Even tiny brains can learn strange and tricky stuff, especially by watching tiny experts.
Buff-tailed bumblebees got several chances to watch a trained bee roll a ball to a goal. These observers then quickly mastered the unusual task themselves when given a chance, researchers report in the Feb. 24 Science. And most of the newcomers even improved on the goal-sinking by taking a shortcut demo-bees hadn’t used, says behavioral ecologist Olli Loukola at Queen Mary University of London. Learning abilities of animals without big vertebrate brains often get severely underestimated, Loukola says. “The idea that small brains constrain insects is kind of wrong, or old-fashioned.”
He and colleagues had previously challenged bees to learn, in stages, the not very beelike skill of pulling a string to reveal a hidden flower. Bees eventually succeeded. So the researchers devised an even more fiendish protocol to see how far insect learning could go.
Loukola invented six-legged sort-of soccer (or football for bees in London) in which a Bombus terrestris rolls a yellow ball about the size of its own body down a trackway to a central goal, where researchers dispense sugary rewards. This time, there was no pampering, no working up in stages to full completion of the test. But bees could observe a trained ball roller, a ball moving on its own (thanks to a researcher sliding a magnet under the arena) or get no advance ball-movement hints at all.
The 10 bees that saw an expert bee roll the ball and score three times before their own attempt succeeded in almost every trial at the task. Watching ghostly movement didn’t help as much, and only a few bees happened on the solution on their own. Social learning matters, but Loukola highlights the way bees changed the technique they watched. Most of the successful bees ignored the ball they had seen rolled and instead used one closer to the goal, doing less work for the same reward. “Fascinating,” says Dave Goulson of the University of Sussex in England, who studies bumblebees. Ball rolling may not be part of routine foraging behavior, but he notes that bees do drag around nesting material, moving backward as they do when playing soccer in the test. And they occasionally remove fat almost ball-like grubs from the nest with a similar technique.
Exactly how the bees solved the problem remains a puzzle, says Bennett Galef of McMaster University in Hamilton, Canada, who has studied social learning. He would like to know more details, for instance, about how untrained bees react to a ball.
Loukola often gets a different question: Could he train bumblebees to play a soccer match? He says he could certainly train some to score on one side of an arena and some on the opposite side. Then he might be able to study whether bumblebees could share a ball.
Astronomers may have spotted some of the earliest stardust ever created in the cosmos.
Astrophysicist Nicolas Laporte of University College London and colleagues detected the dust in a galaxy seen as it was when the universe was only 600 million years old. “We are probably seeing the first stardust of the universe,” Laporte says. The observations, published online March 8 in the Astrophysical Journal Letters, could help astronomers learn more about an early period known as cosmic reionization, when ultraviolet radiation stripped electrons from hydrogen atoms. “Dust is ubiquitous in nearby and more distant galaxies, but has, until recently, been very difficult to detect in the very early universe,” says University of Edinburgh astrophysicist Michal Michalowski, who was not involved in the study. “This paper presents the most distant galaxy for which dust has been detected.”
The galaxy, called A2744_YD4, lies behind a galaxy cluster called Abell 2744. That cluster acts as a gravitational lens, magnifying and brightening the distant galaxy’s light by about a factor of two. Laporte and colleagues observed the galaxy with ALMA, the Atacama Large Millimeter/submillimeter Array in Chile, which revealed the dust. Dust in such a remote galaxy comes from supernova explosions of massive stars that were among the earliest stars in the universe. Astronomers estimate the first stars formed around 400 million years after the Big Bang, which occurred 13.8 billion years ago. Laporte and colleagues estimate that A2744_YD4’s dust, at 600 million years after the Big Bang, weighs in at about 6 million times the mass of the sun. “This means that supernova explosions are able to produce large amounts of dust very quickly,” Michalowski says. Laporte and colleagues also detected positively charged, or ionized, oxygen atoms and a signature of hydrogen, which suggest the galaxy’s gas is ionized. Cosmic reionization completely rebooted the universe so that ionized rather than neutral atoms pervaded space. Understanding this switch from neutral to ionized atoms gives clues to how stars and galaxies arose in the early universe. Finding ionized oxygen in such a remote galaxy “provides evidence that at least a fraction of cosmic reionization was caused by galaxies like A2744_YD4,” Michalowski says.
