Fleas are remarkable jumpers: They can travel 200 times their own body length in a single leap, and can withstand acceleration forces of 100 Gs. But exactly how do they make such incredible jumps? Although we’ve known for decades that fleas store energy in a springy protein called resilin before they launch into the air, it’s remained a mystery whether they use the flea-equivalent of feet (called tarsi) or knees (called trochantera) to transmit that energy to the ground. But with 21st-century high-speed cameras, researchers have now put the debate to rest: the answer is in the feet.
Now, the first task in experimenting with fleas is to find fleas. Luckily, the warmhearted individuals at England’s St. Tiggywinkles Wildlife Hospital Trust have flea-ridden hedgehogs just waiting to lose a few bugs–and so that wonderfully named hospital donated a few fleas to a good cause.
The study, published in the Journal of Experimental Biology, included both video and flea-leap simulations. But the researchers–led by Gregory Sutton at the University of Cambridge–made their first insights using the same methods that were used decades ago:
Neanderthals: They weren’t really into distance running. According to research by David Raichlen in the Journal of Human Evolution, they were more the power walking type: The shape of a Homo sapiens heel compared to that of a Neanderthal would have allowed our ancestors to be much more efficient runners over long distances.
Raichlen stated with living humans, studying them as they ran on treadmills.
By looking at MRI scans of their ankles, he found that the distance between a point on the heel bone just below the ankle bone, and the back of the heel bone where the Achilles tendon attaches, was proportional to the runner’s efficiency. The shorter this distance, the greater is the force applied to stretch the tendon – and the more energy is stored in it. This means that people with shorter distances are more efficient runners, using less energy to run for longer. [New Scientist]
With this knowledge, Raichlen and colleagues looked at the remains of Neanderthals as well as humans of the same era. The difference, he says, was distinct.
If you’ve ever wondered why the seahorse has its elegantly curved body (aside from luring snorkelers into the water), wonder no more: it helps them hunt.
Researchers at the University of Antwerp in Belgium, led by biomechanicist Sam Van Wassenbergh, analyzed video footage of seahorses on the hunt and used mathematical models to come to the conclusion that a seahorse’s curvy neck lets it strike at more distant prey.
“They rotate their heads upward to bring their mouth close to the prey [passing above],” explained Dr Wassenbergh…. The creatures’ curved bodies mean that when they do this, their mouths also moved forward, helping to bring passing small crustaceans within sucking distance of their snouts. [BBC News]
He even has an evolutionary theory to back up his observations.
“My theory is that you have this ancestral pipefish-like fish and they evolved a more cryptic lifestyle,” said Dr Wassenbergh. [BBC News]
Unlike the seahorse, the related pipefish has a straight body and swims while attacking its prey. Seahorses, on the other hand, tend to hide out and wait for the prey to come to them. And according to this study, published in the journal Nature Communications, a longer striking distance is a big advantage for a couch-potato creature.
“Once this shift in foraging behavior is made, natural selection will favor animals that can increase the strike distance, which according to our study puts a selective pressure to increase the angle between head and trunk and to become what we now know as sea horses,” [said] researcher Sam Van Wassenbergh. [LiveScience]
They may not be as adorable as sugar gliders, but they’re just as accomplished: Five species of Asian snake have also developed the ability to “fly” or glide from tree to tree, flattening out their bodies to travel up to 80 feet.
Researcher Jake Socha and his team studied the glide of Chrysopelea paradisi snake and took videos of the snakes in flight, which Socha presented at an ongoing meeting of the American Physical Society. He found that before a snake takes the leap it curls its body into a J-shape, and then launches itself from the tree branch. In the air, it flattens its body and undulates, as if slithering through the air.
The snake differs from other gliding species, like gliding lizards and flying squirrels, in that it doesn’t have specialized body parts that act as wings.
