September 12, 2013
To the best of our knowledge, the mechanical gear—evenly-sized teeth cut into two different rotating surfaces to lock them together as they turn—was invented sometime around 300 B.C.E. by Greek mechanics who lived in Alexandria. In the centuries since, the simple concept has become a keystone of modern technology, enabling all sorts of machinery and vehicles, including cars and bicycles.
As it turns out, though, a three-millimeter long hopping insect known as Issus coleoptratus beat us to this invention. Malcolm Burrows and Gregory Sutton, a pair of biologists from the University of Cambridge in the U.K., discovered that juveniles of the species have an intricate gearing system that locks their back legs together, allowing both appendages to rotate at the exact same instant, causing the tiny creatures jump forward.
The finding, which was published today in Science, is believed to be the first functional gearing system ever discovered in nature. Insects from the Issus genus, which are commonly called “planthoppers,” are found throughout Europe and North Africa. Burrows and Sutton used electron microscopes and high-speed video capture to discover the existence of the gearing and figure out its exact function.
The reason for the gearing, they say, is coordination: To jump, both of the insect’s hind legs must push forward at the exact same time. Because they both swing laterally, if one were extended a fraction of a second earlier than the other, it’d push the insect off course to the right or left, instead of jumping straight forward.
The gearing is an elegant solution. The researchers’ high-speed videos showed that the creatures, who jump at speeds as high as 8.7 miles per hour, cocked their back legs in a jumping position, then pushed forward, with each moving within 30 microseconds (that’s 30 millionths of a second) of the other.
The finely toothed gears in their legs allow this to happen. “In Issus, the skeleton is used to solve a complex problem that the brain and nervous system can’t,” Burrows said in a press statement.
The gears are located at the top of the insects’ hind legs (on segments known as trochantera) and include 10 to 12 tapered teeth, each about 80 micrometers wide (or 80 millionths of a meter). In all the Issus hoppers studied, the same number of teeth were present on each hind leg, and the gears locked together neatly. The teeth even have filleted curves at the base, a design incorporated into human-made mechanical gears because it reduces wear over time.
To confirm that the gears performed this function, the researchers performed a neat (albeit morbid) trick with some dead Issus. They manually cocked their legs back in a jumping position, then electrically stimulated the main jumping muscle in one leg so that the leg extended. Because it was rotationally locked by the gears, the other non-stimulated leg moved as well, and the dead insect jumped forward.
The main mystery is the fact that adults of the same insect species don’t have any gearing—as the juveniles grow up and their skin molts away, they fail to regrow these gear teeth, and the adult legs are synchronized by an alternate mechanism (a series of protrusions extend from both hind legs, and push the other leg into action).
Burrows and Sutton hypothesize that this could be explained by the fragility of the gearing: if one tooth breaks, it limits the effectiveness of the design. This isn’t such a big problem for the juveniles, who repeatedly molt and grow new gears before adulthood, but for the mature Issus, replacing the teeth would be impossible—hence the alternate arrangement.
There have been gear-like structures previously found on other animals (like the spiny turtle or the wheel bug), but they’re purely ornamental. This seems to be the first natural design that mechanically functions like our geared systems.
“We usually think of gears as something that we see in human designed machinery, but we’ve found that that is only because we didn’t look hard enough,” Sutton said. “These gears are not designed; they are evolved—representing high speed and precision machinery evolved for synchronisation in the animal world.”
September 11, 2013
If you’re a drone bee, life is tough. You’re born, live for a month or two, and then die. During that time, you’re not a productive member of the hive—you can’t collect pollen or help incubate eggs, like worker bees—and you can’t even sting anyone.
Drone bees live with one purpose in mind: mating with a queen. When they’re lucky enough to achieve it, it only lasts a few seconds, and they die immediately afterward, because their penis and abdominal tissues are violently ripped from the body as part of the process.
Thus, for a drone bee, those few seconds of mating are the peak of existence. And here are those blissful seconds, captured in slow-motion.
The clip is from the new documentary More Than Honey, released last week, which explores the wondrous world of honeybees and Colony Collapse Disorder, the mysterious affliction that’s causing U.S. bee populations to plummet.
