Some ants are so good at navigating they can do it backward.
Researchers think that foraging ants memorize scenes in front of them to find their way back to the nest. But that strategy only works when facing forward. Still, some species have been observed trekking in reverse to drag dinner home.
To find out how the ants manage this feat, Antoine Wystrach of the University of Edinburgh and colleagues captured foraging desert ants (Cataglyphis velox) near a nest outside Seville, Spain. In a series of tests, the researchers gave the ants cookie crumbles and then released the ants at a fork in the route back to their nest.
Regardless of which direction they took, ants walking backward with cookie bits in tow maintained a straight path. The researchers suspect the ants relied on some sort of sunlight cues. Ants also appeared to peek behind themselves to check and adjust course. After making adjustments, ants maintained their new direction no matter their body orientation. Desert ants combine their celestial compass and long-term visual memories of the route to find their way home, the team concludes online January 19 in Current Biology.
Blobs of gas near the Milky Way’s center may be just the right mass to harbor young stars and possibly planets, too. Any such budding stellar systems would face an uphill battle, developing only about two light-years from the galaxy’s central supermassive black hole with its intense gravity and ultraviolet radiation. But it’s not impossible for the small stars to survive in the hostile place, a new study suggests.
“Nature is very clever. It finds ways to work in extreme environments,” says Farhad Yusef-Zadeh, an astrophysicist at Northwestern University in Evanston, Ill. Four blobs of gas near the galactic center have the right amount of mass to be planetary systems with small, young stars, Yusef-Zadeh and colleagues report online January 20 at arXiv.org. The paper is also slated for publication in the Monthly Notices of the Royal Astronomical Society. “It is fairly likely that planets and low-mass stars do form near the galactic center. But we do not know it for sure at the moment,” says Avi Loeb, an astrophysicist at Harvard University. Loeb, who was not involved in the study, says the new evidence is “tentative at best.”
Yusef-Zadeh and colleagues used ALMA, the Atacama Large Millimeter/submillimeter Array, in Chile to study emissions from five of the 44 blobs of gas that the team discovered in 2014 (SN Online: 3/24/15). Four of the clouds had between 0.03 and 0.05 as much mass as the sun, the team calculated. That’s right in line with what’s needed to generate low-mass stars — ones about the size of the sun or a little bigger — and the planets that orbit them, Yusef-Zadeh says. He points out that the team has not detected these stars or planets, just that conditions are ripe for them to exist.
Loeb notes that the team had to infer the clouds’ entire masses from the ALMA measurements, which may reveal only a surface look at the blobs. The clouds may actually be denser; as a result, they would form more massive stars, challenging the team’s claim that low-mass stars are forming.
Yusef-Zadeh and colleagues are planning additional studies with ALMA and are also working on research that suggests that black holes may, in fact, help star formation. “It’s paradoxical,” Yusef-Zadeh says. “Black holes eat everything that comes too close to them. They tear everything apart. But they may actually make the formation of stars more efficient.”
The breath of oxygen that enabled the emergence of complex life kicked off around 100 million years earlier than previously thought, new dating suggests.
Previous studies pegged the first appearance of relatively abundant oxygen in Earth’s atmosphere, known as the Great Oxidation Event, or GOE, at a little over 2.3 billion years ago. New dating of ancient volcanic outpourings, however, suggests that oxygen levels began a wobbly upsurge between 2.460 billion and 2.426 billion years ago, researchers report the week of February 6 in Proceedings of the National Academy of Sciences.
That time difference is a big deal, says study coauthor and sedimentary geologist Andrey Bekker of the University of California, Riverside. The new date shakes up scientists’ understanding of the environmental conditions that led to the GOE, which prompted the evolution of oxygen-dependent life-forms called eukaryotes. Voluminous volcanic eruptions at the time poured fresh rock over a supercontinent near the equator, and the planet dipped into a frigid period known as a Snowball Earth.
