COLUMBIA, Mo. — Human babies born via cesarean section miss out on an opportunity to pick up beneficial microbes that other babies get when they take a trip through mom’s vagina. And even though the scientific jury’s still out on whether this is a good idea, some parents have been wiping their C-section babies down with vaginal fluid in the hopes that their newborns might get some of those microbial benefits, Laura Sanders reported earlier this yearover at the Growth Curve blog.

Microbial transfer from mom to offspring happens in a lot of species, but researchers are more familiar with how species that give live birth do this than those that lay eggs, biologist Stacey Weiss of the University of Puget Sound in Tacoma, Wash., noted August 1 at the 53rd Annual Conference of the Animal Behavior Society. Researchers have found that moms can transfer microbes right into the egg itself before it is laid or onto or near the egg after laying.

But Weiss thinks that such microbial transfer might happen through another route — as eggs travel through a female animal’s cloaca. (The cloaca is a combination of genital tract and end of the digestive system found in many invertebrates and most vertebrates, except most mammals.) She and her colleagues have been studying whether striped plateau lizard moms transfer microbes that protect their eggs from pathogens.

“Pathogenic infection is one of the leading causes of egg mortality,” she said. And some studies have proposed that microbes might be able to protect against those infections. None have yet proposed that the source of the microbes could be the cloaca, but this might be a common source since “all vertebrate eggs go through cloacas, and all cloacas have microbes,” she said.

Weiss latched onto the idea that microbes from the cloaca might be important after noticing that when she obtained eggs through dissection, they tended to have a lower survival rate than eggs that were laid. The dissected eggs often succumbed to fungal infections, while the laid eggs did not.

She and her team started by comparing the microbiomes of male and female lizards’ cloacas. “Females are different than males,” she said. Males had more diverse microbial communities in their cloacas. Females were missing whole categories of microbes found in males and had one type that is known to have antifungal activity.

The researchers then compared the microbiomes of eggs that were laid with those that had been dissected out. The team is still waiting on the results of DNA tests that will tell them exactly what kinds of microbes are found on the eggs, but initial results showed that the laid eggs are more likely to have any bacteria at all. “There’s something about going through the cloaca that is increasing bacterial load on these eggshells,” Weiss said. Fungi, though, showed up only on eggs that had been obtained through dissection.
Weiss, her colleagues and some high school students then performed tests in which fungus was applied directly to eggs. They found that laid eggs were able to inhibit fungal growth while dissected eggs were not. So it appears that the mom’s cloaca microbiome may indeed be providing some protection for her offspring.

Weiss said that these results, while still preliminary, may help expand what parental protection of offspring means. In species without direct parental care, transfer of microbes might be an important way that moms and dads help to keep their offspring safe.

Going for walks, playing fetch and now participating in genetic research are just a few things people and their dogs can do together.

Darwin’s Dogs, a citizen science project headquartered at the University of Massachusetts Medical School in Worcester, is looking for good — and bad — dogs to donate DNA. The project aims to uncover genes that govern behavior, including those involved in mental illness in both people and pets.

Looking to dogs for clues about mental illness isn’t as strange as it may seem. Certain breeds are plagued by some of the same diseases and mental health issues that afflict people. Researchers have learned about the genetics of narcolepsy and obsessive compulsive disorder, as well as cancer, blindness and many other ailments from studying purebred dogs. Studies of purebreds are mainly useful when the problem is caused by mutations in a single gene. But most behaviors are the product of interactions between many genes and the environment. A search for those genes can’t be done with a small number of genetically similar dogs. So, Darwin’s Dogs hopes to gather data on a large number of canines, including many breeds and genetically diverse mutts.
Finding behavior-related genes, such as ones that lead dogs to chew up shoes or engage in marathon fetch sessions, may give clues to genes that affect human behavior. “It seemed to me that if we could understand how [changes in DNA] make a dog so excited about chasing a ball, we could learn something about how our brains work and what goes wrong in psychiatric disease,” says project leader Elinor Karlsson.

