It would be a memorable sight. But it would also be so wrong to tip over Galápagos giant tortoises to see how shell shape affects their efforts to leg-pump, neck-stretch and rock right-side up again.

Shell shape matters, says evolutionary biologist Ylenia Chiari, though not the way she expected. It’s taken years, plus special insights from a coauthor who more typically studies scorpions, for Chiari and her team to measure and calculate their way to that conclusion. But no endangered species have been upended in the making of the study.
“They’re amazing,” says Chiari of the dozen or so species of Chelonoidis grazing over the Galápagos Islands. Hatchlings start not quite the size of a tennis ball and after decades, depending on species and sex, “could be like — a desk,” says Chiari, of the University of South Alabama in Mobile.

Two extremes among the species’ shell shapes intrigue Chiari: high-domed mountains versus mere hillocks called saddlebacks because of an upward flare saddling the neck. Researchers have dreamed up possible benefits for the shell differences, such as the saddleback flare letting tortoises stretch their necks higher upward in grazing on sparse plants.
At the dryer, lower altitudes where saddleback species tend to live, fields of lava chunks and cacti make walking treacherous. “I fell on a cactus once,” Chiari says. Tortoises tumble over, too, and she wondered whether saddleback shells might be easier to set right again.
She went paparazzi on 89 tortoise shells, taking images from multiple angles to create a 3-D computerized version of each shell. Many shells were century-old museum specimens from the California Academy of Sciences in San Francisco, but she stalked some in the wild, too. The domed tortoises tended to pull into their shells with a huffing noise during their time in front of the lens and just wait till the weirdness ended. A saddleback species plodded toward the interruption, though, butting and biting (toothless but emphatic) at her legs.

To calculate energy needed to rock and roll the two shell types, Chiari needed to know the animals’ centers of mass. No one, however, had measured it for any tortoise. Enter coauthor Arie van der Meijden of CIBIO, Research Center in Biodiversity and Genetic Resources at the University of Porto in Portugal. With expertise in biomechanics, he scaled up from the arthropods he often studies. For a novel test of tortoises, he arranged for a manufacturer to provide equipment measuring force exerted at three points under a tiltable platform. As the first giant tortoise, weighing in at about 100 kilograms, started to lumber aboard the platform at Rotterdam’s zoo, Chiari thought, “Oh my gosh, it’s going to crush everything.” For a gentler and more even landing, four men heaved the tortoise into position.

Calculating the centers of mass for Rotterdam tortoises, the researchers extrapolated to the 89 shells. The low, flattened saddleback shape actually made shells tougher to right, taking more energy, the team reports November 30 in Scientific Reports. Now Chiari muses over whether the saddle at the shell front might let freer neck movements compensate after a trip and a flip.

Hundreds of eggs belonging to a species of flying reptile that lived alongside dinosaurs are giving scientists a peek into the earliest development of the animals.

The find includes at least 16 partial embryos, several still preserved in 3-D. Those embryos suggest that the animals were able to walk, but not fly, soon after hatching, researchers report in the Dec. 1 Science.

