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.
Vinita Surukan knew the mosquitoes were trouble. They attacked her in swarms, biting through her clothes as she worked to collect rubber tree sap near her village in Sabah, the northern state of Malaysia. The 30-year-old woman described the situation as nearly unbearable. But she needed the job.
There were few alternatives in her village surrounded by fragments of forest reserves and larger swaths of farms, oil palm plantations and rubber tree estates. So she endured until a week of high fever and vomiting forced her to stop. The night of July 23, Surukan was trying to sleep off her fever when the clinic she visited earlier in the day called with results: Her blood was teeming with malaria parasites, about a million in each drop. Her family rushed her to the town hospital where she received intravenous antimalarial drugs before being transferred to a city hospital equipped to treat severe malaria. The drugs cleared most of the parasites, and the lucky woman was smiling by morning.
Malaria has terrorized humans for millennia, its fevers carved into our earliest writing on ancient Sumerian clay tablets from Mesopotamia. In 2016, four species of human malaria parasites, which are spread by mosquito from person to person, infected more than 210 million people worldwide, killing almost 450,000. The deadliest species, Plasmodium falciparum, causes most of the infections.
But Surukan’s malaria was different. Hers was not a human malaria parasite. She had P. knowlesi, which infects several monkey species. The same parasite had recently infected two other people in Surukan’s village — a man who hunts in the forest and a teenager. Surukan suspects that her parasites came from the monkeys that live in the forest bordering the rubber tree estate where she worked. Some villagers quit working there after hearing of Surukan’s illness.
Monkey malaria, discovered in the early 1900s, became a public health concern only in the last 15 years. Before that, scientists thought it was extremely rare for monkey malaria parasites, of which there are at least 30 species, to infect humans. Yet since 2008, Malaysia has reported more than 15,000 cases of P. knowlesi infection and about 50 deaths. Infections in 2017 alone hit 3,600. People infected with monkey malaria are found across Southeast Asia near forests with wild monkeys. In 2017, another species of monkey malaria parasite, P. cynomolgi, was found in five Malaysians and 13 Cambodians. And by 2018, at least 19 travelers to the region, mostly Europeans, had brought monkey malaria back to their home countries.
The rise of monkey malaria in Malaysia is closely tied to rapid deforestation, says Kimberly Fornace, an epidemiologist at the London School of Hygiene and Tropical Medicine. After testing blood samples of nearly 2,000 people from areas in Sabah with various levels of deforestation, she found that people staying or working near cut forests were more likely than people living away from forests to have P. knowlesi infections, she and colleagues reported in June in PLOS Neglected Tropical Diseases. Stepping over felled trees, humans move closer to the monkeys and the parasite-carrying mosquitoes that thrive in cleared forests. It’s out there There’s no feasible way to treat wild monkeys for an infection that they show no signs of. “That’s the problem with P. knowlesi,” says Singapore-based infectious disease specialist Fe Espino, a director of the Asia Pacific Malaria Elimination Network.
In 2015, the World Health Organization set a goal for 2030: to stop malaria transmission in at least 35 of the 91 malaria-endemic countries. WHO targets the four human malaria parasites: P. falciparum, P. vivax, P. malariae and P. ovale. Monkey malaria is excluded from the campaign because the agency regards it as an animal disease that has not been shown to transmit among humans.
But as countries reduce human malaria, they will eventually have to deal with monkey malaria, Espino says, echoing an opinion widely shared by monkey malaria scientists.
“Something nasty” could emerge from the pool of malaria parasites in monkeys, says malariologist Richard Culleton of Nagasaki University in Japan. Culleton studies the genetics of human and monkey malaria. Malaria parasites can mutate quickly — possibly into new types that can more easily infect humans (SN: 9/6/14, p. 9). To Culleton, the monkey malaria reservoir “is like a black box. Things come flying out of it occasionally and you don’t know what’s coming next.” Malaysia is very close to reaching the WHO target of human malaria elimination. In 2017, only 85 people there were infected with human malaria. But that success feels hollow as monkey malaria gains a foothold. And while monkey malaria has swelled into a public health threat only in Malaysia, the same could happen in other parts of Southeast Asia and beyond. Even in southeastern Brazil, where human malaria was eliminated 50 years ago, the P. simium malaria parasite that resides in howler monkeys caused outbreaks in humans in 2015 and 2016.