Until now, astronomers have been charting the early history of galaxies by counting them and looking at their colors, notes study coauthor Richard Ellis, a cosmologist currently on leave from University College London at the European Southern Observatory. Spotting dust in the distant universe offers a new route to determine when the earliest galaxies first formed, based on the abundances of oxygen, silicon and other heavier elements that they contain. Fewer heavy elements would point to younger and younger galaxies.
The detection of ionized oxygen could also hint that a black hole lurks at the center of A2744_YD4. Ionized oxygen, seen by the signal it emits in millimeter wavelengths, may be difficult to generate from young hot stars alone. Another strong source of ionizing radiation, such as a black hole, may be needed to account for the signature. “Unfortunately with only one emission line we cannot, for sure, claim there’s a black hole in A2744_YD4,” Ellis says.
Huge cuts could be in store for federal science spending if President Donald Trump’s vision for fiscal year 2018 becomes reality.
Although details are skimpy, Trump’s $1.15 trillion budget proposal, released March 16, would make national security the top priority. The budget blueprint calls for a $54 billion increase in defense spending for 2018, offset by an equally big reduction in nondefense activities. Among the biggest science losers are the Environmental Protection Agency, which could see its budget shrink by 31 percent compared with 2017, and the National Institutes of Health, which faces an 18 percent spending slash. The Department of Energy’s Office of Science could lose about 17 percent of its funding while DOE’s Advanced Research Projects Agency-Energy, or ARPA-E — which supports research on promising energy technologies — faces complete elimination. The bare-bones budget blueprint leaves out figures altogether for many science-related agencies. It doesn’t even mention, for example, the National Science Foundation, a major source of federal funding for basic research across scientific disciplines. NSF is currently operating on a $7.5 billion budget. Full breakdowns aren’t available for most departments, so there’s no information on what’s to come for such programs as the National Institute of Standards and Technology (part of the Department of Commerce), the U.S. Fish and Wildlife Service (part of the Department of the Interior) and the Defense Advanced Research Projects Agency, or DARPA (part of the Department of Defense). More details for these and other omitted agencies may be included in a full budget proposal that the White House expects to release in May.
The White House’s budget outline is already raising alarm in the scientific community. “Major national goals are served by these investments in science and technology,” says Matt Hourihan, director of the R&D Budget and Policy Program at the American Association for the Advancement of Science in Washington, D.C. The proposed cuts, he says, “would set back our scientific leadership and would set back our technologies.” Ultimate authority of the budget rests with Congress. Last year, Congress failed to reach agreements on fiscal 2017 spending; the government has been operating under a continuing resolution that has largely kept agencies funded at their 2016 levels. That resolution expires April 28. But if the House and Senate can find common ground for fiscal 2018, which begins October 1, they are likely to be kinder to science than Trump was, Hourihan predicts. “Overall, Congress tends to find ways to support science and technology.”
Leland Cogliani, a lobbying consultant with Lewis-Burke Associates LLC in Washington, D.C., who specializes in DOE policy, agrees. “There’s a lot of angst and concern and worry about these proposed cuts to federal agencies as a whole,” he says. “My discussions with appropriators is that this budget is dead on arrival.” — Erin Wayman, with additional reporting from SN writers Environmental Protection Agency Trump’s proposed budget would devastate the EPA, dropping its annual budget from $8.2 billion to just $5.7 billion. The agency’s workforce would shed about 3,200 of its approximately 15,000 employees.
EPA’s scientific research arm would lose roughly half of its annual funding, dropping to about $250 million. Those cuts would threaten activities such as STAR grants, which provide research money and graduate fellowships in the environmental sciences.
“Unless we can find a backstop for those cuts from universities or the private sector, this is going to have a devastating impact on the global ability to do a lot of the basic science on environmental issues,” says Andrew Light of George Mason University in Fairfax, Va., a former senior adviser to the State Department’s U.S. Special Envoy for Climate Change.
