Experimental anticancer drugs may help protect against liver damage caused by acetaminophen overdoses.
In mice poisoned with the common painkiller, the drugs prevented liver cells from entering a sort of pre-death state known as senescence. The drugs also widened the treatment window: Mice need to get the drug doctors currently use to counteract an overdose within four hours or they will die, but the experimental drugs worked even 12 hours later, researchers report August 15 in Science Translational Medicine. If the liver-rescuing results are verified in clinical trials, this therapy may buy time for people who accidentally or intentionally overdose on Tylenol or other medications containing the painkiller acetaminophen. In the United States, such overdoses occur more than 100,000 times a year and are the leading cause of acute liver failure. Many people get treatment on time or recover on their own, but some require emergency liver transplants. And 150 people on average die of acetaminophen poisoning each year.
Currently, doctors treat such overdoses with N-acetylcysteine, an antidote that must be given within eight hours of ingesting a potentially fatal dose. Some people don’t make it to a doctor in time, and will die or need transplants.
In the study, untreated mice died within 18 hours. But mice given the new drugs survived at least a week until researchers sacrificed the rodents to examine their livers.
The anticancer drugs work by blocking a signal from a tumor growth-stimulating protein called TGF-beta, which is activated by inflammation provoked by the overdose. When unchecked, TGF-beta sends a stress signal that puts liver cells in senescence, liver specialist Thomas Bird of Cancer Research UK Beatson Institute in Glasgow and colleagues report.
Freshwater is crucial for drinking, washing, growing food, producing energy and just about every other aspect of modern life. Yet more than 2 billion of Earth’s 7.6 billion inhabitants lack clean drinking water at home, available on demand.
A major United Nations report, released in June, shows that the world is not on track to meet a U.N. goal: to bring safe water and sanitation to everyone by 2030. And by 2050, half the world’s population may no longer have safe water.
Will people have enough water to live?
Two main factors are pushing the planet toward a thirstier future: population growth and climate change. For the first, the question is how to balance more people against the finite amount of water available. India has improved water access in rural areas, but remains at the top of the list for sheer number of people (163 million) lacking water services. Ethiopia, second on the list with 61 million people lacking clean water, has improved substantially since the last measurement in 2000, but still has a high percentage of total residents without access.
Short of any major but unlikely breakthroughs, such as new techniques to desalinate immense amounts of seawater (SN: 8/20/16, p. 22), humankind will have to make do with whatever freshwater already exists.
Most of the world’s freshwater goes to agriculture, mainly to irrigating crops but also to raising livestock and farming aquatic organisms, such as fish and plants. As the global population rises, agricultural production rises to meet demand for more varied diets. In recent decades, the increase in water withdrawal from the ground or lakes and rivers has slowed, whether for agriculture, industries or municipalities, but it still outpaced the rate of population growth since 1940. That means every drop is increasingly precious — and tough choices must be made. Plant your fields with sugarcane to make ethanol for fuel, and you can’t raise crops to feed your family. Dam a river to produce electricity, and people downstream can no longer fish. Pump groundwater out for yourself, and your neighbor might just want to fight over it. Researchers call this the food-water-energy nexus and say it is one of the biggest challenges facing our increasingly industrialized, globalized and thirsty world.
“There just isn’t enough water to meet all our needs,” says Paolo D’Odorico, an environmental scientist at the University of California, Berkeley whose team analyzed the food-water-energy nexus in a paper published online April 20 in Reviews of Geophysics.
Overall, the energy sector is expected to consume more and more water in decades to come. And sometimes what sounds like a good idea — such as switching to renewable energy sources to reduce carbon emissions — might help in one area but hurt in another. For example, it can take more water to grow biofuel crops than to consume fossil fuels. ** Water consumption is defined as water that is used and not returned to its source. These projections are based on nations’ stated commitments to phase out fossil fuel subsidies and reduce emissions of greenhouse gases.
Source: World Energy Outlook 2016 Special Report: Water-Energy Nexus/IEA
Then there’s climate change. As greenhouse gases build up in Earth’s atmosphere, trapping heat and altering the planet’s weather and climate, water will become more precious. Rising global temperatures alter weather patterns and change how water cycles between the ground and the atmosphere. Freshwater stores can shrink. Extreme events, such as flooding and drought, are becoming more common on our warming planet (SN: 1/20/18, p. 6). That means more water in places where people don’t need it, and less water where they do.
