Charles Darwin famously derived his theory of evolution from observations he made of species and their geographic distributions during his five-year voyage around the world on the H.M.S. Beagle. But in the introduction of On the Origin of Species, the naturalist also cites another influence: the thousands of fossils that he collected on that trip. Darwin’s Fossils is paleobiologist Adrian Lister’s account of that little-appreciated foundation of evolutionary theory.

While sailors on board the Beagle charted the coastal waters of South America (the actual purpose of the expedition), Darwin explored the shore and rambled inland on excursions that sometimes lasted weeks. The fossils he unearthed — some relatively fresh, others millions of years old — have tremendous significance in the history of science, Lister contends.
Many of the species Darwin discovered in the fossils were previously unknown to science, including several giant ground sloths, compact car–sized relatives of armadillos called glyptodonts (SN Online: 2/22/16) and ancient kin of horses and elephants. Because many of those animals were apparently extinct — but just as apparently related to species still living in the region — Darwin concluded the fossils were strong evidence for the “transmutation,” or evolution, of species. This evidence was all the more convincing to him, Lister suggests, because he had unearthed the fossils himself. He saw firsthand the fossils’ geologic context, which enabled him to more easily infer how species had changed through time.

Copiously illustrated and suitable for general readers as well as the science savvy, Darwin’s Fossils is a quick, easy read that provides a fascinating overview of the naturalist’s wide-ranging fieldwork during the Beagle voyage. His insights from fossils went beyond just biological evolution. Darwin’s studies of coral reefs (the mineralized parts of which are, after all, huge fossils) encircling islands in the Pacific and Indian oceans led him to theorize correctly how such reefs form. And his observations of strata containing marine fossils thousands of meters up into the Andes led to an improved understanding of how geologic forces sculpt the world.

Injecting fluid into the ground for geothermal power generation may have caused the magnitude 5.5 earthquake that shook part of South Korea on November 15, 2017. The liquid, pumped underground by the Pohang power plant, could have triggered a rupture along a nearby fault zone that was already stressed, two new studies suggest.

If it’s confirmed that the plant is the culprit, the Pohang quake, which injured 70 people and caused $50 million in damages, would be the largest ever induced by enhanced geothermal systems, or EGS. The technology involves high-pressure pumping of cold water into the ground to widen existing, small fractures in the subsurface, creating paths for the water to circulate and be heated by hot rock. The plant then retrieves the water and converts the heat into power.
Researchers examined local seismic network data for the locations and timing of the main earthquake, six foreshocks and hundreds of aftershocks to determine whether the temblors might have been related to fluid injections at the Pohang plant. Almost all of the quakes originated just four to six kilometers below surface points that were within a few kilometers of the plant, report geologist Kwang-Hee Kim of Pusan National University in South Korea and colleagues online April 26 in Science. These factors, combined with the lack of seismic activity in the region before the injections, suggest the injections were to blame for the quakes, the researchers found.
Another team led by seismologist Francesco Grigoli of ETH Zurich in Switzerland used the same methodology but analyzed data from regional and international, rather than local seismic stations. The researchers came to a similar conclusion
in a second paper published online April 26 in Science . These findings could be a “game changer” for the geothermal industry, prompting a reevaluation of the dangers associated with EGS, Grigoli and colleagues note.
Previous studies suggest that induced quakes can be closely linked to how much fluid is injected into the ground, whether for fracking (SN Online: 1/18/18), wastewater disposal (SN: 8/10/13, p. 16) or EGS. The higher the volume, the stronger the associated quakes as fluid injections increase subsurface pressures and make it easier for fractures to slip, researchers say. In the United States, the largest known human-induced earthquake, a magnitude 5.7 temblor in Oklahoma in 2011, was triggered by injections totaling some 20 million tons of wastewater from oil drilling.

The largest quake previously known to be triggered by EGS was a magnitude 3.4 temblor in Basel, Switzerland, one of a series of quakes that ultimately led to the shuttering of a geothermal power plant there.

Researchers initially believed that the injected volumes were too small to cause much shaking. The Pohang plant began injecting water in early 2016, putting a total of 12,800 cubic meters into the ground before the 2017 quake. Early quakes were small: Kim and colleagues found that each pulse of injected water was followed by a series of smaller quakes a few days later. But as the total volume in the subsurface increased with each injection, the quakes also grew a bit stronger, the team reported, suggesting that even a small increase in underground pressure can cause certain faults to rupture, depending on the structure of the fault zones.
The South Korean government is currently doing its own investigation into whether the November 15 quake was linked to EGS activity, or influenced by natural seismic activity, says Stanford University geologist William Ellsworth, a member of an international group advising the investigation. Operations at the plant are suspended until the investigation is completed, expected to be by the end of the year or early next year.

