Leaping Land Fish Has Perfect Camouflage, Is Not a Hoax

You might never spot them if not for the jumping. On the coast of Guam, Pacific leaping blennies blend in perfectly with the rocks they live on, their limbless bodies maintaining a sleek profile. But the creatures give themselves away when they coil their tails to one side and shoot like a spring from rock to rock. These unsettling animals are fish that live on land. How they pull it off could give us hints about the evolution of our first earthbound ancestors.

Terry Ord, an evolutionary ecologist at the University of New South Wales, calls the Pacific leaping blenny "an extraordinary animal." It lives its adult life out of water, hopping between rocks and breathing through its skin as well as gills. It relies on splashes from waves to stay wet, but it rarely—or never—goes for a swim.

Even though the coast of Guam teems with leaping blennies, Ord says, "we know surprisingly little about this land fish." Ord and his graduate student Courtney Morgans investigated one mysterious feature: the fish's conveniently rock-like coloration. Without being so well camouflaged, could the blennies have ever made their first leap onto land?

Morgans and Ord traveled around the periphery of Guam and visited five different blenny populations. At each site, they took photographs of the fish and their background rocks. (The blennies aren't always stone-colored; during courtship, males darken to a charcoal hue while females fade nearly to white. Both sexes can flash a bright-red fin on their backs that they normally keep hidden. But the researchers kept a close eye on their subjects during the experiment to make sure they didn't change colors.)

Computer analysis of the photos showed that the blennies' normal skin color is a perfect match to the rocks they live on. Some birds use UV light, which the researchers didn't analyze, to find their prey. But for most of the hungry lizards and crabs patrolling Guam, the blennies should blend right in to the rocks.

To find out how well this camouflage really protects leaping blennies, Morgans and Ord set up 70 fake fish as bait. They molded plasticine blenny bodies with realistic coloration and anchored them to spots around the island with fishing line. Some fake blennies sat on the rocks, while others were on the sand, where they don't blend in as well.

After three days, Morgans and Ord returned to their fake fish. If the props were nicked, punctured, or had bites taken out of them, the scientists assumed predators had come by. They saw that predators attacked blennies on the sand much more often than those on the rocks.

So their coloration seems to be crucial to the leaping blennies' survival on shore. The scientists think that in this regard, the fish may have just been lucky. When they compared the Pacific leaping blenny to 12 closely related blenny species, they found that all the relatives have similar coloration. (Some of these relatives also spend time out of water, but the Pacific leaping blenny is the only one to live on land full-time.) If the ancestor to all these species had the same rocky skin color, then it was well prepared to wriggle out of the ocean and start a new life on land.

That doesn't mean the transition was easy. Blennies also had to evolve a way to breathe air through their skin, like frogs do. Their tail-jumping trick is helpful too, letting the legless fish propel themselves through their habitat. "Obviously moving about on land is critical," Ord says. (You can watch them leaping in the video below, from his lab's YouTube channel.)

Ord says this freak-show fish actually has a lot to tell us about evolution. For one thing, it demonstrates the kinds of adaptations an animal can make after it transitions to a new home. It also speaks to our own ancestry. "In the late Devonian, fish made the first transition onto land, and from that event evolved all of the land vertebrates we now have in the world," he says. The land fish represent a "snapshot of one of the most important evolutionary events in our history." Our ancestors may have looked equally ridiculous as they floundered on land—but like the leaping blenny, they were going places.




Image: Courtney Morgans, UNSW

Courtney L. Morgans, & Terry J. Ord (2013). Natural selection in novel environments: predation selects for background matching in the body colour of a land fish. Animal Behaviour DOI: 10.1016/j.anbehav.2013.09.027

What Left-Handed Ultimate Fighters Tell Us (or Not) About Evolution

Don't despair, left-handers who have just smeared the ink across your paper yet again. You have a true purpose in life, some scientists say—and it's walloping other people in the head. A flying elbow drop would work too. Researchers recently pored over video of hundreds of UFC fights to test the idea that lefties evolved with an edge in hand-to-hand combat.

Various other animals show a preference for one paw, or one swimming direction, over the other. But humans are notable for almost always preferring the right side. Only about 10 or 12 percent of us are lefties. Is this because there's a cost to being a left-handed human (aside from the ink thing)? Lefties are smaller in stature, and there's some evidence that they don't live as long. If these effects really add up to a raw evolutionary deal, perhaps the reason there are any lefties is that there's some advantage too.

Enter the so-called fighting hypothesis, which says that lefties have persisted at low numbers because they have the element of surprise in a fight.

In order for this theory to make sense, you have to imagine that sometime after our ancestors came down from the trees but before they built weapons, punching each other became very important to their survival. And that despite our squishy outer coverings, valuable dextrous hands, and vulnerable heads, we are a species built for combat. It's a speculative theory. A recent review paper about the fighting hypothesis—which shared an author with the current paper—called evidence for the idea "not particularly strong."

Nevertheless, a group of researchers in the Netherlands chose to explore the theory using mixed martial arts fighters. The UFC "seemed like a very interesting arena to test this hypothesis," says lead author Thomas Pollet, "pun intended." Pollet is a psychologist at VU University Amsterdam. Since the UFC is "a fierce fighting sport hardly constrained by rules," the authors write, it might be a good representation of humans scrapping in an ancestral state.

Pollet studies handedness but didn't have a particular interest in the Ultimate Fighting Championship when he began the study. To get perspective from a fan, I wrote to my friend Ryan, who happens to love watching MMA fighting. He's also a lefty. "A left-handed fighter will lead with their right foot, jab with their right, and cross with their left," Ryan explained. This is all unexpected to an opponent who mainly fights righties. "The speedy jab will come from the opposite side, and the lefty fighter will naturally circle the ring in the opposite direction as well."