The map below shows how water stress — the ratio of water use to water supply — is expected to look by the year 2040. It assumes a “business-as-usual” scenario in which carbon emissions rise steadily. The highest stress is expected in areas where water supply is vulnerable because of already arid climates and growing populations. Cities will bear the brunt of future water shortages. Early this year, it looked as if the more than 4 million people living in Cape Town, South Africa, were going to run out of water. Officials calculated a “Day Zero” in April when the taps would run dry. Only through belated and desperate conservation measures, such as slashing the amount of water for irrigating crops, did city residents eke through until the rainy season began in May. That Cape Town crisis is almost certainly the first of many.
By 2050, some 3.5 billion to 4.4 billion people around the world will live with limited access to water, more than 1 billion of them in cities. Among 482 cities, more than a quarter will face demands that outpace supply, according to a study that analyzed water sources and demands. In general, urban growth is the main driver of cities’ future water deficits. Los Angeles tops the list because its population is expected to boom even as climate change dries up its water sources. Cities will be worse off if other sectors get priority for water access. In the face of such inexorable changes, it’s easy to despair. But science offers hope, in the form of alternative paths forward. Computer modelers at MIT, for example, find that policies to fight climate change, such as the 2015 Paris agreement that the United States announced its intention to pull out of last year (SN Online: 6/1/17), can reduce the severity of future water shortages. If nations follow commitments similar to those in the agreement, 60 million people across Asia could avoid dire water scarcity by 2050, the team wrote in June in Environmental Research Letters.
But the Paris agreement is not enough. As research increasingly makes clear, there are trade-offs and decisions to be made. Cape Town’s experience shows how governments need to better prepare for the competing demands on water supplies. Municipalities may need to raise the cost of water to the point where people value it enough to conserve it.
“We can address the problem by thinking about technological solutions, but we also have to think about changing our behavior,” says Martina Flörke, a hydrologist and environmental scientist at the University of Kassel in Germany. “If we can make clear … that water has value, that it’s an ecosystem service that we use and have to take care of — then we are really thinking about how to adapt.”
Here’s good news for anyone who’s had to sweep up pasta shards after snapping dry spaghetti and thought, “there’s got to be a better way.”
There is.
Simply bending a stick of spaghetti in half typically shatters it into three or more fragments. That’s because when the stick breaks, vibrations wrack the remaining halves, causing smaller pieces to splinter off (SN: 11/12/05, p. 315). To avoid this problem, give the spaghetti stick a twist before bending it, researchers report online August 13 in Proceedings of the National Academy of Sciences. Vishal Patil, a mathematician at MIT, and colleagues discovered this technique by breaking hundreds of pieces of pasta with a custom-made spaghetti-snapping device. These observations, along with computer simulations of the system, reveal that when a spaghetti stick is twisted, it doesn’t bend as far before breaking. As a result, the vibrations that rattle the spaghetti halves post-snap aren’t strong enough to cause further fracturing.
The exact amount of twist required to give pasta a clean break depends on the length of the rod, but for a typical stick 24 centimeters long to crack neatly in two, it’s at least 250 degrees.
This strategy may not be much practical help in the kitchen; Patil and colleagues aren’t selling their spaghetti snapper for $19.95 — and even if they were, meticulously twisting and bending pieces of pasta one-by-one is hardly efficient meal prep. Still, the discovery of the bend-and-twist technique may lend new insight into controlling the breakage of all kinds of brittle rods, from pole vault sticks to nanotubes.
Half a century ago, if you asked any teenage science fan to name the best popular science writers, you’d get two names: Isaac Asimov and George Gamow.
Asimov was prominent not only for his nonfiction science books, but also for his science fiction. Gamow was known not only for writing popular science, but was also a prominent scientist who had made important contributions both to physics and biology.
Fifty years ago this month, Gamow’s career ended when he died at the age of 64. His books and scientific papers survive him, leaving plenty of science and science writing worth celebrating. Nuclear physics, astrophysics, modern cosmology and molecular biology all benefited from Gamow’s fertile intellect. Like Asimov, Gamow was born in Russia (Odessa). But while Asimov came to the United States as a child, Gamow grew up in Russia, went to college first in Odessa (studying math) and then to the university in Petrograd (soon to become Leningrad), where he became a physicist. At Leningrad he attended lectures by the mathematician Alexander Friedmann. Friedmann was the first to fully realize that Einstein’s new general theory of relativity implied a dynamic universe — one that would expand or contract — rather than the static never-changing cosmos that most experts (including Einstein) believed in at the time.
