On February 13th, 2018 we learned about

The way we sense sound is strangely tied to our sight

If you’re having a hard time hearing something, try looking more carefully. Despite what every kid learns by kindergarten, there’s mounting evidence that our hearing isn’t just up to our ears. Multiple studies are finding aspects of hearing that are shaped at least partially by our eyes, and that the two sensory systems are actually intertwined in our brains. Of course, that doesn’t mean it’s all perfectly clear, as some of the dynamics in this relationship remain a bit confusing, starting with our eardrums.

Ears move with eyes

The tiniest bones in your body are in your ear. While you probably can’t wiggle your ears as well as some other animals, you do still have some control over this anatomy. Usually, the three bones, or ossicles, in the middle ear move to help or hinder sounds passing through your ear, modulating their volume, and their movement is seen as a reaction to outside sounds. However, researchers using very sensitive microphones in a quiet space were able to listen to the vibrations created by a person’s ossicles, and found that they move in tandem with the eyes. In fact, they seem to actually start vibrating in the ear before eye movement can be detected, suggesting that both bits of anatomy are being triggered by the same motor functions in the brain.

The ossicles’ movement doesn’t appear to be completely arbitrary either. The bones will move inward or outward according to the direction the eyes are looking. They continue this vibration until the eyes stop. It’s unclear at this point why this occurs, although it’s thought that our brains may be merging the visual and auditory information gathered during this activity to build a more cohesive sense of the space around us.

Looking to listen

This kind of cross-sensory augmentation was a bit clearer in a second study that linked visual cues to sound clarity. Previous work had found that around 25 percent of the auditory cortex in the brain is actually responsive to light, despite the fact that light is… generally silent. It now appears that this sensory overlap is a way for our brains to pick which sounds are most deserving of our attention.

An experiment watched the brain activity of ferrets while they were presented with visual and auditory stimuli. Simulating a noisy environment, the ferrets were made to listen to multiple sounds layered on top of each other. While the ferrets listened, a light would flash at different rhythms, sometimes syncing up with one particular set of sounds or another. This synchronization was apparently picked up by the ferrets’ brains, which then started filtering the competing noises to prioritize that particular sound. When the visuals somehow matched the sound, that sound was processed to be easier to perceive.

While you’ve probably never noticed your eardrums wiggling, you may have noticed this second phenomenon at a party. By watching someone’s lips as they spoke, you were seeing visual information that was synced to the timing of their voice. Your brain could then prioritize sounds on that same rhythm, helping you make sense of what was said. However, the ferrets demonstrate that this wasn’t because you were lip-reading necessarily, as the furry critters experience a similar effect without anything resembling human speech. Instead, it seems that many of the relationships between our hearing and our site likely evolved in a distant ancestor, helping them make sense of the clattering sounds to their left, right, or right in front of them.

Source: Visual cues amplify sound by University College London, Medical Xpress

On February 12th, 2018 we learned about

Cheetahs’ high speeds are viable thanks to their uniquely-sized inner ears

Cheetahs don’t run fast to set records. They run to catch food. From that perspective, it makes sense that some of their most important adaptations aren’t only found in their long legs or flexible spines, but in their heads to help guide them towards their prey. A study of the big cats’ inner ears has found that they’re possibly the most advanced, and most recently developed, feature that helps cheetahs not just run after, but also catch their elusive prey.

Inner ears aren’t used for hearing. They’re a specialized structure in the skull that tells vertebrates how their heads are oriented, like the accelerometers in your phone or video game controller. Each inner ear consists of three semicircular canals that contain fluid and sensitive hair cells. The fluid levels off thanks to gravity, tickling some hair cells but not others. With each canal handling a different direction of motion, such as side-to-side versus tilt, the combined data can be used by the brain to figure out how a head is not only oriented, but how it’s moving through space. This kind of information is crucial for movement and balance, especially when that movement is coming from a 65 mile-per-hour sprint after an unpredictable gazelle.