Studying recordings of 210 UFC fights, Pollet found that lefties were significantly more common than in the general population. More than 20 percent of the 246 fighters were left-handed. (You can tell by checking their feet; the back leg corresponds to the dominant hand. "UFC fighters only rarely switch between stances within or between fights unless their lead leg is...severely injured," the authors write.)

To look for a left-handed advantage, Pollet analyzed all the fights between a lefty and a righty. The results were an exact tie. A computer simulation in which the fighters' handedness was randomized led to the same conclusion: left-handers had no advantage over righties.

This alone might not disprove the fighting hypothesis. That's because the UFC represents the cream of the lawless-brawling crop. "A fighter must go through a minor league promotion in their home town before making it to the big stage," Ryan told me. On their way to the professional level, left-handed fighters might have an advantage, which would explain why there are so many of them in the UFC. But once they become more common—and face more opponents who are experienced at fighting lefties—their edge might disappear.

"I think it is a very attractive hypothesis," Pollet says. The advantage of being left-handed in a fight may depend on how many other lefties are around, but "testing frequency dependence can be hard," he says. He's hoping to compare results in the UFC to other competitions that include more amateurs.

Currently, Pollet and his colleagues are working on a meta-analysis of lefties in different sports. In tennis, for example, being left-handed can give players a boost. (My friend Ryan, who just happens to also play tennis, said that being a lefty gave him "a great advantage growing up." A lefty cross-court forehand shot, he explained, forces your right-handed opponent to return the ball with a weaker backhand.)

In addition to the UFC, left-handedness is especially common among badminton players, cricketers, and recent U.S. presidents. Maybe lefties can look to those areas to find their evolutionary reason for being. If they still feel existential angst, they can always go out and punch someone.


Image: by Krajten (via Wikimedia Commons)

Thomas V. Pollet, Gert Stulp, & Ton G.G. Groothuis (2013). Born to win? Testing the fighting hypothesis in realistic fights: left-handedness in the Ultimate Fighting Championship. Animal Behaviour DOI: 10.1016/j.anbehav.2013.07.026

Thanks to Ryan Sponseller for his thoughtful comments on handedness and punching dudes.

The Shambulance: Reflexology and Other Stories

The Shambulance is an occasional series in which I try to find the truth about bogus or overhyped health products. Helping me keep the Shambulance on course are Steven Swoap and Daniel Lynch, both biology professors at Williams College.

Sticking a Q-tip up one’s nose is not the source of many great insights. Yet it’s how an American doctor in the early 20th century developed the theory that became modern reflexology. He would be proud—though maybe a little confused—to see people today flocking to reflexology spas, where practitioners treat all their problems via the soles of their feet.

The American doctor in question was William H. Fitzgerald, an ear, nose and throat specialist. In a 1917 book, he explained the genesis of his big idea:

Six years ago I accidentally discovered that pressure with a cotton tipped probe on the muco-cutinous margin (where the skin joins the mucous membrane) of the nose gave an anesthetic result as though a cocaine solution had been applied . . . Also, that pressure exerted over any bony eminence of the hands, feet or over the joints, produces the same characteristic results in pain relief . . . This led to my ‘mapping out’ these various areas and their associated connections and also to noting the conditions influenced through them. This science I have named "Zone Therapy."

Chapter titles from Zone Therapy include "Zone Therapy for Women" (tongue depressor into the back of the throat for menstrual cramps), "Painless Childbirth" (rubber bands around the toes, among other interventions) and "Curing Lumbago with a Comb."

A nurse and physical therapist named Eunice D. Ingham extended the idea of zone therapy in the 1930s and 1940s, eventually mapping the entire body onto the soles of the feet. She called each important point on the foot a “reflex” because it reflected back to a certain organ or body part. Ingham wrote two books on the subject, now called reflexology: Stories the Feet Can Tell and Stories the Feet Have Told.

Today, the International Institute of Reflexology describes its practice as as “a science which deals with the principle that there are reflex areas in the feet and hands which correspond to all of the glands, organs and parts of the body.” Stimulating these points “can help many health problems in a natural way.” The site insists, “Reflexology…should not be confused with massage.”

There has been some confusion and blending, though, between Western reflexology and traditional Chinese medicine. Ingham and Fitzgerald's idea of "zones" is similar to the Chinese principle of "meridians." In traditional Chinese medicine, meridians are paths that carry qi through the body and connect the acupuncture points. Reflexology groups like to say that Fitzgerald "rediscovered" the science from more ancient roots. They even claim that ancient Egyptians practiced it, based on tomb paintings showing people holding each other's feet.

Whoever thought it up first, the idea that the soles of your feet hold a miniature map of the entire rest of your body defies a scientific explanation.

“The problem is communication,” says physiologist Steven Swoap. “How does the foot talk to the pancreas?”

The foot is full of sensory nerves, Swoap explains. These can detect temperature, pain or position and send that information to the spinal cord. If the signal is something urgent—say, you stepped on a nail—the spinal cord will send a quick command back to the foot (“STOP!”). If the signal from the foot is a non-painful one (“Hey, I’m walking on grass”), it will travel all the way up the spinal cord to the brain.

“But in no instance do those sensory nerves bypass either the spinal cord or the brain and go directly to the liver, or the kidney, or the colon,” Swoap says. This means your foot can’t communicate directly with any other body part except your spinal cord or brain. Whatever stories the feet have told, they’ve had a limited audience.

