Why It's Nearly Impossible to Castrate a Hippo

Chances are you've never wondered how difficult it is to remove the testes of a hippopotamus. Other people have been thinking hard about it, though, because in fact it's almost impossible.

Before sitting down to emasculate a common hippopotamus, Hippopotamus amphibius, it would be reasonable to ask why. They're a threatened species, so usually conservationists try to make more baby hippos—not fewer. But in zoos, hippos turn out to be prolific baby-makers. Females can live for 40 years and may birth 25 calves in that time. This would be great news in the wild, but zookeepers don't always have someplace to store a new two-ton animal.

Male hippos can also be aggressive toward each other, at least while they have all their man parts. For both of these reasons, zoos may want to have their male hippos fixed. But there are a few factors working against them, explains a new paper in the journal Theriogenology (that's reproductive science for vets) by an international group of authors.

The first challenge is that hippopotamuses hide their genitals. The testes are inside the body, instead of outside in a scrotum. (Other mammals in the internal-testes club, since you asked, include the armadillo, sloth, whale, and platypus.) This makes the hippo's testes totally invisible from the outside. Combined with a penis that the paper's authors describe as "discreet," it means it's hard to tell males from females at a distance.

Another problem is that testes aren't in the same place from one hippo to the next, and they may "retract" even farther during surgery. Hippopotamuses are also difficult to safely put to sleep. "In the past, hippopotamus anesthesia has been fraught with serious complications," the authors explain.

After moving past the anesthesia problem (they used an apparently safer blend of drugs, delivered via a dart to the hippo's ear), the researchers turned to the anatomical problems. Their answer was ultrasound. Once they had positioned the animal, they used ultrasound imaging to find the testes—then used it again after cutting into the hippo, if the testis they were looking for had scooted farther away from them.

Even after finding the sneaky organs, the procedure wasn't simple. The depth of the testes' hiding places varied by as much as 16 inches from one hippo to the next. Everything had to be done deep inside the animal's body, making it hard to see what was going on. "Grasping the testicle with forceps proved laborious" in most of the animals, the authors write. They also mention using a "two-handed technique" and "moderate traction." The whole hour-and-a-half procedure, based on a method for castrating horses, is described in detail for anyone who wants to try it themselves.

All ten hippos in the study were successfully castrated, though one died shortly afterward, following a complication from a unknown pre-existing condition. Over the next six months, the authors checked in with the zoos housing the hippos to see whether their behavior or interaction with other animals had changed. There were four cases where zoos wanted their hippos fixed to ease aggression between males; in all four, the problem seemed better. (One zoo, though, reported that castrated males were harassed more by females.) Overall, the authors think their technique will help zoos take better care of their hippos.

The final challenge to hippopotamus surgery—what should be a challenge, anyway—is that the animals spend most of their time in a pool of water packed with feces. The animals in the study lowered their stitched-up bellies into this infectious slurry as soon as they had a chance. Yet all of them healed from surgery without trouble. Hippos in general seem to be especially good healers, the authors write.

A possible explanation for the animals' healing superpower is the "red sweat" or "blood sweat" that oozes from their skin. It's not really sweat and it doesn't contain blood, though it is red. The pigments in this skin secretion have been found to absorb UV light, making the "sweat" a potential sunscreen. The pigments can also keep bacteria from growing. So a built-in antibiotic may be what keeps hippos from getting infections after they tussle and bite each other (or after meddling vets come and cut out their manhood). However the red sweat works, it shows that a hippo's secrets don't end with the location of his testicles.


Images: Charlesjsharp (via Wikimedia Commons); drawings by Eva Polsterer (from Walzer et al.).

Walzer C, Petit T, Stalder GL, Horowitz I, Saragusty J, & Hermes R (2013). Surgical castration of the male common hippopotamus (Hippopotamus amphibius). Theriogenology PMID: 24246424

Citizen Scientists Dig Up the Truth about Decomposing Dung

The amount of cow dung plopped into the world every day is almost unthinkable, but Tomas Roslin is thinking about it.

"We can regard it as either an immense waste problem or an enormous ecosystem service," he says. He means that what starts out as a turd in a field turns into a wealth of nutrients for plants—assuming it can make its way below ground. So understanding how dung gets broken down can help us ensure an ecosystem is running smoothly. To address such a messy, large-scale question, Roslin recruited a big mess of young volunteers.

Roslin is an ecologist at the University of Helsinki, and he found his citizen scientists through the Finnish 4H Federation. In all, 79 volunteers signed up, ranging from 10 to 27 years old (most were under 20). They agreed to sample 82 cattle farms that spanned Finland nearly from end to end.

From each farm, the volunteers collected 20 liters of "fresh dung" in late spring or early summer. They divided their dung into 15 pats (using an official dung measurer that had been provided to them) and put the pats back onto cow pastures. Some of the manmade cow patties were left open to the air, while others were covered with cages of coarse or fine mesh to keep out certain insects.

Roslin and his coauthors were especially interested in large dung beetles called dor beetles. In some cases they prevented dor beetles from burying the dung (as the beetles enjoy doing) by putting mesh underneath the patty, and in other cases a full wire cage kept dor beetles from getting into the dung at all. Smaller insects were kept out with finer mesh cages, and earthworms were blocked from the dung by putting a layer of cloth underneath it.

Volunteers weighed the dung piles periodically over the next two months to see how much was left of them. As the summer went on, the patties dried out and were broken down by whatever insects could reach them, as well as by microbes that couldn't be kept out. (Only 73 farms were left in the final analysis, since a few sites were lost to "lack of sufficient commitment by the volunteer" and others to "cows trampling on the experimental pats.")

The results showed that 13 percent of dung decomposition is done by insects. Microbes and rainstorms take care of the rest. The farther north you are in Finland, the more slowly your dung will disappear, perhaps because cooler weather slows bacterial growth.