A similar series of geologic events around 700 million years ago coincided with a second rise of oxygen, to near-modern levels, and some eukaryotes evolving into the first animals. Both oxygen upswings pushed life toward complexity and the ultimate emergence of humans, Bekker says. “For the first time, we see parallels between these two time intervals,” he says. Oxygen-producing microbes probably first appeared more than 3 billion years ago (SN Online: 9/8/15). But oxygen remained scant until the GOE when, for unknown reasons, atmospheric concentrations of the gas rose from near zero to around 0.1 percent of modern levels.
Dating the GOE’s start has been tricky, though, because few rocks from back then remain. Geologist Ashley Gumsley of Lund University in Sweden, Bekker and colleagues studied ancient volcanic rocks from South Africa that neighbor a layer of minerals that could have formed only in the presence of oxygen. Using an old technique, geologists had previously determined those volcanic rocks to be from around 2.222 billion years ago, well after the GOE’s start.
Applying modern techniques that measure the gradual decay of radioactive uranium in the rocks, the researchers revised the volcanism’s timing to about 2.426 billion years ago. That new date — plus a separate volcanic eruption previously dated to around 2.460 billion years ago that clearly happened before the oxygen rise — helps constrain the potential GOE start date.
The GOE isn’t the only global event to have its timeline tweaked. The oldest known evidence of global glaciation, called a Snowball Earth, lies underneath and alongside the South African rocks. The new eruption dating pushes that Snowball Earth event earlier as well — to around the same time as the start of the GOE.
The oxygen rise and the temperature drop may have been related, the researchers propose.
The new data and existing chemical evidence suggest that oxygen levels during the GOE wavered between pitiful and plentiful several times, rather than steadily rising (SN: 2/18/17, p. 16). (Oxygen concentrations stabilized around 2.250 billion years ago and remained largely unchanged until levels rose again more than a billion years later.) These oscillations coincided with Snowball Earths and volcanic eruptions, Gumsley says.
Climate, oxygen and volcanism were intertwined during the GOE, the researchers propose. Volcanic eruptions covered the supercontinent with fresh rock. That rock formed near the equator where heavy precipitation weathered the rock, drawing carbon dioxide from the air and washing nutrients into the ocean. Those nutrients nourished photosynthetic microbes, which produced an abundance of oxygen. Oxygen built up in the atmosphere and reacted with methane, reducing levels of that greenhouse gas (SN: 10/29/16, p. 17).
With less CO2 and methane warming the climate, Earth froze and oxygen-producing biological activity decreased. The ongoing volcanism spewed replacement CO2 into the atmosphere over time and eventually reheated the planet.
“This is further evidence that oxygen’s history has really been a roller coaster ride rather than a unidirectional rise,” says Yale University geochemist Noah Planavsky. While he’s uncertain about the role rock weathering played in controlling ancient oxygen levels, Planavsky believes the new age will allow scientists to delve into the question of why the GOE began when it did. “Without dates,” he says, it’s impossible “to have any real grounding to tackle these problems.”
People who undergo gastric bypass surgery are more likely to experience a remission of their diabetes than patients who receive a gastric sleeve or intensive management of diet and exercise, according to a new study. Bypass surgery had already shown better results for diabetes than other weight-loss methods in the short term, but the new research followed patients for five years.
“We knew that surgery had a powerful effect on diabetes,” says Philip Schauer of the Bariatric & Metabolic Institute at the Cleveland Clinic. “What this study says is that the effect of surgery is durable.” The results were published online February 15 in the New England Journal of Medicine. The study followed 134 people with type 2 diabetes for five years in a head-to-head comparison of weight-loss methods. At the end of that time, two of 38 patients who only followed intensive diet and exercise plans were no longer in need of insulin to manage blood sugar levels. For comparison, 11 of 47 patients who had a gastric sleeve, which reduces the size of the stomach, and 14 of 49 who underwent gastric bypass, a procedure that both makes the stomach smaller and shortens digestion time, did not need the insulin anymore. In general, patients who had been diabetic for fewer than eight years were more likely to be cured, Schauer says.