Daniel Lynch, a biochemist, points out that sex organs are missing from some reflexology maps. “Why aren’t the gonads on there?” he asks. Other maps label a "testes and ovaries" region around the middle of the heel, but there's variation from one chart to the next.

Setting aside the map itself, Lynch says, “Where is the evidence that it actually works?”

The evidence is slimmer than a stiletto heel. In a 2011 review paper, complementary medicine researchers at the Universities of Exeter and Plymouth dug up every scientific study of reflexology they could find. Out of 23 randomized clinical trials, only 8 “suggested positive effects.”

The quality of the studies was “variable,” the authors write, “but, in most cases, it was poor.” Only four studies that found a positive effect used a placebo control—that is, did massaging the feet without regard to “zones” give patients the same symptom relief? In general, studies tended to use small groups of subjects and not to be replicated by other researchers.

Reflexology has been tested on conditions including asthma, premenstrual syndrome, irritable bowel syndrome, multiple sclerosis, and back pain. If reflexology does have a benefit, “The most promising evidence seems to be in the realm of cancer palliation,” or making patients more comfortable, the authors write. Overall, though, they found no convincing evidence that reflexology has power beyond the placebo.

Not that we should thumb our Q-tip-free noses at the placebo effect. The body has an impressive power to make itself feel better based on our expectations. A foot rub from a professional may very well ease a person’s pain. If that professional says anything about zones, though, it’s only a story.


Image: Foot reflexology chart by Stacy Simone (Wikipedia)

Ernst, E., Posadzki, P., & Lee, M. (2011). Reflexology: An update of a systematic review of randomised clinical trials Maturitas, 68 (2), 116-120 DOI: 10.1016/j.maturitas.2010.10.011

The Composer and the Cassowary: An Appreciation of Mistakes

High in a church balcony last weekend, waiting to perform a solo for Palm Sunday and trying not to panic, I thought about cars being hit with hammers. I'm not sure this is the kind of visualization recommended for singers. But sometimes genetics asserts itself.

A college biology professor once told my class that genetic mutation is like whacking a car with a hammer. You will almost never improve your car this way. More often, you'll damage it. If you're lucky the damage will be only superficial: a change in the silent portion of your genome, or maybe a few funny feathers.

The piece my choir was getting ready to sing, Gregorio Allegri's Miserere, has experienced some mutations in its own DNA over the centuries. Allegri composed the piece way back in the early 1600s, and after that it was sung exclusively during Holy Week at the Sistine Chapel. Even though people had to attend a 3 AM service in Rome to hear it, the Miserere became famous. The Vatican, wanting to keep the piece to itself, threatened excommunication for anyone who copied down the score.

As secrets and life forms tend to do, though, the music leaked out. In the late 18th century, a certain precocious teenager with the last name of Mozart spent Holy Week in Rome with his father. After hearing the Miserere at the Sistine Chapel, young Wolfgang sat down and transcribed the whole thing from memory. He returned for a second performance to double-check his work. From there, the score got into the hands of a music historian who published it.

If the music had really been genetic material, Mozart would have been DNA polymerase, a molecular machine that copies DNA. The polymerase molecule grasps a DNA strand and crawls along, letter by letter, building a matching strand as it goes.

Like Mozart, the enzyme is good at what it does. It proofreads. But sometimes it slips up: A single letter of DNA might be swapped for another one. A section of the code might be flipped backward. One or more letters might be inserted or deleted. (Even one letter lost or gained can cause a major change, since the DNA code is read in three-letter words. In English, imagine losing a letter from the sentence "SHE ATE THE RED BUG" and ending up with "SEA TET HER EDB UG." Some words are still there, but the meaning of the sentence is destroyed.)

Even if DNA polymerase is performing well, damage to the genome can come from outside sources such as UV radiation. But a large fraction of your DNA seems to do nothing at all. If a mutation happens here, you won't know the difference. If a slip-up creates a synonymous change in a gene—the code allows for some words to be spelled in multiple ways—you'll also be fine. And if the mutation does something horrible, it will remove you from the gene pool.

Evolution doesn't care much about any of this. It only notices the rare constructive strokes of the hammer, and it only sees them if they happen in the cells that will become your sperm and eggs (called the "germ line"). If you have DNA damage in the skin of your back from too much tanning, you can't pass it on to your children.

Back when Allegri's Miserere was being sung in the Sistine Chapel, the choirs were made up of men and boys. In choirs like mine, women sing the alto and soprano parts. But that's only a superficial mutation; we singers are the flesh of the piece.

The germ line mutation came in the 19th century. Someone who copied the piece apparently made a mistake, shifting a whole repeated section up by a fourth. What started out as a normal soprano solo now rocketed all the way to a high C, a preposterous note that humans are almost never asked to sing.*

Natural selection didn't weed out this mutation. Once the change had happened and been passed to new generations of the musical score, it stayed in place—even after the error was discovered. We continue to sing the mutated piece because, simply, it's awesome this way. Here's a video. You'll know when the boy soprano hits the high C: it's the note you hear through the bones of your spine instead of your ears.

It's not an overstatement to say that what happened to Allegri's music represents the whole history of life on Earth. Every new development has come from a mistake, small or egregious, that was allowed to stick around for one reason or another. Life started as tiny blobs, then whoops—heads! Legs! Oops again—tulips! Uncorrected errors became tree bark, snail shells, lungs, fur, resistance to antibiotics. Inching along mistake by mistake, life forms developed the machinery to make blood, slime, deadly venom, and spider silk.

