In a big step toward catching up with the rest of the world, the United States cleared the way for using mosquitoes as a commercial pest control for the first time.
The U.S. Environmental Protection Agency has approved using a strain of male Asian tiger mosquitoes (Aedes albopictus) as a biopesticide in the District of Columbia and 20 states, including California and New York. Kentucky-based MosquitoMate was granted the right to sell these mosquitoes, called ZAP Males, for the next five years, the agency announced November 7. These male mosquitoes are not genetically modified. Instead they carry a strain of Wolbachia bacteria that turns them into saboteur dads. When they mate with wild females not carrying the strain, the offspring will die and the population should dwindle. Males don’t bite, so releasing them should not add extra vexation.
Releases of Wolbachia-bearing mosquitoes for pest control already go on in other countries, such as Brazil, although with a different bacterial strain and a different strategy.
This same company has also been testing the effectiveness of a different mosquito species, Aedes aegypti, also carrying bad-dad Wolbachia, near Key West, Fla. (These mosquitoes are not commercially available.) The tests “ended a bit early due to [Hurricane] Irma,” says Stephen Dobson of MosquitoMate, “but we think that we have some good data despite this complication.”
The human brain is teeming with diversity. By plucking out delicate, live tissue during neurosurgery and then studying the resident cells, researchers have revealed a partial cast of neural characters that give rise to our thoughts, dreams and memories.
So far, researchers with the Allen Institute for Brain Science in Seattle have described the intricate shapes and electrical properties of about 100 nerve cells, or neurons, taken from the brains of 36 patients as they underwent surgery for conditions such as brain tumors or epilepsy. To reach the right spot, surgeons had to remove a small hunk of brain tissue, which is usually discarded as medical waste. In this case, the brain tissue was promptly packed up and sent — alive — to the researchers. Once there, the human tissue was kept on life support for several days as researchers analyzed the cells’ shape and function. Some neurons underwent detailed microscopy, which revealed intricate branching structures and a wide array of shapes. The cells also underwent tiny zaps of electricity, which allowed researchers to see how the neurons might have communicated with other nerve cells in the brain. The Allen Institute released the first publicly available database of these neurons on October 25.
A neuron called a pyramidal cell, for instance, has a bushy branch of dendrites (orange in 3-D computer reconstruction, above) reaching up from its cell body (white circle). Those dendrites collect signals from other neural neighbors. Other dendrites (red) branch out below. The cell’s axon (blue) sends signals to other cells that spur them to action. Like the chandelier cell, a Martinotti cell (below) quiets other cells with messages coming from its tangled, tall axon, which spans several layers of the brain’s cortex — the wrinkly, outer layer that’s involved in higher-level thought. And in a basket cell (above), axon branches, which allow the nerve cell to send messages to other neurons, cluster densely around the cell body. Because the neurons play different roles in the brain, the new collection could help researchers figure out the details of those diverse jobs. Similar data exist for cells taken from the brains of other animals, such as mice, but until now, data on live cells from people have been scarce.
“These neurons are amazingly beautiful,” says Ed Lein, a neuroscientist at the Allen Institute who works on the project. “They look like trees. They’re much more complex than similar cells in a mouse.”
BOSTON — Long before anyone opened a bank account or rented a safe deposit box, wealth protection demanded a bit of guile and a broken beer jug. A 3,100-year-old jewelry stash was discovered in just such a vessel, unearthed from an ancient settlement in Israel called Megiddo in 2010. Now the find is providing clues to how affluent folk hoarded their valuables at a time when fortunes rested on fancy metalwork, not money.
At the fortress city of Megiddo, a high-ranking Canaanite family stashed jewelry in a beer jug and hid it in a courtyard’s corner under a bowl, possibly under a veil of cloth, Eran Arie of the Israel Museum in Jerusalem, said November 17 at the annual meeting of the American Schools of Oriental Research. The hoard’s owners removed the jug’s neck and inserted a bundle of 35 silver items, including earrings and a bracelet, which were wrapped in two linen cloths. Other valuables were then added to the jug, including around 1,300 beads of silver and electrum — an alloy of gold and silver — that had probably been threaded into an elaborate necklace. There were 10 additional pieces of electrum jewelry, including a pair of basket-shaped earrings, each displaying a carved, long-legged bird. A Canaanite city palace stood only about 30 meters from the Iron Age building that housed the courtyard, Arie said. Due to the lesser building’s strategic location, its inhabitants must have held key government positions, he proposed. “For the family that lived there, the hoard represented the lion’s share of their wealth.” Those family members presumably fled around the time the structure that held the jewelry hoard was destroyed in a catastrophic event, possibly a battle. The Megiddo hoard was hidden but not buried, giving its owners quick access to their valuables. But no one ever retrieved the treasure. “We will never know why no one returned to claim this hoard,” Arie said.