The country sits atop a number of fault lines and has had several powerful earthquakes, some as large as magnitude 7, in the last few hundred years. Seismic activity has been low since 1905. But some research suggests the magnitude 9 earthquake in Tohoku, Japan, in 2011 may have increased subsurface stress in the nearby Korean peninsula, causing an uptick in its seismicity.

“It’s still a vigorous scientific debate,” Ellsworth says. “This earthquake provides an unusual opportunity to understand much more about the connection between injections and the triggering of an earthquake.”

As bioterrorism fears grow, the first treatment for smallpox has been approved.

Called tecovirimat, the drug stops the variola virus, which causes smallpox, from sending out copies of itself and infecting other cells. “If the virus gets ahead of your immune system, you get sick,” says Dennis Hruby, the chief scientific officer of pharmaceutical company SIGA Technologies, which took part in developing the drug. “If you can slow the virus down, your immune system will get ahead.”
An advisory committee to the U.S. Food and Drug Administration unanimously recommended approval of tecovirimat, or TPOXX, on May 1. The FDA announced the approval July 13.

Unchecked, smallpox kills about 30 percent of people infected and leaves survivors with disfiguring pox scars. Between 300 million and 500 million people died of smallpox in the 20th century before health officials declared the disease eradicated in 1980 after a worldwide vaccination campaign. For research purposes, samples of the virus remain in two locations — one in the United States, the other in Russia.
People haven’t been routinely vaccinated against the disease since the 1970s. So “it would be catastrophic if it were to reappear accidently or in the case of a bioweapon attack,” says molecular virologist Robin Robinson. He is the former director of the Biomedical Advanced Research and Development Authority, a federal agency that’s focused on protecting against biological and other threats and that assisted in the drug’s development.

Fears that the disease could be used as a biological weapon have risen in light of anthrax attacks and other terrorist acts of this century. The National Institute of Allergy and Infectious Diseases classifies smallpox as a Category A priority pathogen, because the disease spreads easily from person to person and can be highly fatal.

Researchers tested how well the drug stops smallpox in animals, while trials to determine the safety and dose of the drug were conducted in people. In monkeys and rabbits infected with viruses related to smallpox, tecovirimat prevented around 90 percent of the animals from dying, says SIGA CEO Phil Gomez. Nearly all of the animals that did not receive the drug died.

A smallpox infection does not produce symptoms right away. After 10 to 14 days, a fever and rash occurs — that’s when a person is most contagious — followed by the formation of poxes. The drug is meant to be taken at the fever and rash stage. Data from the animal studies, Hruby says, suggest that few poxes will form once the drug is taken and patients will heal more quickly.

“Preparing for disasters comes in different shapes and forms,” says Grant McFadden, who studies poxviruses at Arizona State University in Tempe and was not involved with the development of tecovirimat. “This is preparing for an infectious disease disaster.” In the event that smallpox reappears, “you need drugs to actually block the progression of the disease.”

Two million treatments of TPOXX are already in the U.S. Strategic National Stockpile of drugs and supplies for public health emergencies, Gomez says, a move allowed under emergency preparedness legislation. FDA approval of tecovirimat would open the door to studying the drug for other uses (such as a treatment for related poxviruses), assure the supply of the drug and encourage other countries to place the drug in their emergency stocks.

No one can predict if or when a pox virus is going to pop up and cause problems, says Hruby. With this drug, “I’d like to think you can sleep better at night.”

Mars is about to get its first internal checkup. The InSight lander, set to launch at 7:05 a.m. EDT on May 5 from Vandenberg Air Force Base in California, will probe the Red Planet’s innards by tracking seismic waves and taking its temperature.

Finding out what Mars’ interior is like could help scientists learn how the Red Planet formed 4.5 billion years ago, and how other rocky planets, including Earth, might have formed too. “It’s going to fill in some really big holes in our understanding of the universe,” says principal investigator Bruce Banerdt, a geophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
Mars is the perfect planet for this project: It’s large enough to be geologically interesting and, like the Earth, has a core and mantle beneath its crust. But the Red Planet isn’t so large and geologically active that its crust is constantly changing and erasing evidence of what it was like in the past.