“The whole snake itself is just one long wing,” Socha said. “That wing is constantly reconfiguring, it’s constantly reforming and contorting.” [LiveScience]
Hit the jump for a video of the snake in action. (more…)
The enormous wings of pterosaurs testify to the idea that these giant reptiles, which lived at the same time as dinosaurs, would have been masters of flight. But there’s one thing that nags paleontologists: pterosaur takeoff. Just how does a giraffe-sized creature get off the ground?
Birds rely on the strength of their legs to leap into the air or run to gain speed for take-off. Pterosaurs walked on all four limbs, and Habib has developed an anatomical model to explore how they might have launched themselves using their small hind limbs and larger “arms” which formed part of their wings. The animal could have launched itself like a pole vaulter, pushing forward with its hind limbs and using its powerful arms to thrust it high enough into the air to stretch its wings and fly away. [New Scientist]
Cats have been our companions for almost 10,000 years. They have been worshipped by Egyptians, killed (or not) by physicists, and captioned by geeks. And in all that time, no one has quite appreciated how impressively they drink. Using high-speed videos, Pedro Reis and Roman Stocker from the Massachusetts Institute of Technology has shown that lapping cats are masters of physics. Every flick of their tongues finely balances a pair of forces, at high speed, to draw a column of water into their thirsty jaws.
Read the rest of the post at Not Exactly Rocket Science, where Yong explains that each sip is a tug-of-war between inertia and gravity. Here’s a little of that high-speed video:
No, this ostrich is not decked out early for Halloween. The bird’s glowing get-up is part of an experiment that settled just why these elongated creatures can run so much faster and farther than us: They have twice as much bounce in their step.
Jonas Rubenson and colleagues adorned the tame ostriches with the reflectors at points that would show how their joints moved as they sprinted down a test track. The team watched the birds run and then sampled human volunteers the same way. Rubenson’s study appears in the Journal of the Royal Society Interface.
“Cheetahs and lions are great sprinters, but they use a lot of energy when moving,” he says. “However ostriches, horses and antelopes are adapted to running fast and economically over long distances.” Rubenson says previous work had shown the ostrich uses 50% less energy running when compared with humans, yet can run at twice the speed. [Australian Broadcasting Corporation]
About two-fifths of marathon runners “hit the wall” on the big day. That means they completely deplete their body’s stash of readily available energy, which makes them feel wiped out and severely limits their running pace; it sometimes forces people out of the run completely.
Marathoner and biomedical engineer Benjamin Rapoport has been physically and mentally struggling with this phenomenon for years, and had the bright idea to turn it into a research project. He published a mathematical theory in the journal PLoS Computational Biology describing how and why runners hit the wall–and how they can avoid it.
By taking into account the energy it takes to run a marathon, the body’s energy storage capacity and the runner’s power, the researchers were able to accurately calculate how many energy-rich carbohydrates a runner needed to eat before race day and how fast to run to complete all 26.2 miles (42 kilometers). [LiveScience]
Rapoport’s studies of marathoners were prompted by his desire to run in the Boston Marathon in 2005, and his teacher’s desire for him to be in class. In return for missing class, Rapoport was tasked with giving a class lecture on the physiology of the marathoner. That same year, Rapoport himself hit the wall while running the New York Marathon.
High heel wearers likely guessed it: Walking around on your tiptoes isn’t great for your calf muscles. Researchers looking at leg sonograms of women who frequently wear 2-inch or higher heels found that these women had calf muscle fibers that were an average of 13 percent shorter than their flat-wearing counterparts.
The small study, published yesterday in the Journal of Experimental Biology, has given some credence to complaints of lasting pain even after the pumps come off.
Anecdotally it has long been said that regularly wearing high heels shortens the calf muscle. Study leader Professor Marco Narici, from Manchester Metropolitan University, said in the 1950s secretaries who wore high heels complained that they struggled to walk flat-footed when they took their shoes off. [BBC]
Perhaps the original design is still the best. In this week’s Nature, Harvard’s Daniel Lieberman and his team reported on the impact force of people who are used to running barefoot versus those of us who wear spongy sneakers to protect the bottoms of our feet. Those who ran barefoot (the way humans evolved to run) moved differently, and with far less stress on their feet than the shoe-wearing masses.