Karlsson and colleagues launched darwinsdogs.org, inviting people to answer questions about their dogs’ behavior and share their pets’ DNA. More than 7,000 dog owners have already signed up, and the researchers are still recruiting new volunteers.

The process is simple and can be done alone with your dog, or even as a family activity. First, take an online quiz about your canine companion. The quiz is divided into multiple sections. Some sections gather basic information about your dog’s appearance, exercise and eating habits; others ask about simple behaviors, such as whether your dog crosses its front paws when lying down or tilts its head. (Some questions are philosophical puzzles like whether your dog knows it is a dog.) Each question has a comment box in case you want to explain an answer. Plan to spend at least half an hour completing the questionnaire.

Once the questions are answered and the dog is registered, researchers send you a DNA sampling kit that comes with written instructions and an easy-to-follow picture guide. The kit contains a large sterile cotton swab for collecting DNA from your dog’s mouth. (It’s an easy procedure for the human involved, and Sally, the 14-year-old Irish setter “volunteer” Science News sampled, was rather stoic.) Also included is a tape measure for recording your dog’s height, length, nose and collar size. When you’re done, just seal the sample, measurement sheet and consent form inside the return mailer and drop it in a mailbox.

Dog owners don’t need to pay a fee to participate, but they do need patience, Karlsson says. It takes time to analyze DNA, and the researchers can’t say exactly how long it will be before owners (and Science News) learn their dogs’ results. These results will include the dog’s raw genetic data as well as information about the dog’s possible ancestry. Knowing ancestry or particular mutations a dog carries may help veterinarians personalize a dog’s care.
Dog trainers are being enlisted to give owners feedback on their dogs’ personalities and to suggest activities the dogs may enjoy. Karlsson hopes to create a way for impatient owners who are willing to donate money to the project to get their reports back faster.

As of today, antibacterial soaps have a short shelf life. The U.S. Food and Drug Administration has banned soap products containing 19 active ingredients, including the notorious chemical triclosan, marketed as antiseptics.

While the term “antibacterial” suggests to consumers that such soaps prevent the spread of germs, evidence suggests otherwise. After asking companies to submit data on the safety and efficacy of their products back in 2013, the FDA noted in its September 2 final ruling that manufacturers failed to prove that these products were safe to use every day or that they were more effective than plain old soap and water at cutting infectious microbes.

“In fact, some data suggests that antibacterial ingredients may do more harm than good over the long-term,” Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, said in a statement.

Triclosan, in particular, has a pretty bad rap. Found in many household products, the chemical ends up everywhere from vegetables to our snot. It’s been associated with exposure to toxic compounds, risk of staph infections and mucking up sewage treatment. Over a decade of damning data had already prompted some companies to remove triclosan from their products. Others will have a year to remove it and other newly banned ingredients from their recipes.

The FDA ban does not include antibacterial hand sanitizers, which the agency is evaluating separately. In the meantime, the FDA recommends using hand sanitizers that are at least 60 percent alcohol, or washing with old-school soap and water.

Live long and prosper
In Science News’ special report on a­ging (SN: 7/23/16, p. 16), writers Laura Sanders, Tina Hesman Saey and Susan Milius explored the latest research — from the evolution of aging in the animal kingdom to scientists’ quest to delay the process in humans’ bodies and minds.

“I would very much like to know how research into aging may benefit people who are middle-aged or elderly now?” asked leftysrule200 in a Reddit Ask Me Anything about the special report. “Is there any research that can result in treatments in the very near future, or are the real-world applications only going to be visible in the distant future?”
Middle-aged and elderly people will be the first to benefit from aging research, Saey says. “A clinical trial using the diabetes drug metformin as an antiaging therapy will begin soon. That drug will be tested on healthy people aged 60 and older,” she says.