Each added barrier around the dung made it decompose a little more slowly, showing that all the groups of insects were helping to break it down. But the biggest contribution came from dor beetles. This was in line with what previous, small-scale research had shown—but his network of citizen scientists let Roslin confirm that dor beetles are equally important all across Finland.

It matters because "our dor beetles are not doing that well," Roslin says. Out of three species in Finland, one has gone regionally extinct and another is on the decline. Knowing how important the dor beetle is to healthy farms gives Finland more reason to keep it alive.

Additionally, Roslin says, "just figuring out the basics of how the system works" is critical. In the United States, most cattle waste goes into manure lagoons, where beetles or ecosystems don't really enter the equation. But when waste is returned to the soil, Roslin says, "we need to understand who is behind it." He points out that cattle were initially brought to Northern Europe in part to fertilize the fields.

"We love citizen science," Roslin declares. He and his lab have previously organized citizen investigations of dung beetles and gall-wasps, and they're now working with volunteers to study the hermit beetle Osmoderma barnabita. "The volunteers involved have come to appreciate completely new aspects of their own environment," he says.

There are some drawback to the approach, of course —experiments have to be kept simple, and sometimes a volunteer loses interest or flattens a cow patty. But by pairing small-scale lab research with large citizen projects, Roslin says, "we have managed to collect scientific data sets unachievable by relying on professional biologists."

Riikka Kaartinen, Bess Hardwick, & Tomas Roslin (2013). Using citizen scientists to measure an ecosystem service nationwide. Ecology DOI: 10.1890/12-1165.1

Images: top Timo Marttila/Satakunnan Kansa; bottom Riikka Kaartinen.

Why Yellowstone's Grizzlies Should Be Grateful for Wolves

There's only one time a giant domino chain isn't fun: when you're a domino. Humans are great knockers-down of ecosystem domino chains, and sometimes we don't even know which species we've felled until we start propping things back up. When we knocked every last wolf out of Yellowstone National Park, for example, we didn't know how we were hitting bears at the other end of the chain.

When Yellowstone was first created, visitors were free to kill the animals. Then in the early 20th century, government "predator control" efforts gradually finished the job of wiping out the park's wolves. The last ones were killed in 1926. Wolves remained absent from Yellowstone until the mid-1990s, when officials lugged pens of them into the park and set them free.

William Ripple, an ecologist at Oregon State University, and his colleagues investigated how the return of wolves affected grizzly bears in Yellowstone. They compared data from old studies of bear scat to data collected after the wolves came back. Specifically, they wanted to know how many berries bears had been eating.

What do wolves have to do with berries? Nothing. But wolves kill elk—and elk eat all kinds of plants, including berry shrubs that bears would otherwise dine on.

For a few decades after wolves were wiped out of Yellowstone, the booming elk population was culled to keep it under control. But the elk culling ended in the 1960s. Ripple found that in the late 1960s, while the elk population was still low, bears had a relatively high percentage of fruit in their dung. Over the next 20 years, as the elk population more than tripled, the grizzlies' berry diet dropped to almost nothing. And in the late 2000s, after wolves had reestablished themselves in the park and elk numbers had dropped, a hearty helping of berries returned to bear diets.

The researchers also looked at berries themselves, choosing a representative plant called serviceberry. They saw that plants in fenced-off areas (where elk and other grazers can't reach them) had been growing for decades. Outside the fences, though, the berry plants were young—they had all sprung up after wolf reintroduction. The evidence all pointed the same way: more wolves means fewer elk, which means more berries, which means better-fed bears.

Berries are good for a grizzly's diet, the authors explain, because bears use them to fatten up before entering hibernation. Female bears will give birth during their winter doze, so having enough energy stored is crucial to the population's survival.

Ripple says there's not yet any evidence that having more berries in their diets is actually helping bears—his study didn't ask that question. But he is optimistic about the future of grizzlies in Yellowstone. "It is good to see that the bears can at times get significant calories from...the berries," he says. Berries made up as much as 39% of female grizzlies' diets in recent years.

Other studies have shown that beaver and bison numbers both increased after wolves came back to the park. This might be, the authors write, because herbivores have less competition now from the once-ubiquitous elk. All the species that were knocked down while the wolves were gone can now stand back up and give them a thank-you.

Images: Grizzly bear and wolf at Yellowstone from YellowstoneNPS (via Flickr); diagram from Ripple et al.; bear hug card from OldEnglishCo on Etsy (available for $4.71!).

William J. Ripple, Robert L. Beschta, Jennifer K. Fortin, & Charles T. Robbins (2013). Trophic cascades from wolves to grizzly bears in Yellowstone Journal of Animal Ecology DOI: 10.1111/1365-2656.12123

Help Desk: Relationship Edition

A couple months ago I introduced the Help Desk so I could answer real questions from Inkfish readers. These aren't questions people submitted intentionally, though—they're search terms that sent people to this site. (Take note, Googlers and Bingers of the world: anyone using web analytics can see your searches.)

This time, in honor of Valentine's Day, the Help Desk is focusing on relationships. I hope the unsatisfied searchers out there can now find the flower-pooping good twins they're looking for.


does music cause rodents to have more babies

It's been suggested that background music helps lab mice to relax and breed more, according to a 2005 paper in the Institute for Laboratory Animal Research Journal. However, they'll still startle easily at a loud noise, regardless of background sounds. In behavioral studies, new age music in particular seemed to calm mice down (compared to classical music, pop, or silence). So if you're looking to set the mood, try Enya rather than Bieber.

You can also teach mice to like music if you introduce it during a certain window in their development, according to a Harvard study. But this research looked only at Beethoven and bossa nova, and didn't give mice the option of getting romantic while the music was playing.

evil twin symptoms
Evil twin is not a medically recognized condition. Perhaps you should try consulting a psychotherapist or a screenwriter.

most inconvenient moments to have narcolepsy
Wheelbarrow race, optometrist appointment, listening to a deathbed confession, pairs ice dancing. And the obvious one.

