a device. Enter (scuttling in from stage left) the robber crab, Birgus latro. Also called the coconut crab because of its predilection for cracking open coconuts, the species is the largest arthropod on land. Legs included, it can grow to nearly a meter across.

Robber crabs live on islands in the Indian and Pacific Oceans, tucking themselves into hollow trees and rock crevices during the day to keep their shell-less bodies from drying out. Females make an annual migration to the coast to lay their eggs in the ocean. Less is known, though, about the movements of male crabs. To find out what they're up to—and because the heavier males presumably wouldn't mind the bulky GPS tags so much—Jakob Krieger of the University of Greifswald and other German researchers tagged 55 male robber crabs on Christmas Island.

During the day, the GPS satellites didn't return much data, since the crabs were mostly hidden in their burrows. At night, they began to roam.

The crabs were highly faithful to their homes, usually staying close to the one to three hiding spots they preferred. But during the time the scientists were monitoring them—up to three months—15 of the crabs went on mysterious, long-distance journeys to the coast.

The authors report in PLOS ONE that these journeys were up to 4.2 kilometers long, a distance that might not seem impressive, except that the top speed observed in the study was 150 meters per hour. If you set a shuffling robber crab at one end of a soccer field at the beginning of a game, you just might be able to retrieve it from the opposite end at halftime.

All the journeying crabs traveled along a similar route, sharing a "migratory corridor" toward the ocean. Why do they go on these arduous errands, visiting the coast for 1 to 10 days before returning home? Krieger says he and his coauthors are "convinced that it is most likely a combination of factors."

One possible factor is reproduction; athough they mate inland, male crabs may try to boost their success by pursuing females out to shore. Another is nutrition. Krieger says the crabs may need to drink saltwater to get the calcium and sodium that keep their skin sturdy. They also get the nutrients they need by eating other crabs, such as the red crabs that migrate en masse across Christmas Island every year. Traveling robber crabs may take advantage of this mobile red-crab buffet. (Here's a worthwhile video of red crabs dodging traffic and clinging to cliff faces during their own journeys.)

The fact that male robber crabs traveled at all was news to the scientists. But they also wanted to know how well robber crabs can navigate, and that's where the crabnapping came in. A dozen crabs were bagged, moved a kilometer or so, and re-released to see how they'd manage.

Crabs that were freed somewhere within the migratory corridor, that popular robber crab highway, found their way home with no problem. But those released someplace unfamiliar were lost. The GPS data showed that these crabs used their release points as a new home base from which they took exploratory trips outward, trying to get their bearings. Yet they never found their old homes.

Though robber crabs might navigate using cues such as the position of the sun or moon, the scent of the ocean, or the earth's magnetic field, they seem to especially rely on memorizing a path in one direction and retracing it on the way back. The GPS data showed crabs following identical routes on their way to and from the ocean.

The researchers also crabnapped one of their victims twice, and saw that he followed precisely the same path homeward (along the migratory corridor) both times. This suggests that robber crabs remember the landmarks they find along their routes. Of course, when you're moving at a crab's pace, there's plenty of time to observe the scenery.

Krieger, J., Grandy, R., Drew, M., Erland, S., Stensmyr, M., Harzsch, S., & Hansson, B. (2012). Giant Robber Crabs Monitored from Space: GPS-Based Telemetric Studies on Christmas Island (Indian Ocean) PLoS ONE, 7 (11) DOI: 10.1371/journal.pone.0049809

Image: John Tann (Flickr)

Why You Itch When Others Scratch

Itching is contagious, and not only when one party has the chicken pox. The mere sight of a stranger scratching can be enough to trigger an itch in your own flesh. If you're especially prone to contagious itchiness, psychologists say, it's not because you relate well to other people—you're just neurotic.

The researchers who delved into the science of contagious itching thought it might be similar to another famously spreadable phenomenon: yawning. Previous studies found that a person's likelihood of catching someone else's yawns is linked to empathy. It's easier to trigger contagious yawning in people who are good at understanding others' states of mind.

To explore contagious itching, psychologist Henning Holle at the University of Hull, UK, and his colleagues subjected 51 volunteers to videos of people scratching themselves. Each person watched a series of videos with changing variables: some showed a man scratching himself and others showed a woman; the model scratched 5 different body parts (upper or lower left or right arm, or the middle of the chest); and in control videos the model simply tapped the body part in question.

After each video, subjects rated how itchy they felt. Since the experiment was being filmed, researchers could also see how often their subjects scratched themselves, whether they realized they were doing it or not.

