Hominid hubbub
In “Hominid roots may go back to Europe” (SN: 6/24/17, p. 9), Bruce Bower reported that the teeth of Graecopithecus, a chimp-sized primate that lived in southeastern Europe 7 million years ago, suggest it was a member of the human evolutionary family.

“Is it appropriate to use the terms ‘hominid’ and ‘ape’ as if the two are mutually exclusive categories?” asked online reader Tim Cliffe. “The distinction being made is between our clade in particular and all other apes. It seems to me that ‘hominids’ should be described as a subset of apes, not a separate category,” he wrote.
“Yes, hominids are apes,” Bower says. “The terminology gets pretty thick in evolutionary studies, so researchers (and journalists) use some shortcuts.”

Fossils of many ancient apes dating to between 25 million and 5 million years ago have been found, but the interest in this case is in a key transition to a particular kind of ape that walked upright and displayed various skeletal traits similar to traits unique to the human evolutionary family. “That’s why one source in the story, Bernard Wood, wonders whether Graecopithecus was an apelike hominid or a hominid-like ape,” Bower says. “But it’s important to remember that hominids diverged from other, ancestral apes. So did chimps.”

Science News defines “hominid” as a member of the human evolutionary family.

Laser, camera, action
The world’s fastest video camera films 5 trillion frames every second, Ashley Yeager reported in “A different kind of camera captures speedy actions” (SN: 6/24/17, p. 5). The camera works by flashing a laser at a subject and using a computer program to combine the still images into a video. Researchers tested the device by filming particles of light as the particles traveled a short distance.

Online reader JHoughton1 wondered if the researchers really filmed a light particle in their tests. “I thought light ‘sometimes behaves like a wave, sometimes like a particle,’ but that there isn’t really any particle that’s a particle in the usual sense. Is this really a picture of a ‘particle’ of light? A photon-as-ball-of-stuff?”

The camera captured the forward progression of a laser pulse, which is an ensemble of photons, Yeager says.

Photons themselves aren’t “balls of stuff” on quantum scales, says physics writer Emily Conover. All particles, including photons, are spread out in space, propagating like waves. “Only when scientists measure or observe a photon or any other particle do they find it in one place, like the ball of stuff that people typically imagine. I think in that sense, photons are about as tangible as any other quantum particle,” Conover says.

Bringing down the mucus house
Little-known sea animals called giant larvaceans can catch a lot of carbon in disposable mucus casings called “houses,” Susan Milius reported in “ ‘Mucus houses’ catch sea carbon fast” (SN: 6/10/17, p. 13).

Online reader Robert Stenton wondered what happens to mucus houses as they fall to the bottom of the ocean.

What happens to discarded houses isn’t yet clear, Milius says, though researchers have proposed that the houses might carry substantial portions of carbon to life on the sea bottom. And if bits of a house fall fast enough to reach great depths, the carbon could get trapped in water masses that move around the planet for centuries before surfacing. Bits drifting down slowly may be intercepted by microbes and other debris feeders and would not end up sequestered.

Correction
In “Human noises invade wilderness” (SN: 6/10/17, p. 14), Science News incorrectly reported that official wilderness areas in the United States do not allow livestock grazing. Grazing is permitted in protected wilderness areas at preprotection levels under the Wilderness Act of 1964, which created the National Preservation System.

Our view of the earliest flowers just bloomed. A new reconstruction, the most detailed to date, suggests the flowers were bisexual, with more than five female reproductive organs, or carpels, and more than 10 male reproductive organs, or stamen. Petallike structures, grouped in sets of three, surrounded the sex organs, researchers report August 1 in Nature Communications.

Flowering plants comprise roughly 90 percent of plants on Earth. Researchers think they evolved from a common ancestor that lived about 140 million years ago. But it has been hard to reconstruct the structure of such ancient blooms because so few fossils have been found.

In the new study, Hervé Sauquet of the Université Paris-Sud in Orsay, France, and colleagues combined models of flower evolution with a database of features for 792 species of flowering plants, and data from the fossil record. The new picture of ancient flowers suggests some blossoms lost their bisexuality with time. Also, modern blooms lost some of their whorls, the concentric layers of different flower parts. In some flowers, whorls dropped from at least four to two in petals and the leaflike structures at the base of a bloom, and from four to one in stamen, the team concludes. The finding suggests that natural selection pushed the plants to a less complex floral plan over time.