(The most convenient moments to have narcolepsy include mattress testing, portrait sitting, and televised basketball games.)

how to make a sperm cell
Thankfully, it's not up to you.

that boy has a huge belly button
If a giant navel is the worst complaint you have about a person, things probably aren't so bad. Plus, that belly button is a hotbed of bacterial diversity—and so is yours! Look, the two of you have one more topic for dinner conversation already.

a pig look better than u
Pigs can be pretty charming (see below). If you're looking for a creative insult, what about "a giant land crab look better than u"? Or "a Chinese soft-shelled turtle has a smaller tube coming out of the middle of its face than u"? Zing! You're welcome.

pig repeller
If you didn't want the pig around, maybe you shouldn't have flattered it just now.

bloomers for older woman
It sounds like you're searching for a gift for your significant other. What kind of "older" are we talking about—like nineteenth century? If so, bloomers sound great.

how to stay tight with a big guy
Just because a guy has gained some weight doesn't mean you can't be friends with him anymore. (That is what you meant, right?)

girl that poops flowers
If you're wondering why OKCupid rejected your match criterion, I'm sorry to have to tell you that nobody poops flowers. However! If you or your normally excreting girlfriend are willing to commit to a juice cleanse, you can spend a few days pooping vegetables.

how to ruin a party you weren't invited to
That's tough, but I'm going to have to go back to giant land crabs.

mouse quiet too quiet
Maybe that Enya CD did the trick.

don't make sex in the forest
Noted.


Earlier: Help Desk, Part 1.

Images: Help desk by Aryc Ogre; piglet by Ed Mitchell; robber crab by John Tann; Chinese soft-shelled turtle by muzina_shanghai (all via Flickr)

How to Cross the Deep Sea: Stepping Stones of Mollusk Poop

The seafloor has no shortage of spiky wildlife or hairy mysteries. One such mystery is logistical: where do the animals that live around deep-sea vents and cold seeps come from?

On the black and generally barren bottom of the ocean, food is scarce. Hydrothermal vents and cold seeps—places where methane, sulfides and other chemical goodies leak out of the seafloor—are like desert oases. Whole communities of weird creatures that live on these chemicals rather than the sun cluster around them.

Researchers think big pieces of organic junk that fall to the bottom of the ocean, such as sunken ships and deceased whales (called "whale falls"), may act as stepping stones for these communities. Species might disperse from one seafloor chimney to the next via a visit to a wrecked ship.

"Wood is a foreign substance in the deep sea," says Christina Bienhold of the Max Planck Institute. To find out whether resourceful ocean critters can easily make use of wood that falls into the ocean, she and other researchers dropped some in. They rigged together small heaps of Douglas fir logs, weighted them with cement, and carried them a mile down into the Mediterranean.

The researchers used four wood piles, each two meters long. They were at various distances from a known cold seep. The closest log was 70 meters away—so if any animals scooted over from that community, it would be a bit of a trek.

One of the wood heaps was sampled just one day later. (It looked the same.) The other three rested on the ocean floor for a year before robotic vehicles returned to collect wood samples and scoop up the animals that had moved in.

And did they ever move in. Bienhold was surprised to find that her logs, after only a year on the seafloor, held thriving colonies of wildlife.

The logs' most abundant tenants were wood-boring bivalves called Xylophaga, or "shipworms." Built like a worm with a shell on one end, these mollusks burrow into wood while symbiotic bacteria help them digest it. All around the logs were evidence of their work: the researchers observed a layer of "fine wood chips and fecal matter" two to four centimeters thick.

The shipworms seemed to have attracted other animals interested in feeding on the mollusks themselves or on the waste piles they left everywhere. As these creatures ate and respired, they used up oxygen in the water and allowed oxygen-hating bacteria to move in. These bacteria created pockets of sulfides—food for the kinds of animals that live at cold seeps or hydrothermal vents. (Normally, they would find this food coming straight out of the ground.)

Like very unattractive doves out of a hat, those animals began to materialize out of the blackness of the ocean. Clustered around the logs were sea urchins, fish, and deep-sea mussels and crabs. There were small crustaceans that couldn't be identified, and several types of worms, including two brand-new species.

All three wood piles had similar animal communities living on and around (and, in the case of the crabs, hiding underneath) them. Their bacterial communities were more diverse. But they all included bacteria that could break down the cellulose in wood, as well as bacteria that consume sulfate instead of oxygen.

Bienhold says her results show how wood that falls to the seafloor can create hotspots of ocean life. Hunks of organic trash like her log piles, even though they're few and far between on the bottom of the ocean, could help rare deep-sea species to spread. The key player in her set of experiments was the little wood-boring bivalve that moved in first and made the logs into a habitat that other wildlife could use.

"It remains enigmatic," Bienhold says, how the wood-borers (or any of the other organisms) found this new habitat in the first place. The researchers observed a greater density of sea urchins as they got closer to the wood piles; they seemed to be attracted to the wood by some chemical signal. Sea urchins and other animals may sniff out chemical cues from afar that help them find organic matter. For now, though, the secret remains sealed in their lipless bodies.

Bienhold C, Pop Ristova P, Wenzhöfer F, Dittmar T, & Boetius A (2013). How deep-sea wood falls sustain chemosynthetic life. PloS one, 8 (1) PMID: 23301092

Image: Sea urchins, courtesy of New Zealand-American Submarine Ring of Fire 2005 Exploration, NOAA Vents Program.

The Shambulance: Enough Already with the Juice Cleanses

The Shambulance is an occasional series in which I try to find the truth about bogus or overhyped health products. Helping me chart a course are Steven Swoap and Daniel Lynch. 