From tool to threat In the late 1800s, scientists discovered the Plasmodium parasite and its Anopheles mosquito carriers. Humans retaliated by draining marshes to stop mosquito breeding and spraying insecticides over whole communities. Governments and militaries pursued antimalarial drugs as the disease claimed countless soldiers during the two World Wars.
Scientists soon found malaria parasites in birds, rodents, apes and monkeys. To the researchers, the parasites found in monkeys were a tool for testing antimalarial drugs, not a threat. An accident, however, showed otherwise. In 1960, biologist Don Eyles had been studying the monkey malaria P. cynomolgi at a National Institutes of Health lab in Memphis, Tenn., when he fell ill with malarial fevers. He had been infected with the parasites found in his research monkeys. His team quickly confirmed that the malaria parasites in his monkeys could be carried by mosquitoes to humans. Suddenly, monkey malaria was not just a tool; it was an animal disease that could naturally infect humans. The news shook WHO, McWilson Warren said in a 2005 interview recorded by the Office of NIH History. Warren, a parasitologist, had been Eyles’ colleague. Five years before Eyles became infected, WHO had launched the Global Malaria Eradication Programme. Banking on insecticides and antimalarial drugs, the agency had aimed to end all malaria transmissions outside of Africa. A monkey malaria that easily infects humans would sink the program because there would be no way to treat all the monkeys.
A team of American scientists, including Eyles and Warren, traveled to Malaysia — then the Federation of Malaya — where the P. cynomolgi parasites that infected Eyles came from. Funded by NIH, the scientists worked with colleagues from the Institute of Medical Research in Kuala Lumpur, established in 1900 by the British to study tropical diseases.
From 1961 to 1965, the researchers discovered five new species of monkey malaria parasites and about two dozen mosquito species that carry the parasites. But the researchers did not find any human infections. Then, in 1965, an American surveyor became infected with P. knowlesi after spending several nights camping on a hill about 160 kilometers inland from Kuala Lumpur.
Warren surveyed the forested area where the infected American had camped. The hill sat beside a meandering river. Monkeys and gibbons, a type of ape, lived on the hill and in adjacent forests. The closest house was about two kilometers away. Warren sampled the blood of four monkeys and more than 1,100 villagers around the hill; he collected mosquitoes too.
He found P. knowlesi parasites in the monkeys, but none among the villagers. Only one mosquito species, A. maculatus, appeared capable of transmitting malaria between monkeys and humans, but Warren deemed its numbers too low to matter. He concluded that monkey malaria stayed in the forests and rarely ever spilled into humans.
With those results, NIH ended the monkey malaria project, Warren said, and the Institute of Medical Research in Kuala Lumpur returned to its primary focus: human malaria, dengue and other mosquito-borne diseases. Monkey malaria was struck off the list of public health concerns.
Wake-up call P. knowlesi landed back in the spotlight in 2004, with a report in the Lancet by malariologist Balbir Singh and his team. The group had found 120 people infected over two years in southern Malaysian Borneo. The patients were mostly indigenous people who lived near forests. Clinicians initially had checked the patients’ blood samples under microscopes — the standard test — and diagnosed the parasites as human malaria. But when Singh, of Universiti Malaysia Sarawak, applied molecular tools that identify parasite species by their DNA, he revealed that all the samples were P. knowlesi. Monkey malaria was breaking out of the diminishing forests.
By 2018, P. knowlesi had infected humans in all Southeast Asian countries except for East Timor. Singapore, declared malaria free in 1982, reported that six soldiers were infected with P. knowlesi from wild monkeys in a forest reserve. The parasite also turned up in almost 380 out of 3,700 visitors to health clinics in North Sumatra, Indonesia, an area that is close to being deemed free of human malaria. Many scientists now recognize P. knowlesi as the fifth malaria parasite species that can naturally infect humans. It is also the only one to multiply in the blood every 24 hours, and it can kill if treatment is delayed. People pick up P. knowlesi parasites from long-tailed macaques, pig-tailed macaques and Mitred leaf monkeys. These monkeys range across Southeast Asia. So far, malaria parasites have been found in monkeys near or in forests, but rarely in monkeys in towns or cities.
Scientists propose several reasons for the recent rise in monkey malaria infections, but two stand out: improvement in malaria detection and forest loss.
Malaysia, for instance, finds more monkey malaria cases than other Southeast Asian countries because it added molecular diagnostic tools in 2009. Other countries use only microscopy for detection, says Rose Nani Mudin, who heads the vectorborne disease sector at Malaysia’s Ministry of Health. Since 2008, annual monkey malaria cases in Malaysia have climbed tenfold, even as human malaria cases have plummeted. “Maybe there is a genuine increase in [monkey malaria] cases. But with strengthening of surveillance, of course you would detect more cases,” she says.