Steering at top speed

For a cheetah (Acinonyx jubatus) to stay on target, it needs to maintain visual contact with its prey. Even when their body is careening in a new direction, cheetahs do a great job at keeping their head steady so they can keep track of how their prey is moving. Researchers suspected that their inner ears were somehow enhanced to make this possible, and started scanning the skulls of cheetahs and other big cats with X-ray computed tomography, giving them a detailed, 3D view of how each animal’s ears worked. As expected, cheetahs were found to have larger and longer inner ear canals than other cats, which would give the fluid and hair cells more granularity in the signals they could provide. To put it another way, these super-sized sensors could pick up smaller variations in tilt and movement, plus have a slightly bigger range before those signals were “maxed out” at one extreme or the other.

By including the skulls of extinct cat species in this study, researchers were also able to estimate when cheetahs acquired this degree of sophistication in their inner ears. An extinct relative, Acinonyx pardinensis, was also specialized for running, but its ear canals wouldn’t have provided the same feedback found in a modern cheetah. That bulkier relative lived only a few hundred-thousand years ago, showing just how recently this line of cats evolved this degree of sensitivity. That timing may make sense, since A. pardinensis probably wasn’t as fast as a modern cheetah either, and thus didn’t need quite as much control and maneuverability as today’s record-holding runners. As top speeds increased over time, it seems that the sensors and feedback systems to help the animal steer grew as well.

My third-grader asked: If balance is connected to your ear, do deaf people have problems with balance?

They can. One estimate says that as many as 30 percent of deaf people may experience some kind of persistent balance problem. Apparently the cause of the hearing loss, such as meningitis versus  something like Usher’s Syndrome, can affect how severe the balance issues may be.

Source: Cheetahs' inner ear is one-of-a-kind, vital to high-speed hunting by American Museum of Natural History, EurekAlert!

On February 12th, 2018 we learned about

Unintended weight-loss is a consequence of astronauts’ weightlessness

Weight loss in microgravity is unavoidable, in more ways than one. Most directly, anyone on the International Space Station (ISS) will feel weightless thanks to their orbit around the Earth. They’re never in a position where the Earth’s gravity can noticeably pull them “down,” meaning they’d weigh zero pounds if they tried to stand on a scale. However, once astronauts get back to Earth’s surface, NASA’s medical staff has found that they have lost weight in another sense, having lost as much as 10 percent of their overall body mass. This has raised concerns about how people might spend extended amounts of time in space without putting their muscle, bone and cardiovascular health at risk.

Astronauts aren’t eating enough

As it turns out, weightlessness may be contributing to astronauts’ weight loss. On earlier visits to space, astronauts were asked to fill out weekly surveys about what food they were eating, although it’s suspected that those answers weren’t terribly accurate. Astronauts on the ISS are now prompted to record every snack and meal they eat on touch-screen app, giving medical staff on Earth a much better sense of how much food is consumed in space. The resulting pattern is that astronauts unconsciously eat less in space, probably thanks to being weightless all the time.

Living in space dulls appetites in a few different ways. Your muscles need to work less in microgravity, and are thus consuming fewer calories every day. Over time, this can contribute to muscle atrophy, giving you even less muscle tissue to feed at each meal. It’s also suspected that microgravity affects how well your stomach’s stretch receptors can do their job. As organs tend to be reshaped without the constant tug of Earth’s gravity, astronauts’ stomachs may start signaling that they’re full earlier in meal, even if they haven’t hit their nutritional needs for the day. Finally, most of the food on the ISS is carefully packaged in sealed containers, food doesn’t have a chance to stimulate appetites like it does cooking on the stove at home. This isn’t to say that there are no food smells on the ISS— seafood gumbo was actually banned by mission commanders because of its lingering odor. Then again, anyone in an open office probably knows how uninvited fish smells don’t do much for one’s appetite.

Fish and fitness

It’s unfortunate that seafood smells have been a problem, because seafood may be one of the easier ways for astronauts to help keep their bodies healthy in microgravity. Crew members that eat more fish have been found to retain more bone tissue, which is likely thanks to the omega-3 fatty acids found in seafood. The benefit seems most pronounced in astronauts who also skip other kinds of meat, clearly indicating that astronauts should eat a lot of sushi. The second element towards keeping one’s body fit has turned out to be exercise. Some residents of the ISS have managed to avoid unintended weight-loss, and their six-day-a-week exercise program has probably helped keep their muscles and bones in shape, countering the atrophying effects of microgravity.