Before I learned that it costs $65 to $90 to starve yourself for a day, I considered trying one day's worth of "juice cleansing" to put myself into the proper cranky fog for writing this piece. But if I'm going to eat no calories, I prefer to spend no dollars. 

What did I give up by fueling myself on solid foods instead of liquefied produce? Really, one day would have been merely dipping a toe into the celery water. If I were a serious client of a juice cleanse company, I would pay for anywhere from three to ten days' worth of bottled juices, delivered to my doorstep in a cooler every morning. 

The first few days of deprivation would, in theory, "cleanse the blood" and release toxins from my tissues that have been slowing me down and making me sick. I'd give my colon a break while "sweeping" it out. The latter days would boost my immune system and "fight off degenerative diseases." After all that detoxifying and boosting, I would feel energized and restored. I might even have lost a few pounds—but it's about health, not weight.

In the midst of my cleanse, I could experience unpleasant symptoms. "Don't Panic," the website for BluePrintCleanse would reassure me, "It's Just A Healing Crisis!" Apparently, a body that's becoming healthier looks a lot like one that's unwell. Symptoms of detox may include fatigue, headaches, nausea, hives, decreased bowel movements, increased bowel movements, strangely colored bowel movements ("Did you just drink some of our beet juice?"), dry mouth, runny nose, and canker sores. I should ignore those symptoms, drink herbal tea, and be reassured that I'll soon be skinnier. Sorry, healthier.

I sent some promotional materials on juice cleansing to Steven Swoap and Daniel Lynch, both biologists at Williams College. "Where to start?" Swoap said.

The subject of "cleansing" has been covered on this site ad nauseam (not to mention ad headache, ad fatigue and ad canker sores). But to recap, your body does its own cleansing via your kidneys and liver. The wastes and unwanted materials those organs filter out leave you via the toilet—not through your sweat glands or the soles of your feet or water blasted up your colon. And depriving yourself of calories doesn't make the process go any faster.

If anything, it's the opposite, because fasting slows your metabolism. BluePrintCleanse claims that the energy you save on digestion by not eating any real food gets diverted to "other metabolic processes." But Swoap says this is false. Your whole metabolism will slow at once, not just the tasks attached to digesting food. This will make it harder to lose weight. 

The same website reassures users that they won't feel light-headed during a cleanse: "On the contrary, one's mind becomes clearer and one's ability to solve problems enhances." All the blood and oxygen you would normally use to process your food, it explains, get sent to your brain instead.

"Wrong," Swoap says. "The same amount of blood and oxygen is delivered to the brain under nearly all conditions." Reducing your calories won't send more blood to your head. Actually, fasting can make your blood pressure drop, which is the one circumstance in which less blood will reach your brain. 

So much for that clearer mind. In an article from the Boston Globe on juice cleansing companies, registered dietician Marjorie Nolan Cohn says that after a few days of fasting, "you become lightheaded and dizzy, and that euphoric feeling starts to come on." She adds, "I work with a lot of anorexics, and they feel euphoria, too."

Company websites are quick to insist that juice cleansing isn't fasting, even though their plans may provide under a thousand calories a day. And of course it's not about the weight loss—unless you're a bride-to-be. In that case BluePrintCleanse encourages you to "Drink your way to your best shape ever" before walking down the aisle. 

The company offers bridal packages ranging from six to thirty-six days of juice. Elsewhere on its website, it recommends you consult with your doctor before spending more than ten days on a cleanse. But when I emailed to ask how many solid food breaks are in a thirty-six-day juice program, a representative replied that I could schedule my days however I liked. "If you don't use all the juice days before your wedding, you can save them for after your honeymoon," she said. But I'm also free to schedule five consecutive weeks of fasting through the site. 

"Congratulations!" the representative wrote. By the way, that package would be $2,415.00. 

"In reality, for a healthy person to blow a bunch of money to purchase the juices and drink them over a couple days is probably not harmful," Daniel Lynch says. (The operative words being "a couple days.") "And if it serves as some motivational tool to eat better, etc., it is fine." But if your goal is to give your digestive system a rest, he adds, "why not go with an IV bag of dextrose?"

And if you're looking to empty your colon, Lynch points out, a cheap laxative will do the trick in about six hours. "Why spend loads of money and suffer through days of drinking liquified kale?" He sounds a little cranky. Maybe he missed a meal.

Image: Food Thinkers (via Flickr)

The Shambulance: 5 Reasons Not to "Cleanse" Your Colon

The Shambulance is an occasional series in which I try to find the truth about bogus or overhyped health products. Physiologist Steven Swoap is with me at the helm.

If you've been tempted by promotions for "colon hydrotherapy"—that is, sessions in which you would pay someone to put a tube up your rectum and wash out your large intestine with water, like a dirty garage being hosed down in summer—then you've already overcome some impressive mental hurdles. Maybe you're almost ready to enjoy the relaxation, renewed energy, and improved health that the procedure promises. Before you take the plunge, as it were, here are a few points to consider.

It's not the 19th century.
People who offer colon hydrotherapy (also called a colonic) tell you the large intestine is full of "toxic waste and toxins." It does, of course, carry waste out of your body. But is it a two-way street?

"Intestinal autointoxication," the idea that poisons from your feces can move backward from your colon into the rest of your body, is an old one. Old as in ancient Egyptian. The Greeks were into it too, including Hippocrates and Galen.

In the 19th century, doctors prescribed laxative pills and enemas to cure all manner of illnesses. One man created and promoted a popular device called the Cascade. As alternative medicine researcher Edzard Ernst describes it, this was a rubber bottle with a nozzle for a person to insert into his or her rectum. When the person then sat on the bottle, it squirted 5 liters of fluid into up into the colon.