“It’s kind of the Goldilocks planet,” Banerdt says.

InSight — short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport — was originally scheduled to launch in March 2016, but was pushed back because of equipment failure (SN Online: 12/23/15).

Assuming it reaches the surface of Mars in November, as planned, InSight will investigate the planet thousands of kilometers below the surface using two main instruments: a seismometer and a heat probe.
The seismometer will measure seismic waves rippling through the planet, similar to the way geologists study the interior of the Earth (SN: 9/16/17, p. 11). These waves move at different speeds through different materials, so tracking the rate at which the waves move can help scientists paint a detailed picture of Mars’ insides.

“We have spent a lot of effort scratching at the surface of Mars, but InSight is one of the first missions really dedicated to exploring the other 99.9999 percent of Mars,” says planetary scientist Matthew Siegler of the Planetary Science Institute, based in Dallas, who is not part of the InSight team. “We want to know what it is truly made of, not just the thin candy coating.”

Thanks to previous measurements of Mars’ gravity, astronomers expect to find a metallic core and a relatively dense mantle, but aren’t sure how large or dense each layer might be. Measuring these details precisely “will make a lot of models go into the trash,” Banerdt says.

Many of the Earth’s seismic waves are created by earthquakes rippling along tectonic plate boundaries. Mars lacks plate tectonics, but it still has smaller “Marsquakes,” triggered by the crust’s cooling and contraction. That process releases “little cracks and pops,” Banerdt says, which “on a planetary scale are quakes that can shake down buildings.”

The seismometer will also sense seismic waves rippling from Martian surface impacts, as well as gravitational tugs from Mars’ moon Phobos that periodically make the planet bulge by less than a centimeter. Measuring that bulging may yield information about the size and squishiness of the core, which in turn could help explain why Mars lost its magnetic field (SN Online: 3/27/18).
In addition to measuring faint ground vibrations, the seismometer is sensitive enough to pick up winds, temperature shifts and leftover magnetism in the rocks. So InSight’s seismometer will also carry a weather station and a magnetometer to make sure the team can subtract out signals that don’t come from underground. These weather measurements could potentially be used to plan future human missions to Mars (SN: 1/20/18, p. 22) .
To check Mars’ internal temperature, InSight will dig into the surface and measure every half-meter down to 5 meters. Temperature changes over that small distance will probably be tiny. But they could be used to extrapolate to further depths and to calculate how much heat is coming up from inside, revealing how geologically active Mars is. More heat means more activity.

The spacecraft itself might look familiar: The design was reused from the 2008 Phoenix lander, which found water ice in Mars’ polar regions during its five-month mission (SN: 6/21/08, p. 10). But InSight has larger solar panels, which should allow it to measure seismic signals for at least one Martian year (about two Earth years). The lander will touch down near Mars’ equator to get extra sunlight.

InSight will be the first interplanetary mission to launch from California. The spacecraft will spend several months in transit. Once it lands, a robotic arm will pick up each of the instruments and gently place them on the ground over the following month or two.

“From then on, we’re very quiet — these instruments need to make their measurements in as quiet a situation as possible,” Banerdt says. “Nothing much happens after that, except we get great science.”

The mission will also test a new way to relay that data back to Earth. InSight will carry the first interplanetary CubeSats — a pair of tiny satellites called MarCO that will be dropped off in Mars’ orbit. While other existing Mars orbiters will send back much of InSight’s information, the lightweight CubeSats will be tested at the task.

“We’ve been working to get a mission like this for 25 or 30 years,” Banerdt says. “It’s really an incredible rush to be getting close to launching this thing.”

You can watch the launch coverage starting at 6:30 a.m. EDT on NASA’s website.

Somewhere in the wetlands of South Carolina, a buzzing fly alights on a rosy-pink surface. As the fly explores the strange scenery, it unknowingly brushes a small hair sticking up like a slender sword. Strolling along, the fly accidentally grazes another hair. Suddenly, the pink surface closes in from both sides, snapping shut like a pair of ravenous jaws. The blur of movement lasts only a tenth of a second, but the fly is trapped forever.

“We don’t think plants move at all, yet they can move so fast you can’t catch them with the naked eye,” says Joan Edwards, a botanist at Williams College in Williamstown, Mass.
We tend to picture plants as static life-forms rooted in place until they die. To describe something boring, we say it’s “like watching grass grow.” But this is a stale view of plant life.