Data collected by Malaysia’s malaria surveillance system have also revealed strong links between infection risk and deforestation. Fornace, the epidemiologist, examined the underlying drivers of monkey malaria in Surukan’s home state of Sabah. Fornace mapped monkey malaria cases in 405 villages, based on patient records from 2008 to 2012. Satellite data showed changes in forested areas around those villages. The villages most likely to report monkey malaria infections were those that had cut more than 8 percent of their surrounding forests within the last five years, she and colleagues reported in 2016 in Emerging Infectious Diseases. Fornace’s team went into the field for a follow-up study, published in June in PLOS Neglected Tropical Diseases. The team collected blood samples from almost 2,000 people in two areas in Sabah and checked for current and past malaria infection. People who farmed or worked in plantations near forests had at least a 63 percent higher risk of P. knowlesi infection, and — like in the 2016 study — forests and cleared areas escalated risk of infection.
“It feels almost like P. knowlesi follows deforestation,” Fornace says. Several years after a forest is cut back, nearby communities “get a peak of P. knowlesi.”
Today, the hill where the American surveyor camped in 1965 is a small island in a sea of oil palm estates. From 2000 to 2012, Malaysia cleared a total amount of forest equaling 14.4 percent of its land area, more than any other country, according to a study published in 2013 in Science. A study in 2013 in PLOS ONE used satellite images to show that in 2009, only one-fifth of Malaysian Borneo was intact forest. Almost one-fourth of all forest there had been logged, regrown and logged many times over.
Since 2008, oil palm acreage in Malaysian Borneo has increased from 2.08 million hectares to 3.1 million, according to the Malaysian Palm Oil Board. In Malaysia, the four states hit hardest by deforestation — Sabah, Sarawak, Kelantan and Pahang — report 95 percent of the country’s P. knowlesi cases. Fornace thinks deforestation and the ecological changes that come with it are the main drivers of monkey malaria’s rise in Malaysia. She has seen long-tailed macaques spend more time in farms and near houses after their home forests were being logged. Macaques thrive near human communities where food is abundant and predators stay out. Parasite-carrying mosquitoes breed in puddles made by farming and logging vehicles.
Where monkeys go, mosquitoes follow. Indra Vythilingam, a parasitologist at University of Malaya in Kuala Lumpur, studied human malaria in indigenous communities in the early 1990s. Back then, she rarely found A. cracens, the mosquito species that carries monkey malaria in Peninsular Malaysia. But in 2007, that species made up over 60 percent of mosquitoes collected at forest edges and in orchards, she reported in 2012 in Malaria Journal. “It’s so much easier to find them” now, she says.
As Fornace points out, “P. knowlesi is a really good example of how a disease can emerge and change” as land use changes. She recommends that when big projects are evaluated for their impact on the economy and the environment, human health should be considered as well.
What to expect While P. knowlesi cases are climbing in Malaysia, scientists have found no evidence that P. knowlesi transmits directly from human to mosquito to human (though many suspect it happens, albeit inefficiently). Following a review by experts in 2017, WHO continues to exclude P. knowlesi from its malaria elimination efforts. Rabindra Abeyasinghe, a tropical medicine specialist who coordinates WHO malaria control in the western Pacific region, says the agency will reconsider P. knowlesi as human malaria if there is new evidence to show that the parasite transmits within human communities.
In Malaysia last year, only one person died from human malaria, but P. knowlesi killed 11. “We don’t want that to happen, which is why [P. knowlesi] is our priority even though it is not in the elimination program,” says Rose Nani Mudin from the country’s Ministry of Health.
Unable to do much with the monkeys in the trees, Malaysian health officers focus on the people most likely to be infected with P. knowlesi. Programs raise awareness of monkey malaria and aim to reduce mosquitoes around houses. New mosquito-control methods are needed, however, because conventional methods like insecticide-treated bed nets do not work for monkey malaria mosquitoes that bite outdoors around dusk.
Fighting malaria is like playing chess against an opponent that counters every good move we make, says Culleton in Japan. Malaria parasites can mutate quickly and “go away and hide in places and come out again.” Against malaria, he says, “we can never let our guard down.”
This article appears in the November 10, 2018 Science News with the headline, “The Next Malaria Menace: Deforestation brings monkeys and humans close enough to share an age-old disease.”