By the 1920s, though, some actual scientific study had been done on the subject. Unlike the Cascade, the theory of intestinal autointoxication did not hold water.

A toilet is not a gym.
"Having colonics is like taking your colon to the gym," declares the website for one colon hydrotherapy center. Filling the colon up with water and emptying it again, the theory goes, "exercises" the intestinal muscle so it can do its job better in the future.

"Injecting water into the colon will cause the colon to swell, and cause so-called 'stretch-activated' contractions of the smooth muscle surrounding the intestine," says Williams College physiologist Steven Swoap. These contractions are called peristalsis. "But the colon does this naturally as food stuffs pass through," he adds. "There is definitely no need to help this along for peristalsis to occur."

Colorectal surgeon Francis Seow-Choen points out in a review paper that since the colon is lined with smooth muscle (a type we can't voluntarily control), it cannot be toned like the muscles you work at the gym. Toned muscles are ones that we've consciously flexed so often, our brains learn to flex them automatically. Sit-ups work; water up the rectum doesn't.

It's rude to firehose your friends.
In addition to waste, your colon houses a large portion of your body's friendly bacteria. These gut microbes manufacture several vitamins we need, and seem to be involved in defending us from dangerous microorganisms and generally keeping us healthy.

One study found that cleaning the colon to prepare patients for a colonoscopy—in this case with a straightforward laxative, not with large volumes of pumped-in fluid as in a colonic—immediately altered the types of bacteria in patients' intestines. Another study found that cleaning out the colon both knocked down the bacterial population there and seemed to make it easier for new, potentially unfriendly bacterial strains to move in.

It might kill you.
"My biggest worry would be perforations caused by the water," Swoap says. "If abrasions or tears in the colon occur, you have the possibility of a dangerous bacterial infection." Ironically, one way to make the material in your colon as dangerous as colonic practitioners claim is to blast it with water. Breaking up the feces and creating tiny tears in the colon can turn a one-way street into a two-way hazard.

According to a paper in the Journal of Family Practice, reported complications from colon cleansing include cramping, abdominal pain, vomiting, rectal perforation, blood poisoning, kidney failure, fatal amoebic infection, and fatal accumulation of gas in the veins. Even if such a consequence is rare, Swoap points out, "it is sure not to happen if I don't let some technician put a hose in my rear."

Everybody poops.

Colons have been doing their job without outside intervention for hundreds of millions of years. "Your colon does not need help in a non-disease state," Swoap says. "Your colon is a pro!" If you want to thank it, step away from the hose and have some broccoli.

Image: Mykl Roventine

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.)

The Shambulance: Zero-Calorie Noodles?

(The Shambulance is an occasional series in which I try to find the truth about overhyped health products. My Shambulance co-captains this week are Steven Swoap and Daniel Lynch, both of Williams College.)

It could almost be a Zen question: What do you call a food with no food in it? In Japan they're called shirataki noodles, and are made from the root of the konjac plant. In the United States they're called "Miracle Noodles" or a "healthier alternative to pasta" and promise "NO calories...NO net carbs...NO GUILT!!!"

The konjac root's contribution to the noodle is straight dietary fiber, in a form called glucomannan. Since the noodles are made of nothing but fiber and water, the idea goes, they'll hurry right through you without leaving any calories behind. This is attractive to American dieters who would like to be able to eat a whole plate of food without actually eating any food. A dinner of pasta topped with marinara sauce becomes a dinner of marinara sauce topped with time on the toilet.

The Chicago-based brand "NoOodles" displays a set of nutrition facts with zeros nearly all the way down, like a perfect report card. However, "Don't be mistaken," says Williams College physiologist Steven Swoap. "These noodles have calories!"

Insoluble fiber, Swoap explains, does pass through our bodies untouched and make up the bulk of our feces. But glucomannan is a soluble fiber. This means it's dissolvable in water; it's also digestible by the bacteria living in our guts. The bacteria break down soluble fiber into products that we absorb as calories. (They also make methane, which, as Swoap points out, "we don't absorb but rather share with our surroundings.")

The key to the zero-calorie claim made by NoOodles might lie in that 1.6-ounce serving size at the top of the label. The FDA permits calories under 5 to be rounded to 0. If each of those dainty servings really has 4 calories, a whole package—which would fill a plate—has about 20. It's hardly a calorie count that will ruin anyone's diet. But zero, in this case, doesn't really mean zero.

Shirataki noodles have a distinctly non-zero amount of offensive odor, as I discovered when I tried some NoOodles for myself. (They're in the refrigerator aisle, which I only mention in case you want to buy your own and also want to avoid having this conversation with two different grocery store clerks: "I'm looking for a product called noodles?")

The product's website describes the smell, caused by the calcium hydroxide, as "a little odd." I would have used different words, like maybe "neglected fish." But the odor rinses away with water. The rectangular shape of the package is harder to dispel.

I followed directions and heated my NoOodles in a dry nonstick pan until all the water had evaporated, though they looked otherwise the same. At this point it's recommended that you cook the NoOodles with some sort of sauce (or eggs or ice cream), but I wanted to try them in their unadulterated form. As promised, they tasted like nothing at all. They had a texture, though, that I was deeply not okay with, like biting through rubber bands. I managed one mouthful followed by a lot of water.

The water is recommended too, because soluble fiber sucks up water in your body. In 2010, Health Canada issued an advisory about the importance of drinking a full glass of water when taking pills or powders containing glucomannan. It also urged consumers not to use glucomannan supplements right before bed, because the stuff can swell up and cause choking or blockages in the intestine while you sleep. The health advisory didn't address shirataki noodles.

The water that NoOodles absorb makes the material passing through your gut especially slippery, so your small intestine can't absorb nutrients (which is to say, calories) as easily. Their website claims this makes the rest of your meal less caloric too, as everything slides through you along with the NoOodles. But Swoap says that experiments have shown this simply isn't true. "The small intestine is still long enough to get all of the calories from your food."