Gamow planned to pursue a career in relativity under Friedmann’s direction. But Friedmann died young, in 1925. So Gamow fell in with a group of students more interested in quantum physics than relativity. “We spent all our time following the new [quantum] publications and trying to understand them,” Gamow wrote in his autobiography.
While a visitor at one of Europe’s top centers for quantum theory — the University of Göttingen in Germany — he solved a mystery about radioactive decay by identifying one of the quantum world’s most important phenomena: tunneling. In one form of radioactive decay, an atomic nucleus emits alpha particles that are moving too slowly to have overcome an energy “barrier” supposedly preventing their escape. (The analogy is a hill too steep for a slow-moving ball to reach the top without rolling back down.) Gamow showed that the wave mechanics version of quantum physics permitted the alpha particle to “tunnel” through the energy-barrier hill. Quantum tunneling turned out to be important for many other features of nature, such as how the sun shines, how many chemical reactions proceed and maybe even how the universe began. His work on tunneling impressed Niels Bohr, the leading quantum physicist in the world, earning Gamow a fellowship for study at Bohr’s Institute for Theoretical Physics in Copenhagen. During time there and at Cambridge University, Gamow became one of the world’s leading experts on nuclear physics theory. He also became well-known for his humor and irreverence, including a “relentless mockery of science’s solemnity,” as one biographical account put it. Returning to the Soviet Union in 1929, Gamow found the political atmosphere for continuing his work unfavorable. He eventually managed to emigrate to the United States, where he obtained a position at George Washington University in Washington, D.C., in 1934. There he studied the evolution and energy production of stars, producing fruitful insights into the stellar explosions known as supernovas. Later, he turned his attention to the universe at large, developing early versions of what became the Big Bang theory (Gamow didn’t like the name) of the origin and evolution of the universe. In 1942, the historian Helge Kragh wrote, “Gamow clearly endorsed a big-bang picture and suggested that the gross material of the present world is the result of what happened some two billion years ago in a highly compressed primeval state.” Gamow’s timing was off (it was nearly 14 billion years ago), but his basic idea was right. After World War II, Gamow found new fun with the “physics of biology.” He wondered, for instance, about the physical processes allowing cells to make proteins. Inspired by Watson and Crick’s 1953 paper on the structure of DNA — the molecule that makes genes — Gamow speculated that some sort of code could be translated from DNA to build the long chains of amino acids that constituted proteins. Nature provided merely 20 such amino acids for constructing thousands of distinct proteins.
Gamow realized that DNA’s four subcomponent “bases” could be thought of as numbers that could be translated into “words” specifying a chain of amino acids, linked in a specific order, chosen from their 20-letter “alphabet.” He saw that if you chose three DNA bases at a time, there were about 20 possible combinations, indicating that each three-base “triplet” might correspond to an amino acid. He couldn’t crack the code for which base combinations went with which amino acids, though, even with help from some U.S. Navy cryptologists. But Gamow had more or less the right idea, although he didn’t recognize at first that an intermediate molecule, RNA, had to “read” the DNA code first before transferring the information to the cell’s protein-making apparatus.
Throughout his career, Gamow desired to share his enthusiasm for the science he investigated, not only with fellow scientists but with people in general. Today, it is fairly common for prominent scientists to write popular books. But it was not that way in the 1930s, when Gamow first tried to explain relativity and quantum physics through the eyes of his fictional character, Mr. Tompkins. Mr. Tompkins lived in worlds where the speed of light was small or Planck’s constant was large, allowing Gamow to illustrate the strangeness of the new physics in an entertaining and intuitively accessible way. To learn about Heisenberg’s uncertainty principle, for instance, Mr. Tompkins visited a billiard parlor where a professor placed a ball inside a wooden triangle. The ball began to move rapidly at varying speeds within the triangle, because restricting its position to the triangular space increased the uncertainty about its velocity. (And then the ball escaped the triangle, not by jumping over its wooden wall, but by “leaking” through it. Tunneling.)