Editor’s note: This story was updated on November 6, 2018 to correct the WHO’s position on monkey malaria. The agency excludes monkey malaria parasites from its malaria eradication goals, not because those particular parasites rarely infect humans, but because the parasites have not been shown to transmit among humans.
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.”
The United States is poised to take a powerful economic hit from climate change over the next century. Heat waves, wildfires, extreme weather events and rising sea levels could cost the country hundreds of billions of dollars in lost labor, reduced crop yields, health problems and crumbling infrastructure.
A report authored by hundreds of U.S. climate scientists from 13 federal agencies presents a stark picture of the country’s fate due to climate change. The Fourth National Climate Assessment, released November 23, predicts the U.S. economy will shrink by as much as 10 percent by the end of the century if global warming continues apace. A separate report released November 27 by the United Nations Environment Programme reveals that in 2017, global emissions of carbon dioxide — a major driver of warming — rose for the first time in three years. That suggests that the nations that promised to curb emissions as part of the historic 2015 Paris agreement are falling short (SN: 1/9/16, p. 6).
It’s unclear what effect, if any, the reports will have on the U.S. government’s strategy on dealing with climate change and its consequences. President Donald Trump has previously announced he would withdraw the United States from the Paris agreement (SN Online: 6/1/17). And on November 26, Trump told reporters that he had read “some of” his scientists’ report. “It’s fine,” he said. But when it comes to the dire predictions of economic losses, he added, “I don’t believe it.”
The National Climate Assessments are mandated by Congress and produced every four years, focusing on the risks of climate change specifically to the United States. What’s different about the new report compared with previous editions is its precision about the risks to different parts of the U.S. economy, putting a price tag on the potential losses in agriculture, trade and energy generation.
To put a dollar value on bad air quality or worsening heat waves, for instance, scientists try to assess the measurable impacts of those issues — for example, the number of days of work or school missed, or the number of doctors’ visits triggered (SN Online: 10/14/18). The more-than-1,600-page report includes detailed examinations of the effects of climate change on the country’s different regions. People living in the northeastern United States, for example, will be among the hardest hit by deaths due to poor air quality and temperature extremes by the end of the century. Labor losses in the southeastern United States are the highest of all regions, as are projected damages to roads and bridges, the report found.
Meanwhile, the Midwest will see the highest increase in premature deaths from increased amounts of ozone. And the Southwest, which includes California in these analyses, will suffer from extreme heat, drought and an increase in future cases of the mosquito-borne West Nile virus.
The report estimates that cumulatively the country will spend $23 billion responding to wildfires by the end of the century, even if greenhouse gas emissions are modestly reduced. The Southwest will bear the brunt of that impact, spending $13 billion dollars.
The report also details the many ways in which climate change is already hurting the country economically. For example, three storms that made landfall during the 2017 Atlantic hurricane season — Harvey, Irma and Maria — together cost the United States at least $265 billion, according to the National Oceanic and Atmospheric Administration.
By continuing on its current trajectory of greenhouse gas emissions, the “business-as-usual” scenario, the United States will see the greatest losses, the assessments concludes. However, the report also considers climate impacts in an alternate future, in which the world has taken modest actions to curb greenhouse emissions, including using more carbon-neutral fuels and the growth of technological innovations to remove carbon dioxide from the atmosphere (SN Online: 10/20/18).
A new type of implantable bandage could help mend broken hearts.
Each bandage is a thin film that oozes a cocktail of molecules to heal tissue damaged during a heart attack. In experiments with rats and pigs, these patches helped minimize scarring and preserve the heart’s ability to pump blood, researchers report online November 28 in Science Advances. Such devices could someday curb heart attack survivors’ risk of heart failure.
The base of each heart-healing film is a polymer sheet studded with tiny needles — similar to other microneedle patches that deliver vaccines but designed to stick to a patient’s heart rather than her skin (SN: 8/5/17, p. 8). The surface of the polymer opposite the array of microneedles is coated in a gel containing cardiac stromal cells. These cells secrete molecules, such as proteins and tiny pieces of genetic material known as microRNAs, that support the growth of heart muscle cells. “We’re treating [the patch cells] as little pharmacies,” says study coauthor Ke Cheng, a biological engineer at North Carolina State University in Raleigh. When a patch is attached to the heart, the microneedles funnel curative molecules from the cardiac stromal cells directly into the damaged tissue.