Earthquake warning systems face a tough trade-off: To give enough time to take cover or shut down emergency systems, alerts may need to go out before it’s clear how strong the quake will be. And that raises the risk of false alarms, undermining confidence in any warning system.
A new study aims to quantify the best-case scenario for warning time from a hypothetical earthquake early warning system. The result? There is no magic formula for deciding when to issue an alert, the researchers report online March 21 in Science Advances. “We have a choice when issuing earthquake warnings,” says study leader Sarah Minson, a seismologist at the U.S. Geological Survey, or USGS, in Menlo Park, Calif. “You have to think about your relative risk appetite: What is the cost of taking action versus the cost of the damage you’re trying to prevent?”
For locations far from a large quake’s origin, waiting for clear signs of risk before sending an alert may mean waiting too long for people to be able to take protective action. But for those tasked with managing critical infrastructure, such as airports, trains or nuclear power plants, an early warning even if false may be preferable to an alert coming too late (SN: 4/19/14, p. 16).
Alerts issued by earthquake early warning systems, called EEWs, are based on several parameters: the depth and location of the quake’s origin, its estimated magnitude and the ground properties, such as the types of soil and rock that seismic waves would travel through.
“The trick to earthquake early warning systems is that it’s a misnomer,” Minson says. Such systems don’t warn that a quake is imminent. Instead, they alert people that a quake has already happened, giving them precious seconds — perhaps a minute or two — to prepare for imminent ground shaking. Estimating magnitude turns out to be a sticking point. It is impossible to distinguish a powerful earthquake in its earliest stages from a small, weak quake, according to a 2016 study by a team of researchers that included Men-Andrin Meier, a seismologist at Caltech who also coauthors the new study. Estimating magnitude for larger quakes also takes more time, because the rupture of the fault lasts perhaps several seconds longer – a significant chunk of time when it comes to EEW. And there is a trade-off in terms of distance: For locations farther away, there is less certainty the shaking will reach that far. In the new study, Minson, Meier and colleagues used standard ground-motion prediction equations to calculate the minimum quake magnitude that would produce shaking at any distance. Then, they calculated how quickly an EEW could estimate whether the quake would exceed that minimum magnitude to qualify for an alert. Finally, the team estimated how long it would take for the shaking to strike a location. Ultimately, they determined, EEW holds the greatest benefit for users who are willing to take action early, even with the risk of false alarms. The team hopes its paper provides a framework to help emergency response managers make those decisions.
EEWs are already in operation around the world, from Mexico to Japan. USGS, in collaboration with researchers and universities, has been developing the ShakeAlert system for the earthquake-prone U.S. West Coast. It is expected be rolled out this year, although plans for future expansion may be in jeopardy: President Trump’s proposed 2019 budget cuts the USGS program’s $8.2 million in funding. It’s unclear whether Congress will spare those funds.
The value of any alert system will ultimately depend on whether it fulfills its objective — getting people to take cover swiftly in order to save lives. “More than half of injuries from past earthquakes are associated with things falling on people,” says Richard Allen, a seismologist at the University of California, Berkeley who was not involved in the new study. “A few seconds of warning can more than halve the number of injuries.”
But the researchers acknowledge there is a danger in issuing too many false alarms. People may become complacent and ignore future warnings. “We are playing a precautionary game,” Minson says. “It’s a warning system, not a guarantee.”
The history of New England’s most damaging earthquake is written in the mud beneath a Massachusetts pond. Researchers identified the first sedimentary evidence of the Cape Ann earthquake, which in 1755 shook the East Coast from Nova Scotia to South Carolina. The quake, estimated to have been at least magnitude 5.9, took no lives but damaged hundreds of buildings.
Within a mud core retrieved from the bottom of Sluice Pond in Lynn, Mass., a light brown layer of sediment stands out amid darker layers of organic-rich sediment, the researchers report March 27 in Seismological Research Letters. The 2-centimeter-thick layer contains tiny fossils usually found near the shore, as well as types of pollen different from those found in the rest of the core. Using previous studies of the pond’s deposition rates, geologist Katrin Monecke of Wellesley College in Massachusetts and her colleagues determined the layer dates to between 1740 and 1810. That light-brown layer is likely a turbidite, sediment jumbled up by a sudden lake slope failure, the study says. There are no other turbidites in the core, which spans about 400 years, suggesting the slopes held fast through floods and hurricanes. But the Cape Ann quake was likely a strong enough trigger to cause the slope failure.