Led by vertebrate paleontologist Xiaolin Wang of the Chinese Academy of Sciences in Beijing, the scientists uncovered at least 215 eggs in a block of sandstone about 3 meters square. All of the eggs belonged to one species of pterosaur, Hamipterus tianshanensis, which lived in the early Cretaceous Period about 120 million years ago in what is now northwestern China.
Previously, researchers have found only a handful of eggs belonging to the winged reptiles, including five eggs from the same site in China (SN: 7/12/14, p. 20) and two more found in Argentina. One of the Argentinian eggs also contained a flattened but well-preserved embryo.
One reason for the dearth of fossils may be that the eggs were rather soft with a thin outer shell, unlike the hard casings of eggs belonging to dinosaurs, birds and crocodiles but similar to those of modern-day lizards. Due to that soft shape, pterosaur eggs also tend to flatten during preservation. Finding fossilized eggs containing 3-D embryos opens a new window into pterosaur development, says coauthor Alexander Kellner, a vertebrate paleontologist at Museu Nacional/Universidade Federal do Rio de Janeiro.
The eggs weren’t found at an original nesting site but had been jumbled and deformed, probably transported by a flood during an intense storm, Kellner says. Sand and other sediments carried by the water would then have rapidly buried the soft eggs, which was necessary to preserve them, Kellner says. “Otherwise, they would have decomposed.”
Using computerized tomography, the researchers scanned the internal contents of the eggs. Two of the best-preserved embryos revealed a tantalizing clue to pterosaur development, Kellner says. A key part of a wing bone, called the deltopectoral crest, was not fully developed in the embryos, even in an embryo the researchers interpret as nearly at term. The femur, or leg bone, of the embryo, however, was well developed. This suggests that, when born, the hatchlings could walk but not yet fly and may have still required some parental care for feeding, the scientists propose.
Such an interpretation requires an abundance of caution, says D. Charles Deeming, a vertebrate paleontologist at the University of Lincoln in England not involved in the study. For example, he says, there isn’t enough evidence to say for certain that the embryo in question was nearly at term and, therefore, to say that it couldn’t fly when born, a point he also raises in a column published in the same issue of Science. “There’s a real danger of overinterpretation.” But with such a large group of eggs, he says, researchers can make quantitative measurements to better understand the range of egg sizes and shapes to get a sense of variation in animal size.

Kellner says this work is ongoing and agrees that there is still a significant amount of study to be done on these and other eggs more recently found at the site. And the hunt is on for more concentrations of eggs in the same site. “Now that we know what they look like, we can go back and find more. You just have to get your knees down and look.”

A new computer program has an ear for dolphin chatter.

The algorithm uncovered six previously unknown types of dolphin echolocation clicks in underwater recordings from the Gulf of Mexico, researchers report online December 7 in PLOS Computational Biology. Identifying which species produce the newly discovered click varieties could help scientists better keep tabs on wild dolphin populations and movements.

Dolphin tracking is traditionally done with boats or planes, but that’s expensive, says study coauthor Kaitlin Frasier, an oceanographer at the Scripps Institution of Oceanography in La Jolla, Calif. A cheaper alternative is to sift through seafloor recordings — which pick up the echolocation clicks that dolphins make to navigate, find food and socialize. By comparing different click types to recordings at the surface — where researchers can see which animals are making the noise — scientists can learn what different species sound like, and use those clicks to map the animals’ movements deep underwater.
But even experts have trouble sorting recorded clicks, because the distinguishing features of these signals are so subtle. “When you have analysts manually going through a dataset, then there’s a lot of bias introduced just from the human perception,” says Simone Baumann-Pickering, a biologist at the Scripps Institution of Oceanography not involved in the work. “Person A may see things differently than person B.” So far, scientists have only determined the distinct sounds of a few species.
To sort clicks faster and more precisely, Frasier and her colleagues outsourced the job to a computer. They fed an algorithm 52 million clicks recorded over two years by near-seafloor sound sensors across the Gulf of Mexico. The algorithm grouped echolocation clicks based on similarities in speed and pitch — the same criteria human experts use to classify clicks. “We don’t tell it how many click types to find,” Frasier says. “We just kind of say, ‘What’s in here?’”
The algorithm picked out seven major kinds of clicks, which the researchers think are made by different dolphin species. Frasier’s team recognized one class as being made by a species called Risso’s dolphin. The scientists suspect that another group of clicks, most common in recordings near the Green Canyon south of Louisiana, was produced by short-finned pilot whales that frequent this region. Another type resembles sounds from the eastern Pacific Ocean that a dolphin called the false killer whale makes.
To confirm the identifications, the researchers now need to compare their computer-generated categories against surface observations of these dolphins, Frasier says.

The algorithm’s click classes may not match up with dolphin species one-to-one, says Baumann-Pickering. If that were the case, “we would expect to see a heck of a lot more categories, really, based on the number of species that ought to be in that area,” she says. That absence suggests that some closely related species produce highly similar clicks the algorithm didn’t tease apart.