Among several other promises, NoOodles makers also say their product makes you feel fuller, so that "one tends to eat less when NoOodle is part of the meal." It's certainly possible, though it's also possible that one tends to make up those calories at one's next meal, when one is starving because one only ate marinara sauce for dinner. "The key word that gets them off the hook is 'tends,'" Swoap says. "Otherwise the FDA would have a major problem with this."

Not all the claims made about glucomannan noodles are spurious. The product does let dieters eat more food for fewer calories. And some studies have found that glucomannan can lower cholesterol, both in healthy and diabetic subjects.

So is an all-fiber noodle really a "healthier alternative?"

"The 'benefits' are in comparison to refined wheat flour that is used to make breads, pastas, etc. Most everyone acknowledges that is not good in excess," says Daniel Lynch, a biochemist who's also at Williams College. "But moderation is the key." He adds, "You might as well just have a glass of Metamucil or Citracel as a pre-dinner cocktail and then enjoy real food in smaller portions!"

Swoap says, "I don’t think this is necessarily bad for you. I would just prefer to get my fiber with vegetables that also bring along a lot of micronutrients." In other words, if you want to bulk up your meal with a low-calorie fiber source, there are less rubbery and more vitamin-filled ways to do it.

If you're still tempted to try a food-free plate of pasta, go for it. Just remember to drink water.


Arvill A, & Bodin L (1995). Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men. The American journal of clinical nutrition, 61 (3), 585-9 PMID: 7872224

Chen HL, Sheu WH, Tai TS, Liaw YP, & Chen YC (2003). Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects--a randomized double-blind trial. Journal of the American College of Nutrition, 22 (1), 36-42 PMID: 12569112

Thanks to Chris F. for the tip! If you want to summon the Shambulance to the site of an emergency, leave a comment or send me an email at the address above.

Why Successful Leaders Share Their Harems

A male monkey cruising through the grasslands with a harem of females all to himself might seem to have hit the primate jackpot. What simian doesn't want a dozen lady monkeys to bear his long-tailed young and then tote them around? But he's better off sharing the wealth. By letting other males infiltrate his group and mate with his females, the leader lands himself a longer term in office—and more, not fewer, of his own offspring.

The gelada (pronounced not unlike the Italian frozen dessert) is a social animal that lives only in Ethiopia. Males have luxurious hair capes and bright red hourglass shapes on their chests. The lucky ones live in groups called reproductive units that include one "leader" male and up to twelve females. About a third of reproductive units also include one or more "follower" males.

Unattached males, meanwhile, live in bachelor groups that wait for the right moment to attack leader males and try to take over their women.

Attention Marvel: New character concept? Cape is cool but logo needs tweaking.

For females, it doesn't much matter which males they're following around. But for male geladas, society is deeply divided between haves and have-nots. Leader males have mates, and therefore babies. Almost everyone else is stuck waiting their turn to contribute to the gene pool.

Researchers led by Noah Snyder-Mackler at the University of Pennsylvania wanted to investigate gelada society more deeply. Does a leader male sometimes allow follower males to intrude into his group, and mate with his females, only because it's too hard to fight them off? Or does the leader actually gain something from letting his mates have a couple boyfriends on the side?

In a study that will prepare their resumés for future work on daytime talk shows, the team went into the field and did some paternity testing. They collected feces from all the babies born during their three-year study period, as well as the mothers and potential fathers, which gave them enough DNA to find out where all the young monkeys had really come from.

They also closely observed the dynamics of the 21 reproductive units in their study population. When did bachelor groups clash with the males in reproductive units? Were the attacked males leaders or followers, and how effectively did they fight back? For how long did leaders keep control of their groups before being ousted by another monkey?

A gelada reproductive unit.

The researchers found that leader males could be kicked out of their groups at any time; the longer they stayed, the more likely they were to go. The average leader held onto his group for 3 years or so.

While those males were in charge, they kept a tight rein on the females in their groups. Leader males that had a whole reproductive unit to themselves fathered 100 percent of the offspring born. (Impressive, considering gelada groups come together in very large meet-ups—as many as 1100 monkeys at a time—to forage for food. Apparently those conventions are all business.) When follower males were present, all the mating stayed inside the group, but now leaders fathered just 83 percent of the young.

Despite losing out on fatherhood, though, leader males experienced a clear advantage when they let follower males into their groups. Followers helped defend the group against aggressors; units with multiple males were less likely to be taken over by interloping bachelors. Consequently, the leaders of these groups stayed in charge for 30 percent longer than males who had a group all to themselves. Units with more than one male also had greater numbers of females.

Between the extra mates and the longer time in office, leaders who put aside their jealousy and allowed followers into their groups ended up fathering more babies than leaders who flew solo. On average, leaders with followers had 7 babies before getting kicked out of power. Solo leaders had just 4.

Snyder-Mackler writes that systems like the geladas' could help explain how social behavior evolved in mammals in the first place. For the monkeys, playing nice with potential competitors isn't about being friendly—it's a fruitful reproductive strategy. Follower males don't father very many children, but they do better than bachelors. And later, they might become leaders of their own groups.

The system benefits female geladas too: When bachelors take over a group, they may kill the babies that are there already. Living in a group with multiple males gives females a little more security for their infants, since the group isn't as likely to be taken over. Females may even encourage leader males to allow followers. After all, a little mate-sharing is the neighborly thing to do.

Snyder-Mackler N, Alberts SC, & Bergman TJ (2012). Concessions of an alpha male? Cooperative defence and shared reproduction in multi-male primate groups. Proceedings. Biological sciences / The Royal Society PMID: 22764162


Images: Male gelada focusshoot/Flickr; gelada group dave watts/Wikimedia Commons; female gelada mc_bos/Flickr.