All plants grow, a rather slow form of motion, but many can also move rapidly. The snapping jaws of the Venus flytrap (Dionaea muscipula) are the most famous example, but far from the only one. The botanical world offers plenty of equally impressive feats. The explosive sandbox tree (Hura crepitans), also known as the dynamite tree, can launch seeds far enough to cross an Olympic-sized swimming pool; sundews (genus Drosera) have sticky tendrils that curl around prey; and the touch-me-not (Mimosa pudica) folds in its compound leaves within seconds of a touch.

“Plants have evolved a number of different approaches and mechanisms for movement,” Edwards says. This variety has resulted in a huge spectrum of plant speed, from the crawl of roots (1 millimeter per hour) to the explosive launch of seeds (tens of meters per second).
Fascinated with the Venus flytrap’s fast, forceful snap, Charles Darwin called the plant “one of the most wonderful in the world.” He performed all manner of flytrap-focused experiments, described in his 1875 book Insectivorous Plants. Darwin baited the plants with raw meat, prodded them with objects as fine as human hairs and even tested how the plants’ traps reacted to drops of chloroform. Although Darwin didn’t fully unlock the flytrap’s secrets, he understood that its speed had to do with the geometry of its leaves.

Modern research on rapid plant movement has precision that Darwin would envy. A little over a decade ago, scientists began using high-speed digital cameras and computer modeling to get a new view on plant motion. Frame-by-frame analyses, along with improved resolution, at long last offered a detailed look at the mechanisms that give plants their speed.

Most recently, evidence points to the existence of a startling variety of these mechanisms. In the last few years alone, researchers have discovered contraptions that kick like a soccer player, throw like a lacrosse player and even generate heat to launch seeds explosively.

Nearly 150 years after Darwin’s work, the impetus for such research remains the same — a fascination with the movement of plants.
Moving without muscles
Yoël Forterre was a postdoc at Harvard University in the early 2000s when his adviser was given a Venus flytrap as a gift. Never having seen the plant before, Forterre was amazed at its ability to move without muscles. He soon realized that the motion could be understood through the lens of his own specialty: soft matter physics, a field concerned with the mechanics of deformable materials like liquids, foams and some biological tissues.

Forterre published a study in 2005 in Nature that was among the first to leverage both high-speed cameras and computer modeling to study mechanisms of rapid plant movement (SN: 1/29/05, p. 69).

“The big transformation was digital high-speed cameras,” says Dwight Whitaker, an experimental physicist at Pomona College in Claremont, Calif. Around this time, the cameras were making their way into academic labs. “With film, you get one chance,” he says. Everything has to be arranged in advance, “which is why directors need to say ‘lights, camera, action!’ in that order.”

With the new technology, Forterre and colleagues could track the tiniest changes in the curvature of the flytrap’s leaves, which face each other like two halves of a book. This allowed the team to see how the plant’s speed relies on the special geometry of those leaves. When the trap is triggered by a fly or other wayward prey, cells on the green outer surfaces of the leaves expand while the pink inner surfaces don’t. This creates a tension as the outer surface pushes inward. Eventually, the pressure becomes too great and the leaves, originally convex in shape, rapidly flip to concave, slamming the trap shut in a process known as snap-buckling.

One way of understanding this elastic motion is to look at a popular children’s toy, says Zi Chen, an engineer at Dartmouth College who also studies the flytrap. Rubber poppers are little rubber hemispheres that can be inverted. Like a compressed spring, the inverted toys have a lot of potential energy. The poppers convert that energy into kinetic energy as they revert to their original shape, launching several feet into the air. Similarly, potential energy from the tension of the outer surfaces against the inner surfaces of a flytrap’s leaves is converted to kinetic energy, allowing the trap to slam shut in about a tenth of a second.
Blasting off
Around the same time Forterre was scrutinizing flytraps, Edwards and her husband were at Lake Superior’s Isle Royale, leading a group of budding researchers doing fieldwork on native plants.

As Edwards tells it, a student stuck her head down to sniff a flower of the bunchberry dogwood (Cornus canadensis) and announced that “something went poof.” Intrigued by this distraction, the team brought specimens back to the lab to capture the behavior on video camera. But whatever triggered the dogwood poof wasn’t visible. So Edwards upgraded to a 1,000-frames-per-second camera.

“It was still blurry, so I thought something was wrong with the camera,” she says.