In total, the budget blueprint targets more than 50 EPA programs for elimination, including the Energy Star program for boosting efficiency in appliances as well as restoration efforts to clean up the Great Lakes and Chesapeake Bay. — Thomas Sumner National Institutes of Health The president’s budget proposal would slash $5.8 billion from the $31.7 billion the NIH currently receives. Supporters of biomedical research call the proposal “disastrous” and say such deep cuts will topple the United States from its position as the world leader of biomedical research. “We’re not going to be No. 1 anymore. We’re going to slide down to the bottom of the pile,” says Jennifer Zeitzer, director of legislative relations at the Federation of American Societies for Experimental Biology, headquartered in Bethesda, Md.
Singled out in the budget proposal was the Fogarty International Center, which Trump wants to eliminate entirely. The center operates on a roughly $70 million budget and supports international collaboration for research and training in global health and infectious diseases.
“I think this is extraordinarily wrongheaded and dangerous,” says Chris Beyrer, an AIDS researcher at Johns Hopkins Bloomberg School of Public Health. Eliminating the center “is really a threat to the health and well-being of American people.” — Tina Hesman Saey Department of Energy DOE as a whole faces a 5.6 percent cut in Trump’s proposal, dropping it from $29.7 billion to $28 billion. The cut “falls disproportionately on the basic research and applied energy programs,” says Cogliani.
DOE’s Office of Science would lose about $900 million, coming from both cuts to the DOE and changing priorities for the agency. Currently funded at $5.3 billion, the Office of Science oversees 10 national labs and funds basic physics and energy research at over 300 schools in the United States.
Another DOE office, the Advanced Research Projects Agency-Energy, or ARPA-E, would get scrapped entirely. ARPA-E backs new energy technologies that show promise but aren’t far enough along to garner private sector funding. ARPA-E supports scientists working on nuclear fusion, for example, as well as new types of batteries.
One bright spot for the DOE is a call to increase funding of the National Nuclear Security Administration, which helps ensure the safety and efficacy of the U.S. nuclear weapons stockpile. — Laurel Hamers National Oceanic and Atmospheric Administration No specific budget request is included for NOAA, part of the Department of Commerce. NOAA, which monitors short- and long-term changes in the world’s oceans and atmosphere, is currently funded at $5.8 billion. The blueprint does, however, include targeted cuts that would eliminate more than $250 million for coastal and marine management, research and education. Those cuts include completely defunding NOAA’s $73 million Sea Grant program, which supports university-based research programs promoting the conservation and practical use of coastal and marine areas.
Other NOAA programs wouldn’t be hit as hard. The National Weather Service appears to avoid any major cuts, and the budget proposal maintains the development of current-generation weather satellites, including the Joint Polar Satellite System and the Geostationary Operational Environmental Satellite programs. — Thomas Sumner
NASA NASA’s proposed slice of the pie for fiscal 2018 is $19.1 billion — down 1 percent from 2017, before accounting for inflation.
“I think NASA’s top-line budget for 2018 is favorable,” says planetary scientist Alan Stern of the Southwest Research Institute in Boulder, Colo. “I bet there are many agency heads who would trade numbers with NASA in a heartbeat.”
The Trump administration plan is to refocus NASA’s priorities on “deep space exploration rather than Earth-centric research.” Planetary science research would see a boost from $1.6 billion to $1.9 billion, with continuing support for a Mars rover mission and an emphasis on exploring Jupiter’s moon Europa. The plan calls for a mission to repeatedly fly by Europa but does not provide funds for a mission to land on the Jovian moon and possibly penetrate its ice (SN: 5/17/15, p. 20).
The White House appears to be committed to human exploration of deep space, at least in part. With $3.7 billion, engineers and scientists can continue to build the Orion crew vehicle and Space Launch System, which is supposed to support a human journey to Mars. The plan, however, eliminates the multibillion-dollar Asteroid Redirect Mission, which would bring a boulder from an asteroid into the moon’s orbit and send astronauts to explore it around 2025.