Even those surgical patients who still needed to take insulin had greater weight loss and lower median glucose levels than others in the study. This study was also one of the few to show that bariatric surgery could help those with only mild obesity, defined as a body mass index between 27 and 34. How bariatric surgery might improve diabetes is still unknown, but scientists have pointed to effects on the body’s metabolism (SN: 8/24/13, p. 14) and gut microbes (SN: 9/5/15, p. 16). The same research team had published similar results at one and three years after surgery, but few studies looked further, says Kristoffel Dumon, a bariatric surgeon with the University of Pennsylvania Health System in Philadelphia. “The criticism of bariatric research has been that there are no good long-term results. With weight-loss surgery, you often see rapid initial results, but you want to see that to a five-year time point.” Dumon also notes that the patients who received only intensive medical therapy did not report an improvement in their quality of life, and their emotional well-being worsened. People in the surgical group reported improvements in quality of life, but not in emotional well-being, a finding that Schauer says has more to do with stress management and other characteristics that wouldn’t necessarily be affected by surgery.
Schauer hopes to have even longer-term data in the future. His team will combine their results with those from similar research at three other U.S. sites with the goal of following patients for up to 10 years.
Eijiro Miyako gets emotional about the decline of honeybees.
“We need pollination,” he says. “If that system is collapsed, it’s terrible.”
Insects, especially bees, help pollinate both food crops and wild plants. But pollinators are declining worldwide due to habitat loss, disease and exposure to pesticides, among other factors (SN: 1/23/16, p. 16).
Miyako, a chemist at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, became passionate about the loss of pollinators after watching a TV documentary. He remembers thinking: “I need to create something to solve this problem.” His answer was in an 8-year-old jar in his lab.
In 2007, he had tried to make a gel that conducts electricity, but it was “a complete failure,” he says. So he poured the liquid into a jar, put it in a drawer and forgot about it. Cleaning out his lab in 2015, he accidentally dropped and broke the jar. Surprisingly, the gel was still sticky and picked up dust from the floor. Miyako realized that the gel’s ability to capture the tiny particles was similar to how honeybee body hairs trap pollen. His thoughts jumped to artificial pollination.
First, he investigated whether non-pollinating insects could help do the job. He dabbed his gel onto ants and set them loose in a box of tulips. The ants were coated with pollen after three days.
Still, Miyako worried that predators would snack on his insect pollinators. To give them camouflage, he mixed four light-reactive compounds into the gel. He tested the new concoction on flies, placing a droplet on their backs and setting the insects in front of blue paper. Under ultraviolet light, the gel changed from clear to blue, mimicking the color of the backdrop.
Though this chemical invisibility cloak might protect the insects, Miyako wanted a pollinator that could be controlled and wouldn’t wander off at the first scent of a picnic.
He bought 10 kiwi-sized drones and taught himself to fly them, breaking all but one in the process. Miyako covered the bottom of the surviving drone with short horsehair, using electricity to make the hair stand up. Adding his gel made the horsehair work like bee fuzz. In tests so far, the drone has successfully pollinated Japanese lilies more than a third of the time, brushing up against one flower to collect pollen, then flying into another to knock the grains off, his team reports in the Feb. 9 Chem. Glad he saved that failed gel, Miyako thinks it is possible to automate a fleet of 100 drones, using GPS and artificial intelligence, to pollinate alongside bees and other insects. “It’s not science fiction,” he says.
One of Jupiter’s companions is a bit of a nonconformist.