The researchers first traveled to Kenya to watch endurance runners who grew up running sans shoes. The study—the first to test lifelong barefoot runners and not simply people trying it out—found that the barefoot runners landed on the front or middle of their feet. By contrast, runners in shoes typically land on their heels. Lieberman says: “This creates an impact; it’s like someone hitting your heel with a hammer with up to three times your body weight” [BBC News]. In follow-up tests in the United States, the team noted that barefoot runners put, on average, only a third of the initial impact force on their feet than their shod counterparts did.
If you read this blog last week, you might have seen us cover a study suggesting that South African sprinter Oscar Pistorius ought to be allowed to compete in the same track and field events as everyone else because his prosthetic legs confer no advantage over a sprinter with biological legs. But if you saw a study cited by the Associated Press and many other publications yesterday, you might think that Pistorius would soon be banned from competitions, because his “blades” let him swing his legs far faster than even the world’s fastest man, Usain Bolt. So what the heck is going on?
The AP’s study isn’t actually a “study,” per se. Rather, what the Journal of Applied Physiology published was a point-counterpoint (pdf), now freely available for anyone to read. In in, Peter Weyand and Matthew Bundle argue that Pistorius’ prosthetics are a huge advantage, particularly in what matters most: how fast he can move his legs. Weyand and Bundle say that the lightweight blades allow Pistorius “to reposition his limbs 15.7 percent more rapidly than five of the most recent former world-record holders in the 100-meter dash” [AP].
There is, however, a counterpoint to this argument in the journal piece that yesterday’s news reports neglected, coauthored by Alena Grabowski of the MIT Media Lab (who led the research on Pistorius’ blades that 80beats covered last week). Her team has found that the limiting factor determining an athlete’s top speed was how hard the foot or prosthesis hit the ground. Their study showed this “ground force” was around 9% lower in the prosthetic limb versus the unaffected leg [The Guardian]. Grabowski’s research focused on professional runners with only one prosthetic leg.
The world domination achieved by such fearsome bipedal dinosaurs as the T. rex may have been a result of their warm-blooded biology, according to new research. For decades, scientists assumed that because dinosaurs resembled lizards, they were cold-blooded as well, their internal temperature rising and falling with the outside world. However, birds are warm-blooded, and the fact that birds seem to be descended from dinosaurs raises the question of whether their ancestors were as well [LiveScience]. The new study, published in the journal PLoS ONE, examined the anatomy of 14 species of bipedal dinosaurs, and argues that many of them needed more energy to power their massive leg muscles than a cold-blooded metabolism could provide.
Lead researcher Herman Pontzer based his findings on the estimated amount of energy dinosaurs must have expended moving about. Recent research by Dr Pontzer has shown that the energy cost of walking and running is strongly associated with leg length. Hip height – the distance from the hip joint to the ground – can predict the observed cost of locomotion with 98 per cent accuracy for a wide range of land animals [Telegraph]. The research team also used measurements of fossilized leg bones to determine the leg muscle mass of each species, and found that the muscles would have required a great deal of energy during walking and running.
The dinosaurs would have benefited from a warm-blooded metabolism, Pontzer says, because they could have been agile and active even when the temperature dipped, and could have therefore spread through areas with colder climates. But there would also have been a downside: Maintaining a stable internal temperature … costs a lot of energy and requires the animals to feed more regularly [The Guardian]. At any rate, the new results aren’t likely to convince paleontologists who aren’t in the warm-blooded camp, and you can expect the debate to continue.
South African sprinter Oscar Pistorius raised a ruckus last summer when the he wanted to qualify for the Beijing Olympics, thanks to the J-shaped carbon fiber blades that the double-amputee uses to run. Pistorius didn’t get to run in last summer’s games, but now an MIT team has released a study declaring that he doesn’t have an unfair advantage. Rather, the researchers found quite the opposite: Running blades for amputees, even made with today’s best materials, can’t compete with the legs that humans have evolved.