She brought the problem to Whitaker, who was then at Williams. It turned out the plant was moving too quickly for the camera to capture. Edwards ordered a special 10,000-frames-per-second camera — then top of the line — and for the first time saw the mechanism clearly (SN: 6/11/05, p. 381).

Four petals fused together barely hold down four bent, armlike stamens that protrude from the petals’ embrace. When disturbed — by a fat bumblebee or the nose of an inquisitive human — the petals split apart, freeing the stamens. The stamens flip outward, accelerating to a g-force of 2,400, each flinging a pollen sack attached to the tip. (For comparison, fighter pilots can handle a g-force of about 9 before passing out.) This flower trebuchet launches the pollen at whatever triggered the burst, or into the wind.
This early work signaled the start of a now-flourishing research area. High-speed cameras and other high-tech equipment were soon used to study more plants, revealing the secrets of their speed.

Edwards and Whitaker, for example, discovered that, like a detonating nuclear bomb, a peat moss named Sphagnum affine explodes into a mushroom cloud. On dry, sunny days, tiny, bloated spore capsules dotting the moss’ surface dehydrate, shrinking down and increasing the air pressure within the capsules to several atmospheres. When the pressure becomes too great, a capsule explodes into a cloud of spores. With the help of computer modeling, the duo reported in 2010 that the ominously shaped explosion granted the spores 20 times the height they would otherwise have, boosting their chances of catching a good breeze.

Some plants manage such impressive motion underwater. Bladderworts (genus Utricularia) come in aquatic forms, with flowers thrusting up from freshwaters and thin leafy stalks below the surface. The stalks are dotted with traps that are a few millimeters in size and shaped like a sack with a hinged lid. To set a trap, a plant pumps out water from inside the sack, which inverts its sides like a pair of sucked-in cheeks. When prey such as mosquito larvae trigger hairs at the trap’s mouth, the lid opens. Water from outside rushes in, pulling in the prey, which is trapped when the lid closes. From open to close, bladderworts can trap prey in about a millisecond.
Water is, in fact, a key player in the most fundamental of plant movements: growth.

“Growth occurs when water moves into a cell and inflates it,” says Wendy Kuhn Silk, a biologist at the University of California, Davis. “The speed of most growth responses is determined by the rate of water movement in a tissue.”

By moving water from cell to cell, plants can push out their branches and send their roots through the soil or angle their leaves toward the sun. But such movements are only so fast; a Venus flytrap relying on water-driven motion might take 10 seconds to close its trap. It’s hard to imagine even the most lethargic fly falling for this kind of slow-motion ambush.

Plants overcome these constraints through mechanical instabilities, created by storing energy through growth. Like the string of a bow pulled until taut, plants can store up potential energy. When the string is pulled too far, or nudged enough, it releases, transforming potential energy into kinetic energy.

Mechanical instabilities give the flytrap its snap, and even allow some plants to jump. Commonly known as the horsetail plant, Equisetum releases microscopic spores shaped like a bendy X. When wet, the legs of Equisetum spores curl up. As the spores dry, their legs uncurl. The curling and uncurling that come with humidity changes let the spores skitter around. Sometimes the legs compress before releasing, a forceful kick that sends a spore hopping into the wind.
Myriad mechanisms
The variety of mechanisms has proven as impressive as the speed. To the snap traps and catapults that were the focus of the initial inquiries, in just the last few years researchers have added mechanisms that rely on explosive heat, kicking teeth and lacrosselike flicks. “What we know today is the sheer diversity of it,” says Whitaker, before rattling off half a dozen different plant species, all with different mechanisms for rapid movement.

The American dwarf mistletoe (Arceuthobium americanum) had long been known to harbor rapid movement. Studies in the 1960s found that the parasitic plant, which grows in bulbous sprigs from the branches of pine trees on the West Coast, could disperse its seeds up to about 20 meters per second. But in 2015, after studying the mistletoe with thermal imaging that could detect minute changes in temperature across areas smaller than a millimeter, researchers reported in Nature Communications that the dispersal was triggered by self-produced heat. About a minute before the mistletoe releases its seeds, the plant warms up by roughly 2 degrees Celsius, thanks to a heat-producing reaction in its mitochondria. Like a lit fuse, this reaction triggers a gooey gel in the plant to expand, launching the seeds explosively.
One of the smallest and strangest mechanisms yet discovered was reported this February in the journal AoB Plants. Using cameras that can record microscopic movements at 1,000 frames per second, researchers found that the moss Brachythecium populeum is a star soccer player that can kick with its “teeth,” pliable structures of tissue that surround the spores. When the plant’s microscopic teeth absorb water, they bend and warp. As they dry, the teeth flick outward, lifting the spores to get caught in the wind.