Source: Astronauts lose weight in space, and it might be because their food is literally floating around inside them by Mary Beth Griggs, Popular Science

On February 11th, 2018 we learned about

Migrating mallards may be moving a considerable quantity of seeds and spores in their stool

A nearby park has become home to over a growing number of both domesticated and mallard ducks. At busier times, it almost seems like the shores of the two artificial ponds are completely lined with ducks. This naturally means that the plants and paths nearby end up nearly completely covered in poop, to the point where my four-year-old is looks like he’s playing hop-scotch to avoid stepping in it. Soiled shoes aside, the poop from the mallards in particular may be making an important impact on the ecology of the park. Since those birds migrate from other locales, they’re likely bringing seeds and spores with them, although scientists are only just starting to measure how much of an impact their poop might make.

Deposits from digestive tracts

The duck poop at my local park wasn’t tested, but a more extensive study was recently completed that looked specifically at mallard (Anas platyrhynchos) migration in central and eastern Europe. Even ignoring the larger seasonal migrations these ducks make each year, a mallard may fly as far as 12 miles in 30 minutes, giving them ample opportunity to disperse seeds around an ecosystem. Scientists knew that seeds may sometimes get stuck to the birds’ wings or feet, but this was the first serious look at ducks’ endozoochory, or seed and spore dispersal, as a product of their digestive tracts. Basically, the question was how many seeds are these birds eating and indirectly planting in new places?

The 200 fecal samples collected in the wetlands of Hungary showed a fair amount of diversity. 21 species of flowering plants were found, including 13 that were terrestrial enough to grow outside a pond. More unusually, the duck poop was also turned up with spores from the watermoss Salvinia natans. This adds mallards to the short list of animals like deer, mice and fruit bats, that was previously known to help spread ferns across large distances. So while most expectations about seed and spore dispersal point to frugivores, or fruit-eaters, it turns out that the common mallard may also be shaping ecosystems around the world.

How significant are these seeds?

The full extent of the ducks’ poop isn’t known yet. While they clearly carried a number of plants seeds in their stomachs, the most frequently found seed was for the fig Ficus carcica, and none of those seeds seemed to actually germinate in their new Hungarian home. This is probably good news, as some less-welcome seeds were discovered as well. The hackberry tree is normally found in North America, and while only one such seed was found in this sample, it would likely function as an invasive species around the wetlands of Hungary. The combination of both diversity and unpredictable germination suggests that we really need to find out more about what these ducks are depositing around or ponds, parks and paths.

Source: Duck faeces shed light on plant seed dispersal by Sabrina Weiss, British Ecological Society

On February 11th, 2018 we learned about

Boiling and smushing blocks of wood can make them as strong as steel

Wood hasn’t been a big component of car design since 1912. We’ve long been accustomed to vehicles made of steel, aluminum and even plastics for their balance of strength, weight and cost, but this may change in the near future. Recent experiments with treated wood suggest that trees may have more potential than most of us would expect. As a result, we may soon be looking to wood plates as a lighter alternative to steel for our cars, trains and even infrastructure.

The strength of cellulose

The key to wood’s strength is cellulose. The natural polymer is generally structured as long, parallel fibers that not only provide strength in a tree, but also help funnel water through the plant. Researchers are looking to really maximize cellulose’s potential, starting by stripping out other components that naturally occur in a piece of wood. The latest technique involves boiling the wood for seven hours in a water-based solution of sodium hydroxide and sodium sulfite, then pressing it between heated metal plates for 24 hours. This process first removes a large portion of a a component called lignin, then eliminates the resulting gaps in the wood by smushing everything together. It’s theorized that with less lignin in the wood, the remaining cellulose can interlock, or at least form hydrogen bonds that significantly strengthen the resulting material.

The result is a remarkable block of wood with greater strength, density and relatively little weight. A block of boiled, squashed wood was only one-fifth its original width, making it three-times its original density. It was then measured as being 11.5 times stronger than before, able to stop a metal pellet moving at 67 miles-per-hour. That wouldn’t make it bulletproof, but it would be comparable to the steel found in car, just with a lot less weight to lug around.

Priced for mass production?