Some living things have come together so elegantly that they bring an audience to its feet. There are racing cheetahs, swooping owls, orchids that mimic bees. But even the giant, gut-colored flower that stinks like a corpse to attract flies is a success in its family line. The cassowary is a bird that made so many mistakes, it traded the ability to fly for tree-trunk legs and a head with a sail on top. Even the cassowary, though, is doing something right. Errors become the high notes.

Postscript: My choir director turns out to have a son who, at age three, actually took a hammer to the family car while it was in the garage. The car was not improved. 

Images: Top, cassowary from The New Student's Reference Work and Gregorio Allegri, both via Wikimedia Commons. Bottom, cassowary by Peter Nijenhuis via Flickr.

*Plot clarification, in case anybody is worrying about me up there in the loft: this is not the part I sang.

The Evolution of Humans and Lice in 13 Reality TV Titles

Humans and our lice are even closer travel companions than Kourtney and Kim when they took New York. The parasites cling to us more tightly than Paris Hilton's new BFF. They've been such cozy acquaintances of ours, in fact, that the story of human evolution is written into their genes.

That's what Marina Ascunce and other researchers at the University of Florida found when they sampled lice from around the world and compared their DNA. In the chromosomes of these wingless bloodsuckers, they discovered a window on human culture almost as good as a flip through the TV guide.

Fear Factor
"Lice" is a four-letter word that can inspire dread in the hearts of kindergarten teachers, moms and dads, and well-coiffed middle schoolers. An infestation of head lice is usually harmless, if horrifying. Ascunce and her coworkers point out, though, that head lice in the United States, Nepal and Ethiopia have been found carrying disease-causing bacteria.

What Not to Wear
More dangerous than head lice are body or clothing lice, which mostly affect the homeless and people living in refugee camps. These lice can carry at least three kinds of bacteria that are dangerous to humans. Over the past few decades, the authors write, there have been several disease outbreaks tied to body lice—including an outbreak of epidemic typhus (caused by the bacterium Rickettsia prowazekii) in Burundi that sickened more than 45,000 people.

Body and head lice belong to the same species (Pediculus humanus). Yet the two subspecies, like knockoff shows on different TV channels, make up separate populations that don't encounter each other in nature.

The Pickup Artist
The researchers used lice that had been plucked off of humans in 11 locations around the world. Head lice came from a few sites each in the United States, Asia, and Europe, plus Honduras. There were also body lice from Nepal and from a homeless shelter in Canada, for a total of 93 lice.

The Bachelor
Incidentally, head lice infestations usually include more females than males. It's not clear why, but when you have lice, your scalp is like one big rose ceremony.

House Hunters International
By letting them stow away in our hair while our own species migrated around the world, we've created unique geographic populations of lice. The head lice in this study fell into into three distinct groups based on their shared DNA. Asian lice (from Thailand, Nepal and Cambodia) made up one group. Lice from Honduras were another distinct group. Lice in the United States, though, were in the same genetic cluster as those from Europe.

Temptation Island
Louse DNA shows plenty of evidence of inbreeding. This isn't too surprising when you consider that populations reproduce as fast as they can while staying marooned on one person's head (and that new infestations can result from just one egg-bearing female crawling onto a fresh scalp). The most-inbred lice were found in New York.

19 Kids and Counting 

Compared to their highly inbred head cousins, body lice showed a little more diversity. One reason for this, the authors point out, may be that body lice have more young. A female head louse can leave 150 eggs nestled and glued into her host's hair; a female body louse may leave twice that many eggs in the seams and hems of a person's clothing.

MXC: Most Extreme Elimination Challenge
Another factor that has probably contributed to low diversity in lice populations is our ongoing effort to kill them. Head lice infestations have increased around the world, the authors write, in part because the bugs have developed resistance to the insecticides we dump on kids' heads. A dousing with poison may leave behind a few hardy lice, which can then repopulate the whole area. (Biologists call this kind of population narrowing and regrowth a "bottleneck.")

Britain's Worst Celebrity Driver

Actually it has nothing to do with lice, but did you guys know this was a real show?

The Real World: Boston

The American lice sampled by Ascunce and her colleagues (from New York, San Francisco, and Florida) were a genetic match to the European lice (which came from Norway and the United Kingdom). If this pattern holds up across the United States and Europe, it would suggest that the lice Americans carry traveled to the New World along with European colonists. In other words, we have Columbus's lice.

Sarah Palin's Alaska

The genetically distinct lice found in Honduras, though, don't seem to have come over with the pilgrims. The authors think it's possible that the Honduran bugs represent the native American lice. Perhaps they came here on the heads of more ancient humans who crossed into this continent from Asia, traveling across the Bering Strait and down through Alaska long before Europeans arrived.

Wife Swap

An earlier study of louse mitochondrial DNA (genetic material that's only passed through mothers) turned up a distinct genetic group that's present in Europe, Australia, and the New World, but not in Africa. It's possible that this DNA, rather than having come from the lice our most ancient ancestors carried out of Africa, represents lice those humans picked up while hobnobbing with Neanderthals on their way through Eurasia. 

Survivor: Heroes vs. Villains

The story of our conflict with lice is a classic one. As long as the insects keep developing resistance to our poisons and fighting back when we try to kill them, this series isn't likely to ever get canceled.


Ascunce, M., Toups, M., Kassu, G., Fane, J., Scholl, K., & Reed, D. (2013). Nuclear Genetic Diversity in Human Lice (Pediculus humanus) Reveals Continental Differences and High Inbreeding among Worldwide Populations PLoS ONE, 8 (2) DOI: 10.1371/journal.pone.0057619

Image: Gilles San Martin (via Wikimedia Commons)

This post has been submitted to the 2013 blog contest held by the National Evolutionary Synthesis Center (NESCent).