Soon after, in March, researchers described a mechanism similar to how a lacrosse stick flings a ball, in the hairyflower wild petunia (Ruellia ciliatiflora). The flower (which despite its name, isn’t part of the petunia family) has elongated seedpods. Each pod holds about 20 disk-shaped seeds in hooks. As the seedpod grows, it strains at its seams, which can be weakened by water. When the pod splits in two, the hooks fling the seeds, giving them a dizzying spin of nearly 100,000 revolutions per minute, the researchers reported in the Journal of the Royal Society Interface. This spin, which is the fastest yet observed in any plant or animal, keeps the seeds in stable flight.
In search of speed
Despite all these efforts, the physicists, botanists and engineers who have taken part in these studies are still a disparate group. “I wander around, a bit like an outcast,” Whitaker admits. Whether it’s a biology conference or a physics conference, people are interested but unsure what he’s doing there. “This is a very young field.”

And there’s a lot still to figure out, adds Forterre, now at Aix-Marseille University in Provence, France. The Venus flytrap, extensively studied, still holds mysteries.

Researchers know that an electrical signal is sent to the plant’s leaves when a fly brushes the trap’s hairs. Somehow, the plant cells expand, resulting in now-understood snap-buckling. But researchers aren’t sure what the electrical signal is telling the cells or how exactly the cells expand.

One theory proposes that the electrical signal triggers the release of an acid that weakens the cell walls. Another posits that the electrical signal causes the plant to pump water into the cells of its outer surface, beginning the snap-buckling. Forterre is attempting to use cell pressure probes to settle the dispute, but getting the tool to work in a moving plant is easier said than done.
Researchers are also keen to understand how plants evolved their myriad movement methods. For a lot of plants, the “why” is fairly clear: Plants that can quickly capture insects get a good source of nutrients — nitrogen and phosphorus — that the plants might not be able to get in abundance from the soil. Similarly, plants that move quickly may disperse their seeds farther, gaining an evolutionary advantage over those that don’t.

But understanding how the speed came to be is much trickier. A recent clue might help piece together the evolutionary story of bladderworts. In a 2017 overview published in Scientific Reports, Anna Westermeier reported something intriguing: one species that had the architecture of the trap, but did not open or close.

This species appears to be a more primitive form in which a trap developed but did not become fully functional, according to Westermeier, of the University of Freiburg in Germany. Identifying relatives that have pieces of mechanisms could help reveal how rapid motions evolved. Whitaker is hoping to find similar potential clues by looking more broadly at plants in the family Acanthaceae, which includes the hairyflower wild petunia and thousands of other species of flowering plants, nearly all of which have some form of explosive seed dispersal.

The great diversity so far uncovered is impressive, but is it unexpected?

“It’s not surprising at all,” says Karl Niklas, a plant expert at Cornell University. Niklas has studied plant evolution for over four decades. “It’s human ego,” he says, dismissing the idea that animal movement is anything special. “And I think plants will be around a lot longer than we will.”

A measly 250 million years after the Big Bang, in a galaxy far, far away, what may be some of the first stars in the universe began to twinkle. If today’s 13.8-billion-year-old universe is in middle age, it would have been just starting to crawl when these stars were born.

Researchers used instruments at the Atacama Large Millimeter/submillimeter Array observatory in Chile to observe light emitted in a galaxy called MACS1149-JD1, one of the farthest light sources visible from Earth. The emissions are a clue to the galaxy’s redshift — a stretching of the wavelength of light that signifies the speed at which an object is moving away from an observer. Scientists can use redshift to estimate how far away (and by extension, how old) a celestial object is.

The galaxy’s redshift suggests that the starlight was emitted when the universe was about 550 million years old, researchers report May 17 in Nature. But many of those stars were already about 300 million years old, further calculations indicate. That finding suggests that the stars would have blinked into existence some 250 million years after the universe’s birth, says study coauthor Takuya Hashimoto, an astronomer at Osaka Sangyo University in Japan.