A 13-million-year-old infant’s skull, discovered in Africa in 2014, comes from a new species of ape that may not be far removed from the common ancestor of living apes and humans.

The tiny find, about the size of a lemon, is one of the most complete skulls known of any extinct ape that inhabited Africa, Asia or Europe between 25 million and 5 million years ago, researchers report in the Aug. 10 Nature. The fossil provides the most detailed look to date at a member of a line of African primates that are now candidates for central players in the evolution of present-day apes and humans.
Most fossils from more than 40 known extinct ape species amount to no more than jaw fragments or a few isolated teeth. A local fossil hunter spotted the nearly complete skull in rock layers located near Kenya’s Lake Turkana. Members of a team led by paleoanthropologist Isaiah Nengo estimated the fossil’s age by assessing radioactive forms of the element argon in surrounding rock, which decay at a known rate.

Comparisons with other African ape fossils indicate that the infant’s skull belongs to a new species that the researchers named Nyanzapithecus alesi. Other species in this genus, previously known mainly from jaws and teeth, date to as early as around 25 million years ago.

“This skull comes from an ancient group of apes that existed in Africa for over 10 million years and was close to the evolutionary origin of living apes and humans,” says Nengo, of Stony Brook University in New York and De Anza College in Cupertino, Calif.

He and colleagues looked inside the skull using a powerful type of 3-D X-ray imaging. This technique revealed microscopic enamel layers that had formed daily from birth in developing adult teeth that had yet to erupt. A count of those layers indicates that the ape was 16 months old when it died.

Based on a presumably rapid growth rate, the scientists calculated that the ancient ape would have weighed about 11.3 kilograms as an adult. Its adult brain volume would have been almost three times larger than that of known African monkeys from the same time, the researchers estimate.
N. alesi’s tiny mouth and nose, along with several other facial characteristics, make it look much like small-bodied apes called gibbons. Faces resembling gibbons evolved independently in several extinct monkeys, apes and their relatives, the researchers say. The same probably held for N. alesi, making it an unlikely direct ancestor of living gibbons, they conclude.
No lower-body bones turned up with the new find. Even so, it’s possible to tell that N. alesi did not behave as present-day gibbons do. In gibbons, a part of the inner ear called the semicircular canals, which coordinates balance, is large relative to body size. That allows the apes to swing acrobatically from one tree branch to another. N. alesi’s small semicircular canals indicate that it moved cautiously in trees, Nengo says.

Several of the infant skull’s features, including those downsized semicircular canals, connect it to a poorly understood, 7-million- to 8-million-year-old ape called Oreopithecus. Fossils of that primate, discovered in Italy, suggest it walked upright with a slow, shuffling gait. If an evolutionary relationship existed with the older N. alesi, the first members of the Oreopithecus genus probably originated in Africa, Nengo proposes.

Without any lower-body bones for N. alesi, it’s too early to rule out the possibility that Nyanzapithecus gave rise to modern gibbons and perhaps Oreopithecus as well, says paleontologist David Alba of the Catalan Institute of Paleontology Miquel Crusafont in Barcelona. Gibbon ancestors are thought to have diverged from precursors of living great apes and humans between 20 million and 15 million years ago, Alba says.

Despite the age and unprecedented completeness of the new ape skull, no reported tooth or skull features clearly place N. alesi close to the origins of living apes and humans, says paleoanthropologist David Begun of the University of Toronto.

Further studies of casts of the inner braincase, which show impressions from surface features of the brain, may help clarify N. alesi’s position in ape evolution, Nengo says. Insights are also expected from back, forearm and finger fossils of two or three ancient apes, possibly also from N. alesi, found near the skull site in 2015. Those specimens also date to around 13 million years ago.

On the morning of August 21, a pair of jets will take off from NASA’s Johnson Space Center in Houston to chase the shadow of the moon. They will climb to 15 kilometers in the stratosphere and fly in the path of the total solar eclipse over Missouri, Illinois and Tennessee at 750 kilometers per hour.