Flightless Giant's Flower Diet Revealed by Poop Fossils

If Big Bird had ever invited his weird armless cousin from Down Under to visit Sesame Street, American kids would have met the moa. These flightless birds lived in New Zealand until hungry humans arrived; the last moa species predictably went extinct around 1500. Thanks to fossilized droppings, though, scientists are learning how the hapless giants lived, what they ate, and what holes they left in the ecosystem by vanishing.

Here are some fossil turds. In polite company, you can refer to them as "coprolites."

Researchers led by Jamie Wood of Landcare Research in Canterbury, New Zealand, discovered about a hundred moa coprolites in the entrance to a remote cave. Thanks to the sunlight and breezy air, the desiccated droppings had been well preserved. They picked out 35 choice specimens (above) to take back to the lab.

To turn the rocky clumps into open books, the researchers used every tool they had. They carbon dated the coprolites to find out their ages. They cracked them open and looked for tiny bits of leaves or seeds that had been fossilized inside. They extracted DNA from the coprolites, both belonging to the moas that had left them behind and the plants those birds had eaten. And they dissolved their samples to get out pollen grains, which could be traced to plant species.

There were 11 or so species of moa alive in the past, ranging from hefty to alarmingly large. The biggest were nearly twice the weight of a large ostrich today. However, the DNA sequences inside the coprolites revealed that they all belonged to just one species: the upland moa, Megalapteryx didinus. Jamie Wood says this was one of the smaller moa species, standing about three feet tall (minus the neck and head) and weighing around 80 pounds. "It had sharp claws and was feathered right down to the feet," he adds.

The upland moa was also the last one to go extinct. Carbon dating showed that the most recent fossil droppings were only dropped about 700 years ago. Other coprolites in the cave were closer to 6400 years old. Based on the pollen and moa DNA inside them, the authors think certain clusters of coprolites within their sample came from "a single defecation event." Nearly half their sample might be accounted for by just five birds, using this cave as a latrine at different points in history.

Plant DNA, pollen, and microscopic fossils inside the coprolites revealed what those historic birds had recently eaten. The upland moa wasn't picky: At least 67 types of plants were accounted for in the droppings. Some of the pollen may have blown onto the birds' food from elsewhere. But overall, the upland moa was an indiscriminate herbivore, eating whatever plants were around. In addition to trees, shrubs, and grasses, it likely ate the flowers of flax and fuchsia plants. (These nectar-filled treats are eaten by some living birds as well.)

The pollen and seeds inside the coprolites came from plants that flower in the spring and summer, which let the researchers infer that the birds moved to warmer forests during the winter months. And they squeezed a further bit of information from the stony droppings: Seeds from several plant species had survived intact inside them. This means the birds would have scattered these seeds—possibly to sprout again—wherever they did their business.

Certain regional plant species may have relied on the moas to distribute their seeds in this way. In evolutionary terms, the birds haven't been gone long; the authors point out that some very old trees alive today might have been planted by moas. Dominos tipped by the extinction of the moa may still be falling throughout the New Zealand ecosystem.

Jamie Wood says he and his colleagues still haven't exhausted the information that can be extracted from a fossil turd. In the future, they'd like to use DNA evidence to discover the sex of each dung-depositing moa. "Some moa species had vast size differences between sexes, so we are interested in working out whether the diets and habitat use also varied with the different sexes," he says.

Six-thousand-year-old poop might not have gone over well as a Sesame Street topic, even if Big Bird's extinct cousin had shown up. But for scientists, the fossils are providing an elementary education about a vanished species.

Jamie R. Wood, Janet M. Wilmshurst, Steven J. Wagstaff, Trevor H. Worthy, Nicolas J. Rawlence, & Alan Cooper (2012). High-Resolution Coproecology: Using Coprolites to Reconstruct the Habits and Habitats of New Zealand’s Extinct Upland Moa (Megalapteryx didinus) PLoS ONE : 10.1371/journal.pone.0040025


Images: Upland moa by George Edward Lodge/Wikipedia; coprolites Wood et al.

Human Dung Wins Interspecies Taste Test

A panel of experts in Nebraska has declared human dung more appealing than that of several other species. These experts didn't so much announce their decision as fall headfirst into baited poop traps while looking for a meal. Still, you won't find a more discerning group of judges than nine thousand dung beetles.

The various species of dung beetle that live together in the Great Plains region have evolved to consume, and share peacefully, its turd piles.* Some species are specialists, preferring one animal's feces to any others. Others will eat anything that falls their way. Two entomologists--Sean Whipple at the University of Nebraska, Lincoln, and W. Wyatt Hoback at the University of Nebraska, Kearney--set out to mess with the balance between these dung beetle species.

The researchers set traps all over a large organic cattle ranch. Each trap consisted of a large bucket sunken into the ground with a pile of dung at the bottom. The bait came from 11 different species that included carnivores, herbivores, and omnivores. Some of these dung flavors were ones the beetles might encounter regularly: bison, moose, cougar. Others were "exotic," from animals that don't normally leave their excrement around Nebraska: zebra, lion, human.

(The animal feces came fresh from a local zoo. As for the human specimens? "I will say this much," Sean Whipple said when I asked. "It is difficult to find volunteers for a study such as this.")

Human and chimpanzee feces were the clear winners of the popularity contest. Almost 9,100 dung beetles stumbled into the authors' traps, belonging to 15 different species. The beetles in the human and chimp dung buckets far outnumbered any of the rest.

Different beetle species preferred different types of dung, which explains how they can all share resources normally. But overall, omnivores were a favorite. Pig dung, while not as wildly popular as human or chimpanzee, still attracted a lot of beetles.

Whipple says the scent of omnivore dung is especially alluring. "Previous research has shown that the dung of omnivores is generally more attractive than that of herbivores, likely as a result of odor," he wrote in an email.