Though the eastern United States is not at the seismically active edge of a tectonic plate, it has occasionally had its ground-shakers (SN Online: 8/23/11). The study suggests other East Coast lakes and ponds may contain evidence of prehistoric quakes, giving researchers a new way to estimate their frequency.
The Cape Ann quake also left its mark on the colonists, inspiring poems that suggested the temblor was a warning from a wrathful God. Harvard University scientist John Winthrop chronicled witness accounts of the quake in a 1757 paper to the Royal Society of London. “The earthquake began with a roaring noise,” Winthrop quoted one man as saying, “like thunder at a distance.”
A famous 4.4-million-year-old member of the human evolutionary family was hip enough to evolve an upright gait without losing any tree-climbing prowess.
The pelvis from a partial Ardipithecus ramidus skeleton nicknamed Ardi (SN: 1/16/10, p. 22) bears evidence of an efficient, humanlike walk combined with plenty of hip power for apelike climbing, says a team led by biological anthropologists Elaine Kozma and Herman Pontzer of City University of New York. Although researchers have often assumed that the evolution of walking in hominids required at least a partial sacrifice of climbing abilities, Ardi avoided that trade-off, the scientists report the week of April 2 in the Proceedings of the National Academy of Sciences. “Ardi evolved a solution to an upright stance, with powerful hips for climbing that could fully extend while walking, that we don’t see in apes or humans today,” says Pontzer, who is also affiliated with CUNY’s Hunter College. Ardi’s hip arrangement doesn’t appear in two later fossil hominids, including the famous partial skeleton known as Lucy, a 3.2-million-year-old Australopithecus afarensis.
Ardi’s lower pelvis is longer than that of humans, which led some researchers to argue that Ardipithecus mainly climbed in trees and walked slowly with bent knees and hips, or perhaps not at all. But the new study shows it “would not have impeded its ability to walk upright in a humanlike fashion,” says paleoanthropologist Carol Ward of the University of Missouri in Columbia. Unlike other hominids and living apes, Ardi’s upper pelvis is positioned behind the lower pelvis, enabling a straight-legged gait, Pontzer and his colleagues find. An evolutionary reorienting of the pelvis in that way enabled back muscles to support an upright spine, Ward suggests. A relatively large gluteus maximus works with hamstring muscles to push humans into a straight-legged stance. Ardi may have had a small rear-end muscle for her size, making a forward-positioned lower pelvis especially critical for walking, Pontzer says.
Using previous data from present-day humans, chimps and monkeys, Pontzer’s group documented a relationship between the shape and orientation of the lower pelvis and the energy available for a range of motions involved in walking and climbing. They used those findings to examine fossil pelvises of Ardi, Lucy and a 2.5-million-year-old Australopithecus africanus. No other fossil hominids from that long ago included a pelvis complete enough for analysis.
The researchers also evaluated a nearly 18-million-year-old fossil pelvis from an African ape, Ekembo nyanzae.
A. afarensis and A. africanus displayed pelvic arrangements for upright walking, but not for Ardi’s apelike climbing power. In particular, the lower pelvis of the two Australopithecus species was nearly as short as the walking-specialized lower pelvis of people today. E. nyanzae’s pelvis was specialized for climbing, as in modern apes and monkeys. Its long, straight pelvis enabled walking with bent hips and knees.
The new study coincides with previous evidence that Ardi’s lower back was flexible enough to support straight-legged walking, says paleoanthropologist Owen Lovejoy of Kent State University in Ohio. Lovejoy, who led an initial investigation of Ardi’s lower-body bones, has long contended that ancient hominids had a humanlike gait (SN: 7/17/10, p. 5).
“A. afarensis and A. africanus walked much like we do, and for the most part that goes for Ardi as well,” Lovejoy says.
Ardi’s unusual mix of walking and climbing abilities spurred the evolution of hominid bodies geared toward minimizing lower-limb injuries, Lovejoy proposes. Ardi’s long lower pelvis and apelike, opposable big toe were replaced in Lucy’s kind by a short lower pelvis connected to smaller hamstring muscles, a humanlike big toe and a fully developed arch (SN: 3/12/11, p. 8). Those changes made climbing harder for A. afarensis, but stabilized its upright stance, helping to prevent foot injuries and hamstring tears when stopping suddenly or accelerating quickly, Lovejoy says.