The gas giant shares its orbit around the sun with a slew of asteroids, but scientists have now discovered one that goes against the flow. It journeys around the solar system in reverse — in the opposite direction of Jupiter and all the other planets. Asteroid 2015 BZ509 is the first object found that orbits in the same region as a planet but travels backward, researchers from Canada and the United States report March 30 in Nature. The asteroid was discovered with the Pan-STARRS observatory in Hawaii in 2015, and the researchers made additional observations with the Large Binocular Telescope Observatory in Arizona.
Backward-going asteroids are rare — only 0.01 percent of known asteroids are in retrograde orbits. Until now, none were known to share a planet’s orbit. It was thought that asteroids going in reverse couldn’t coexist with a planet because interactions with the celestial body, twice each orbit, would knock the asteroid off track. But because 2015 BZ509 passes on alternating sides of Jupiter, the interactions cancel each other out, the researchers say. The first flyby in orbit pulls the asteroid outward, and the next tugs it inward — keeping the maverick asteroid in line.
The asteroid’s relationship with Jupiter is no short-term fling: The researchers determined that the two have shared an orbit for a million years.
The oldest known specimens of bedbug relatives have been unearthed in an Oregon cave system where ancient humans once lived. The partial fossils from three different species in the bedbug family date back 5,000 to 11,000 years, predating a previous find from 3,500 years ago, researchers report April 4 in the Journal of Medical Entomology.
“The bedbugs that we know in modern times originated as bat parasites, and it’s believed that they became human parasites when humans lived in caves with bats,” says study coauthor Martin Adams of Paleoinsect Research in Portland, Ore. When humans moved elsewhere, bedbugs came along for the ride.
These three species (Cimix antennatus, Cimex latipennis and Cimex pilosellus) probably coexisted with humans in Oregon’s Paisley Five Mile Point Caves, and probably snacked on people at least occasionally, Adams says. Even though all three species are still around today, they still feast mostly on bats.
Archaeologists think that ancient humans lived in the Paisley Caves only seasonally, which could explain why these particular species of bedbugs didn’t switch to a human-centric diet.
The quantitative abilities of lizards may have their limits.
From horses to salamanders, lots of different species display some form of number sense, but the phenomenon hasn’t been investigated in reptiles. So a team of researchers in Italy set up two experiments for 27 ruin lizards (Podarcis sicula) collected from walls on the University of Ferrara’s campus. In the first test, the team served up two house fly larvae of varying sizes. Lizards consistently chose to scarf down bigger maggots.
Then in the second experiment, the researchers gave lizards a choice between different numbers of larvae that were all the same size. The lizards didn’t show a preference. While the data suggest that the reptiles do discriminate between larger and smaller prey, they don’t distinguish between higher and lower numbers of maggots in a meal, the scientists report April 12 in Biology Letters.
The researchers cite two potential explanations for the discrepancy. Selecting larger prey rather than more prey might sometimes be advantageous for a predator. Or reptiles simply lack the numerical know-how seen in vertebrate relatives, such as fish.
Editor’s note: This story was updated April 17, 2017, to replace the previous image of a Podarcis muralis lizard with one that shows P. sicula, the species used in the study.
The solar system doesn’t have a long, twisted tail after all.
Data from the Cassini and Voyager spacecraft show that the bubble of particles surrounding the solar system is spherical, not comet-shaped. Observing a spherical bubble runs counter to 55 years of speculation on the shape of this solar system feature, says Tom Krimigis of the Johns Hopkins Applied Physics Laboratory in Laurel, Md. He and colleagues report the result online April 24 in Nature Astronomy. “You can’t really argue with the new result,” says Merav Opher of Boston University, who was not involved in the study. “The data so loudly say that there is no tail.”
The bubble, called the heliosphere, is inflated by particles streaming from the sun and envelops all of the material in the solar system. Its shape is important because it provides clues about how the solar system interacts with interstellar space.