Still, “it would be great to be able to confidently assign certain species to each of the different click types, even if more than one species is assigned to a single click type,” says Lynne Hodge, a marine biologist at Duke University who wasn’t involved in the work. More precisely monitoring dolphins with seafloor recordings could provide new insight into how these animals respond to environmental problems such as oil spills and the long-term effects of climate change.

During the world’s first telephone call in 1876, Alexander Graham Bell summoned his assistant from the other room, stating simply, “Mr. Watson, come here. I want to see you.” In 2017, scientists testing another newfangled type of communication were a bit more eloquent. “It is such a privilege and thrill to witness this historical moment with you all,” said Chunli Bai, president of the Chinese Academy of Sciences in Beijing, during the first intercontinental quantum-secured video call.

The more recent call, between researchers in Austria and China, capped a series of milestones reported in 2017 and made possible by the first quantum communications satellite, Micius, named after an ancient Chinese philosopher (SN: 10/28/17, p. 14).
Created by Chinese researchers and launched in 2016, the satellite is fueling scientists’ dreams of a future safe from hacking of sensitive communiqués. One day, impenetrable quantum cryptography could protect correspondences. A secret string of numbers known as a quantum key could encrypt a credit card number sent over the internet, or encode the data transmitted in a video call, for example. That quantum key would be derived by measuring the properties of quantum particles beamed down from such a satellite. Quantum math proves that any snoops trying to intercept the key would give themselves away.

“Quantum cryptography is a fundamentally new way to give us unconditional security ensured by the laws of quantum physics,” says Chao-Yang Lu, a physicist at the University of Science and Technology of China in Hefei, and a member of the team that developed the satellite.

But until this year, there’s been a sticking point in the technology’s development: Long-distance communication is extremely challenging, Lu says. That’s because quantum particles are delicate beings, easily jostled out of their fragile quantum states. In a typical quantum cryptography scheme, particles of light called photons are sent through the air, where the particles may be absorbed or their properties muddled. The longer the journey, the fewer photons make it through intact, eventually preventing accurate transmissions of quantum keys. So quantum cryptography was possible only across short distances, between nearby cities but not far-flung ones.

With Micius, however, scientists smashed that distance barrier. Long-distance quantum communication became possible because traveling through space, with no atmosphere to stand in the way, is much easier on particles.
In the spacecraft’s first record-breaking accomplishment, reported June 16 in Science, the satellite used onboard lasers to beam down pairs of entangled particles, which have eerily linked properties, to two cities in China, where the particles were captured by telescopes (SN: 8/5/17, p. 14). The quantum link remained intact over a separation of 1,200 kilometers between the two cities — about 10 times farther than ever before. The feat revealed that the strange laws of quantum mechanics, despite their small-scale foundations, still apply over incredibly large distances.

Next, scientists tackled quantum teleportation, a process that transmits the properties of one particle to another particle (SN Online: 7/7/17). Micius teleported photons’ quantum properties 1,400 kilometers from the ground to space — farther than ever before, scientists reported September 7 in Nature. Despite its sci-fi name, teleportation won’t be able to beam Captain Kirk up to the Enterprise. Instead, it might be useful for linking up future quantum computers, making the machines more powerful.

The final piece in Micius’ triumvirate of tricks is quantum key distribution — the technology that made the quantum-encrypted video chat possible. Scientists sent strings of photons from space down to Earth, using a method designed to reveal eavesdroppers, the team reported in the same issue of Nature. By performing this process with a ground station near Vienna, and again with one near Beijing, scientists were able to create keys to secure their quantum teleconference. In a paper published in the Nov. 17 Physical Review Letters, the researchers performed another type of quantum key distribution, using entangled particles to exchange keys between the ground and the satellite.

The satellite is “a major development,” says quantum physicist Thomas Jennewein of the University of Waterloo in Canada, who is not involved with Micius. Although quantum communication was already feasible in carefully controlled laboratory environments, the Chinese researchers had to upgrade the technology to function in space. Sensitive instruments were designed to survive fluctuating temperatures and vibrations on the satellite. Meanwhile, the scientists had to scale down their apparatus so it would fit on a satellite. “This has been a grand technical challenge,” Jennewein says.