Sanders cautions that most antiaging treatments are still a long way off. But various studies in rodents and humans provide potential clues to aging’s secrets. Blood from young rats, for instance, has been shown to rejuvenate the bodies and brains of old rats. Based on those findings, a clinical study in humans is now under way that is looking at the effects of plasma from young donors on the brains of people with Alzheimer’s. “If scientists could pinpoint the compounds that give young blood its power, then they could presumably develop drugs that mimic that process,” Sanders says.
In the meantime, people may be able to slow the effects of aging by leading a healthy lifestyle. Sanders points to a long-term study of middle-aged women in Australia. Women who were more physically active had sharper memories 20 years later, the researchers found. Until proven antiaging treatments are available, “it seems that keeping the body physically active and strong is one of the best ways to keep your brain sharp as you age,” she says.
Dino spills its guts
Tiny tracks discovered in the blackened stomach contents of a 77-million-year-old duck-billed dinosaur fossil suggest gut parasites infected dinosaurs, Meghan Rosen reported in “Parasites wormed way into dino’s gut” (SN: 7/23/16, p. 14).

Online reader Jim Stangle Dvm thought the worms may not have been parasites at all. “It is more likely that the tunnels were formed by a scavenger worm [after the dino had died]. Still I think the findings are way cool!” he wrote.

It’s hard to say definitively whether the burrows were made by parasites or not, says paleontologist Justin Tweet. Scavenger worms could have tunneled through the gut after the dino’s death, but his team found only one type of worm burrow “which suggests that either only one kind of scavenger had access to the carcass,” or “that these burrows were an inside job,” Tweet says.

That’s no moon!
A recently discovered asteroid appears to orbit Earth, but that’s just an illusion. The asteroid orbits the sun, but its constant proximity to Earth makes it the planet’s only known quasisatellite, Christopher Crockett reported in “Say What? Quasi­satellite” (SN: 7/23/16, p. 5).

Reader Mike Lieber wondered if the moon could also be a quasisatellite. “The gravitational attraction of the sun on the moon is twice that of the Earth,” he wrote. “It seems that the apparent looping of the moon around the Earth is also illusory.”

The moon is a true satellite, Crockett says. If the sun were to dis­appear, the moon would continue orbiting Earth. “The moon is within Earth’s ‘Hill sphere,’ the volume of space in which Earth’s gravity is the dominant influence,” he says. “The strength of the gravitational force isn’t as important as by how much it changes from one place to another.” Given the moon’s proximity to our planet, Earth prevails. “The moon orbits Earth and the Earth-moon s­ystem orbits the sun,” he says.

Your summer suntan is almost entirely locally sourced. But a smidgen of that healthy glow hails not from the sun but from the ultraviolet light of nearby stars and other galaxies: less than one-billionth of 1 percent. Even photons lingering from the Big Bang contribute some: roughly 0.001 percent.

Simon Driver, an astronomer at the University of Western Australia in Crawley, and colleagues calculated these numbers, but not because they’re interested in tanning. They were trying to decipher the extragalactic background light, or EBL, a diffuse glow that fills the universe (SN: 9/7/13, p. 22). Using galaxy observations from multiple telescopes, they assessed the number of EBL photons, from infrared to ultraviolet, that reach Earth. About half originated with the formation of galaxy cores and supermassive black holes during roughly the first 4 billion years of cosmic history, the researchers report in the Aug. 20 Astrophysical Journal. The growth of disks of stars in galaxies since that time accounts for the other half.

For some dropped foods, the five-second rule is about five seconds too long. Wet foods, such as watermelon, slurp up floor germs almost immediately, scientists report online September 2 in Applied and Environmental Microbiology.

Robyn Miranda and Donald Schaffner of Rutgers University in New Brunswick, N.J., tested gummy candy, watermelon and buttered and unbuttered bread by dropping morsels onto various surfaces coated with Enterobacter aerogenes bacteria. Food was left on each surface — stainless steel, ceramic tile, wood and carpet — for time periods ranging from less than a second to five minutes. Afterward, the researchers measured the amount of E. aerogenes on the food, harmless bacteria that share attachment characteristics with stomach-turning Salmonella.

