When looking for love, some small-mouthed salamanders can really go the distance.
These intrepid amphibians (Ambystoma texanum) will risk death and dehydration to travel almost nine kilometers on average and as far as 14 to find a mate, researchers report December 20 in Functional Ecology. But all-female populations of a closely related group of salamanders that reproduce by cloning can’t go nearly as far.
Scientists tested the amphibians’ endurance on tiny treadmills. Then the team analyzed genetic differences between salamanders in patches of Ohio wetlands to see how far the amphibians might roam in the wild. Unisexual salamanders could only go a quarter of the treadmill distance that the small-mouthed salamanders could. And in the wild, they only dispersed about half as far from the pools where they were born. By making the treacherous trek to a different pool to mate, A. texanum salamanders can mix up their genes and keep healthy variation in each population. Unisexual salamanders may have less stamina because they don’t mate in the usual way. Instead of searching for the perfect partner, they steal sperm from nearby male salamanders of different species. The sperm kick-start egg production but rarely actually fertilize eggs; only occasionally does a male’s DNA sneak into a female’s offspring.
Ditching the guys can be efficient — every member of an all-female population can give birth, and that means more babies. But it seems that going it alone has drawbacks, too: These salamanders’ poorer endurance could be a disadvantage if environmental changes forced them to colonize new territory.
Scientists have produced a new form of hydrogen in the lab — negatively charged hydrogen clusters.
Each cluster consists of hydrogen molecules arranged around a negatively charged hydrogen ion — a single hydrogen atom with an extra electron — at temperatures near absolute zero, the researchers report in the Dec. 30 Physical Review Letters. Similar, positively charged ion clusters have previously been found, but this is the first time scientists have seen negative hydrogen cluster ions beyond the simplest possible pairing of one molecule and one ion. Physicist Michael Renzler of the University of Innsbruck in Austria and colleagues infused tiny droplets of liquid helium with hydrogen gas. Then, the scientists bombarded the droplets with a beam of electrons, which converted some hydrogen molecules into negatively charged hydrogen ions. Neighboring hydrogen molecules (two bonded hydrogen atoms) clustered around the ion, in groups of a few molecules to over 60.
The scientists also determined the geometric structures of the clusters. Hydrogen molecules organized into shells that surrounded the central ion. Clusters were most stable, and most common, when molecules filled shells to their capacity. In the first shell, for example, the cluster formed an icosahedron — a 3-D shape with 12 vertices — when 12 molecules filled this shell.
In space, hydrogen cluster ions might form naturally in cold, dense clouds of hydrogen or in atmospheres of gas giant planets.
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.
Clusters of a toxic bacterial protein have a surprising structure, differing from similar clumps associated with Alzheimer’s and Parkinson’s in humans, scientists report in the Feb. 24 Science.
These clusters, called amyloids, are defined in part by their structure: straight regions of protein chains called beta strands, folded accordion-style into flat beta sheets, which then stack up to form a fiber. That definition might now need to be broadened.
“All the amyloids that have been structurally looked at so far have certain characteristics,” says Matthew Chapman, a biologist at the University of Michigan in Ann Arbor who wasn’t part of the work. “This is the odd amyloid out right now.” In the human brain, misfolded proteins can form amyloids that trigger neurodegenerative diseases. But amyloids aren’t always a sign of something gone wrong — some bacteria make amyloids to help defend their turf.
In Staphylococcus aureus, for example, the PSMα3 protein assembles into amyloids that help the bacteria kill other cells. Previous research suggested that PSMα3 clusters were like any other amyloid. But researchers using X-ray crystallography found that instead of straight beta strands, the PSMα3 fiber was made up of curly structures called alpha helices that resemble an old-fashioned phone cord. The helices still formed a familiar fiber shape just like the beta strands did, but the sheets making up that fiber were rippled instead of flat. “From the outside, it looks exactly the same. But zooming in, it looks completely different in its fundamental units,” says study coauthor Meytal Landau, a biologist at the Technion–Israel Institute of Technology in Haifa. “It’s something that really threw me off.”