Eventually, the Chinese team is planning to launch about 10 additional satellites, which would fly in formation to allow for coverage across more areas of the globe.

A type of spiraling wave has been busted for disorderly conduct.

Spiral waves are waves that ripple outward in a swirl. Now scientists from Germany and the United States have created a new type of spiral wave in the lab. The unusual whorl has a jumbled, disordered center rather than an orderly swirl, making it the first “spiral wave chimera,” the researchers report online December 4 in Nature Physics.

Waves, which exhibit a variety of shapes, are common in nature. For example, they can be found in cells that undergo cyclical patterns, such as heart cells rhythmically contracting to produce heartbeats or nerve cells firing in the brain. In a normal heart, electrical signals propagate from one end to another, triggering waves of contractions in heart cells. But sometimes the wave can spiral out of control, creating swirls that can lead to a racing or irregular heartbeat. Such spiral waves emanate in an orderly fashion from a central point, reminiscent of the red and white swirls on a peppermint candy. But the newly observed spiral wave chimera is messy in the middle.
Harnessing an oscillating chemical process known as the Belousov–Zhabotinsky reaction, the researchers created the wave using an array of small beads, each containing a catalyst for the reaction. When placed in a chemical solution, the beads acted as individual pulsating oscillators — analogous to heart cells — in which the reaction took place.

The researchers monitored the brightness of each bead as it alternated between a fluorescent state that emits red light and a dim state. Because the reaction is light sensitive, illuminating individual beads allowed the researchers to induce nearby beads to sync up. Thanks to that syncing, a spiral wave took shape. But, unlike any seen before, it had a muddled center.
The wave is a new kind of “chimera,” a grouping of oscillators in which some sync up, but others march to their own drummer, despite being essentially identical to their neighbors. Although researchers have previously created other kinds of chimeras in the lab, “it’s a step further to show that you can have this in even more complex setups” such as spiral wave chimeras, says Erik Martens of the Technical University of Denmark in Kongens Lyngby, who was not involved with the research.

While spiral wave chimeras had been predicted theoretically, there were some surprises to the real-world curlicues. Single spirals, for example, sometimes broke up into several independent swirls, each with disordered centers. “That was quite unexpected,” says chemist Kenneth Showalter of West Virginia University in Morgantown, a coauthor of the study.

It’s still not known whether the chimera form of spiral waves can appear in biological systems like the heart or the brain — but the new whorl is one to watch out for.

Robots are on their way to passing gym class.

The design of a new life-size bot named Kengoro closely resembles the anatomy of a teenage boy in body proportion, skeletal and muscular structure, and joint flexibility, researchers report online December 20 in Science Robotics. Compared with previous humanoid robots with more rigid, bulky bodies, Kengoro’s anatomically inspired design gives the bot a wide range of motion to perform humanlike, full-body exercises.
Constructed by Masayuki Inaba, an engineer at the University of Tokyo, and colleagues, Kengoro has a multi-jointed spine that allows the robot to curl into a sit-up or do back extensions. The bot’s arms are limber enough to execute various stretches or swing a badminton racket. And its artificial muscles are strong enough that Kengoro can stand on tiptoe or do push-ups. Batteries in each leg power Kengoro through about 20 minutes of exercise at a time, and water seeping from inside Kengoro’s metal skeleton like sweat keeps the motors of the artificial muscles cool while the bot works out.

Such a nimble robot that so closely imitates human movement and anatomy is “very unique,” says Luis Sentis, an engineer at the University of Texas at Austin not involved in the work. Building more humanlike robots could lead to the development of more sophisticated prosthetics or more realistic crash-test dummies that make humanlike reflexive movements during an accident.

A complex coral reef full of nooks and crannies is a coastline’s best defense against large ocean waves. But coral die-offs over the next century could allow taller waves to penetrate the corals’ defenses, simulations suggest. A new study finds that at some Pacific Island sites, waves reaching the shore could be more than twice as high as today’s by 2100.