In the 1960s, researchers proposed that the heliosphere was either shaped like a comet or was spherical. Magnetic fields surrounding the sun and the planets look sort of like comets, with long tails extending behind them. So, scientists speculated that the heliosphere would have a tail, too. In 2013, data from the Interstellar Boundary Explorer, or IBEX, spacecraft found signs that the tail assumption was right. The probe counted the number of fast-moving atoms that are thought to be kicked inward from the edge of the solar system when they collide with charged particles from the sun. Detecting those atoms offers clues to the shape of the heliosphere, and the images suggested that solar system had a long, twisted tail that looked like a four-leaf clover (SN: 8/24/13, p. 9).
But it wasn’t clear from the data exactly how far away from the spacecraft the atoms were and therefore how far the heliosphere’s tail extended, Krimigis says. By combining more than a decade’s worth of data from the Voyager and Cassini probes, he and colleagues sought a clearer picture. The team specifically tracked how the abundance of the speedy atoms changed in different parts of the heliosphere as the intensity of charged particles streaming from the sun, the solar wind, waxed and waned.
At the front of the heliosphere, where the Voyager probes sit, when the intensity of the solar wind decreased, so did the abundance of speedy atoms. When it increased, the number went up, in lockstep. Looking at speedy atoms at the back of the heliosphere, the team saw the same changes. If there were a long tail, Krimigis says, the changes in the number of atoms wouldn’t be the same in both directions. Because the atoms would have farther to travel in a tail, it would take longer for their abundance to build up there again.
While the observational evidence now favors a spherical shape for the heliosphere, recent simulations suggest something more exotic. The bubble might actually be shaped like a croissant, Opher says. The simulations, which incorporate data from Voyager 1, show that the interaction of the magnetic fields from the sun and interstellar space squish the solar wind into two jets — what might be observed as two short tails. These jets haven’t been detected yet. But if they are, she says, they could give clues to other sets of jets seen in the universe such as those shooting from young stars or possibly even black holes.
Most people who eat octopus prefer it immobile, cut into pieces and nicely grilled or otherwise cooked. For some, though, the wiggly, sucker-covered arms of a live octopus are a treat — even though those arms can stick to the throat and suffocate the diner if they haven’t been chopped into small enough pieces.
Dolphins risk the same fate when eating octopus — and they can’t cook it or cut it up with a chef’s knife. “Octopus is a dangerous meal,” notes Kate Sprogis of Murdoch University in Australia. Even if a dolphin manages to remove an octopus’ head, it still has to deal with those sucker-covered tentacles. “The suckered arms would be difficult to handle considering dolphins don’t have hands to assist them,” Sprogis says.
A group of hungry dolphins off the coast of Western Australia have figured out a solution. They shake and toss their prey until the head falls off, the animal is in pieces and its arms are tender and not wiggling anymore, Sprogis and her colleagues report April 2 in Marine Mammal Science.
The behavior, never before reported, was discovered during observations between March 2007 and August 2013 of bottlenose dolphins living in the waters off Bunbury, Western Australia. During that time, researchers witnessed 33 events in which dolphins handled an octopus with two different methods.
In one technique, a dolphin held an octopus in its mouth and shook it, slamming its prey into the water’s surface until the meal was in pieces. Each dolphin would repeat its preferred motion, or combine the two, usually around a dozen times, over several minutes until the octopus was safe to eat. (See video below.)
“If the dolphins haven’t prepared their meal enough, then this can cause problems,” Sprogis notes. There have been two dead dolphins found in this area with whole octopuses lodged in their throats. The researchers assume that the dolphins suffocated.
Dolphins have garnered a reputation for tackling difficult-to-eat foods in creative ways. Some have been spotted using cone-shaped sponges to flush out little fish from the sandy ocean floor. Others use a six-step process to prepare a cuttlefish meal. The Bunbury dolphins eat both octopus and cuttlefish, and those meals appear to be more common in the winter and spring, when waters are cooler, Sprogis notes. That may be when the octopus and cuttlefish breed and lose some of their camouflage abilities — making them easy prey for dolphins brave or knowledgeable enough to take advantage of the potential meal.