Cuts would also be made to NASA’s earth science program. The White House proposes to eliminate four earth science missions: PACE, the Plankton, Aerosol, Cloud, ocean Ecosystem mission; OCO-3, the Orbiting Carbon Observatory–3 mission; DSCOVR, the Deep Space Climate Observatory; and a pathfinder mission for CLARREO, the Climate Absolute Radiance and Refractivity Observatory.
NASA’s Office of Education, with its estimated price tag of $115 million, would also be eliminated. — Ashley Yeager U.S. Geological Survey Last year the USGS was funded at about $1.1 billion; under the White House’s proposed budget, USGS would receive “more than $900 million,” though just how much more remains unclear. The amount includes funding for “research and data collection that informs sustainable energy development, responsible resource management, and natural hazard risk reduction.”
“The budget is vague, but what I can say is that overall what we’re seeing is very alarming and very disheartening,” says Christine McEntee, executive director and CEO of the American Geophysical Union in Washington, D.C. — Thomas Sumner U.S. Centers for Disease Control and Prevention No one can say exactly how the CDC fares in the proposed budget, which mentions the public health agency only once and offers no funding total. The CDC’s 2017 funding level included about $6.3 billion in appropriated funds.
President Trump’s budget proposes a “new Federal Emergency Response Fund” to respond to outbreaks such as Zika, but there’s no mention of how much money this fund would include, or which agencies would actually receive it.
Only one specific figure in the budget pertains to the CDC directly: a $500 million block grant “to increase State flexibility and focus on the leading public health challenges specific to each State.”
“500 million sounds like a lot of money, but is that over 10 years, five years, or what?” asks Karen Goraleski, executive director of the American Society of Tropical Medicine and Hygiene in Oakbrook Terrace, Ill. “With no details whatsoever, it’s anybody’s guess where the money will go, and what’s being cut in order to pay for this.” — Meghan Rosen U.S. Food and Drug Administration User fees that companies pay to the FDA to review medical products would increase to “over $2 billion in 2018,” approximately double 2017 levels, according to the budget proposal. Along with an unspecified “package of administrative actions,” the extra money could help “speed the development of safe and effective medical products.”
More money is good but isn’t likely to do much to move products along, says Jeff Allen, president and CEO of Friends of Cancer Research, an advocacy group. “The review process is just a fraction of the amount of time it takes for a new drug to reach the market,” he says.
The budget request glossed over the main source of FDA dollars, taxpayer money appropriated by Congress. The agency currently receives $2.72 billion in appropriated funds, nearly $1 billion in medical product user fees and almost another $1 billion in user fees for other products.
Unlike appropriated funds, user fees can be used only for specifically defined activities, like reviewing product applications. Without naming a number for appropriated funds, the fate of many FDA programs, including food safety, remain in the dark. And expecting the FDA to function mainly on user fees “seems rather unrealistic and totally unfeasible,” Allen says. — Meghan Rosen
When choosing more attractive guys, girl guppies with larger brains have an advantage over their smaller-brained counterparts. But there’s a cost to such brainpower, and that might help explain one of the persistent mysteries of sex appeal, researchers report March 22 in Science Advances.
One sex often shows a strong preference for some trait in the other, whether it’s a longer fish fin or a more elaborate song and dance. Yet after millions of years, there’s still variety in many animals’ color, size, shape or song, says study coauthor Alberto Corral-López, an evolutionary biologist at Stockholm University. Somehow generations of mate choice have failed to make the opposite sex entirely fabulous.
Mate choice could require a certain amount of brainpower, with animals weighing the appeal of suitors and choosing among them. Previous research suggests a smaller brain dims guppies’ mental abilities, and the researchers wondered how brain size might affect the fish’s choice of mate.
To test the idea, researchers used female guppies bred for either a larger or smaller brain. Guppy brains are tiny to begin with, but after five generations of breeding the brain sizes in the study differed by about 13 percent, within the range of what biologists find in the wild. Each female was offered a choice between a colorful male with orange spots and a bigger tail versus a drab male of about the same weight but without much glory behind. The male fish were installed in compartments at either end of a tank, and females swam back and forth, forced to remember and mentally compare one suitor with his rival.