But some of the instruments the jets carry won’t be looking at the sun, or even at Earth. They’ll be focused on a different celestial body: Mercury. In the handful of minutes that the planes zip along in darkness, the instruments could collect enough data to answer this Mercury mystery: What is the innermost planet’s surface made of?
Because it’s so close to the sun, Mercury is tough to study from Earth. It’s difficult to observe close up, too. Extreme heat and radiation threaten to fry any spacecraft that gets too close. And the sun’s brightness can swamp a hardy spacecraft’s efforts to send signals back to Earth.

NASA’s Messenger spacecraft orbited Mercury from 2011 to 2015 and revealed a battered, scarred landscape made of different material than the rest of the terrestrial planets (SN: 11/19/11, p. 17).
But Messenger only scratched the surface, so to speak. It analyzed the planet’s composition with an instrument called a reflectance spectrometer, which collects light and then splits that light into its component wavelengths to figure out which elements the light was reflected from.
Messenger took measurements of reflected light from Mercury’s surface at wavelengths shorter than 1 micrometer, which revealed, among other things, that Mercury contains a surprising amount of sulfur and potassium (SN: 7/16/11, p. 12). Those wavelengths come only from the top few micrometers of Mercury. What lies below is still unknown.

To dig a few centimeters deeper into Mercury’s surface, solar physicist Amir Caspi and planetary scientist Constantine Tsang of the Southwest Research Institute in Boulder, Colo., and colleagues will use an infrared camera, specially built by Alabama-based Southern Research, that detects wavelengths between 3 and 5 micrometers.

Copies of the instrument will fly on the two NASA WB-57 research jets, whose altitude and speed will give the observers two advantages: less atmospheric interference and more time in the path of the eclipse. Chasing the moon’s shadow will let the planes stay in totality — the region where the sun’s bright disk is completely blocked by the moon — for a combined 400 seconds (6.67 minutes). That’s nearly three times longer than they would get by staying in one spot.
Mercury’s dayside surface is 425° Celsius, and it actually emits light at 4.1 micrometers — right in the middle of the range of Caspi’s instrument. As any given spot on Mercury rotates away from the sun, its temperature drops as low as ‒179° C. Measuring how quickly the planet loses heat can help researchers figure out what the subsurface material is made of and how densely it’s packed. Looser sand will give up its heat more readily, while more close-packed rock will hold heat in longer.

“This is something that has never been done before,” Caspi says. “We’re going to try to make the first thermal image heat map of the surface of Mercury.”

Unfortunately for Caspi, only two people can fly on the jet: The pilot and someone to run the instrument. Caspi will remain on the ground in Houston, out of the path of totality. “So I will get to watch the eclipse on TV,” Caspi says.

Every few years, for a handful of minutes or so, science shines while the sun goes dark.

A total eclipse of the sun is, for those who witness it, something like a religious experience. For those who understand it, it is symbolic of science’s triumph over mythology as a way to understand the heavens.

In ancient Greece, the pioneer philosophers realized that eclipses illustrate how fantastic phenomena do not require phantasmagoric explanation. An eclipse was not magic or illusion; it happened naturally when one celestial body got in the way of another one. In the fourth century B.C., Aristotle argued that lunar eclipses provided strong evidence that the Earth was itself a sphere (not flat as some primitive philosophers had believed). As the eclipsed moon darkened, the edge of the advancing shadow was a curved line, demonstrating the curvature of the Earth’s surface intervening between the moon and sun.

Oft-repeated legend proclaims that the first famous Greek natural philosopher, Thales of Miletus, even predicted a solar eclipse that occurred in Turkey in 585 B.C. But the only account of that prediction comes from the historian Herodotus, writing more than a century later. He claimed that during a fierce battle “day suddenly became night,” just as Thales had forecast would happen sometime during that year.

There was an eclipse in 585 B.C., but it’s unlikely that Thales could have predicted it. He might have known that the moon blocks the sun in an eclipse. But no mathematical methods then available would have allowed him to say when — except, perhaps, a lucky coincidence based on the possibility that solar eclipses occurred at some regular cycle after lunar eclipses. Yet even that seems unlikely, a new analysis posted online last month finds.