Just like lions, tigers and bears, certain kinds of seals have claws that help the animals grasp prey and tear it apart. X-rays show that the bones in these seals’ forelimbs look like those found in the earliest seals, a new study finds.
Ancestors of these ancient seals transitioned from land to sea at some point, preserving clawed limbs useful for hunting on land. But clawed paws in these northern “true seals,” which include harbor and harp seals, seem to be more than just a holdover from ancient times, says David Hocking, a marine zoologist at Monash University in Melbourne, Australia. Instead, retaining the claws probably helps northern true seals catch a larger meal than they could with the stiff, slippery fins of other pinnipeds such as sea lions and fur seals, Hocking and his colleagues report April 18 in Royal Society Open Science. Hocking and his colleagues spent 670 hours observing wild harbor and gray seals hunting salmon in Scotland. Tests with three captive seals, two harbor seals born in captivity and one spotted seal born in the wild allowed the team to observe eating behaviors at closer range. While some of the captive seals seemed to prefer swallowing their prey whole, both the wild and captive animals relied heavily on their claws overall, the scientists found. The critters were frequently spotted using their slashers to hold onto prey and rip off smaller bites, much as a land animal like a wolverine or a bear might. Up-close observations revealed seals caught prey underwater, but ripped it apart at the surface. That probably lets them breathe while eating without inhaling gulps of seawater — a challenge when devouring a large meal underwater. Northern true seals have flexible joints that allow the animals to curl their claws to grasp prey. These flexible joints are also seen on early pinnipeds such as Enaliarctos mealsi, a seal that lived 23 million years ago, Hocking and his colleagues found. Fur seals and sea lions, however, “have inflexible fingers that help them to maintain a stiff flipper,” Hocking says.
The evolution of flipperlike forelimbs helped some pinnipeds propel themselves through the water more efficiently. But slippery flippers aren’t as useful for grasping prey. That could explain why fur seals and sea lions tend to target smaller fish that they can swallow whole underwater without needing to grasp, Hocking says.
But this fully aquatic feeding style might have been a challenge for the earliest pinnipeds, who probably used their clawed paws to hunt more like today’s true seals, the researchers say. Catching prey underwater and then shredding it at the surface was probably a smaller behavioral leap from full-on land feeding than other aquatic hunting strategies.
Documenting seals using their paws to grasp food is a “nice observation,” says Frank Fish, a biologist at West Chester University in Pennsylvania. Without knowing what early seals ate, though, it’s hard to say for sure whether they actively used their claws to hold onto large prey, he says.
Other scientists have documented true seals using their pawlike forelimbs in stereotypically terrestrial ways, too, such as using the claws to dig out lairs in ice or uncovering buried fish from the seafloor.
When it comes to tiny ocean swimmers, the whole is much greater than the sum of its parts. Ocean turbulence stirred up by multitudes of creatures such as krill can be powerful enough to extend hundreds of meters down into the deep, a new study suggests.
Brine shrimp moving vertically in two different laboratory tanks created small eddies that aggregated into a jet roughly the size of the whole migrating group, researchers report online April 18 in Nature. With a fluid velocity of about 1 to 2 centimeters per second, the jet was also powerful enough to mix shallow waters with deeper, saltier waters. Without mixing, these waters of different densities would remain isolated in layers. The shrimp represent centimeter-sized swimmers, including krill and shrimplike copepods, found throughout the world’s oceans that may together be capable of mixing ocean layers — and delivering nutrient-rich deep waters to phytoplankton, or microscopic marine plants, near the surface, the researchers suggest. “The original thinking is that these animals would flap their appendages and create little eddies about the same size as their bodies,” says John Dabiri, an expert in fluid dynamics at Stanford University. Previous work, including acoustic measurements of krill migrations in the ocean ( SN: 10/7/06, p. 238 ) and theoretical simulations of fluid flow around swimmers such as jellyfish and shrimplike copepods ( SN: 8/29/09, p. 14 ), had suggested that they may be stirring up more turbulence than thought. In 2014, Dabiri coauthored a study that debuted the laboratory tank setup also used in the new research. That paper noted that migrating brine shrimp created jets and eddies much larger than themselves. “But there was skepticism about whether those lab results were relevant to the ocean,” Dabiri says. The 2014 study didn’t account for how ocean water stratifies into layers that don’t easily mix, due to differences in salinity or temperature. It wasn’t clear if shrimp-generated turbulence could be strong enough and extend deep enough to overcome the physical barriers and mix the layers.