In rats, Cheng’s team tested how well the microneedle patches promoted healthy tissue growth and mitigated scarring. Three weeks after researchers induced rats to have heart attacks, the animals with microneedle patches had roughly 40 percent healthy tissue in the regions of their hearts affected by the heart attack, whereas as untreated rats had only about 10 percent. For the pigs, the researchers tracked heart health by measuring how much blood was pumped from the animal’s left ventricle to the rest of its body with each heartbeat. Four hours after a heart attack, each heartbeat released about 56 to 57 percent of all the blood in the left ventricle, in both treated and untreated pigs. But 48 hours after the attack, the results began to diverge: Hearts treated with microneedle patches pumped about 60 percent of the left ventricle’s volume, while untreated hearts pumped about 50 percent. The new microneedle design “is a very interesting and exciting” idea, but researchers need to investigate how animals implanted with these patches fare over longer periods, says Tamer Mohamed, a cardiovascular researcher at the University of Louisville in Kentucky not involved in the work. Before these microneedle patches are used to treat humans, Cheng’s team plans to swap out the polymer used in this study for a material that gradually dissolves inside the body. The researchers are also exploring less invasive ways to implant patches than open-heart surgery, Cheng says.
Earth’s heart may have a secret chamber. The planet’s inner core isn’t just a solid ball of nickel and iron, researchers say, but contains two layers of its own: a distinct central region nestled within an outer shell.
Scientists say they have confirmed the existence of this innermost inner core using a type of previously undescribed seismic wave that not only travels through Earth’s core but also bounces back and forth through the interior, collecting invaluable data about the core’s structure along the way. Focusing on earthquakes of magnitude 6 or larger that struck in the last decade, the researchers combined data on these quakes that were collected at seismic stations around the world. Combining these signals made it possible to detect even very faint reflections of the seismic waves. Of the 200 or so quakes analyzed, 16 events spawned seismic waves that detectably bounced through the inner core multiple times.
The origin, structure and fate of Earth’s core is of intense interest because the core generates the planet’s magnetic field, which shields the Earth from charged particles ejected by the sun and helps keep the planet’s denizens safe from too much radiation.
“Understanding how the magnetic field evolves is extremely important for the life on Earth’s surface,” says Hrvoje Tkalčić, a seismologist at the Australian National University in Canberra.
The entire core, about 6,600 kilometers across, consists of two main parts: a liquid outer core and a solid inner core (SN: 1/23/23). As iron-rich fluid circulates in the outer core, some of the material cools and crystallizes, sinking to form a solid center. That interplay generates Earth’s magnetic field.
When this swirling dance first began isn’t certain, but some studies suggest it was as recent as 565 million years ago, just a fraction of Earth’s 4.6-billion-year-long life span (SN: 1/28/19). That dance has faltered from time to time, its stuttering steps preserved in tiny magnetic grains in rocks. These data suggest the planet’s magnetic poles have flip-flopped many times over the years, temporarily weakening the magnetic field (SN: 2/18/21). As more and more crystals cool, the dance will eventually slow and stop, shutting off the planet’s magnetic field millions or billions of years from now.
Different types and structures of minerals, as well as different amounts of liquid in the subsurface, can change the speed of seismic waves traveling through Earth, offering clues to the makeup of the interior. In 2002, researchers noted that seismic waves traveling through the innermost part of Earth move slightly slower in one direction relative to the planet’s poles than in other directions. That suggests there’s some oddity there — a difference in crystal structure, perhaps. That hidden heart, the team suggested, might be a kind of fossil: a long-preserved remnant of the core’s early formation.
Since that observation, Tkalčić and others have pored over seismic data, finding independent lines of evidence that help support the idea of an innermost inner core. The reverberating seismic waves, described February 21 in Nature Communications, also show a slowdown, and are the strongest evidence yet that this hidden heart exists. Using that seismic data, Tkalčić and seismologist Thanh-Son Phạm, also of the Australian National University, estimate that this inner heart is roughly 600 kilometers across, or about half the diameter of the full inner core. And the pair was able to assess the direction of the slowest waves at about 50 degrees relative to the Earth’s rotation axis, providing more insight into the region.
The exact source of the wave slowdown isn’t clear, Tkalčić says. The phenomenon might be related to the structure of the iron crystals, which may be packed together differently farther into the center. Or it could be from a different crystal alignment caused by some long-ago global event that changed how inner core crystals solidified out of the outer core.