“Some scholars … have flatly denied the prediction, while others have struggled to find a numerical cycle by means of which the prediction could have been carried out,” writes astronomer Miguel Querejeta. Many such cycles have already been ruled out, he notes. And his assessment of two other cycles concludes “that none of those conjectures can be regarded as serious explanations of the problematic prediction of Thales: in addition to requiring the existence of long and precise eclipse records … both cycles that have been examined overlook a number of eclipses which match the visibility criteria and, consequently, the patterns suggested seem to disappear.”

It’s true that the ancient Babylonians worked out methods for predicting lunar eclipses based on patterns in the intervals between them. And the famous Greek Antikythera mechanism from the second century B.C. seems to have used such cycle data to predict some eclipses.

Ancient Greek astronomers, such as Hipparchus (c. 190–120 B.C.), studied eclipses and the geometrical relationships of the Earth, moon and sun that made them possible. Understanding those relationships well enough to make reasonably accurate predictions became possible, though, only with the elaborate mathematical description of the cosmos developed (drawing on Hipparchus’ work) by Claudius Ptolemy. In the second century A.D., he worked out the math for explaining the movements of heavenly bodies, assuming the Earth sat motionless in the center of the universe.

His system specified the basic requirements for a solar eclipse: It must be the time of the new moon — when moon and sun are on the same side of the Earth — and the positions of their orbits must also be crossing the ecliptic, the plane of the sun’s apparent orbital path through the sky. (The moon orbits the Earth at a slight angle, crossing the plane of the ecliptic twice a month.) Only precise calculations of the movements of the sun and moon in their orbits could make it possible to predict the dates for eclipsing alignments.

Predicting when an eclipse will occur is not quite the same as forecasting exactly where it will occur. To be accurate, eclipse predictions need to take subtle gravitational interactions into account. Maps showing precisely accurate paths of totality (such as for the Great American Eclipse of 2017) became possible only with Isaac Newton’s 17th century law of gravity (and the further development of mathematical tools to exploit it). Nevertheless Ptolemy had developed a system that, in principle, showed how to anticipate when eclipses would happen. Curiously, though, this success was based on a seriously wrong blueprint for the architecture of the cosmos.

As Copernicus persuasively demonstrated in the 16th century, the Earth orbits the sun, not vice versa. Ptolemy’s geometry may have been sound, but his physics was backwards. While demonstrating that mathematics is essential to describing nature and predicting physical phenomena, he inadvertently showed that math can be successful without being right.

It’s wrong to blame him for that, though. In ancient times math and science were separate enterprises (science was then “natural philosophy”). Astronomy was regarded as math, not philosophy. An astronomer’s goal was to “save the phenomena” — to describe nature correctly with math that corresponded with observations, but not to seek the underlying physical causes of those observations. Ptolemy’s mathematical treatise, the Almagest, was about math, not physics.

One of the great accomplishments of Copernicus was to merge the math with the physical realty of his system. He argued that the sun occupied the center of the cosmos, and that the Earth was a planet, like the others previously supposed to have orbited the Earth. Copernicus worked out the math for a sun-centered planetary system. It was a simpler system than Ptolemy’s. And it was just as good for predicting eclipses.

As it turned out, though, even Copernicus didn’t have it quite right. He insisted that planetary orbits were circular (modified by secondary circles, the epicycles). In fact, the orbits are ellipses. It’s a recurring story in science that mathematically successful theories sometimes are just approximately correct because they are based on faulty understanding of the underlying physics. Even Newton’s law of gravity turned out to be just a good mathematical explanation; the absolute space and invariable flow of time he believed in just aren’t an accurate representation of the universe we live in. It took Einstein to see that and develop the view of gravity as the curvature of spacetime induced by the presence of mass.
Of course, proving Einstein right required the careful measurement by Arthur Eddington and colleagues of starlight bending near the sun during a solar eclipse in 1919. It’s a good thing they knew when and where to go to see it.

Scientists have created the largest map of dark matter yet, part of a slew of new measurements that help pin down the universe’s dark contents. Covering about a thirtieth of the sky, the map (above) charts the density of both normal matter — the stuff that’s visible — and dark matter, an unidentified but far more abundant substance that pervades the cosmos.