To get shots like this, the filmmakers used mini-helicopters equipped with ultra-high speed cameras (the clip above has 300 frames-per-second) and a so-called “bee-whisperer,” who carefully tracked the activity of 15 different hives so the crew could move them to a filming studio when a particular event was imminent. “The mating queen was the biggest challenge: we spent days on a scaffolding tower attracting drones with queen pheromones,” director Markus Imhoff said in an interview with the Honeybee Conservancy. “Her wedding flight, which was 36 seconds, took more than ten days—and we only actually saw it one and a half times.”
September 9, 2013
Mosquitoes are utterly, stupendously annoying. They can also carry diseases, such as malaria and West Nile virus. Some people—those with type O blood and robust colonies of bacteria on their skin, among other traits—are especially prone to getting bitten by them, and there’s growing evidence that many of the insects are evolving resistance to DEET, the main repellant we’ve relied upon for years.
All of which makes an ongoing project led by Ulrich Bernier, a chemist at the U.S. Department of Agriculture (USDA) Mosquito and Fly Research Unit, especially exciting. He’s taking a new approach to battling mosquitoes: Instead of developing chemicals that repel mosquitoes with unpleasant scents, he’s searching for substances that disrupt their ability to smell in the first place.
And as he announced today at the annual meeting of the American Chemical Society, his group has isolated a few chemicals that are naturally present on human skin in trace quantities and appear to inhibit mosquitoes’ capability to smell and locate humans. If one of these chemicals—mostly likely one called 1-methylpiperzine, which has been the most successful so far—holds up in future tests and can be produced synthetically on a bigger scale, wearing it could be a way of rendering yourself effectively invisible to mosquitoes.
Conventional insect repellants take advantage of the fact that the creatures rely mainly on their sense of smell to locate humans (they can smell us from as far as 100 feet away). DEET, which was developed during World War II, works mainly because it smells unpleasant to mosquitoes and other insects, so when you wear it, they prefer to fly elsewhere.
But DEET may be gradually growing less effective and has other drawbacks. Some people avoid using it because of evidence that it can, in rare cases, cause central nervous system problems—the EPA found (PDF) that it causes seizures in roughly one out 100 million users.
“We are exploring a different approach, with substances that impair the mosquito’s sense of smell,” Bernier explained in a press statement on his presentation. “If a mosquito can’t sense that dinner is ready, there will be no buzzing, no landing and no bite.”
To find these kinds of substances, he looked back at USDA research that started in the 1990s and was aimed at finding the natural compounds that attracted mosquitoes to human skin. As researchers isolated and analyzed 277 different substances that we naturally secrete in trace quantities, though, they found a handful that seemed to have the opposite effect, making mosquitoes less likely to come near.
Bernier and colleagues have since tested larger quantities of these chemicals to precisely measure their effect on the insects. In a lab, they built a cage divided in half by a screen. One half was filled with a swarm of mosquitoes; in the other half, they sprayed each of the chemicals to see how many of the mosquitoes would try to cross over.
Many of the compounds (most notably 1-methylpiperzine) seemed to inhibit the mosquitoes’ sense of smell, leaving them unable to detect other chemicals they normally find quite appealing. In trials, lactic acid—a substance that occurs in large amounts in sweat—pulled about 90 percent of the mosquitoes toward the screen, but when they mixed in a bit of 1-methylpiperzine, the mosquitoes stayed in place, seemingly unaware of the lactic acid nearby.
The group proceeded to tests with actual human skin and found the same results. “If you put your hand in a cage of mosquitoes where we have released some of these inhibitors, almost all just sit on the back wall and don’t even recognize that the hand is in there,” Bernier said.
He says that these inhibitors induce anosmia (the inability to detect odors) in the insects, making the secretor invisible. As it turns out, some people produce more of these inhibitors than others—which may account for part of why, for example, some people can emerge from an hour outside with bites on every inch of exposed skin, while a friend nearby can come back from the same place entirely unscathed.