That’s earlier than the 550 million years ago suggested in a previous estimate that also measured starlight from the early universe (SN Online: 2/9/2015). But it’s in the same ballpark as observations reported in March (SN: 3/31/18, p. 6), which suggest star formation began around 180 million years after the Big Bang. That conclusion, however, was drawn from radio signals rather than direct observations of starlight. “If [those] results were true, our results would independently support their claims that star formation activity had already initiated at a very early stage of the universe,” Hashimoto says.

The largest particle detector of its kind has failed to turn up any hints of dark matter, despite searching for about a year.

Known as XENON1T, the experiment is designed to detect elusive dark matter particles, which are thought to make up most of the matter in the cosmos. Physicists don’t know what dark matter is. One of the most popular explanations is a particle called a WIMP, short for weakly interacting massive particle. XENON1T searches for WIMPs crashing into atomic nuclei in 1,300 kilograms of chilled liquid xenon. But XENON1T saw no such collisions. The particles’ absence further winnowed down their possible hiding places by placing new limits on how frequently WIMPs can interact with nuclei depending on their mass.

Researchers describe the results May 28 in two talks, one at Gran Sasso National Laboratory in Italy, where XENON1T is located, and the other at the European particle physics lab CERN in Geneva. XENON1T had previously reported no hint of WIMPs using about a month’s worth of data (SN: 9/30/17, p. 17). The new study, however, was highly anticipated by physicists, as the longer search provided a better chance for spotting WIMPs.

As the WIMP window narrows, scientists are preparing to rev up the search, creating larger, more sensitive WIMP detectors, and moving on to search for other possible dark matter particles, such as axions (SN Online: 4/9/18).

The first estimate of how many deaths and heart problems could be avoided under new blood pressure guidelines shows it’s well worth it for the U.S. population to get its blood pressure under control, researchers say.

The new guidelines, announced in 2017 by the American College of Cardiology and the American Heart Association, redefined hypertension as a blood pressure reading of 130/80 or higher (SN: 12/9/17, p.13). The previous threshold was 140/90. As a result, 105 million U.S. adults age 20 and older are now considered to have hypertension, 31 million more than before.
An estimated 334,000 deaths could be prevented annually if those aged 40 and older keep their blood pressure below the new threshold, researchers report online May 23 in JAMA Cardiology. And 610,000 heart attacks, strokes and other consequences of cardiovascular disease could also be avoided each year. The shift to the lower blood pressure target prevents an additional 156,000 deaths and 340,000 cardiovascular-related illnesses compared with the previous target.

But adhering to the guidelines means doctors may recommend that 83 million adults, 11 million more than before, take blood pressure medications. Those drugs carry a risk of side effects, including kidney damage or abnormally low blood pressure. Of those taking the drugs, 62,000 people’s blood pressure could dip too low and 79,000 might suffer kidney injury or failure, epidemiologist Jiang He of Tulane University in New Orleans and his colleagues estimate.

More research is needed on whether kidney damage related to blood pressure drugs is long-term or temporary, He says. But taking the medication is far less expensive than dealing with a possible heart attack or stroke, he adds.

“Our data really show the beneficial effect of lower blood pressure,” He says.

Some dogs in China carry a mixed bag of influenza viruses. The discovery raises the possibility that dogs may be able to pass the flu to people, perhaps setting off a pandemic.

About 15 percent of pet dogs that went to the vet because of respiratory infections carried flu viruses often found in pigs, researchers report June 5 in mBio. Of the virus strains detected, three have recombined in dogs to form new varieties.

That mixing generates genetic diversity in the viruses that makes them potentially a pandemic threat, says study coauthor Adolfo García-Sastre, a virologist who directs the Global Health and Emerging Pathogens Institute of the Icahn School of Medicine at Mount Sinai in New York City.
Evolution of the flu viruses in dogs has been very rapid, occurring in just a few years, García-Sastre says. There’s no sign yet that the dog flu viruses can infect people, but that could change. “The more diversity of viruses there is in an animal reservoir, the higher the chances that it will lead to a version of the virus that is able to jump” to humans, he says.

Pigs and birds remain the prime suspects for mixing up the next human pandemic influenza virus, says Amesh Adalja, an infectious disease physician at Johns Hopkins University and a spokesperson for the Infectious Diseases Society of America. Even if a dog flu virus infected a person, the pathogen may not be able to transmit easily from person-to-person — an important characteristic a virus must have before it can circulate around the world.