Impressively, the initial critiques of this engineered wood aren’t that it’s improbable, but that it should probably be even better. Other techniques focus more on steaming, heating and applying resins to wood, boosting strength almost as much as the procedure described above. Any trade-off in strength is likely made up in cost, particularly if the seven-hour boiling phase is eliminated from the process. Even if the sodium hydroxide and sodium sulfite do prove to be too expensive for mass production, the study’s authors are still happy with the knowledge gained from their work. While multiple approaches looked to remove lignin from the cellulose, we now know that leaving some lignin in wood is more effective than removing it all. As these materials continue to get refined, we’re hopefully a step closer to growing, rather than mining, the materials needed for our next car.

Source: Crushed wood is stronger than steel by Mark Zastrow, Nature

On February 8th, 2018 we learned about

Ancient arachnid appears to be an amalgam of spiders and scorpions

Arachnids have apparently been experimenting with limbs for the last 400 million years. While modern arachnids’ eight legs may seem weird enough, what we live with today is relatively tame compared to what was scuttling around during the Mesozoic era. Specimens recovered from ancient amber have revealed other offshoots of the arachnid family tree, some of which are almost an amalgam of spiders and scorpions, complete with long, whip-like tails. There’s no evidence that those tails delivered venom, but it does give us a better sense of the wide spectrum of spidery creatures that left us with the arachnids we know today.

The latest specimen has been named Chimerachne yingi, as it’s body looks like it combines features from both spiders and scorpions. Like it’s modern kin, the “chimera spider” sported eight legs, as well as function, silk-producing spinnerets. These critical organs are actually highly specialized limbs, and weren’t present on older arachnid ancestors. Combined with an age of 100 million years, C. yingi is probably one of the closest relatives to modern spiders ever found, even though it’s not thought to be a direct ancestor of what lives today.

Defined by differences

This is where C. yingi’s differences become relevant. Its exoskeleton is structured more like a scorpion than a true spider, with segmented plates along its abdomen that would have made its rear end more flexible. Even more dramatically, C. yingi sported a tail longer than its tiny, 0.07-inch body. That tail was thin and probably fairly flexible, evolved from yet another limb structure. It probably didn’t get used like a scorpion’s tail though, as researchers suspect it acted more like a rear-mounted antenna, allowing arachnid to probe its surroundings. Like other specific behavior, this can’t be completely confirmed from the specimen trapped in amber, but the overall structure looks more like a sensory tool than any kind of weapon or leg.

In the end, C. yingi wasn’t technically a spider. It was classified as an uraraneid, which was an order of arachnids that likely diverged from the modern spider lineage hundreds of millions of years ago. Their common ancestor likely sported the signature limbs and spinnerets, possibly along with tails too. It’s thought that the arachnids that eventually became our modern spiders must have then lost their shared tail and solidified their abdomens, diverging from both the uraraneids and arachnids like scorpions. So while this tailed creature wasn’t a direct relative of today’s spiders, its unusual anatomy is still helping us understand how spiders evolved.

Source: Part spider, part scorpion creature captured in amber by Elizabeth Pennisi, Science

On February 8th, 2018 we learned about

Forced perspective fakes sizes and spaces by manipulating a structure’s proportions

It may seem redundant to point out that something in Disneyland is fake, but on a recent trip to the theme park my family was surprised to “discover” visual tricks hidden right in front of us. While the robotic pirates and dancing cartoon characters may be obvious, an architectural concept known as forced perspective manipulates our perception of space in a more subtle way, particularly in its application on Disney’s “Main Street, USA.” It’s a trick that Disney is said to have borrowed from film-makers in Hollywood, but its use extends all the way back to architecture in ancient Greece, not to mention some really tall depictions of people.

Building smaller to look big

Forced perspective is a series of small adjustments a designer can make to create the perception that a space is larger or smaller than it really is. It taps into our brains’ understanding of how parallel lines seem to converge at a distance, and how objects appear smaller when they’re further away. In Disneyland, this means that structures are made to look taller by making their upper extremities smaller, giving the illusion that they’re extending further away from a viewer’s eye than they really are.

There are many examples of this kind of design, many of which are right at the front of the park. Buildings are made to look like they’re three stories tall, but the second and third “floors” are reduced in scale by 3/8 and 1/2 respectively. The Matterhorn has full-sized trees at its base, with smaller model trees higher up to imply a soaring peak. The castle at the center of the park has small upper floors, and thanks to strategic angling on the buildings leading up to it, looks further away, and therefore bigger, than it really is when you first see it.