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

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.

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

The Hazards of Being an Athletic Ape

This post first appeared at the Scientific American Guest Blog and is republished with permission.

With a single bad step as he ran untouched across a field this September, one of the best cornerbacks in the National Football League removed himself from the game for a whole season. New York Jets fans who saw Darrelle Revis’s left knee buckle under him that day may have pled with their televisions: not the ACL. But it was too late for Revis and his anterior cruciate ligament, which will undergo surgery this week.

Football fans are all too familiar with the ways in which a knee or ankle can fail a person. But athletes, like other humans, are simply doing the best that an ape running around on two legs can.

Before we lived and walked on the ground, our ancestors inhabited the tree branches. They didn’t look quite like chimpanzees or any other modern animal, but they were large apes built for climbing. They had big, grasping toes and extremely flexible feet and ankles. “These things were just brilliantly adapted for living in the trees,” says Boston University anthropologist Jeremy DeSilva. He studies the evolution of ape and human locomotion by looking at both ancient fossils and modern-day animals in motion.

When our ancestors descended from the trees and began walking upright, they faced some major mechanical challenges. “Being on two limbs is just a real problem,” DeSilva says. “If you were taking shop class and your assignment was to build a chair, and you built a chair with two legs, you’d fail the class because it would fall over all the time.” Simply balancing an animal upright is a feat of evolutionary engineering—and that’s before the animal starts moving around.

To walk on two limbs, our ancestors had to make several modifications to the feet they’d inherited from tree-climbing apes. Flexible, grasping appendages with 26 individual bones had to become stable surfaces that we could push off of with each step. “We’ve stiffened things up by patching these bones together with a bunch of ligaments that make up the arch,” DeSilva says. And muscles that were once used for grasping branches now support the foot’s arch. “But boy,” he says, “these are just a bunch of band-aids.”

Though these new two-legged bodies worked well enough to keep our lineage alive, bipedalism may not be the best idea evolution has ever had. “If you look across the animal world,” DeSilva says, “good ways of moving evolved multiple times.” Flight, for example, has evolved many times. So has a streamlined body in swimming animals. But striding on two legs evolved just once in mammals.

The only other animals that walk like we do are birds. And with a couple hundred million years to work on the problem, rather than the mere 5 million or so that we’ve had, birds have come up with what DeSilva thinks is a tidy solution: they’ve fused several bones together to create rigid, immobile feet.

In humans, DeSilva says, “I find the foot to be incredibly problematic.” He thinks a lifetime of walking and running on feet held together by evolutionary band-aids is bound to lead to the kinds of problems people frequently experience: plantar fasciitis, collapsed arches, shin splints, Achilles pain.

What’s more, DeSilva says, “We have evidence that these things are not just modern problems.” In the ancient hominins whose fossils he studies, there are many who suffered from the same injuries that plague us. There are broken ankles in individuals 1.9 and 3.4 million years old (both healed). There’s osteoarthritis in a creature that may have been Homo habilis. An Australopithecus has what looks like a compression fracture in its heel. Another individual sustained, and healed from, a severe high ankle sprain 1.8 million years ago.

Modern-day humans know a thing or two about twisted ankles. The most commonly sprained ligament in the whole human body is a tiny one in the ankle called the anterior talofibular ligament. What’s notable about this ligament, DeSilva says, is that almost none of our living ape relatives has it.

DeSilva’s opinion is that humans evolved this ligament to keep the ankle stable. An upright human is like a balanced stack of blocks, he says. Our ankle bones have flattened surfaces that sit on top of each other, unlike the curved and snugly fitted ankle bones of a chimp. When a human steps on an unexpected rock, this extra ligament in the ankle might be necessary to keep the whole stack of blocks from slipping off its foundation. We don’t dislocate a foot entirely when we trip on a curb—but we might be benched for a couple of months.

Like our ankles, our knees have wide, flattened surfaces that spread out the weight we’re carrying on two limbs instead of four. And they’re large, compared to our body size. “The whole bed-of-nails idea is at work here,” DeSilva says. “Human joints tend to be very puffy.” Structurally, though, our knees are similar to those of our climbing relatives; they have all the same components that a modern chimp’s knee does.

But chimps don’t ever land funny after a layup shot, or change direction too sharply while cutting upfield. That kind of sudden sideways motion is the knee’s downfall, and can rip or snap the ligaments that stabilize the joint.

The infamous ACL sits inside the front of the knee joint, holding the thigh bone in place on top of the shin bone. Its counterpart at the back of the knee is the posterior cruciate ligament. The MCL and LCL, or medial and lateral collateral ligaments, cradle the knee joint on either side and are especially vulnerable to sideways jarring. Too much twisting in the knee can tear the menisci, pads of cartilage tucked inside the knee socket.

Our knees have no problem with the normal folding and straightening of our legs. “When you go too far out of range in the other directions, that’s when you get in trouble,” says Irene Davis.

Davis is a physical therapist and biomechanics researcher at the Spaulding National Running Center at Harvard University Medical School. Despite how often we suffer injuries, Davis says, “I think we’re designed really well for both walking and running.”

Davis cites the theory, promoted by Harvard anthropologist Daniel Lieberman and others, that early humans evolved as so-called persistence hunters. Before they developed effective spears, the theory goes, our ancestors obtained meat by separating an animal from its herd and simply chasing it on foot until it couldn’t run any farther. Researchers point to various skeletal features and cooling mechanisms—and the fact that some people seem to enjoy it so much—as evidence that our species is built for long-distance running.