As expected, longer contact times generally meant more bacteria on the food. But the transfer depended on other factors, too. Carpet, for instance, was less likely to transfer germs than the other surfaces. Gummy candies, particularly those on carpet, stayed relatively clean. But juicy watermelon quickly picked up lots of bacteria from all surfaces in less than a second. These complexities, the authors write, mean that the five-second rule is probably a rule worth dropping.

Shock waves may have jolted the infant cosmos. Clumpiness in the density of the early universe piled up into traveling waves of abrupt density spikes, or shocks, like those that create a sonic boom, scientists say.

Although a subtle effect, the shock waves could help scientists explain how matter came to dominate antimatter in the universe. They also could reveal the origins of the magnetic fields that pervade the cosmos. One day, traces of these shocks, in the form of gravitational waves, may even be detectable.
Scientists believe that the early universe was lumpy — with some parts denser than others. These density ripples, known as perturbations, serve as the seeds of stars and galaxies. Now, scientists have added a new wrinkle to this picture. As the ripples rapidly evolved they became steeper, like waves swelling near the shore, until eventually creating shocks analogous to a breaking wave. As a shock passes through a region of the universe, the density changes abruptly, before settling back down to a more typical, slowly varying density. “Under the simplest and most conservative assumptions about the nature of the universe coming out of the Big Bang, these shocks would inevitably form,” says cosmologist Neil Turok of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

In a paper published September 21 in Physical Review Letters, Turok and Ue-Li Pen of the Canadian Institute for Theoretical Astrophysics in Toronto performed calculations and simulations that indicate shocks would form less than one ten-thousandth of a second after the Big Bang.

“It’s interesting that nobody’s actually noticed that before,” says cosmologist Kevork Abazajian of the University of California, Irvine. “It’s an important effect if it actually happened.”

These shocks, Turok and Pen found, could produce magnetic fields, potentially pointing to an answer to a cosmological puzzle. Magnetic fields permeate the Milky Way and other parts of the cosmos, but scientists don’t know whether they sprang up just after the birth of the universe or much later, after galaxies had formed. Shock waves could explain how fields might have formed early on. When two shocks collide, they create a swirling motion, sending electrically charged particles spiraling in a way that could generate magnetic fields.
Shocks could also play a role in explaining why the universe is made predominantly of matter. The Big Bang should have yielded equal amounts of matter and antimatter; how the cosmic scales were tipped in matter’s favor is still unexplained. Certain theorized processes could favor the production of matter, but it’s thought they could happen only if temperatures in the universe are uneven. Shocks would create abrupt temperature jumps that would allow such processes to occur.

Scientists may be able to verify these calculations by detecting the gravitational waves that would have been produced when shocks collided. Unfortunately, the gravitational ripples produced would likely be too small to detect with current technologies. But under certain theories, in which large density fluctuations create regions so dense that they would collapse into black holes, the gravitational waves from shocks would be detectable in the near future. “If there was anything peculiar in the early universe, you would actually be able to detect this with upcoming technology,” says Abazajian. “I think that is remarkable.”

Like many abandoned mines, the Eureka uranium mine in northern Spain is a maze of long, dank tunnels. Water seeping down the walls carries dissolved substances that percolated through rocks overhead. As the water evaporates into the tunnels’ cool air, some of those dissolved ingredients combine to make new substances in solid form.

“The mine is a crystallization factory of weird minerals,” says Jordi Ibáñez-Insa, a physicist at the Institute of Earth Sciences Jaume Almera in Barcelona.
Including the uranium-bearing ores that attracted miners to Eureka in the first place, scientists visiting the mine have cataloged 61 different minerals — solids that have a distinct chemical recipe and arrangement of atoms. The latest find, called abellaite, is a rarity that grows in small pincushions of tiny crystalline needles about 40 to 50 micrometers long. Discovered in July 2010, the mineral has been found only on the walls of a 3-meter-long stretch of one tunnel, says Ibáñez-Insa.