The next step is figuring out how to incorporate these chemicals into commercial products. Bernier’s group isn’t the only one analyzing these natural inhibitors, and so far, others have run into a key problem: It’s hard to get the substances to stay on human skin instead of evaporating off, as they naturally do over time. But if they can figure that out and produce insect sprays that inhibit mosquitoes, rather than simply repelling them, all of us may someday be able to enjoy the same benefits as the lucky few who secrete these chemicals naturally.
September 6, 2013
The city of Manila, in the Philippines, is home to more than 1.6 million people, packed into an area smaller than 15 square miles—less than a quarter of the size of Washington, D.C. It’s the most densely populated city in the world. Metropolitan Manila, with a population of some 12 million people, is the 10th largest megacity.
This dense urban environment seems like an unlikely place to find a new species. But within the jumble of markets, alleys and skyscrapers of this megacity, Ateneo de Manila University has preserved a 200-acre tract of forested campus, interlaced by ponds and small creeks. Recently, when the university’s biology students and faculty conducted a survey of the forest, they found something remarkable: a new species of water beetle, called Hydraena ateneo, which was previously unknown to science.
The students—Arielle Vidal and Kimberly Go—collected a few dozen closely-related water beetles from shallow rock pools and slow-moving creeks on the heavily forested campus. The insects were feeding on the bacteria and fungi that get trapped in leaf litter.
An analysis showed that the beetles mostly came from six known species, but there were four from a new, unidentified one. The unfamiliar beetles (named ateno after the university) could be differentiated from similar species by slight differences in their size (they range between 1.25 and 1.33 millimeters in length, whereas the closely-related scabara are slightly longer and the palawanensis are a bit shorter), their leg structure and the shape of their aedeagus, the male reproductive organ.
When Freitag compared them to similar beetles housed in the collections of natural history museums in Germany, Denmark and Austria, he found several ateneo specimens that had previously been collected in the Philippines but were unidentified. The group has also since found the new species outside the city, on the island of Mindoro. They speculate that the bug occurs most often in more remote areas, but recolonized the college campus sometime over the past 50 years, as the campus’s formerly sparse forests and dried-up creeks have been allowed to regenerate over that period.
The fact that the beetle repopulated the campus demonstrates the surprising amount of biodiversity that can occur even in the tiny niches that survive among heavy human development—especially in an already biologically rich country like the Philippines. This is the thinking behind the UN’s Urban Biodiversity program and calls to preserve small natural habitats interspersed between the roads and buildings we construct.
Freitag believes that many more unknown species are there to be found within the barely studied Hydraena genus of this newly discovered water beetle. That an unidentified species can be found hiding in an urban college campus, right under our feet, shows just how much of the world’s biodiversity is still yet to be cataloged by science.
Editor’s Note, September 7, 2013: Earlier versions of this post incorrectly stated or implied Ateneo de Manila University was in Manila itself. In fact, the university is in nearby Quezon City, which is a part of Manila’s metropolitan area. To fix this, a few sentences were added to the first and second paragraphs, and the title of the post was changed.
August 22, 2013
Modern archeologists, excavating ancient Egyptian tombs, have often found something unexpected amongst the tombs’ artifacts: pots of honey, thousands of years old, and yet still preserved. Through millennia, the archeologists discover, the food remains unspoiled, an unmistakable testament to the eternal shelf-life of honey.
There are a few other examples of foods that keep–indefinitely–in their raw state: salt, sugar, dried rice are a few. But there’s something about honey; it can remain preserved in a completely edible form, and while you wouldn’t want to chow down on raw rice or straight salt, one could ostensibly dip into a thousand year old jar of honey and enjoy it, without preparation, as if it were a day old. Moreover, honey’s longevity lends it other properties–mainly medicinal–that other resilient foods don’t have. Which raises the question–what exactly makes honey such a special food?
The answer is as complex as honey’s flavor–you don’t get a
food source with no expiration date without a whole slew of factors working in perfect harmony.