Of course, early humans would have done it without Reeboks on. In the clinic, Davis advocates what she calls a more natural style of running. She teaches people to land gently on the front of their foot with each step, as barefoot runners do, rather than hard on their heels as people with cushioned running shoes tend to.

Davis believes that wearing structured, arch-supporting shoes makes feet weak and lazy, and that this weakness leads to common foot injuries such as plantar fasciitis. Yet feet are largely ignored until they give us trouble. “You don’t see people at the gym strengthening their feet,” she says, but you should. “Strong feet are healthy feet.”

Despite what DeSilva sees as evolutionary patchwork, Davis thinks the human foot is “just a fantastic structure.” Each time the foot hits the ground, it must be both flexible enough to absorb shock and adjust to uneven terrain and rigid enough to push off of again. Davis thinks the problems come when we don’t use our feet and legs as evolution intended.

When treating patients with overuse injuries, Davis teaches them to run with better mechanics so they avoid getting the same injury in the future. Runners receive feedback on their motion from tools such as accelerometers or mirrors, then practice carrying their bodies in better alignment.

Davis says people can also be taught to prevent future acute injuries such as ACL tears. Most ACL injuries are non-contact; as Darrelle Revis knows, one awkward step is all it takes. So there are programs that teach athletes to land their jumps more gently, or aim to strengthen stabilizing muscles around the knee to protect its ligaments. Though some people will still choose to put themselves in the paths of linebackers, they can at least learn ways to run and jump that put less strain on their vulnerable ligaments to start with.

Having recovered from recent injuries of his own, Jeremy DeSilva will be lacing up his minimalist Nike Free sneakers to run a marathon this weekend. Influenced by the research on barefoot running, he’s left cushioned sneakers behind and is now propelling himself more like his Australopithecus subjects did. “I guess I take my work home with me,” he says.

Davis runs completely barefoot, though in the winter or when she needs more protection for her feet she’ll wear a minimal covering such as water shoes. She also rollerblades.

One sport Davis doesn’t enjoy is football. “I don’t like watching the injuries,” she says. “I see a big pile of people with someone underneath it and it just drives me crazy.”


Image credit: Cpl. Michelle M. Dickson

Close Look at Bison DNA Reveals Our Dirty Fingerprints

We really owe the American bison an apology. But where do you buy a card that says, "Sorry we wiped out nearly your entire species, then muddied your DNA by forcing you to mate with cows"? Would flowers be better?

In the 19th century Americans slaughtered bison (also referred to as buffaloes) with impunity. We killed them to sell their skins, to get them out of the way of our new trains, and to make life harder for Native Americans. It wasn't a shining moment. By the end of the 1800s the bison were nearly gone, reduced to perhaps as few as 100 animals in several small herds.

Even as Americans worked to restore bison in the early 20th century, we botched their genetics by breeding the animals with domestic cattle. Breeders wanted to make their cattle beefier and hardier. But the crossing wasn't easy, since the two species are separated by 1 to 2 million years of evolution. In addition to the question of genetic incompatibility, there was one of attraction: female bison refused to mate with male cattle.

James Derr, a professor in the veterinary college at Texas A&M University, explains that the hopeful breeders could only get male bison to mate with female cattle. And their offspring were all female; the species' mismatched genes apparently couldn't create a surviving male. These female hybrids were mated with more male bison. The result was a population of cattle-bison hybrids whose mitochondrial DNA—a little loop of genetic material passed solely through mothers—was 100% cattle.

In today's restored population, many bison still carry cattle mitochondrial DNA left over from the two species' historical tryst. To find out whether that genetic souvenir has any effect on today's animals, James Derr led a study of bison living in the wild and on a feedlot.

The herd of wild bison Derr studied live on Santa Catalina Island, off the southern coast of California, where they were introduced in 1924 for the filming of a silent movie. (Oops, better add that to the card.)  Looking at their DNA, Derr found that almost half the bison carried mitochondrial DNA from cattle.

The second bison population in the study was a group living on a feedlot in Montana, preparing to become products such as bison burgers. (On second thought, maybe a card won't cut it.) In these animals, cattle mitochondrial DNA was much rarer, at 6 percent.

By comparing the animals from the two populations, Derr could look for the effects of cattle mitochondrial DNA in both a wild population with limited resources and a well-fed ranch population. The feedlot bison were clearly beefier; at age 2 the feedlot males had reached a size that the island bison wouldn't attain until they were 17 years old.

Despite the two very different body types in the study, cattle genes had a clear effect across populations. Derr reports in Conservation Biology that bison with cattle mitochondrial DNA were slightly but significantly smaller than bison with mitochondrial DNA from their own species.

Bison that are smaller because of their domestic cattle DNA might be at a disadvantage. Derr says it's not clear yet whether this is the case—smaller size might have no effect on the fitness of bison, or it might even help them in places with limited resources like Santa Catalina Island. He plans to answer that question in a separate study.

If it turns out that having mitochondrial DNA from cattle hurts bison, the next question will be whether conservationists should try to weed these genes out of the population. Overall, Derr says, about 6 percent of bison carry cattle mitochondrial DNA, though in individual herds that number can range from 0 to 100 percent. It may be that by restoring the bison's genome to what it once was, we can start to make amends.


Derr JN, Hedrick PW, Halbert ND, Plough L, Dobson LK, King J, Duncan C, Hunter DL, Cohen ND, & Hedgecock D (2012). Phenotypic Effects of Cattle Mitochondrial DNA in American Bison. Conservation biology : the journal of the Society for Conservation Biology PMID: 22862781

Image: Michael Lusk/Flickr

Enjoy Wine? Thank a Wasp

Where would we be without yeast? Sober, for one thing. And stuck assembling our sandwiches between two crackers. Humans have relied on the hardworking microorganism for millennia to keep us fed and festive. Without realizing it, we may also have been relying on yeast's insect helpers: wasps that escort it around, store it during winter, and regurgitate it up for the next generation.