Abellaite is uncommon in another sense: It contains carbon. Of the 5,161 minerals characterized by scientists and recognized by the International Mineralogical Association, just 8 percent, or 416, include carbon.

The Carbon Mineral Challenge, launched last December and running until September 2019, exhorts researchers to scour the landscape — and their museum drawers — for unknown carbon-bearing minerals. In a recent analysis, scientists estimate that there are at least 548 carbon minerals on Earth. That means well over 100 are waiting to be noticed.

The analysis, published in the April American Mineralogist, even provides clues about where scientists and rock hounds should look and what recipes and atomic arrangements such minerals might have.
The hunt for carbon minerals is much more than stamp (or rock) collecting. The challenge aims to identify minerals that could help tell the story of the planet’s carbon and water cycles — past and present. Besides having a specific recipe and structure, minerals form only in certain conditions (on Earth and elsewhere), making them keen chroniclers of the environments that existed at the time and place they formed, as well as the conditions since then.

A census of minerals
A few minerals are, forgive the phrase, as common as dirt. Of the more than 5,000 recognized minerals, about 100 have been reported by geologists and amateur collectors at more than 1,000 sites worldwide. Many more are very rare: At least 1,000 minerals have been found in only one locale, says Robert Hazen, a geophysicist at the Carnegie Institution for Science in Washington, D.C. More than half of the world’s minerals have been found at five or fewer locations.

Not every mineral on Earth has been discovered, of course. But by analyzing a massive database of known minerals and how common or rare they are, scientists can use a standard statistical tool to estimate the number of minerals yet to be uncovered. Hazen and his colleagues suggest in the August 2015 issue of Mathematical Geosciences that there are at least 1,500 undiscovered minerals out there. About 140 of those minerals contain carbon, the team predicted in the follow-on analysis published in April.

Both professional mineralogists and amateur collectors can participate in the Carbon Mineral Challenge, but any potential discoveries have to survive the strict screening process of the International Mineralogical Association, which Ibáñez-Insa and a raft of colleagues navigated for abellaite. (The mineral was approved in December 2015.) The researchers submitted a portfolio of data — the sample’s appearance, chemical makeup, arrangement of atoms, color, hardness, transparency, fluorescence, a proposed name and more — to the IMA’s Commission on New Minerals, Nomenclature and Classification.

Promising places
In the search for hidden carbon-bearing minerals, scientists and rock hounds aspiring to geologic fame should visit these locales (or analyze samples already collected there).

Tap the map to explore carbon mineral “hot spots” around the world.
A few dozen new minerals are recognized each year, says Hans-Peter Schertl, a mineralogist at Ruhr University in Bochum, Germany, and an IMA officer. Approval can be straightforward, or it can drag out for months or longer, especially if additional data are required, Schertl says. One strict requirement is that a sample be natural, not lab-made or a result of human interference. Thus, any unusual crystals that grow on the surfaces of rocks that were pulled from a mine and then dumped nearby and exposed to the elements wouldn’t qualify as a mineral, he notes, “Those would just be pretty crystals.”

Oddly, the “natural sample” requirement long prevented official recognition of what is purported to be the most common mineral on Earth. Bridgmanite, an iron- and magnesium-rich silicate, received the IMA seal of approval only in 2014 (SN: 1/10/15, p. 4). Estimated to make up a whopping 38 percent of the planet’s volume, bridgmanite can exist only at the high pressures found between 660 and 2,900 kilometers below Earth’s surface — too deep to dig up. Scientists had long studied lab-made samples but hadn’t found a natural bit of the mineral until earlier this decade in a meteorite that landed in Australia in 1879.

Where to look
In their analysis published in April, Hazen and colleagues included general recipes for a variety of Earth’s yet-to-be-discovered carbon minerals. One formula — a complex mix of sodium, lead and carbonate and hydroxyl ions, written scientifically as NaPb2(CO3)2(OH) — matches abellaite from the Spanish mine. Bingo. One more carbon mineral in the bag.