After many rejections, Mr. Tompkins in Wonderland appeared in 1940, followed by Mr. Tompkins Explores the Atom in 1944. Later Gamow produced other more straightforward accounts of the frontiers of physics, and science more generally, in such books as One Two Three … Infinity and Matter Earth and Sky.
Gamow moved to the University of Colorado in 1956, focusing on his popular books as his prominence in science diminished. His nonconformity and irreverent attitude, along with his emphasis on popularization, did not play well with many of his peers. And he was a heavy drinker, impairing his ability to engage with other physicists and possibly contributing to his death.
Still, his science was substantial. And even if it hadn’t been, his writing contributed to the scientific enterprise via another important avenue — by opening the wonders of the world of science to a great many teenagers who are scientists, or science writers, today.
A scientific takedown of a famous finding known as the 30-million-word gap may upend popular notions of how kids learn vocabulary.
Research conducted more than 20 years ago concluded that by age 4, poor children hear an average of 30 million fewer words than their well-off peers. Since then, many researchers have accepted the reported word gap as a driver of later reading and writing problems among low-income youngsters. A Providence, R.I., program inspired by the study, for example, now teaches poor parents how to talk more with their kids. But here’s the rap on the word gap: It doesn’t exist, says a team led by psychologist Douglas Sperry of Saint Mary-of-the-Woods College in Indiana. In a redo of the original study, virtually no class differences appeared in the number of words addressed to young children by a primary caregiver, Sperry and colleagues report in a study to be published in Child Development.
What’s more, after including speech spoken directly to children by various caretakers as well as family members’ conversations that the youngsters could easily overhear, kids in some poor and working-class communities heard more words on average than middle-class youngsters, the scientists say. Within each of those communities, some children heard many more words than others did despite belonging to the same social class, Sperry’s team adds.
“It’s time to turn a skeptical eye to the word-gap claim,” Sperry says.
Researchers usually treat word learning as a product of one or both parents regularly talking to a child. But different, equally effective ways exist for children to learn vocabulary, Sperry contends. Depending on culture and community, word learning depends to varying extents on a main caretaker talking to a child, many caretakers talking to a child and youngsters overhearing family members talking, he says (SN: 2/17/18, p. 22). The original word-gap study included 42 children in Kansas from either of four communities — poor, working class, middle class or wealthy professional. Sperry’s group analyzed data on word use collected during home observations of 42 children in five communities — poor whites in South Baltimore, poor blacks in Alabama, working-class (largely blue-collar) whites in Indiana and Chicago, and middle-class (largely white-collar) whites in Chicago. Videotaped home observations began when children were 18 to 30 months old. Intermittent observations continued until kids reached ages 32 to 48 months. Most primary caregivers were children’s mothers.
Primary caregivers in poor, black Alabama families directed an average of 1,838 words per hour to their children, close to the corresponding figure of 2,153 words per hour for high-income, white caregivers in Kansas in the original word-gap study. The earlier study reported that primary caregivers on welfare in Kansas spoke an average of 616 words per hour to their children, about one-third the total spoken to poor, black children in the new study. Primary caregivers from working-class and middle-class families in the new study uttered an average of 1,048 to 1,491 words per hour to youngsters.
Taking multiple caregivers into account, average hourly words spoken to children in each community increased by 17 percent or more. An increase of 58 percent occurred in Alabama’s poor, black households. In addition, kids in poor families overheard an average of 3,203 words per hour. Eavesdropping figures reached no higher than about 2,500 words per hour in the other households. Greater numbers of older siblings in the poor, black families contributed to that disparity, the researchers suspect.
The new study convincingly rejects claims of a word-gap for poor children, says cultural anthropologist Jennifer Keys Adair of the University of Texas at Austin.
White, middle-class parents and many educators wrongly assume that vocabulary learning always proceeds best via one-on-one interactions of parents with children, or teachers with grade-school students, Adair says. That assumption may not apply to kids from other cultural backgrounds. Adair has found, for instance, that first-graders from Latin American immigrant families — who were allowed to devise classroom projects, collaborate with one another and ask questions without raising their hands — did especially well three years later on state English assessments.
But some child researchers say the new study falls short of showing that poor kids are generally exposed to as much language as better-off peers.