Females with larger brains showed a preference overall for the more colorful male. Smaller-brained females showed no preference. (The difference did not come from differences in color vision, Corral-López says. The researchers checked the eye genes of the fish and also tested their ability to distinguish colors.)
Interest in flashy-looking males may not be just a fashion choice for females. Orange colors come from pigments in food, suggesting that brighter males may be better fed and healthier, which could lead to healthier offspring. And more colorful males are typically better at finding food. Corral-López also tested females that had not been specially bred for brain size, and these fish preferred the colorful males, too.
But bigger-brained females did not beat their small-brained compatriots in all tests. The smaller-brained guppies tended to grow faster when they were young and to have better immune systems and more offspring.
Thus, circumstances might tip the balance toward or against braininess, the researchers say. Having more babies might be more useful than a discriminating brain, for instance, when food is plentiful and most males manage a decent orange. Such changes in fortune might help explain how variety in appearance persists despite strong mating preferences, Corral-López and colleagues argue. Sometimes flashier males win females, but sometimes drab is just fine.
“Exciting work,” says Molly Cummings of the University of Texas at Austin, who studies fish brains and sexual selection. Checking the fish’s vision was especially important, she says. The results show that females were not “simple slaves to their sensory system.”
The new paper, of course, tracked lab animals, and there’s little data on what differences in brain size mean for mate choice in the wild, says evolutionary biologist Kimberly Hughes of Florida State University in Tallahassee. The new guppy study suggests it’s certainly worth looking at what girl guppies do naturally, she says.
Sea ice skylights formed by warming Arctic temperatures increasingly allow enough sunlight into the waters below to spur phytoplankton blooms, new research suggests. Such conditions, probably a rarity more than two decades ago, now extend to roughly 30 percent of the ice-covered Arctic Ocean during July, researchers report March 29 in Science Advances.
The microscopic critters need plenty of sunlight to thrive, so scientists were stunned by the discovery of a sprawling bloom below the normally sun-blocking Arctic ice in July 2011 (SN: 7/28/12, p. 17). Satellites can’t peek below the ice, though, so scientists at the time didn’t know whether the bloom was an oddity or representative of a shift in the Arctic environment.
Harvard University oceanographer Christopher Horvat and colleagues created a computer simulation of sea ice conditions from 1986 through 2015. Warming temperatures have thinned the ice, the researchers found, and increased the prevalence of meltwater pools on top of the ice that allow more light to pass through than bare or snow-covered ice.
Whether blooms are in fact more commonplace under the ice remains unclear, though, because the study didn’t consider whether there would be enough nutrients such as nitrogen and iron for budding blooms. If more blooms are lurking in the Arctic Ocean, they may already be dramatically reshaping the Arctic ecosystem. A boost in phytoplankton could alter marine food webs as well as soak up more planet-warming carbon dioxide from the environment.
Big bloom Increasingly large swaths of the ice-covered Arctic Ocean allow enough light into the waters below to support phytoplankton blooms, new research suggests. Green regions indicate bloom-friendly conditions in July over the last few decades, with darker shades representing longer duration.
WASHINGTON — Immune cells engineered to hunt and destroy cancer cells may help some people with acute lymphoblastic leukemia (ALL) live much longer.
Outcomes depended upon disease severity before treatment, oncologist Jae Park reported April 3 at the American Association for Cancer Research annual meeting.
In ALL — expected to strike 5,970 people and kill 1,440 in the United States in 2017 — immune cells called B cells grow out of control in bone marrow and can spread to other tissues. Overall, five-year survival rates are 71 percent. But fewer than 10 percent of people survive for five years after a relapse of the cancer, said Park of Memorial Sloan Kettering Cancer Center in New York City. Park and colleagues genetically engineered T cells from 51 people whose leukemia came back or who didn’t respond to initial chemotherapy. These CAR-T cells seek out and kill the rogue B cells.