Incidentally, if the dung beetles had gotten a chance to eat all that sweet-smelling human dung, it would have been a good choice nutritionally. Chemical analysis showed that the human dung had the highest nitrogen content, a measure of "dung quality," Whipple says.

Herbivore dung wasn't only less popular than omnivore dung. It was also beaten out by carnivore dung. And the most widely ignored droppings came from bison--a species that local dung beetles evolved alongside, and that would have provided much of their diet just a century and a half ago.

Like five-year-olds who are bored with their green beans and would like some dessert already, please, most dung beetle species in this study were eager to switch from their usual plant-based poops to something new and exciting. They're not likely to start encountering a lot of human or chimpanzee feces on their Nebraska ranch. But a non-native animal that's introduced to an area where dung beetles live (and they live all over the world) could upset the balance between its native inhabitants. Beetles might start competing for the exotic food source, for example, or ignoring piles of poop they would ordinarily clean up.

If you're wondering what makes our own species' dung so appealing, the authors say diet doesn't seem to be a factor. Among the zoo animals whose dung they used, all the carnivores were fed the same diet, and so were the herbivores. But the dung beetles preferred some carnivore or herbivore dung to others, suggesting there's more to poop flavor than the food it started out as.

Though the human subjects may have eaten different diets, their specimens were "thoroughly mixed to ensure homogeneity," Whipple says. Now that's appetizing.

Whipple, S., & Hoback, W. (2012). A Comparison of Dung Beetle (Coleoptera: Scarabaeidae) Attraction to Native and Exotic Mammal Dung Environmental Entomology, 41 (2), 238-244 DOI: 10.1603/EN11285


Image: icadrews/Flickr


*Yes, I realize that three out of the last four posts here have involved poop (hyena, penguin, and that eaten by dung beetles). Apparently I'm in a dung rut. At least it's not a dung bucket.

Space Census Finds Extra Penguins, Poop

Playing what might have been the world's most tedious game of Where's Waldo?, scientists used photos taken from space to count all the emperor penguins in Antarctica. They found more than a hundred thousand birds that hadn't been spotted before. The news may affect the penguins' fate in a warming world. Besides, what's a better surprise than extra penguins?

Researchers from several institutions, including the British Antarctic Survey in Cambridge, undertook the emperor penguin space census. They thought previous penguin counts might not be accurate. For one thing, the last estimate of the Antarctic penguin population is almost 20 years old. For another, humans can't easily travel very far from their Antarctic research bases to seek out half-frozen bird huddles. So penguin colonies that are farther out in no man's land might have never been spotted by people.

Thanks to emperor penguins' habit of clumping together in giant colonies during breeding season--and their convenient lack of camouflage against the snow--the researchers knew high-resolution satellite photos should reveal the penguins. They used images from all around Antarctica's coastline, where penguin colonies camp out. Forty-six colonies appeared, including several that hadn't been counted before.

A penguin colony on the Antarctic coastline, spotted from above.

After zooming in on each colony and sharpening the images, the researchers used computers to count the penguins one by one. The challenge was for the computer to decide which dark pixels represent penguins, rather than shadows on the snow--or penguin poop. Author Peter Fretwell explains that in this method, "you 'train' the computer to recognize the pixels that are penguin, guano, snow or shadow by giving it sample pixels. The computer then goes away and splits the whole image into each pixel type."

Zooming in on a penguin colony and sharpening the image. I think I found the guano.

As long as the images have a high enough quality, Fretwell says, this technique is "usually quite accurate." Where the satellite pictures were more shadowy, penguin counts would be a little less certain. For some of the colonies, though, researchers were able to check their numbers against estimates others had made from the ground or from aerial photography.

And then there were the missing penguins. All the satellite images were taken during the breeding season, when emperor penguins congregate to create adorable new baby penguins. The new parents take turns babysitting: While one penguin takes care of the chick, the other goes out to sea and swallows lots of fish to regurgitate later. While the chicks are small, they spend most of their time balancing on top of their parents' feet to keep warm. Once the chicks are old enough to walk around on their own, both parents may leave to forage.

So for every individual counted in a satellite photo, the authors assumed there was a hidden chick and a second adult at sea hunting for food. (They were only interested in counting breeding adults, not the chicks, most of which will die.) Later in the season, some of the penguin pixels may have been kids instead of adults. But since a young penguin standing on the ice probably has two parents away foraging, the researchers figured that pixel still stood for two adult penguins.

The final count was about 595,000 adult emperor penguins in all of Antarctica. That's roughly the (human) population of Milwaukee. It's also substantially higher than the last estimate, which put the population between 270,000 and 350,000 adult birds.

The census could easily have overestimated or underestimated the true number of penguins. But, Peter Fretwell says, "The main thing is that this gives us an initial benchmark from which we can monitor emperor penguin numbers in the long term."

As climate change tightens its grip on every part of the globe--all the way to the poles--penguins will certainly see some changes around them. The sea ice along the coastlines they inhabit will disappear; shifting food webs may make their prey scarcer; and severe storms might become more frequent. Knowing how many emperor penguins are there now, and where to find their colonies, will help scientists monitor how the species is coping with the changes. We might even be able to keep them from becoming harder to find than Waldo.

Fretwell, P., LaRue, M., Morin, P., Kooyman, G., Wienecke, B., Ratcliffe, N., Fox, A., Fleming, A., Porter, C., & Trathan, P. (2012). An Emperor Penguin Population Estimate: The First Global, Synoptic Survey of a Species from Space PLoS ONE, 7 (4) DOI: 10.1371/journal.pone.0033751 


Image: Close-up penguins from Hannes Grobe/AWI/Wikimedia Commons; satellite images from Fretwell et al.


Note for British readers: You may know Waldo as Wally.