The results showed that itching is highly contagious, the authors report this week in PNAS. People reported feeling itchier after the scratching videos than the tapping videos, and most subjects scratched themselves at some point during the experiment. It's normal to feel itchy when you see someone else scratching. But the degree of itchiness varies from person to person.

To find out what makes someone especially vulnerable, the researchers gave subjects a group of standard personality tests. "We expected to find contagious itching to be associated with empathy," Holle says. A questionnaire that measured empathy, though, turned up no connection.

But the researchers did find a correlation between their subjects' contagious itching and their neuroticism. As defined by psychologists, neuroticism is someone's tendency toward worry and insecurity. Holle and his colleagues measured this and other personality traits using a test called the Big Five personality inventory. (The other four traits in this test are openness, conscientiousness, extraversion, and agreeableness. Worried you're a worrier? You can take a version of the test here.)

Making a study of itching and scratching even less physically comfortable, 18 of the subjects watched the videos while inside an fMRI scanner. They weren't allowed to scratch themselves, since that motion might interfere with the machine. But when they saw scratching videos, the activated areas in their brains matched a previously observed group of regions called the "itch matrix."

Among other areas, this brain network included the premotor cortex (involved in planning and carrying out motions) and the primary somatosensory cortex (headquarters for our sense of touch). Also active was the anterior insula, an area the authors say may be crucial to our feeling of sharing another person's pain.

When asked how itchy this research had made him personally, Holle declined to comment.

Holle, H., Warne, K., Seth, A., Critchley, H., & Ward, J. (2012). Neural basis of contagious itch and why some people are more prone to it Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1216160109

Image: Holle et al.

City Birds Adapt to a New Enemy: Cats

Moving from a rural home into the city brings challenges like figuring out trains, maneuvering couches up staircases, and not being eaten. Birds that move into urban homes have to worry about a different set of predators than their relatives in the countryside do. Although they haven't learned how to avoid hungry truck grilles, urban birds have evolved some new tricks that help them dodge the claws of predatory house cats.

For a bird living in a rural habitat, the main threat is birds of prey. But when that same bird moves to a city, it's much less likely to get snatched from above by a swooping hawk or falcon. Instead, it has to contend with roaming cats. The American Bird Conservancy says that cats (both pets and strays) kill hundreds of millions of birds each year in the United States alone.

To find out whether urbanized birds have evolved in response to their new predators, a pair of researchers captured birds inside and outside of two cities: Brønderslev, Denmark, and Granada, Spain. The researchers are Juan Diego Ibáñez-Álamo, at the University of Granada, and Anders Pape Møller at Paris-Sud University. Using mist nets and traps, they collected 1132 birds.

Each time a bird was caught, a researcher immediately collected and tested it. By simply holding a bird in their hands briefly, the scientists could score all the ways it responded to capture. Did the bird scream out distress calls? Bite? Shed its feathers? When released, did it fly off right away or lie frozen in panic?

The researchers collected members of 15 bird species that lived in both the city and the country. For each of these species, they compared the behaviors of urban and rural birds to determine how the birds had adapted since moving into the city.

Like newly minted Manhattanites learning to keep their doors locked, urban birds have developed new safety habits, the authors report in Animal Behaviour. One such habit is screaming bloody murder. When researchers seized city birds and held them in their hands, the birds were much more likely to make alarm calls and "fear screams" than birds of the same species that lived in the country. Møller and Ibáñez-Álamo think this behavior has evolved because in the city, birds live close to their relatives instead of dispersing widely. Families that alert each other to predators keep their genes alive.

Other habits that may have helped birds escape from raptors when they lived in the country—namely, biting and wriggling around when caught—were less common in city birds. (I'm guessing biting was not as uncommon, however, as the researchers holding the birds would have liked.)

Urban birds also showed off a trick that was less common in their rural relatives: shedding feathers. This trait seems to help deter hungry cats. When finding yourself in the mouth of a house cat is a real danger, being able to shimmy away and leave that cat with a mouthful of feathers will help you survive.

Some of the bird species studied had lived in the city since the late 19th century, while others had only moved in during the 21st century (according to local bird experts who'd monitored their populations). For a couple of the escape behaviors they studied, the researchers were able to see changes increasing over time: birds that had spent a lot of generations in the city had changed more dramatically than recent immigrants had.

This suggests that as birds and other animals continue to reside and reproduce in the city, they'll keep evolving in response to their urban predators. If we give them long enough, maybe they'll even figure out how to escape cars.

Møller, A., & Ibáñez-Álamo, J. (2012). Escape behaviour of birds provides evidence of predation being involved in urbanization Animal Behaviour, 84 (2), 341-348 DOI: 10.1016/j.anbehav.2012.04.030

Image: Jody Sticca (Flickr)