Matter of both types is gravitationally attracted to other matter. That coupling organizes the universe into more empty regions of space (No. 1 below and blue in the map above) surrounded by dense cosmic neighborhoods (No. 2 below and red in the map above).
Researchers from the Dark Energy Survey used the Victor Blanco telescope in Chile to survey 26 million galaxies in a section of the southern sky for subtle distortions caused by the gravitational heft of both dark and normal matter. Scientists unveiled the new results August 3 at Fermilab in Batavia, Ill., during a meeting of the American Physical Society.

Dark matter is also accompanied by a stealthy companion, dark energy, an unseen force that is driving the universe to expand at an increasing clip. According to the new inventory, the universe is about 21 percent dark matter and 5 percent ordinary matter. The remainder, 74 percent, is dark energy.

The new measurements differ slightly from previous estimates based on the cosmic microwave background, light that dates back to 380,000 years after the Big Bang (SN: 3/21/15, p. 7). But the figures are consistent when measurement errors are taken into account, the researchers say.
“The fact that it’s really close, we think is pretty remarkable,” says cosmologist Josh Frieman of Fermilab, who directs the Dark Energy Survey. But if the estimates don’t continue to align as the survey collects more data, something might be missing in cosmologists’ theories of the universe.

A new genetics study adds fuel to the debate about muscle aches that have been reported by many people taking popular cholesterol-lowering drugs called statins.

About 60 percent of people of European descent carry a genetic variant that may make them more susceptible to muscle aches in general. But counterintuitively, these people had a lower risk of muscle pain when they took statins compared with placebos, researchers report August 29 in the European Heart Journal.
Millions of people take statins to lower cholesterol and fend off the hardening of arteries. But up to 78 percent of patients stop taking the medicine. One common reason for ceasing the drugs’ use is side effects, especially muscle pain, says John Guyton, a clinical lipidologist at Duke University School of Medicine.

It has been unclear, however, whether statins are to blame for the pain. In one study, 43 percent of patients who had muscle aches while taking at least one type of statin were also pained by other types of statin (SN: 5/13/17, p. 22). But 37 percent of muscle-ache sufferers in that study had pain not related to statin use. Other clinical trials have found no difference in muscle aches between people taking statins and those not taking the drugs.

The new study hints that genetic factors, especially ones involved in the immune system’s maintenance and repair of muscles, may affect people’s reactions to statins. “This is a major advance in our understanding about myalgia,” or muscle pain, says Guyton, who was not involved in the study.

People with two copies of the common form of the gene LILRB5 tend to have higher-than-usual blood levels of two proteins released by injured muscles, creatine phosphokinase and lactate dehydrogenase. Higher levels of those proteins may predispose people to more aches and pains. In an examination of data from several studies involving white Europeans, people with dual copies of the common variant were nearly twice as likely to have achy muscles while taking statins as people with a less common variant, Moneeza Siddiqui of the University of Dundee School of Medicine in Scotland and colleagues discovered.

But when researchers examined who had pain when taking statins versus placebos, those with two copies of the common variant seemed to be protected from getting statin-associated muscle pain. Why is not clear.
People with double copies of the common form of the gene who experience muscle pain may stop taking statins because they erroneously think the drugs are causing the pain, study coauthor Colin Palmer of the University of Dundee said in a news release.

The less common version of the gene is linked to reduced levels of the muscle-damage proteins, and should protect against myalgia. Yet people with this version of the gene were the ones more likely to develop muscle pain specifically linked to taking statins during the trials.

The finding suggests that when people with the less common variant develop muscle pain while taking statins, the effect really is from the drugs, the researchers say.

But researchers still don’t know the nitty-gritty details of how the genetic variants promote or protect against myalgia while on statins. Neither version of the gene guarantees that a patient will develop side effects — or that they won’t. The team proposes further clinical trials to unravel interactions between the gene and the drugs.

More study is needed before doctors can add the gene to the list of tests patients get, Guyton says. “I don’t think we’re ready to put this genetic screen into clinical practice at all,” he says. For now, “it’s much easier just to give the patient the statin” and see what happens.

Patience is a virtue in the hunt for dark matter. Experiment after experiment has come up empty in the search — and the newest crop is no exception.