The inner core holds many other mysteries too. Lighter elements present in small amounts in the core — hydrogen, carbon, oxygen — may flow around the solid iron in a liquidlike “superionic” state, further complicating the seismic picture (SN: 2/9/22).
By identifying and reporting seismic waves that bounced back and forth through the planet’s interior multiple times, the researchers have made an invaluable contribution that will help researchers study the core in new ways, says seismologist Paul Richards of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y.
Still, the team’s interpretation of the inner core’s structure from those waves “is probably more iffy,” says Richards, who wasn’t involved in the work.
One reason for this uncertainty is that as the waves bounce back and forth, they can become weaker and more difficult to see in the data, he says. “Many further observations will help decide” what these new data can reveal about the heart of the planet.
In 2018, we saw just how much power science has to make a real impact.
Science News’ top stories of the year include a literal impact — the hidden contours of what appears to be a massive crater created when a meteorite slammed into Greenland long ago. That discovery ranks among our Top 10 partly because it’s just cool, but also because it raises the tantalizing prospect of solving a scientific mystery: Did the impact kick the planet into a roughly 1,000-year cold snap, called the Younger Dryas, almost 13,000 years ago? The mammoths and other species that died out by the end of that period didn’t see climate change coming. But we can. That’s why human-driven climate change is our top story of the year. The rising tide of attribution studies shows that climbing temperatures are already turning extreme events, such as Hurricane Florence, more extreme. This year’s barrage of climate reports gave us a clearer picture of how climate change will affect Earth in the near future — fueling wildfires, sparking heat waves, raising sea levels —and how human actions to curb warming can have an impact.
2018 is also the year a Chinese researcher made the startling claim that he had created the first babies to be born with an edited gene. The ensuing uproar over the controversial birth of twin girls in China, whose genes were allegedly tweaked to reduce their risk of contracting HIV, is sure to have a lasting impact on the future of gene-editing technology.
Two other genetics stories made our Top 10. Genetic genealogy is shaking up the field of forensics, ID’ing suspects in cold cases while raising privacy issues. And in a lab experiment, a gene drive — a genetic tool designed to be inherited by 100 percent of offspring — wiped out a population of mosquitoes. That feat ushers in the enticing but perilous possibility of both eliminating certain diseases and deliberately driving a species to extinction.
Other stories rounding out our Top 10 examine issues close to home (how to sort through conflicting advice about drinking alcohol) and very far away (tracing a high-energy neutrino back to its source in a distant galaxy). We’ll be watching these stories to see what happens in 2019 and beyond. — Macon Morehouse, News Director hurricane flooding SN TOP 10 1 Can half a degree save us? This is the year we learned that the 2015 Paris Agreement on global warming won’t be enough to forestall significant impacts of climate change. And a new field of research explicitly attributed some extreme weather events to human-caused climate change. This one-two punch made it clear that climate change isn’t just something to worry about in the coming decades. It’s already here. FULL STORY Jiankui He SN TOP 10 2 Gene-edited babies A Chinese scientist surprised the world in late November by claiming he had created the first gene-edited babies. Many researchers and ethicists say implanting gene-edited embryos to create babies is premature and exposes the children to unnecessary health risks. Critics also fear the creation of “designer babies.” FULL STORY Sacramento sheriff and Golden State killer SN TOP 10 3 Genealogy solves crimes In 2018, criminal investigators in the United States embraced genetic genealogy, a forensic technique for tracking down suspects through their family trees, to solve decades-old cold cases and some fresh crimes. But this new type of DNA-based detective work has raised questions about genetic privacy and police procedures. FULL STORY IceCube detector SN TOP 10 4 A neutrino’s distant source Mysterious particles called neutrinos constantly barrel down on Earth from space. No one has known where, exactly, the highest-energy neutrinos come from. This year, scientists finally put a finger on one likely source: a brilliant cosmic beacon called a blazar. The discovery could kick-start a new field of astronomy that combines information gleaned from neutrinos and light. FULL STORY Greenland crater illustration SN TOP 10 5 Impact crater unearthed For three years, a team of scientists kept a big secret: They had discovered a giant crater-shaped depression buried beneath about a kilometer of ice in northwestern Greenland. In November, the researchers revealed their find to the world. The crater may have reignited a debate over a controversial hypothesis about a mysterious cold snap known as the Younger Dryas. FULL STORY Anopheles gambiae mosquitoes SN TOP 10 6 The end of mosquitoes? For the first