Chapman first thought the finding must have been a mistake. Alpha helices are a very common protein structure, but “they don’t typically stack on each other to form a sheet,” he says. “That’s a really rare structure in nature.” Now, he says, it’s quite clear that alpha helices are building this amyloid.
Getting such a detailed picture of an amyloid is a challenge, so Landau isn’t sure whether PSMα3 is truly an exception or whether other proteins can make similar amyloid-like clusters.
Either way, knowing the structure can be useful. When Landau and her colleagues prevented the PSMα3 from forming an amyloid-like structure, the bacteria weren’t as good at attacking human immune cells. Rather than hunting for strong drugs that target the hard-to-kill bacteria themselves, Landau suggests, scientists might eventually be able to develop drugs that target the proteins controlling the bacteria’s aggression.
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.
Not all of the newborn Earth’s surface has been lost to time. Transformed bits of this rocky material remain embedded in the hearts of continents, new research suggests. These lingering remnants hint that full-fledged plate tectonics, the movements of large plates of Earth’s outer shell, began relatively late in the planet’s history, researchers report in the March 17 Science.
These revelations come from ancient continental rock in Canada that preserves geochemical traces of the even older, 4.2-billion-year-old rock from which it formed. “For the first time, we can say something about what kind of rock was a precursor to the first continental crust,” says study coauthor Jonathan O’Neil, a geochemist at the University of Ottawa. Earth began as a molten ball around 4.54 billion years ago, and over the next tens of millions of years, its surface cooled and solidified. Almost all of Earth’s early rocky surface has been destroyed and recycled by geologic processes such as plate tectonics. The oldest known unaltered bits of the planet aren’t rocks but tiny zircon crystals formed nearly 4.4 billion years ago (SN Online: 2/23/14). The oldest actual rocks date back to only about 4 billion years. “We’re missing a lot of Earth’s history,” O’Neil says.
The new discovery fills in some of that history. In northeastern Canada, along the eastern shore of the Hudson Bay, O’Neil and geochemist Richard Carlson of the Carnegie Institution for Science in Washington, D.C., discovered 2.7-billion-year-old continental rocks that hinted at something much older. The rocks contain an unusually large abundance of an isotope of neodymium that formed only during the first few hundred million years of Earth’s history. To have so much of this neodymium, the rocks must have formed from material that was first created more than 4.2 billion years ago, the researchers calculate. That’s far older than the oldest rocks ever studied.
Based on the composition of the Canadian rocks, the researchers think that the precursor material was similar to the crust that underlies modern oceans. The finding affirms previous studies that suggested that the first continental crust arose from the partial melting of oceanic crust (SN Online: 9/20/16).
But unlike modern oceanic crust, which typically lingers for less than 200 million years before getting recycled into Earth’s interior by plate tectonics, the precursor crust survived for more than a billion years before being reworked into continental crust 2.7 billion years ago. Plate tectonics during the precursor crust’s life span must have therefore been nonexistent, sluggish or limited to certain regions, O’Neil concludes.
“If you ask five geologists the simple question of when did plate tectonics start, you’ll have answers from 4.3 billion years ago to 1 billion years ago,” he says. The new finding seems to rule out the idea that full-blown, global plate tectonics began early in Earth’s history.
The new work is exciting and sheds light on the processes that set the scene for Earth’s subsequent evolution and habitability, says geologist Tony Kemp of the University of Western Australia in Crawley. Other vestiges of early crust may lurk undiscovered elsewhere on Earth as well, he says. “It will be intriguing to see how this [research] unfolds with future studies of this type.”
The standard dinosaur family tree may soon be just a relic.