Faking and fixing ancient architecture

This kind of deception certainly didn’t originate in Anaheim or Hollywood. An example of many of these concepts can be found in the Palazzo Spada in Rome. Architect Francesco Borromini didn’t have room to build the traditional 100-foot-long hallway and colonnade in the palace, so he did the math to figure out what adjustments were needed to make a 26-foot-long hallway appear nearly four times longer than it really was. The tiles in the floor were carefully sized to appear further away. The floor is actually on an incline to imply more depth. Finally, a sculpture that appears to be the size of an adult at the far end of the hall is actually the size of a child, all to create the illusion of a full-length building. All together, it’s an aggressive set of adjustments that make the space look bigger, at least until you try to walk down the hall.

The ancient Greeks employed some similar ideas, but for slightly different effect. With a building like the Parthenon, the goal wasn’t to use forced perspective to make the structure look larger than reality, but to fix what perspective normally does to a large building. Regularly spaced columns, for instance, don’t look regularly spaced when viewed at once. So the Greeks made the columns in the Parthenon wider apart at the corners and closer together in the middle. This way, a viewer looking at one side of the building would see what appears to be a perfectly regular pattern of columns. The columns themselves were adjusted as well, being tilted and made wider in the middle, all so that they appeared to look straight and even when viewed from below.

Resizing statues

That viewing angle doesn’t only matter to buildings, but sculptures as well. Large sculptures, from Michelangelo’s David to the Statue of Liberty, are often created with the understanding that their relative height to the viewing audience will make the heads and shoulders look “too” small. To undo this effect of perspective, these sculptures’ have unnaturally large heads and shoulders so that they would look “right” to someone looking up at them from the ground. In an era of zoom lenses, drone-mounted cameras and more, this may seem a bit arcane, but may help explain why seeing something in person can be so much better than photo or video reproductions.

Source: Forced Perspective in Architecture by Christopher Muscato, Study.com

On February 7th, 2018 we learned about

Skin temperature may offer a less intrusive way to measure wildlife’s well-being

Mood rings may soon be making a comeback, at least among the animal conservation crowd. While jewelry for animals probably isn’t a great idea, the underlying principle that skin temperature is tied to a creature’s overall well-being does make sense. Thanks to improvements in thermal imaging cameras, biologists can now measure an animal’s temperature from afar, avoiding the need for intrusive practices like trapping and sedating an animal just to see how healthy it is. Even better, the gaudy rings are now unnecessary too.

The basic idea behind a mood ring is that your stress levels affect your skin temperature. As your body is stressed, or even just concentrating on a difficult problem, blood is diverted from less critical anatomy, like your fingers and nose, towards areas that are likely to need more oxygen and nutrients, like your brain and major organs. The reduced blood flow in those skinny extremities leads to lower temperatures, which in the case of a mood ring causes the liquid crystals in the ‘stone’ to change color, not unlike some thermometers.

Finding clues in birds’ faces

These changes in blood flow have now been confirmed in animals such as the blue tit (Cyanistes caeruleus). Rather than rely on an object in contact with the bird’s skin, thermal imaging of their face may provide enough detail to tell which birds are doing well and which are being affected by poor nutrition or health. Blood was found to be reduced in the area around the blue tit’s eye in particular, a correlation later verified by measuring the level of cortisol, a stress hormone, in the bird’s blood.

As this method is validated in other species, it should allow for easier surveys of animal welfare without the need for a blood sample. This would be more pleasant for the animals who wouldn’t need to be captured and handled by humans, but also allow for measurements of animals that are just too difficult to capture on a regular basis. So surveys of wildlife could be expanded to a wider range of species, giving scientists a more complete picture of how a particular ecosystem is functioning.

Source: Thermal imaging can detect how animals are coping with their environment, avoiding the need for capture by University of Glasgow, Phys.org

On February 7th, 2018 we learned about

Lasers let archaeologists map miles of Mayan civilization in mere minutes

It turns out the easiest way to map an ancient Mayan city is by blasting the jungle with lasers. Traditionally, the thick canopy of the jungle would require archaeologists to find ancient structures on foot, creeping through the thick, mosquito-infested forests one step at a time. Airplane-mounted lasers are changing all that, effectively clearing out every tree and shrub that may have obscured the view of everything from irrigation ditches to hidden pyramids. Mapping that would have once taken months can now be done in less than an hour, and is understandably being hailed as a “game-changer” for archaeologists.