Of 20 people who started the study with leukemia cells making up less than 5 percent of their bone marrow, 95 percent had a complete response to the CAR-T treatment. Most are still alive with no signs of leukemia; one patient remains in remission five years after treatment.
But 31 people who started immune therapy with leukemia cells composing more than 5 percent of their bone marrow didn’t fare as well. After good initial responses, the cancer came back a median of 6.3 months later. Patients survived a median of 17 months, although some are still alive after three years.
The second group also tended to have more severe side effects, including an immune reaction called cytokine release syndrome and neurotoxicity, or nerve problems.
Park and his colleagues are not yet sure why the therapy works better for some people than others. But, he said, CAR-T cell therapy “still provides better survival than traditional treatments.”
Gravel devil GRAV-uhl DEV-uhl n. A whirlwind containing gravel-sized debris
Towering, crystal-filled twisters periodically swirl in a valley nestled between two volcanoes in the Andes Mountains, newly reported observations show. The odd weather events are the first record of large pieces of gravel efficiently moving across a landscape by suspension in air.
Geologist Kathleen Benison of West Virginia University in Morgantown spotted the whirlwinds during an expedition in 2007 to an otherworldly region of northern Chile. There, gypsum crystals form from evaporating volcanic pools of salty, acidic water. When the pools dry, exposing the crystals within, whirlwinds as big as half a kilometer across can sweep the crystals aloft, Benison reports online March 15 in Geology. She saw storms of crystals travel as far as five kilometers before dropping their payloads into large, dunelike piles. Over time the far-flung crystals, some as long as 27 centimeters (which geologists still classify as gravel), meld together into a massive hunk. If found in the rock record, such crystal conglomerations could help geologists identify where strong whirlwinds howled long ago, Benison proposes.
Albert Einstein was a master of physics, but his talent in personal relationships was decidedly underdeveloped. A new 10-episode series, Genius, airing on the National Geographic Channel, focuses on the facets of Einstein’s life where he was anything but a virtuoso.
Genius is a dramatization, not a documentary. The series reveals the human side of the famously brainy physicist — through Einstein’s numerous romantic liaisons and his reactions to world political events, including two world wars and his departure from Nazi Germany. Unfortunately, although Einstein’s personal life reveals insights into his character, Genius ends up sacrificing science for the sensational. The first episode, for instance, opens with a murder followed by a sex scene. Viewers shouldn’t expect to learn much about the science of Einstein’s discoveries, at least based on the first two episodes that were available for review. The explanations are vague enough that those unfamiliar with Einstein’s theories will understand little, and those who know them won’t learn anything new.
Based on Walter Isaacson’s book Einstein: His Life and Universe, the television series leapfrogs from one time period to another, contrasting the scientific enthusiasm of the brash young Einstein (played by Johnny Flynn) with the more sedate ruminations of the elder, established physicist (Geoffrey Rush). While time traveling from one period to another, the show plays up Einstein’s fascination with time. The young Einstein is portrayed as a brilliant, willful character. After dropping out of high school, he fails an entrance exam to Zurich Polytechnic. He is finally admitted a year later, in 1896, after additional schooling. There, he skips classes, challenges professors who are reluctant to teach cutting-edge theories and studies mainly on his own. Meanwhile, the young Einstein’s love life makes for surprisingly dramatic vignettes. In one scene, his lover Mileva Marić (Samantha Colley) — a fellow physics student in Zurich who would later become his first wife — realizes Einstein has yet to break things off with his first flame, Marie Winteler (Shannon Tarbet). Marić smashes a teapot against the wall and then, distraught, berates Einstein for his thoughtlessness.
Despite his smarts, Einstein is not always the hero of his own story. As he plays fast and loose with his lovers’ hearts, viewers may find themselves siding with the women. As the show recounts Marić’s childhood in Serbia and her struggle to become a physicist when few institutions were willing to educate women, Marić sometimes seems the more impressive member of the pair. (Marić doesn’t continue on in physics, after failing her exams and becoming pregnant.) Einstein eventually marries Marić in 1903, then divorces her in 1919, a few years after beginning an affair with his cousin Elsa (Emily Watson), who becomes his second wife.