Sperry’s group, for example, did not study children in upper-class, professional households, as researchers did in the 1990s. And other studies of early word learning point to a need for programs that help low-income parents engage their children in language-boosting conversations, conclude psychologist Roberta Golinkoff of the University of Delaware in Newark and colleagues in comment that will appear in the same journal.
“Overhearing language about death and taxes — topics of interest to adults — can never be as effective for language learning as participating in conversations about what matters to children,” Golinkoff and her colleagues write in their comment.
Kids frequently eavesdrop, Sperry responds. Ongoing research shows that “young children are very interested in talk that occurs around them, particularly when parents or siblings are talking about the child.”
While that may be so, little is known about the role of overheard speech and social context in language learning. Sperry and his colleagues plan to take a closer look at the difficult-to-study issue of how eavesdropping on family members influences later reading and writing skills.
Late-night comedians skewered Vice President Mike Pence in August when he announced preliminary plans for a new branch of the U.S. military dubbed the “Space Force.” Jimmy Kimmel likened the idea to a Michael Bay action movie, while Jimmy Fallon quipped that the Space Force’s chain of command would go “E.T., Yoda, then Groot.”
But, as a new book by astrophysicist Neil deGrasse Tyson and researcher-writer Avis Lang demonstrates, the militarization of space is no joke. In Accessory to War, Tyson and Lang chronicle how war-makers have long wielded knowledge of outer space as a weapon. This bloody history features Christopher Columbus exploiting his awareness of an upcoming lunar eclipse to threaten natives on the island of Hispaniola with divine retribution, as well as the United States using satellite intelligence to fight the Gulf War.
“As for America’s forthcoming wars,” Tyson and Lang predict, “they will be waged with even more formidable space assets.”
But just as militaries have long used space science and space-based technology to their advantage, astronomers and astrophysicists have reaped the rewards of military investment. James Cook, a captain in the British Navy, for example, established an observatory in Tahiti. Observations of Venus passing across the face of the sun in 1769 from that observatory helped astronomers pin down the distance between Earth and the sun. During the Cold War, U.S. military satellites designed to watch for nuclear detonations discovered gamma-ray bursts, some of the most spectacular explosions in the universe (SN: 1/10/15, p. 15). Tyson and Lang’s millennia-long world history is sprawling. The book is exhaustively researched, almost to the point of information overload. It’s easy to get bogged down in parenthetical asides about minor characters or paragraph-long lists. The book is the antithesis of Tyson’s starry-eyed, bite-sized Astrophysics for People in a Hurry and may end up on the shelves of more history buffs than astro nerds.
Still, Accessory to War lives up to much of the promise of a Neil deGrasse Tyson read: Written from Tyson’s perspective, the narration is rich with wry humor and vivid descriptions of cosmic goings-on. For anyone who is, like Tyson, “smitten by the cosmos,” the book is a stark reminder that astrophysics has been both a benefactor and beneficiary of human conflict — and that the final frontier will likely be the battleground of many future skirmishes.
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The 28-year-old space telescope, in orbit around the Earth, put itself to sleep on October 5 because of an undiagnosed problem with one of its steering wheels. But once more, astronomers are optimistic about Hubble’s chances of recovery. After all, it’s just the latest nail-biting moment in the history of a telescope that has defied all life-expectancy predictions.
There is one major difference this time. Hubble was designed to be repaired by astronauts on the space shuttle. Each time the telescope broke previously, a shuttle mission fixed it. “That we can’t do anymore, because there ain’t no shuttle,” says astronomer Helmut Jenkner of the Space Telescope Science Institute in Baltimore, who is Hubble’s deputy mission head. The most recent problem started when one of the three gyroscopes that control where the telescope points failed. That wasn’t surprising, says Hubble senior project scientist Jennifer Wiseman of NASA’s Goddard Space Flight Center in Greenbelt, Md. That particular gyroscope had been glitching for about a year. But when the team turned on a backup gyroscope, it didn’t function properly either.
Astronomers are working to figure out what went wrong and how to fix it from the ground. The mood is upbeat, Wiseman says. But even if the gyroscope doesn’t come back online, there are ways to point Hubble and continue observing with as few as one gyroscope.
“This is not a catastrophic failure, but it is a sign of mortality,” says astronomer Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Like cataracts, he says, it’s “a sign of aging, but there’s a very good remedy.” While we wait for news of how Hubble is faring, here’s a look back at some of its previous hiccups and repair missions.