The first comes from the chemical make-up of honey itself. Honey is, first and foremost, a sugar. Sugars are
hygroscopic, a term that means they contain very little water in their natural state but can readily suck in moisture if left unsealed. As Amina Harris, executive director of the Honey and Pollination Center at the Robert Mondavi Institute at Univeristy of California, Davis explains, “Honey in its natural form is very low moisture. Very few bacteria or microorganisms can survive in an environment like that, they just die. They’re smothered by it, essentially.” What Harris points out represents an important feature of honey’s longevity: for honey to spoil, there needs to be something inside of it that can spoil. With such an inhospitable environment, organisms can’t survive long enough within the jar of honey to have the chance to spoil.
Honey is also naturally extremely acidic. “It has a pH that falls between 3 and 4.5, approximately, and that acid will kill off almost anything that wants to grow there,” Harris explains. So bacteria and spoil-ready organisms must look elsewhere for a home–the life expectancy inside of honey is just too low.
But honey isn’t the only hygroscopic food source out there. Molasses, for example, which comes from the byproduct of cane sugar, is extremely hygroscopic, and is acidic, though less so than honey (molasses has a pH of around 5.5). And yet–although
it may take a long time, as the sugar cane product has a longer shelf-life than fresh produce, eventually molasses will spoil.
So why does one sugar solution spoil, while another lasts indefinitely? Enter bees.
“Bees are magical,” Harris jokes. But there is certainly a special alchemy that goes into honey. Nectar, the first material collected by bees to make honey, is naturally very high in water–anywhere from 60-80 percent, by Harris’ estimate. But through the process of making honey, the bees play a large part in removing much of this moisture by flapping their wings to literally dry out the nectar. On top of behavior, the chemical makeup of a bees stomach also plays a large part in honey’s resilience. Bees have an enzyme in their stomachs called glucose oxidase (PDF). When the bees regurgitate the nectar from their mouths into the combs to make honey, this enzyme mixes with the nectar, breaking it down into two by-products: gluconic acid and hydrogen peroxide. “Then,” Harris explains, “hydrogen peroxide is the next thing that goes into work against all these other bad things that could possibly grow.”
For this reason, honey has been used for centuries as a medicinal remedy. Because it’s so thick, rejects any kind of growth and contains hydrogen peroxide, it creates the perfect barrier against infection for wounds. The earliest recorded use of honey for medicinal purposes comes from Sumerian clay tablets, which state that honey was used in 30 percent of prescriptions. The ancient Egyptians used medicinal honey regularly, making ointments to treat skin and eye diseases. “Honey was used to cover a wound or a burn or a slash, or something like that, because nothing could grow on it – so it was a natural bandage,” Harris explains.
What’s more, when honey isn’t sealed in a jar, it sucks in moisture. “While it’s drawing water out of the wound, which is how it might get infected, it’s letting off this very minute amount of hydrogen peroxide. The amount of hydrogen peroxide comes off of honey is exactly what we need–it’s so small and so minute that it actually promotes healing.” And honey for healing open gashes is no longer just folk medicine–in the past decade, Derma Sciences, a medical device company, has been marketing and selling MEDIHONEY, bandages covered in honey used in hospitals around the world.
If you buy your honey from the supermarket, that little plastic bottle of golden nectar has been heated, strained and processed so that it contains zero particulates, meaning that there’s nothing in the liquid for molecules to crystallize on, and your supermarket honey will look the same for almost forever. If you buy your honey from a small-scale vendor, however, certain particulates might remain, from pollen to enzymes. With these particulates, the honey might crystallize, but don’t worry–if it’s sealed, it’s not spoiled and won’t be for quite some time.
A jar of honey’s seal, it turns out, is the final factor that’s key to honey’s long shelf life, as exemplified by the storied millennia-old Egyptian specimens. While honey is certainly a super-food, it isn’t supernatural–if you leave it out, unsealed in a humid environment, it will spoil. As Harris explains, ” As long as the lid stays on it and no water is added to it, honey will not go bad. As soon as you add water to it, it may go bad. Or if you open the lid, it may get more water in it and it may go bad.”
So if you’re interested in keeping honey for hundreds of years,
do what the bees do and keep it sealed–a hard thing to do with this delicious treat!