The older, famous Einstein possesses the same stubborn determination as his younger self. Despite the anti-Semitic sentiment in the run-up to World War II, Einstein, a Jew, initially resists leaving Germany. But circumstances eventually change his mind. In 1922, Einstein’s friend, German foreign minister Walther Rathenau, who is also Jewish, is assassinated. And then prominent anti-Semitic scientists, including Nobel laureate Philipp Lenard, denounce Einstein. By 1933, the situation becomes unbearable, and Albert and Elsa leave for the United States.
Overall, Genius portrays Einstein as a complicated human, not just a cartoonish brainiac. Those unfamiliar with Einstein’s personal life will see the scientist in a new light. But be prepared for an emphasis on drama, sex and love stories, not science.
Continental drift, a theory often considered amusing but rarely important, seems about to become the focus of a revolution in geology. At the least, it has already split the geological community into those who find the evidence for it “formidable” and those who think it is not yet formidable enough to constitute a proof. — Science News, April 29, 1967
Update That continents shift is now widely accepted and explained by plate tectonics. Plenty of evidence supports the idea that the Earth’s outer layer is divided into large slabs that gradually move over the mantle. But researchers don’t agree on when the plates first began shifting. New evidence from ancient rocks found in Canada suggests the slipping and sliding didn’t get going until Earth was at least a billion years old (SN: 4/15/17, p. 8). In about 250 million years from now, the continents may drift together into a supercontinent called Amasia (SN: 1/21/17, p. 18).
Groundwater that has lingered in Earth’s depths for more than 12,000 years is surprisingly vulnerable to modern pollution from human activities. Once in place, that pollution could stick around for thousands of years, researchers report online April 25 in Nature Geoscience. Scientists previously assumed such deep waters were largely immune to contamination from the surface.
“We can’t just drill deep and expect to run away from contaminants on the land surface,” says Scott Jasechko, a study coauthor and water resources scientist at the University of Calgary in Canada. Groundwater quenches the thirst of billions of people worldwide and accounts for roughly 40 percent of the water used in agriculture. Water percolating from the surface into underground aquifers can carry pollutants such as pesticides and salt along for the ride.
Jasechko and colleagues weren’t looking for contamination when they tested water from 6,455 water wells around the world. Their goal was to use carbon dating to identify how much of that deep water was “fossil” groundwater formed more than 12,000 years ago. Previous studies had looked at average water age, rather than the age of its individual components.
While there’s no C in H2O, carbon dating can still be used to date groundwater by examining the carbon dissolved in the water. Radioactive carbon atoms decay as the water ages. After around 12,000 years, only stable carbon isotopes remain. Comparing the relative abundance of these carbon isotopes in the various wells, the researchers discovered that over half of wells more than 250 meters deep yielded mostly groundwater at least 12,000 years old. How much older is unknown. Worldwide, the researchers estimate that fossil groundwater accounts for 42 to 85 percent of water in the top kilometer of Earth’s crust. In a second measurement, the researchers looked for a common modern pollutant. They found that around half of wells containing mostly fossil groundwater had elevated traces of tritium, a radioactive hydrogen isotope spread during nuclear bomb tests that’s hazardous in very high concentrations. While the tritium levels weren’t dangerous, its presence suggests that at least some groundwater in the wells postdates the 1950s nuclear testing. That relatively young water may introduce other contaminants in addition to tritium, the researchers say. How new groundwater enters deep wells is still unclear, Jasechko says. Old and young waters could mix within an aquifer or, alternatively, the construction and use of the well itself could churn the waters together.
No matter where the young water comes from, the new technique for identifying the percentage of fossil groundwater in a well could be an important tool for communities, says Audrey Sawyer, a hydrogeologist at Ohio State University in Columbus. The study raises awareness that even in wells with mostly older water “a fraction of that same water can be pretty young and susceptible to contamination,” she says.