Observations hint at the presence of an unknown kind of matter sprinkled throughout the cosmos. Several experiments are focused on the search for one likely dark matter candidate: weakly interacting massive particles, or WIMPs (SN: 11/12/16, p. 14). But those particles have yet to be spotted.

Recent results, posted at arXiv.org, continue the trend. The PandaX-II experiment, based in China, found no hint of the particles, scientists reported August 23. The XENON1T experiment in Italy also came up WIMPless according to a May 18 paper. Scientists with the DEAP-3600 experiment in Sudbury, Canada, reported their first results on July 25. Signs of dark matter? Nada. And the SuperCDMS experiment in the Soudan mine in Minnesota likewise found no hints of WIMPs, scientists reported August 29.

Another experiment, PICO-60, also located in Sudbury, reported its contribution to the smorgasbord of negative results June 23 in Physical Review Letters.

Scientists haven’t given up hope. Researchers are building ever-larger detectors, retooling their experiments and continuing to expand the search beyond WIMPs.

Physicists often ponder small things, but probably not the ones on Kerwyn Casey “KC” Huang’s mind. He wants to know what it’s like to be a bacterium.

“My motivating questions are about understanding the physical challenges bacterial cells face,” he says. Bacteria are the dominant life-forms on Earth. They affect the health of plants and animals, including humans, for good and bad. Yet scientists know very little about the rules the microbes live by. Even questions as basic as how bacteria determine their shape are still up in the air, says Huang, of Stanford University.

Huang, 38, is out to change that. He and colleagues have determined what gives cholera bacteria their curved shape and whether it matters (a polymer protein, and it does matter; the curve makes it easier for cholera to cause disease), how different wavelengths of light affect movement of photosynthetic bacteria (red and green wavelengths encourage movement; blue light stops the microbes in their tracks), how bacteria coordinate cell division machinery and how photosynthetic bacteria’s growth changes in light and dark.

All four of these findings and more were published in just the first three months of this year.
Huang also looks for ways to use tools and techniques his team develops to solve problems unrelated to bacteria. Computer programs that measure changes in bacterial cell shape can also track cells in plant roots and in developing zebrafish embryos. He’s even helped determine how a protein’s activity and stability contribute to a human genetic disease.

A physicist by training, Huang delves into biology, biochemistry, microbial ecology, genetics, engineering, computer science and more, partnering with a variety of scientists from across those fields. He’s even teamed up with his statistician sister. He’s an “all-in-one scientist,” says longtime collaborator Ned Wingreen, a biophysicist at Princeton University.

When Huang started his lab at Stanford in 2008, after getting his Ph.D. at MIT and spending time at Princeton as a postdoctoral fellow, his background was purely theoretical. He designed and ran the computer simulations and then his collaborators carried out the experiments. But soon, he wanted to do hands-on research too, to learn why cells are the way they are.
Such a leap “is not trivial,” says Christine Jacobs-Wagner, a microbiologist at Yale University who also studies bacterial cell shape. But Huang is “a really, really good experimentalist,” she says.

Jacobs-Wagner was particularly impressed with a “brilliant microfluidics experiment” Huang did to test a well-established truism about how bacteria grow. Researchers used to think that turgor pressure — water pressure inside a cell that pushes the outer membrane against the cell wall — controlled bacterial growth, just like it does in plants. But abolishing turgor pressure didn’t change E. coli’s growth rate, Huang and colleagues reported in 2014 in Proceedings of the National Academy of Sciences. “This result blew my mind away,” Jacobs-Wagner says. The finding “crumbled the foundation” of what scientists thought about bacterial growth.

“He uses clever experiments to challenge old paradigms,” Jacobs-Wagner says. “More than once he has come up with a new trick to address a tough question.”
Sometimes Huang’s tricks require breaking things. Zemer Gitai, a microbiologist at Princeton, remembers talking with Huang and Wingreen about a question that microbiologists were stuck on: How are molecules oriented in bacterial cell walls? Researchers knew that the walls are made of rigid sugar strands connected by flexible proteins, like a chain link fence held together by rubber bands. What they didn’t know was whether the rubber bands circled the bacteria like the hoops on a wine barrel, ran in stripes down the length of the cell or stuck out like hairs.