time, humans have built a set of pushy, destructive genes that infiltrated small populations of mosquitoes and drove them to extinction. This test and other news from 2018 feed one of humankind’s most persistent dreams: wiping mosquitoes off the face of the Earth. FULL STORY person covering wine glass SN TOP 10 7 Health risks of alcohol For people who enjoy an occasional cocktail, 2018 was a sobering year. Headlines delivered the news with stone-cold certainty: Alcohol — in any amount — is bad for your health. “The safest level of drinking is none,” a group of scientists concluded. FULL STORY Mars south pole SN TOP 10 8 Mars’ ice-covered lake Researchers reported this year that they found a wide lake of standing liquid near the Red Planet’s south pole, buried beneath 1.5 kilometers of ice. The purported polar pool is the largest volume of liquid water ever claimed to currently exist on Mars, and has probably been around for a long time. Both of those features raise hopes that life could survive on Mars today. FULL STORY Gert-Jan Oskam walking with crutches SN TOP 10 9 Progress against paralysis Intensive rehabilitation paired with electric stimulation of the spinal cord allowed six paralyzed people to walk or take steps years after their injuries, three small studies published this year showed. More importantly, they show that the spinal cord can make a comeback. FULL STORY painting on cave walls in Spain SN TOP 10 10 Origins of human smarts Archaeological discoveries reported this year broadened the scope of what scientists know about Stone Age ingenuity. These finds move the roots of innovative behavior ever closer to the origins of the human genus. FULL STORY
Behavioral ecologist Anna Holzner recalls first seeing a southern pig-tail macaque munching on a headless rat. These monkeys were known to eat fruits, insects and even dirt, but nobody had reported them eating rats. “It was funny,” says Holzner, “and disgusting.”
This unexpected act occurred dozens of times from March to August 2016 as Holzner, of the University of Leipzig in Germany, and colleagues recorded what the macaques ate on oil palm plantations in northwest Peninsular Malaysia. To planters there, the macaques are pests.
Holzner did the work as part of the Macaca Nemestrina Project led by primate ecologist Nadine Ruppert of Universiti Sains Malaysia, in Penang. She presented the results on July 2 at the annual meeting of the Association of Tropical Biology and Conservation in Kuching, Malaysia.
While pig-tail macaques, Macaca nemestrina, spend most of their time in the forest, they visit adjacent plantations daily to forage, report Ruppert, Holzner and others in a related study in the April 4 International Journal of Primatology.
Holzner’s new study shows that in the plantations, pig-tail macaques ate mostly oil palm fruits, spending only 1 percent of their meal times on rats. But the monkeys would peel open the bark on oil palm trunks to expose rats hiding within. The researchers estimate that a group of 30 macaques might eat as many as 2,080 rats in a year. Holzner’s team counted fewer rats wherever they located macaques.
The study has local plantation owners reconsidering the monkeys, which may not be pests after all, but agents of rat control, Holzner says. But as macaques adapt to the encroaching plantations and their numbers grow, they can reduce birds and other creatures living in adjacent forests, warns ecologist Matthew Luskin at the Nanyang Technological University in Singapore.
Future therapy patients may spend a lot more time exploring virtual environments than sitting on sofas.
In a clinical trial of a new virtual reality treatment for fear of heights, participants reported being much less afraid after using the program for just two weeks. Unlike other VR therapies, which required that a real-life therapist guide patients through treatment, the new system uses an animated avatar to coach patients through ascending a virtual high-rise. This kind of fully automated counseling system, described online July 11 in the Lancet Psychiatry, may make psychological treatments for phobias and other disorders far more accessible. This is “a huge step forward” for therapeutic VR, says Jennifer Hames, a clinical psychologist at the University of Notre Dame in Indiana, who wasn’t involved in the work. By bringing expert therapy out of the counselor’s office and into primary care clinics — or even people’s homes — the new system could help those who aren’t comfortable or don’t have the means to speak with a therapist face-to-face, she says. Users immerse themselves in this virtual reality program using a VR headset, handheld controllers and headphones. An animated counselor guides the user through a virtual 10-story office complex, where upper floors overlook a ground-level atrium. On every floor, the user performs tasks designed to test their fear responses and help them learn that they’re safer than they might think. The tasks start out relatively easy — like standing close to a drop-off where a safety barrier gradually lowers — and progress to more difficult challenges — like riding a moving platform out into the open space over the atrium. By working through these activities, “the person builds up memories that being around heights is safe, and this counteracts the old fear beliefs,” says Daniel Freeman, a clinical psychologist at the University of Oxford.