Yeast—avert your eyes now if you're squeamish about fungus—is a fungus. Just by going about its regular business, it makes our wines and beers alcoholic and our bread puffy. We use strains of the species Saccharomyces cerevisiae for most of these tasks, though there are many hundreds of other species in the world. And we've been doing it since ancient times: The DNA of S. cerevisiae used for winemaking has turned up in Chinese pots more than 7,000 years old.

The yeast strains we bake and brew with live all over the world. These days we produce them commercially, but they also appear in the wild. Yeast lives on the surface of ripe grapes, for example, where it can be used in the winemaking process. One of many unanswered questions about the history of our relationship with yeast is how it gets there, or anywhere else.


S. cerevisiae can't float through the air; it needs to be carried from place to place. So how have our favorite strains spread all over the world, even to places where humans don't take them? How does yeast appear among the grape vines just in time for the harvest each year?

Researchers led by Irene Stefanini and Leonardo Dapporto at the University of Florence suspected that wasps might hold an answer. Social wasps (the kinds that live together in colonies) are known for feeding on grapes. Additionally, the scientists had a hunch about how wasps might usher yeast from one year into the next, despite the brief lifespans they share with other insects.

From sites around Italy, the researchers gathered 61 wasps that included species of paper wasps (Polistes) and European hornets (Vespa crabro). Then they dissected their stomachs in search of yeast. Hundreds of varieties turned up, including 17 strains of S. cerevisiae. When they checked some honeybee stomachs for comparison, they found no S. cerevisiae strains. Wasps were the right track.

Unlike the other yeast species inside wasps, which tended to vary depending on the season the wasps were collected (and therefore what they were eating), S. cerevisiae remained at a steady level throughout the spring, summer, and fall. This supported the researchers' idea that wasps have a special relationship with S. cerevisiae, and showed that wasps could be responsible for spreading the yeast onto ripe grapes.

But they still had to demonstrate that wasps could account for the whereabouts of the yeast year-round, including in the winter. For this, they looked to certain celebrity females in the wasp world.

Each fall, as temperatures drop, most of the wasps in a colony die off. They leave behind young females that were fertilized during the mating season. These survivors hunker down to hibernate during winter. When it warms up again, the females emerge to start new nests. After these "foundresses" lay enough of their own fertilized eggs to create an entire new wasp colony, they die off too.

The researchers thought that foundress wasps might be the key: By feeding their larvae regurgitated meals, they could pass on the S. cerevisiae they've harbored in their guts all winter, completing the annual cycle and allowing new wasps to one day spread that yeast back to ripe grapes. They tested this idea by feeding young female wasps yeast that had been tagged with a fluorescent protein.

When those females were cut open after their winter hibernation, the fluorescent yeast was still in their guts. And when females were allowed to found new colonies, the tagged yeast appeared in the guts of their new larvae too. Although the larvae hadn't gone into the world to feed yet, regurgitated food from their mothers' gut had seeded new yeast collections in their bellies.

Just because wasps are a carrier for humans' preferred yeast strains doesn't mean they're the only carrier, the authors point out. Yeast might hide out in other homes during the winter. But social wasps certainly seem to be a close friend to S. cerevisiae. Looking at the genes of yeast found in wasp guts, the researchers found a menagerie that included wine, bread, and beer strains. It seems wasps have helped yeast maintain a diverse population around the world, and ensured that humans are never too far from our favorite microscopic fungus.

Irene Stefanini, Leonardo Dapporto, Jean-Luc Legras, Antonio Calabretta, Monica Di Paola, Carlotta De Filippo, Roberto Viola, Paolo Capretti, Mario Polsinelli, Stefano Turillazzi, & Duccio Cavalieri (2012). Role of social wasps in Saccharomyces cerevisiae
ecology and evolution. PNAS


Image: Thomas Quine/Flickr

Inner Ears Reveal Speed of Early Primates

It's 20 million years ago in the forests of Argentina, and Homunculus patagonicus is on the move. The monkey travels quickly, swinging between tree branches as it goes. Scientists have a good idea of how Homunculus got around thanks to a new fossil analysis of its ear canals and those of 15 other ancient primates. These previously hidden passages reveal some surprises about the locomotion of extinct primates—including hints that our own ancestors spent their lives moving at a higher velocity than today's apes.

Wherever skeletons of ancient primates exist, anthropologists have minutely analyzed arm, leg, and foot bones to learn about the animals' locomotion. Some of these primates seem to have bodies built for leaping. Others look like they moved more deliberately. But in species such as H. patagonicus, there's hardly anything to go on aside from skulls.

That's where the inner ear canals come in. "The semicircular canals function essentially as angular accelerometers for the head," helping an animal keep its balance while its head jerks around, says Timothy Ryan, an anthropologist at Pennsylvania State University, University Park. In the new study, he and colleagues used computed tomography scans to peer inside the skulls of 16 extinct primates, spanning 35 million years of evolution, and reconstruct the architecture of their inner ears.

Also called the bony labyrinth, the area in question is a set of three twisting cavities, one oriented along each axis of the body. The sloshing of fluid inside the canals provides information for an animal's system of balance. An earlier study of living and recently extinct mammals showed that more agile or acrobatic animals have bigger semicircular canals relative to their body size. A sedentary sloth, for example, has small and insensitive canals. A gibbon needs larger, more sensitive canals to keep its head and gaze stabilized while it trapezes through the tree branches.