The new research used a 1.2-meter-deep tank and a 2-meter-deep tank. Each held tens of thousands of wiggly brine shrimp in two layers of water of different densities. The researchers used LED lights to prompt the shrimp to migrate upward or downward, mimicking the massive daily, vertical migrations of krill, copepods and other ocean denizens. The shrimp migrated in close proximity to one another – and that helped to magnify their individual efforts, the scientists found.
“As one animal swims upward, it’s kicking backward,” Dabiri says. That parcel of water then gets kicked downward by another nearby animal, and then another. The result is a downward rush that gets stronger as the migration continues, and eventually extends about as deep as the entire migrating group. In the ocean, that could be as much as hundreds of meters.“At the heart of the investigation is the question about whether life in the ocean, as it moves about the environment, does any important ‘mixing,’ ” says William Dewar, an oceanographer at Florida State University in Tallahassee. “These results argue quite compellingly that they do, and strongly counter the concern that most marine life is simply too small in size to matter.”
The team’s finding opens the door to a host of interesting questions, Dewar adds. Ocean mixing is an important part of the global climate cycle: It churns up nutrients that feed phytoplankton blooms and aids the exchange of gases with the atmosphere. Adding biologically driven mixing to physical processes in the ocean makes the equation even more complex, he says.
The next step will be to try to observe the effect at sea, using shipboard measurements, Dabiri says. “Previous studies looked for turbulence or eddies on the scale of the animals’ size,” he says, instead of large downward jets. “This paper tells us for the first time what to look for.”
Shooting small rocks from a high-speed cannon showed that some asteroids could have brought water to the early Earth — without all the water boiling away on impact, a new study finds.
“We can’t bring an asteroid to Earth and crash it into the Earth, bad things would happen,” says planetary geologist R. Terik Daly, who did the research while a graduate student at Brown University in Providence, R.I. “So we went into the lab and tried to re-create the event as best we can.” After the solar system formed about 4.6 billion years ago, Earth grew up relatively close to the sun, where it was too hot for water to condense out of the gas phase. And Earth was too small to hold on to much nearby gas anyway. So scientists think the pale blue dot may have received its water from somewhere else — although exactly how that happened is still up for debate (SN: 5/16/15, p. 18).
Daly, now at Johns Hopkins University, and Brown planetary scientist Peter Schultz made marble-sized pellets of antigorite, a mineral found in Japan that is similar to the kinds of rocks that may have brought water to Earth billions of years ago. To simulate a dry planetary surface, the team baked pumice at 850° Celsius for 90 minutes. Then the team shot the pellets at the pumice at about 5 kilometers per second using the NASA Ames Vertical Gun Range in California. That speed is similar to those at which asteroids probably crashed into each other when the planets were forming, Daly says. Previous simulations suggested that all of an asteroid’s water would vaporize upon impact if the asteroid had been traveling faster than 3.1 kilometers per second. On a planet like the early Earth, which lacked an atmosphere, that water vapor would then have been lost to space. But Daly and Schultz found that some of the water vapor released by the pellets’ impacts was captured within glass created from shocked rock, or conglomerates of “busted-up” rocks called breccias. Asteroids could have delivered up to 30 percent of their stored water to growing planets, the scientists conclude April 25 in Science Advances. The next step is working out how the water could escape from rocks to create oceans and other water bodies, Daly says.
“I really like this work,” says planetary scientist Yang Liu of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the study. “The experimental setup is very clever.”
Liu studies water in lunar material, and one frequent question about her work is how the moon can have water at all (SN: 10/24/09, p. 10). Earth’s nearest celestial neighbor lacks a thick atmosphere where vapor can accumulate, which means the moon should have had an even harder time keeping impact-delivered water than the Earth did.
“This work demonstrates that this is feasible even for airless bodies,” she says. The finding even suggests a way for future crewed missions to find water on the moon: “Perhaps we should just look for impact melts to get the water we need.”
Animal experiments demonstrate for the first time that transplanted tumors release a chemical into the host’s bloodstream that causes the host to produce blood vessels to supply the tumor.… If such a factor can be identified in human cancers … it might be possible to prevent the vascularization of tumors. Since tumors above a certain small size require a blood supply to live, they might by this method be starved to death. — Science News, May 4, 1968
Update By the 1990s, starving tumors had become a focus of cancer research. Several drugs available today limit a tumor’s blood supply. But the approach can actually drive some cancer cells to proliferate, researchers have found. For those cancers, scientists have proposed treatments that open up tumors’ gnarled blood vessels, letting more oxygen through. Boosting oxygen may thwart some cancer cell defenses and promote blood flow — allowing chemotherapy drugs and immune cells deeper access to tumors (SN: 3/4/17, p. 24).