After examining more than 400 anatomical traits, scientists have proposed a radical reshuffling of the major dinosaur groups. The rewrite, reported in the March 23 Nature, upsets century-old ideas about dinosaur evolution. It lends support to the accepted idea that the earliest dinosaurs were smallish, two-legged creatures. But contrary to current thinking, the new tree suggests that these early dinosaurs had grasping hands and were omnivores, snapping up meat and plant matter alike. “This is a novel proposal and a really interesting hypothesis,” says Randall Irmis, a paleontologist at the Natural History Museum of Utah and the University of Utah in Salt Lake City. Irmis, who was not involved with the work, says it’s “a possibility” that the new family tree reflects actual dinosaur relationships. But, he says, “It goes against our ideas of the general relationships of dinosaurs. It’s certainly going to generate a lot of discussion.”
The accepted tree of dinosaur relationships has three dominant branches, each containing critters familiar even to the non–dinosaur obsessed. One branch leads to the “bird-hipped” ornithischians, which include the plant-eating duckbills, stegosaurs and Triceratops and its bony-frilled kin. Another branch contains the “reptile-hipped” saurischians, which are further divided into two groups: the plant-eating sauropods (typically four-legged, like Brontosaurus) and the meat-eating theropods (typically two-legged, like Tyrannosaurus rex and modern birds). This split between the bird-hipped and reptile-hipped dinos was first proposed in 1887 by British paleontologist Harry Seeley, who had noticed the two strikingly different kinds of pelvic anatomy. That hypothesis of dinosaur relationships was formalized and strengthened in the 1980s and has been accepted since then.
The new tree yields four groups atop two main branches. The bird-hipped ornithischians, which used to live on their own lone branch, now share a main branch with the reptile-hipped theropods like T. rex. This placement suggests these once-distant cousins are actually closely related. It also underscores existing questions about the bird-hipped dinos, an oddball group with murky origins; they appear late in the dinosaur fossil record and then are everywhere. Some scientists have suggested that they evolved from an existing group of dinosaurs, perhaps similarly herbivorous sauropods. But by placing the bird-hipped dinos next to the theropods, the tree hints that the late-to-the-party vegetarian weirdos could have evolved from their now close relatives, the meat-eating theropods.
Sauropods (like Brontosaurus) are no longer next to the theropods but now reside on a branch with the meat-eating herrerasaurids. Herrerasaurids are a confusing group of creatures that some scientists think belong near the other meat eaters, the theropods, while others say the herrerasaurids are not quite dinosaurs at all.
The new hypothesis of relationships came about when researchers led by Matthew Baron, a paleontologist at the University of Cambridge and Natural History Museum in London, decided to do a wholesale examination of dinosaur anatomy with fresh eyes. Using a mix of fossils, photographs and descriptions from the scientific literature, Baron and colleagues surveyed the anatomy of more than 70 different dinosaurs and non-dino close relatives, examining 457 anatomical features. The presence, absence and types of features, which include the shape of a hole on the snout, a cheekbone ridge and braincase anatomy, were fed into a computer program, generating a family tree that groups animals that share specialized features.
In this new interpretation of dinosaur anatomy and the resulting tree, many of the earliest dinosaurs have grasping hands and a mix of meat-eating and plant-eating teeth. If the earliest dinos were really omnivores, given the relationships in the new four-pronged tree, the evolution of specialized diets (vegetarians and meat eaters) each happened twice in the dinosaur lineage.
When the researchers saw the resulting tree, “We were very surprised — and cautious,” Baron says. “It’s a big change that flies in the face of 130 years of thinking.”
The arrangement of the new tree stuck even when the researchers fiddled around with their descriptions of various features, Baron says. The close relationship between the bird-hipped, plant-eating ornithischians and the reptile-hipped, meat-eating theropods, for example, isn’t based on one or two distinctive traits but on 21 small details.
“The lesson is that dinosaur groups aren’t characterized by radical new inventions,” says paleontologist Kevin Padian of the University of California, Berkeley. “The relationships are read in the minutiae, not big horns and frills.” That said, Padian, whose assessment of the research also appears in Nature, isn’t certain that the new tree reflects reality. Such trees are constructed based on how scientists interpret particular anatomical features, decisions that will surely be quibbled with. “The devil is in the details,” Padian says. “These guys have done their homework and now everyone’s going to have to roll up their sleeves and start checking their work.”