To test their program’s effectiveness, Freeman and colleagues recruited 100 adult volunteers who were moderately to severely afraid of heights. The researchers randomly assigned 49 people to undergo VR treatment, which involved using the program for about six 30-minute sessions over two weeks, while the other 51 participants received no treatment.
Participants filled out a questionnaire that rated their fear of heights from 16 to 80 (with 80 being most severe), before treatment, immediately afterward, and two weeks later. People who underwent VR treatment dropped about 25 points on average on the questionnaire’s scale, while patients who received no treatment remained stable. Participants who used the VR program found they “could go to places that they wouldn’t have imagined possible,” Freeman says, like steep mountains, rope bridges or simply escalators in shopping malls.
“When I’ve always got anxious about an edge, I could feel the adrenaline in my legs, that fight/flight thing; that’s not happening as much now,” one participant said. “I’m still getting a bit of a reaction to it, both in VR and outside as well, but it’s much more brief, and I can then feel my thighs soften up as I’m not bracing up against that edge.”
While the clinical trial results provide strong evidence that the new VR program mitigates fear better than no treatment at all, researchers still need to investigate how VR therapy stacks up against sessions with a therapist, Hames says. And since Freeman’s team only tracked treatment effects up to a couple of weeks after their experiment, it remains to be seen how long the effects of this therapy last — although previous research on therapist-led VR treatment have shown lasting impacts for at least a year.
While fully automated VR therapy may be good news for people who fear heights, it’s not clear how well this type of system could address more complex mental health issues, says Mark Hayward, a clinical psychologist at the University of Sussex in England whose commentary on the study appears in the same issue of the Lancet Psychiatry. Virtual environments may be well suited for helping people who fear everyday situations, like those who suffer from common phobias, social anxiety or paranoia, Hayward says. But when it comes to helping people with more severe symptoms, like psychosis, VR probably won’t stand in for trained therapists any time soon.
“We can’t get carried away and say we can automate all [mental health] treatment,” says Albert Rizzo, a clinical virtual reality developer at the University of Southern California in Playa Vista not involved in the work. But the new standalone system for curbing fear of heights is “an excellent first effort.”
Data from NASA’s now-defunct Cassini spacecraft show that five odd-shaped moons embedded in Saturn’s rings are different colors, and that the hues come from the rings themselves, researchers report. That observation could help scientists figure out how the moons were born.
“The ring moons and the rings themselves are kind of one and the same,” says planetary scientist Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “For as long as the moons have existed, they’ve been accreting particles from the rings.” Saturn has more than 60 moons, but those nearest to the planet interact closely with its main band of rings. Between December 2016 and April 2017, Cassini passed close to five of these ring-dwelling moons: ravioli-shaped Pan and Atlas (SN Online: 3/10/17), ring-sculpting Daphnis and Pandora (SN: 9/2/17, p. 16) and potato-shaped Epimetheus. The flybys brought Cassini between two and 10 times closer to the moons than it had ever been, before the spacecraft deliberately crashed into Saturn in September 2017 (SN Online: 9/15/17).
Examining those close-ups, Buratti and her colleagues noticed that the moons’ colors vary depending on the objects’ distances from Saturn. And the moon hues are similar to the colors of the rings that the objects are closest to, the team reports online March 28 in Science. Close-in Pan was the reddest moon, while the farthest-out Epimetheus was the bluest. The researchers think the red material comes from Saturn’s dense main rings, and mostly consists of organics and iron (SN Online: 10/4/18). The blue material is probably water ice from Saturn’s more distant E ring, which is created by plumes erupting from the larger, icy moon Enceladus. The team thinks that the rings are continually depositing material onto the moons. “It’s an ongoing process,” Buratti says. She notes that “skirts” of material at Atlas and Pan’s equators are probably made of accreted ring debris, too.
The overall similarity between the moons and rings led the researchers to conclude that these small moons are leftover shards of a destructive event that created the rings in the first place. But it’s unknown whether that event was a collision between long-gone, larger moons, the shredding of one moon by Saturn’s gravity, or some other occurrence (SN: 1/20/18, p. 7).
Saturn, its rings and its moons are “very dynamic,” says planetary scientist Matija Ćuk of the SETI Institute in Mountain View, Calif. The idea that the rings are still shedding material onto the moons today “sounds perfectly reasonable.” He isn’t sure the moons formed at the same time as the rings, though. It’s possible “they formed from the rings since that catastrophic event,” he says.