The rough, complex structures of coral reefs dissipate wave energy through friction, calming waves before they reach the shore. As corals die due to warming oceans (SN: 2/3/18, p. 16), the overall complexity of the reef also diminishes, leaving a coast potentially more exposed. At the same time, rising sea levels due to climate change increasingly threaten low-lying coastal communities with inundation and beach erosion — and stressed corals may not be able to grow vertically fast enough to match the pace of sea level rise. That could also make them a less effective barrier.

Researchers compared simulations of current and future sea level and reef conditions at four sites with differing wave energy near the French Polynesian islands of Moorea and Tahiti. The team then simulated the height of a wave after it has passed the reef, known as the back-reef wave height, under several scenarios. The most likely scenario studied was based on the Intergovernmental Panel on Climate Change’s projections of sea level height by 2100 and corresponding changes in reef structure.

Under those conditions, the average back-reef wave heights at the four sites would be 2.4 times as high in 2100 as today, the team reports February 28 in Science Advances. That change would be largely due to the decrease in coral reef complexity rather than rising sea levels, the simulations suggest. Coastal communities around the world will likely see similar wave height increases, dependent on local reef structures and extent of sea level rise. The finding, the researchers say, shows that conserving reefs is crucial to protecting coastal communities in a changing climate.

As a physics reporter and lover of mathematics, I won’t be celebrating Pi Day this year. That’s because pi is wrong.

I don’t mean that the value is incorrect. Pi, known by the symbol π, is the number you get when you divide a circle’s circumference by its diameter: 3.14159… and so on without end. But, as some mathematicians have argued, the mathematical constant was poorly chosen, and students worldwide continue to suffer as a result.

A longtime fixture of high school math classes, pi has inspired books, art (SN Online: 5/4/06) and enthusiasts who memorize it to tens of thousands of decimal places (SN: 4/7/12, p. 12). But some contend that replacing pi with a different mathematical constant could make trigonometry and other math subjects easier to learn. These critics — including myself — advocate for an arguably more elegant number equal to 2π: 6.28318…. Sometimes known as tau, or the symbol τ, the quantity is equal to a circle’s circumference divided by its radius, not its diameter.

This idea is not new. In 2001, mathematician Bob Palais of the University of Utah in Salt Lake City published an article in the Mathematical Intelligencer titled “ π is wrong!” The topic gained more attention in 2010 with The Tau Manifesto, posted online by author and educator Michael Hartl. But the debate tends to reignite every year on March 14, which is celebrated as Pi Day for its digits: 3/14.
The simplest way to see the failure of pi is to consider angles, which in mathematics are typically measured in radians. Pi is the number of radians in half a circle, not a whole circle. That makes things confusing: For example, the angle at the tip of a slice of pizza — an eighth of a pie — isn’t π/8, but π/4. In contrast, using tau, the pizza-slice angle is simply τ/8. Put another way, tau is the number of radians in a full circle.

That factor of two is a big deal. Trigonometry — the study of the angles and lines found in shapes such as triangles — can be a confusing whirlwind for students, full of blindly plugging numbers into calculators. That’s especially true when it comes to sine and cosine, two important functions in trigonometry. Many trigonometry problems involve calculating the sine or cosine of an angle. When graphed, the two functions look like a series of wiggles, shaped a bit like an “S” on its side, that repeat the same values every 2π. That means pi covers only half of an S. Tau, on the other hand, covers the full wiggle, a more intuitive measure.

Pi has become so embedded in mathematics that it could be hard to excise. A more practical approach may be to introduce tau as a teaching tool alongside pi, rather than a replacement. Education is where tau’s impact is most likely to be felt: Professional scientists and mathematicians can comfortably handle the factors of two that crop up with pi in equations.

You might argue that multiplying by two isn’t that hard, even for students. But it isn’t the arithmetic that concerns me. Trigonometry is notorious for creating a divide between the math-fluent and math-phobic. But helping more people understand and enjoy mathematics isn’t some pie-in-the-sky fantasy. Everyone is capable of doing math. We just need to work smarter, and speak more clearly, to help those who struggle.

So here’s to June 28 — Tau Day.