But because most people encounter dog noses far more frequently than those of pigs, it’s worth keeping an eye on the pups, Adalja says. “Knowing that dogs could contribute is important for preparing for the next pandemic, because we don’t know exactly what that virus will be,” he says.
The first flu virus in dogs was discovered in 2005 in the United States. That pathogen, from a horse flu virus called H3N8 that had jumped to canines, sometimes spreads among pooches in shelters (SN: 10/8/05, p. 237). And, in 2010, some dogs in Asia were found carrying a version of the H3N2 virus from birds. (Cats can catch the dog H3N2 flu virus, but don’t transmit it to other cats, as far as scientists know.)

In the new study, the team swabbed the noses of 800 dogs in the Guangxi region of southern China from 2013 to 2015. All of the dogs had respiratory illnesses, but only 116 were infected with influenza viruses. To the scientists’ surprise, the dogs had various swine H1N1 flu viruses. The researchers determined the genetic makeup of 16 of the samples and discovered that some of these swine viruses had previously circulated in people and pigs in Europe and Asia. Some are strains of bird flu that have infected pigs.

In pigs, the viruses swapped genes among themselves, creating new varieties, some of which were passed to dogs. A virus genetically similar to one of the swine viruses passed to dogs was found in a person in China, raising the possibility that some swine flus can strike both pups and people. Dogs remixed some of the viruses from the pigs with bits of the dog flu virus in Asia, creating the three new canine influenza virus strains, the researchers found.

Since the study collected samples from only one part of China, the team doesn’t know how widespread flu is among dogs, or how many canine-infecting influenzas may be out there.

Finding flu viruses in dogs isn’t cause for alarm. But researchers should monitor the situation and use vaccines, quarantine and other infection-control methods to limit outbreaks and keep the canine viruses from catching hold in humans, García-Sastre says.

From beef to beer, coffee to chocolate, there are environmental costs in what humanity chooses to eat and drink. Now a new study that quantifies the impact on the planet of producing and selling 40 different foods shows how these choices make a difference.

Agricultural data from 38,700 farms plus details of processing and retailing in 119 countries show wide differences in environmental impacts — from greenhouse gas emissions to water used — even between producers of the same product, says environmental scientist Joseph Poore of the University of Oxford. The amount of climate-warming gases released in the making of a pint of beer, for example, can more than double under high-impact production scenarios. For dairy and beef cattle combined, high-impact providers released about 12 times as many greenhouse gases as low-impact producers, Poore and colleague Thomas Nemecek report in the June 1 Science.
Those disparities mean that there is room for high-impact producers to tread more lightly, Poore says. If consumers could track such differences, he argues, purchasing power could push for change.

The greatest changes in the effect of a person’s diet on the planet, however, would still come from choosing certain kinds of food over others. On average, producing 100 grams of protein from beef leads to the release of 50 kilograms of greenhouse gas emissions, which the researchers calculated as a carbon-dioxide equivalent. By comparison, 100 grams of protein from cheese releases 11 kilograms in production, from poultry 5.7 kilograms and from tofu two kilograms.
Replacing meat and dairy foods from producers with above-average environmental effects with plant-based products could make a notable difference in greenhouse gas emissions. If cuts came from these higher-impact suppliers, replacing half of each kind of animal product with something from a plant could reduce food’s share of emissions by 35 percent. That’s not too far from the 49 percent drop that could be achieved if the whole world, somehow, went vegan.
The case for switching to a plant-based diet was already pretty powerful, says Ron Milo of the Weizmann Institute of Science in Rehovot, Israel, who studies cell metabolism and environmental sustainability. The new data “make it even stronger, which is an important thing given how strongly we tend to adhere to our food choices,” he says.
In their study, Poore and Nemecek, of the Swiss government research organization Agroscope in Zurich, also considered the amounts of water and land used as well as nutrient runoff and air pollution created from food production. For such an unusually broad analysis, the researchers crunched the numbers from 570 studies of what are called life-cycle assessments for 40 kinds of food. These studies calculated the environmental impacts of the whole process from growing or processing to transporting and retailing each food.

Producing food overall accounts for 26 percent of global climate-warming emissions, and takes up about 43 percent of the land that’s not desert or covered in ice, the researchers found. Out of the total carbon footprint from food, 57 percent comes from field agriculture, livestock and farmed fish. Clearing land for agriculture accounts for 24 percent and transporting food accounts for another 6 percent.

After the first year of putting the study together, Poore himself gave up eating animal products.