Looking under the trees with lasers

Importantly, these lasers aren’t actually removing any of the flora or fauna from the Guatemalan countryside. Rather than physically burning away trees, the Light Detection and Ranging (LiDAR) lasers shoot harmless pulses of light hundreds of times per second. Those might be absorbed by whatever they hit, but enough reflect back to the plane to measure the time and therefore distance they traveled. Like a light-based version of a bat’s echolocation, this allows a computer to build a detailed, three-dimensional view of the terrain below.

By firing different wavelengths of light, LiDAR can also detect what kind of materials the laser pulses are hitting. For example, a green, translucent leaf will scatter and absorb high-frequency photons differently than low-frequency photons, which can then be used to infer when a laser is hitting a leaf versus a stone. Combined with taking measurements from multiple angles in the airplane, a LiDAR map can then remove all the organic growth of the jungle, leaving behind a representation of the buildings and walls that were built by the Mayans over 2000 years ago.

New maps of Mayan engineering

LiDAR mapping has already yielded new advances in our picture of Mayan culture. So far, over 770 square miles of the Guatemalan jungle have been mapped, leading to the discovery of 60,000 Mayan structures. Aside from the sheer volume of new buildings to investigate, these surveys have also revealed new types of Mayan construction. While the Mayans were known to farm, advanced agricultural technology has been revealed, including extensive irrigation canals. Additionally, defensive structures like walls and watchtowers have been found, suggesting more advanced levels of warfare in Mayan society than had previously been appreciated. As more of these pieces of engineering are found, the overall picture of the ancient Mayans is becoming much richer than the sum of its parts. Or at least the parts that people had had time to map out on foot.

Source: 'Game Changer': Maya Cities Unearthed In Guatemala Forest Using Lasers by Merrit Kennedy, NPR

On February 1st, 2018 we learned about

Small titanosaur answers big questions about ancient African geography

Mansourasaurus shahinae was only the size of a bus, probably weighing around five tons when it was alive 80 million years ago. That’s nothing to sneeze at, but it’s certainly not a record-breaker among its titanosaur relatives. Like other dinosaurs in this family, it sported a small head, long neck and small bony osteoderms on its back. Nonetheless, the discovery of M. shahinae is turning heads, not because of any unusual anatomy, but because of the place where it was found. It’s the seventh titanosaur from Africa, and only the sixth dinosaur species ever discovered in Egypt. As such, these fossils represent a relatively huge expansion of our understanding of African ecology in the late Cretaceous period.

M. shahinae was found in the Sahara desert, but certainly was not the only dinosaur living there. While Africa was habitable throughout the Mesozoic era, little is known of the animals that lived there thanks to a dearth of fossils. Much of the continent lacks the crisp, cliff-filled geology paleontologists benefit from in areas like the South Dakota Badlands, which often expose fossils from ancient layers of rock. Instead, much of Africa is covered in vegetation, making excavations much trickier get started.

No signs of African isolation

Fortunately, the fossils the team from Mansoura University found were in good condition. While there wasn’t a full skeleton, enough of the animal was preserved to clearly place it in the titanosaur family tree. As it turns out, M. shahinae’s closest known kin weren’t from Africa. The morphology of the available bones indicates that this dinosaur was more closely related to dinosaurs from Europe, not southern counterparts like Shingopana songwensis of Tanzania. M. shahinae, or rather its ancestors, must have had some way to access Europe.

This relationship then confirms a long-held hypothesis that Africa was connected to Europe and Asia by the Cretaceous period, similar to the geography of today. This may seem obvious from our modern perspective, but geologists know that the world’s continents were being considerably reshaped throughout the Mesozoic. Earlier on, most of the Earth’s land masses were clumped together in a huge super-continent known as Pangea. As the continents broke apart, it wasn’t clear when an animal living in Africa would necessarily have access to places like Europe, leaving a definite chance that dinosaurs like M. shahinae would have actually been geographically isolated. The similarities to European dinosaurs found in M. shahinae‘s fossils then provide critical evidence for this question, certainly making it a bigger discovery than the simple sum of the animal’s parts.

Source: New Egyptian dinosaur reveals ancient link between Africa and Europe by Ohio University, Phys.org