1990: The blurry mirror On June 27, 1990, three months after the space telescope launched, astronomers discovered an aberration in Hubble’s primary mirror. Its curvature was off by two micrometers, making the images slightly blurry.
The telescope soldiered on, despite being the butt of jokes on late-night TV. It observed a supernova that exploded in 1987 (SN: 2/18/17, p. 20), measured the distance to a satellite galaxy of the Milky Way and took its first look at Jupiter before the space shuttle Endeavour arrived to fix the mirror in December 1993. 1999: The first gyroscope crisis On November 13, 1999, Hubble was put into safe mode after the fourth of its six gyroscopes failed, leaving it without the three working gyros necessary to point precisely. An already planned preventative maintenance shuttle mission suddenly became more urgent. NASA split the mission into two parts to get to the telescope more quickly. The first part became a rescue mission: Astronauts flew the space shuttle Discovery to Hubble that December to install all new gyroscopes and a new computer.
2004: Final shuttle mission canceled After the space shuttle Columbia disintegrated while re-entering Earth’s atmosphere in 2003, NASA canceled the planned fifth and final Hubble reservicing mission. “That could really have been the beginning of the end,” Jenkner says.
The team has known for more than a decade that someday Hubble will have to work with fewer than three gyroscopes. To prepare, Hubble’s operations team deliberately shut down one of the telescope’s gyroscopes in 2005, to observe with only two.
“We’ve been thinking about this possibility for many years,” Wiseman says. “This time will come at some point in Hubble’s mission, either now or later.”
Shutting down the third gyroscope was expected to extend Hubble’s life by only eight months, until mid-2008. In the meantime, two of the telescope’s scientific instruments — the Space Telescope Imaging Spectrograph and the Advanced Camera for Surveys — stopped working due to power supply failures. 2009: New lease on life Fortunately, NASA restored the final servicing mission, and the space shuttle Atlantis visited Hubble in May 2009 (SN Online: 5/11/09). That mission restored Hubble’s cameras, installed new ones and crucially, left the space telescope with six new gyroscopes, three for immediate use and three backups. The three gyroscopes still in operation (including the backup that is currently malfunctioning) are of a newer type, and are expected to live five times as long as the older ones, which last four to six years.
The team expects Hubble to continue doing science well into the 2020s and to have years of overlap with its successor, the James Webb Space Telescope, due to launch in 2021. “We are always worried,” says Jenkner, who has been working on Hubble since 1983. “At the same time, we are confident that we will be running for quite some time more.”
Call it an October surprise: Hurricane Michael strengthened unusually quickly before slamming into the Florida panhandle on October 10 and remained abnormally strong as it swept into Georgia. The storm made landfall with sustained winds of about 250 kilometers per hour, just shy of a category 5 storm, making it the strongest storm ever to hit the region, according to the National Oceanographic and Atmospheric Administration’s National Hurricane Center, or NHC.
Warm ocean waters are known to fuel hurricanes’ fury by adding heat and moisture; the drier air over land masses, by contrast, can help strip storms of strength. So hurricanes nearing the Florida panhandle, a curving landmass surrounding the northeastern Gulf of Mexico, tend to weaken as they pull in drier air from land. But waters in the Gulf that were about 1 degree to 2 degrees Celsius warmer than average for this time of year, as well as abundant moisture in the air over the eastern United States, helped to supercharge Michael. Despite some wind conditions that scientists expected to weaken the storm, it strengthened steadily until it made landfall, which the NHC noted “defies traditional logic.” The fast-moving storm weakened only slightly, to a category 3, before hurtling into Georgia. Although it is not possible to attribute the generation of any one storm to climate change, scientists have long predicted that warming ocean waters would lead to more intense tropical cyclones in the future. More recent attribution studies have borne out that prediction, suggesting that very warm waters in the tropical Atlantic helped to fuel 2017’s powerful storm season, which spawned hurricanes Irma and Maria.
Hurricane Harvey, fueled by unusually warm waters in the Gulf of Mexico in August 2017, also underwent a rapid intensification, strengthening from a tropical storm to a category 4 hurricane within about 30 hours. And this year, scientists reported that Hurricane Florence, which slammed into the Carolinas in September, was probably warmer and wetter due to warmer than average sea surface temperatures in the Atlantic Ocean.