When the researchers scanned the extinct animals' bony labyrinths, some unexpected results emerged. One came from the species Apidium phiomense. Found fossilized in Egypt, this is one of the earliest anthropoids (a group that includes monkeys, apes, and humans). Apidium's skeleton suggests a creature adapted for leaping. Inside its skull, though, were the smaller canals of a less agile animal. "That was definitely a surprise," Ryan says. Given the previous research in living species, mismatches between an animal's locomotive style and its canal size should be uncommon. Apidium may have been slower than we thought, Ryan notes, or its inner ear may have lagged behind while its skeleton evolved rapidly for agility.

Another twist came from a species of Proconsul, "the best-known early ape," Ryan says. From its extensively studied skeletal fossils, "It was considered to be kind of a slow, cautious quadruped in the trees," Ryan says. The ear canals of Proconsul heseloni were larger than expected, suggesting a more agile animal. "Now we believe that it's probably more like a macaque," Ryan says, a primate that moves at a modest pace but is able to leap and clamber at times.

The findings, published last month in the Proceedings of the Royal Society B, "suggest that the basal ape, that first common ancestor of apes and humans, was faster than we would have thought," Ryan says. The slower locomotion of today's gorillas and humans, rather than being inherent to apes, may have evolved later on.

"This is really valuable because it gives us another source of data to say what an extinct organism might have been doing," says Laura MacLatchy, an anthropologist at the University of Michigan, Ann Arbor, who was not involved in the research. She points out, however, that P. heseloni is on the smaller side of the four or five species of Proconsul. The larger species may have moved more slowly. Rather than representing how the original apes moved, P. heseloni might simply be a more agile member of a diverse genus.

Researchers will need to delve deeper into the fossil evidence to resolve the apparent mismatches between the inner ear and skeleton, as in Apidium. Ryan says that further studies in living primates, too, will help clarify the relationship between an animal's semicircular canals and its style of movement. Eventually, we may be able to put more of our long-fossilized relatives back into motion.

This piece was first published on June 22 at ScienceNOW.


Image: Timothy Ryan/Pennsylvania State University

Ryan TM, Silcox MT, Walker A, Mao X, Begun DR, Benefit BR, Gingerich PD, Köhler M, Kordos L, McCrossin ML, Moyà-Solà S, Sanders WJ, Seiffert ER, Simons E, Zalmout IS, & Spoor F (2012). Evolution of locomotion in Anthropoidea: the semicircular canal evidence. Proceedings. Biological sciences / The Royal Society PMID: 22696520

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.

Dinosaur Age Not Dramatic Enough? Add Fire

As if a world dominated by hungry, house-sized lizards weren't sufficiently exciting, scientists have added another set piece to our image of the Cretaceous: raging wildfires.

The Cretaceous period, which ended about 65 million years ago with the extinction of the dinosaurs, was hot. That's thanks to volcanos that pumped carbon dioxide into the atmosphere and created a greenhouse effect. Researchers from London and Chicago now say it was also a "high-fire" world. Frequent blazes may have kept animals on the run, created some of the fossil beds we study today, and helped determine which plant species survived into the next era.

Led by graduate student Sarah Brown from the Royal Holloway University of London, the researchers tracked the appearance of charcoal in ancient sediments. Like a set of sooty footprints right through the fossil record, the charcoal evidence showed when and where fires had occurred.

The team saw that wildfires had increased during the Cretaceous period. These fires were probably sparked by lightning, and their flames were fanned by the high concentration of oxygen in the ancient atmosphere. Today, oxygen makes up about 21% of our air. But during the Cretaceous, it may have risen as high as 25% or more.

This high oxygen content, the authors say, would have allowed plants to burn without being bone dry. A spark in a green forest, instead of dying out as it would today, might become a full-blown fire.

Brown and her coauthors did not find any evidence that these fires contributed to killing off the dinosaurs. But they note that after a fire burns through a piece land, erosion is likely. There may be rapid flooding or mudslides. In the Cretaceous, these events might have trapped and killed dinosaurs and other animal life--and helped preserve their bones.

The authors point to certain fossil beds that lie in floodplains and contain charcoal, as well as plant and animal remains. These could be sites where wildfires triggered flooding, conveniently sweeping lots of informative fossils into one place for future scientists to find.

Charred plant remains in these fossil beds provide another clue about the effect of fire. As the Cretaceous went on, the types of plants being fossilized gradually changed. Flowering plants, called angiosperms, became more and more common. Gymnosperms--the more ancient, flowerless species such as cone-bearing trees, cycads, and ginkgos--faded into the background.

A charred flower fossil from the Late Cretaceous.

Frequent fires may have given an added edge to the angiosperms. The new types of plumbing these plants had invented let them grow faster and more efficiently. Rather than trees, the flowering plants growing during the Cretaceous seem to have been weedy and shrubby types. After a fire, they could regrow faster than the gymnosperms. And their new growth provided fresh fuel for wildfires, creating a cycle that encouraged the growth of flowering plants and left older models in the dust.

Though fire didn't do in the dinosaurs, then, it may have helped set the stage for the dominant plants of the modern age. (As if we needed any more drama.)

Brown, S., Scott, A., Glasspool, I., & Collinson, M. (2012). Cretaceous wildfires and their impact on the Earth system Cretaceous Research DOI: 10.1016/j.cretres.2012.02.008


Images: Gorgosaurus from Nobu Tamura/Wikimedia Commons; flower fossil from Brown et al.