Pistorius has long argued that he should be allowed to compete alongside able-bodied athletes in races, but athletics authorities banned him from doing so in last year’s Olympic games, claiming that his blades gave him an unfair advantage over able-bodied athletes [The Guardian]. The MIT Media lab team led by Alena Grabowski helped to reverse his racing ban before turning its attention this year to the general question of whether blades or legs are better.
The team concocted a clever solution to the problem of testing this question. The study participants were six elite sprinters who had one intact leg and one leg that had been amputated below the knee. Researchers decided to study these types of amputees because they could compare their affected leg to their unaffected leg [Los Angeles Times].
Inside the brain of someone who’s learning to juggle, some interesting changes take place. Researchers used MRI scans to study the brains of people before and after a six-week training course in juggling, and say they saw a 5% increase in white matter – the cabling network of the brain [BBC News].
The study, published in Nature Neuroscience, follows up on previous work that found changes in the more famous gray matter of the brain, which consists of the cell bodies of the neurons where processing and computation take place. The white matter, which consists mostly of the axons that stretch away from the cell bodies, can be thought of as the brain’s wiring, and researchers say this is the first time that changes have been observed in the white matter of a healthy adult.
A prehistoric armadillo-like animal swung its tail like a baseball bat, taking advantage of the “sweet spot” the same way tennis and baseball players do today, according to a study published in the journal Proceedings of the Royal Society B.
The tail sported spikes at a specific location that allowed the mammals, known as glyptodonts, to deliver a strong blow while minimizing the risk of harming the tail, the researchers found; spiny-tailed dinosaurs may have used the same mechanism. Known as the “sweet spot” today in sports like baseball, this so-called “center of percussion” helps athletes avoid wrist injuries. “The center of percussion is a point where you can deliver a very powerful blow with a baseball bat, a tennis racket, a sword, an axe or any hand-held implement, but the forces against your hands are almost zero” [Discovery News], said lead author Rudemar Ernesto Blanco. The glyptodont, which went extinct about 8,000 years ago after its emergence about 2.5 million years ago, would have swung its tail about 15 meters per second–about as fast as a modern-day tennis player swinging his or her racket.
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
Fleas are remarkable jumpers: They can travel 200 times their own body length in a single leap, and can withstand acceleration forces of 100 Gs. But exactly how do they make such incredible jumps? Although we’ve known for decades that fleas store energy in a springy protein called resilin before they launch into the air, it’s remained a mystery whether they use the flea-equivalent of feet (called tarsi) or knees (called trochantera) to transmit that energy to the ground. But with 21st-century high-speed cameras, researchers have now put the debate to rest: the answer is in the feet.
The enormous wings of 
No, this ostrich is not decked out early for Halloween. The bird’s glowing get-up is part of an experiment that settled just why these elongated creatures can run so much faster and farther than us: They have twice as much bounce in their step.
About two-fifths of marathon runners “hit the wall” on the big day. That means they completely deplete their body’s stash of readily available energy, which makes them feel wiped out and severely limits their running pace; it sometimes forces people out of the run completely.
Perhaps the original design is still the best. In this week’s Nature, Harvard’s Daniel Lieberman and his team 
If you read this blog last week, you might have seen us cover a study suggesting that South African sprinter Oscar Pistorius ought to be allowed to compete in the same track and field events as everyone else because his prosthetic legs 
The world domination achieved by such fearsome bipedal dinosaurs as the T. rex may have been a result of their warm-blooded biology, according to new research. 
South African sprinter Oscar Pistorius raised a ruckus last summer when the he wanted to qualify for the Beijing Olympics, thanks to the J-shaped carbon fiber blades that the double-amputee uses to run. Pistorius didn’t get to run in last summer’s games, but now an MIT team has 
Inside the brain of someone who’s 
A prehistoric armadillo-like animal swung its tail like a baseball bat, taking advantage of the “sweet spot” the same way tennis and baseball players do today, according to a 