We may truly be led by our noses. A sense of smell and a sense of navigation are linked in our brains, scientists propose.
Neuroscientist Louisa Dahmani and colleagues asked 57 young people to navigate through a virtual town on a computer screen before being tested on how well they could get from one spot to another. The same young people’s smelling abilities were also scrutinized. After a sniff of one of 40 odor-infused felt-tip pens, participants were shown four words on a screen and asked to choose the one that matched the smell. On these two seemingly different tasks, the superior smellers and the superior navigators turned out to be one and the same, the team found.
Scientists linked both skills to certain spots in the brain: The left orbitofrontal cortex and the right hippocampus were both bigger in the better smellers and better navigators. While the orbitofrontal cortex has been tied to smelling, the hippocampus is known to be involved in both smelling and navigation. A separate group of nine people who had damaged orbitofrontal cortices had more trouble with navigation and smell identification, the researchers report October 16 in Nature Communications. Dahmani, who’s now at Harvard University, did the work while she was at McGill University in Montreal.
A sense of smell may have evolved to help people find their way around, an idea called the olfactory spatial hypothesis. More specific aspects of smell, such as how good people are at detecting faint whiffs, could also be tied to navigation, the researchers suggest.
Climate change may be flipping good Arctic neighborhoods into killing fields for baby birds.
Every year, shorebirds migrate thousands of kilometers from their southern winter refuges to reach Arctic breeding grounds. But what was once a safer region for birds that nest on the ground now has higher risks from predators than nesting in the tropics, says Vojtěch Kubelka, an evolutionary ecologist and ornithologist at Charles University in Prague. With many shorebird populations dwindling, nest success matters more every year. A longtime fan of shorebirds, Kubelka had heard about regional tests of how predator risk changes by latitude for bird nests. He, however, wanted to go global. Shorebirds make a great group for such a large-scale comparison, he says, because there’s not a lot of variation in how nests look to predators. A feral dog in the United States and a fox in Russia are both creeping up on some variation of a slight depression in the ground. So Kubelka and his colleagues crunched data from decades of records of predator attack rates on about 38,000 nests of various sandpipers, plovers and other shorebirds. After a massive literature search, the study zeroed in on the experiences of 237 populations of a total of 111 shorebird species at 149 places on six continents. It’s the first attempt at a global comparison by latitude of predator attack rates on shorebird nests over time, he says.
Historical data of predator attack rates worldwide averaged about 43 percent before 1999, but has since reached 57 percent, the team reports in the Nov. 9 Science. The most dramatic upward swoop came from the Arctic nest reports. There, the rate of predator attacks averaged around 40 percent in the last century, jumping to about 65 or 70 percent since 1999. Meanwhile, tropical perils in the Northern Hemisphere changed “only modestly” the researchers say, from around 50 percent to about 55 percent. Researchers also looked at how much, and how erratically, temperatures had changed at each site. Overall, the growing dangers to nests fit with climate change trends. Biologists have discussed the idea that nest predation generally lessens when birds move out of the tropics. One advantage of migrating toward the pole to breed was, in theory, to escape from tropical abundance of snakes, rodents and other egg-lovers.
But rapid warming in the Arctic might have discombobulated some of the old predator-prey relationships, says coauthor Tamás Székely, a conservation biologist at the University of Bath in England. For instance, Arctic foxes used to get much of their nourishment from lemmings, voles and other small rodents. Skimpy snow cover in warmer winters, however, doesn’t insulate little rodents as well as it used to. Boom-and-bust cycles of lemming populations are in many places now “mostly bust,” he says. Foxes and other predators may be shifting more to bird eggs and nestlings.
That scenario of rodent-loving predators hunting more birds sounds “highly probable,” but may be just part of what’s going on, says Dominique Fauteux, an ecologist at the Canadian Museum of Nature in Ottawa who studies small mammals. Lemming collapses haven’t been reported across the whole Canadian Arctic, he says.
Instead, some researchers have proposed that shorebird nest failures come from a boom in geese that attract more bird predators overall. Also, a 2010 study suggests that nest predation in the Canadian Arctic was still lower than in temperate areas. There may be some global pattern, but on the ground, Fauteux says, “there clearly are nuances.”