If bacteria were put under pressure, the cells would crack along the weak rubber band–like links, Huang and Wingreen reasoned. If the cells split like hot dogs on a grill, it would mean the links ran the length of the cells. If they opened like a Slinky, it would suggest a wine-barrel configuration. The researchers reported the results — opened like a Slinky — in 2008. Another group, using improved microscope techniques, got the same result.

Huang teamed up with other researchers to do microfluidics experiments, growing bacteria in tiny chambers and tracking individual cells to learn how photosynthetic bacteria grow in light and dark.

But in nature, bacteria don’t live alone. So Huang has also worked with Stanford colleague Justin Sonnenburg to answer a basic question: “Where and when are bacteria in the gut growing? No one knows,” Huang says. “How can we not know that? It’s totally fundamental.” Without that information, it’s impossible to know, for example, how antibiotics affect the microbial community in the intestines, he says.

Stripping fiber from a mouse’s diet not only changes the mix of microbes in the gut, it alters where in the intestines the microbes grow, the researchers discovered. Bacteria deprived of fiber’s complex sugars began to munch on the protective mucus lining the intestines, bumping against the intestinal lining and sparking inflammation, Huang, Sonnenburg and colleagues reported in Cell Host & Microbe in 2015.

Huang’s breadth of research — from deciphering the nanoscale twists of proteins to mapping whole microbial communities — is sure to lead to many more discoveries. “He’s capable of making contributions to any field,” Jacobs-Wagner says, “or any research question that he’s interested in.”

Eggs, long condemned for making raw cookie dough a forbidden pleasure, can stop taking all the blame. There’s another reason to resist the sweet uncooked temptation: flour.

The seemingly innocuous pantry staple can harbor strains of E. coli bacteria that make people sick. And, while not a particularly common source of foodborne illness, flour has been implicated in two E. coli outbreaks in the United States and Canada in the last two years.

Pinning down tainted flour as the source of the U.S. outbreak, which sickened 63 people between December 2015 and September 2016, was trickier than the average food poisoning investigation, researchers recount November 22 in the New England Journal of Medicine.
Usually, state health departments rely on standard questionnaires to find a common culprit for a cluster of reported illnesses, says Samuel Crowe, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta, who led the study. But flour isn’t usually tracked on these surveys. So when the initial investigation yielded inconclusive results, public health researchers turned to in-depth personal interviews with 10 people who had fallen ill.

Crowe spent up to two hours asking each person detailed questions about what he or she had eaten around the time of getting sick. Asking people what they ate eight weeks ago can be challenging, Crowe says: Many people can’t even remember what they ate for breakfast that morning.

“I got a little lucky,” Crowe says. Two people remembered eating raw cookie dough before getting sick. They each sent Crowe pictures of the bag of flour they had used to make the batter. It turned out that both bags had been produced in the same plant. That was a “pretty unusual thing,” he says.
Follow-up questioning helped Crowe and his team pin down flour as the likely source. Eventually, U.S. Food and Drug Administration scientists analyzed the flour and isolated strains of E. coli bacteria that produce Shiga toxins, which make E. coli dangerous.

Disease-causing bacteria, including E. coli, usually thrive in moist environments, like bags of prewashed lettuce (SN: 12/24/16, p. 4). But the bacteria can also survive in a desiccated state for months and be re-activated with water, says Crowe. So as soon as dry flour mingles with eggs or oil, dormant bacteria can reawaken and start to replicate.

Cookie dough wasn’t the culprit in every case. A few children who got sick had been given raw tortilla dough to play with while waiting for a table at a restaurant. The cases all involved wheat flour from the same facility, leading to a recall of more than 250 flour-containing products.

There are ways to kill bacteria in flour before it reaches grocery store shelves, but they aren’t in use in the United States. Heat treatment, for example, will rid flour of E. coli and other pathogens. But the process also changes the structure of the flour, which affects the texture of baked goods, says Rick Holley, a food safety expert at the University of Manitoba in Canada who wasn’t part of the study. Irradiation, used to kill parasites and other pests in flour, might be a better option, Holley says. But it takes a higher dose of radiation to zap bacteria than it does to kill pests.

Or, of course, people could hold out for warm, freshly baked cookies.