Many of those “missing” minerals will be very similar to known forms, with combinations that differ by only a single element — swapping out a magnesium atom for a calcium atom in the recipe for a known mineral, for example, or a sodium atom for a potassium atom.

“The chemical formula tells you a lot about the conditions that a mineral forms in,” says Daniel Hummer, a geochemist at Southern Illinois University in Carbondale and lead scientist for the Carbon Mineral Challenge. It also suggests that existing minerals that have a very similar formula can, in many cases, serve as a guide for what the missing minerals might look like, in terms of the colors or shapes of their crystals.

In fact, similarities could be so strong that a mineral might be overlooked because it looks so much like a known, or even common, mineral. “It’s possible that some of these missing minerals are hiding in plain sight,” Hummer notes.

If not camouflaged, some carbon minerals may simply be so scarce that they’ve never been encountered. In June in American Mineralogist, Hazen and environmental scientist Jesse Ausubel of Rockefeller University in New York City discuss several reasons why minerals can be rare — so rare, in fact, that the entire world’s supply might fit into a thimble, Hazen says.

First, a mineral might form or remain stable only in extremely unusual combinations of temperature, pressure and pH. The mineral hatrurite (Ca3SiO5), for example, forms only at temperatures above 1,250° Celsius and only in the absence of aluminum, the third most common element in Earth’s crust. Hatrurite was first found in Israel, in an ancient limestone deposit that was probably exposed to intense heat generated when hydrocarbons in nearby sediments burned.

Second, a mineral might include chemical elements that are rare to begin with and even rarer in combination. Examples include swedenborgite (which contains the scarce combination of beryllium and antimony) and any mineral that includes tellurium, which on average is found in Earth’s crust at concentrations of 5 parts per billion.

Third, a mineral may be exceptionally ephemeral. Some are so hygroscopic, or humidity-absorbing, that they pull moisture from the air and dissolve themselves, Hazen says. Hygroscopic minerals have to be collected or observed in the field as they form and before they disappear. Then there are the minerals that form in conditions so remote or harsh that scientists hardly ever get near them (think deep-sea hydrothermal vents or active volcanoes).

Some minerals present more than one of these challenges. Consider fingerite, Cu11O2(VO4)6, an unstable shiny black mineral that forms only at high temperatures and includes the rare combination of copper and vanadium. This exceedingly rare mineral is known only from samples recovered from rocks near heat-belching fissures and holes atop El Salvador’s Izalco volcano.

There are less hostile places to search for new minerals, though. Fourteen sites worldwide, including mines, have each given up 20 or more carbon minerals, Hazen says. Scientists could revisit those 14 sites and look for more unrecognized minerals, he notes. Or they could simply take a closer look at or perform additional tests on samples already collected from such locales.
Or researchers could target areas where ephemeral minerals could be expected to form, if ever so briefly. For example, calcium carbide — a substance produced on an industrial scale to create acetylene for miner’s lamps — reacts so quickly with water that it hasn’t been found in a natural setting. But small, short-lived quantities might be produced when lightning strikes near rocks containing both limestone and coal (admittedly, a pretty hostile situation).

There’s no reason to be limited by the 14 promising locations. Scientists found the yellowish-white crystals of tinnunculite (C5H4N4O3•2H2O), mineral just recognized in December, in an unexpected milieu: inside the residue of bird poop that had landed on extremely hot rocks overlying an underground coal fire in northwestern Russia. The elevated temperatures drive the crystallization of uric acid in the excrement, the researchers say.

The exotic mineral was dubbed tinnunculite to honor the European kestrel (Falco tinnunculus), whose indispensable contribution to mineralogy cannot be denied.

For his part, Ibáñez-Insa plans to spend more time at Spain’s Eureka mine. Although the site’s uranium ores are no longer worth extracting, scientific treasures akin to abellaite may still lie undiscovered. “I’m pretty sure,” he says, “we’ll find some more new minerals there.”
This article appears in the October 15, 2016, issue of Science News with the headline, “Digging Carbon: A new challenge has scientists searching for dozens of unknown, beguiling crystals.”

Deep-sea viruses aren’t just dealers of disease; they’re crucial players in Earth’s nutrient cycles. In marine sediments, virus assassinations of single-celled life-forms called archaea play a much larger role in carbon and other chemical cycles than previously thought, new research suggests. For instance, those microbial murders release as much as 500 million metric tons of carbon annually worldwide, researchers report online October 12 in Science Advances.

Viruses are a major killer of bacteria and archaea in the deep sea, busting open infected cells like water balloons and spewing the cells’ innards. To find the relative number of massacred microbes, marine ecologist Roberto Danovaro of Polytechnic University of Marche in Ancona, Italy, and colleagues studied the spilled guts of the viruses’ victims.

Tallying the number of archaeal versus bacterial genes released from the carnage in more than 480 sediment samples, the researchers discovered that viruses kill archaea disproportionately more often than bacteria. Despite making up on average about 12 percent of the microbial population in the top 50 centimeters of sediment, archaea accounted for up to one-third of the total biomass killed by viruses, Danovaro and colleagues report. The researchers do not speculate on why archaea were such frequent targets. Those deaths were not in vain, though: Archaea corpses supply nutrients such as carbon that help sustain other life-forms.

When the body’s internal sense of time doesn’t match up with outside cues, people can suffer, and not just from a lack of sleep.

Such ailments are similar in a way to motion sickness — the queasiness caused when body sensations of movement don’t match the external world. So scientists propose calling time-related troubles, which can afflict time-zone hoppers and people who work at night, “circadian-time sickness.” This malady can be described, these scientists say, with a certain type of math.
The idea, to be published in Trends in Neurosciences, is “intriguing and thought-provoking,” says neuroscientist Samer Hattar of Johns Hopkins University. “They really came up with an interesting idea of how to explain the mismatch.”

Neuroscientist Raymond van Ee of Radboud University in the Netherlands and colleagues knew that many studies had turned up ill effects from an out-of-whack circadian clock. Depression, metabolic syndromes and memory troubles have been found alongside altered daily rhythms. But despite these results, scientists don’t have a good understanding of how body clocks work, van Ee says.

Van Ee and colleagues offer a new perspective by using a type of math called Bayesian inference to describe the circadian trouble. Bayesian inference can be used to describe how the brain makes and refines predictions about the world. This guesswork relies on the combination of previous knowledge and incoming sensory information (SN: 5/28/16, p. 18). In the case of circadian-time sickness, these two cues don’t match up, the researchers propose.

Some pacemaking nerve cells respond directly to light, allowing them to track the outside environment. Other pacemakers don’t respond to light but rely on internal signals instead. Working together, these two groups of nerve cells, without any supervision from a master clock, can set the body’s rhythms. But when the two timekeepers arrive at different conclusions, the conflict muddies the time readout in the body, leading to a confused state that could cause poor health outcomes, van Ee and colleagues argue.

This description of circadian-time sickness is notable for something it leaves out — sleep. While it’s true that shifted sleep cycles can cause trouble, a misalignment between internal and external signals may cause problems even when sleep is unaffected, the researchers suggest. That runs counter to the simple and appealing idea that out-of-sync rhythms cause sleep deprivation, which in turn affects the body and brain. That idea “was totally linear and beautiful,” Hattar says. “But once you start looking very carefully at the data in the field, you find inconsistencies that people ignored.”
It’s difficult to disentangle sleep from circadian misalignments, says neuroscientist Ilia Karatsoreos of Washington State University in Pullman. Still, research by him and others has turned up detrimental effects from misaligned circadian rhythms — even when sleep was normal. This new paper helps highlight why “it is important to be able to study and understand the contribution of each,” he says.

The concept of circadian-time sickness is an idea that awaits testing, Karatsoreos cautions. Yet it’s a “useful way for us to talk about this general problem, if only for the fact that it’s a way of thinking that I’ve really never seen before.”