October 9, 2013
Climate change is a global problem, but that doesn’t mean it’s going to hit us all the same time.
If you live in Moscow, scientists estimate that your local climate will depart from the historical norm in the year 2063. In New York, that date is the year 2047. And if you happen to reside in Mexico City or Jakarta, those numbers are 2031 and 2029, respectively.
See a pattern here? These estimates, which all come from a new study published today in Nature by scientists from the University of Hawaii, reflect a concerning trend that some scientists believe will define the arrival of climate change’s effects on the planet: It’ll arrive in tropical, biodiverse areas first.
Most climate models simulate how changes in greenhouse gas concentration will affect the worldwide climate in a given year (most often 2020, 2050 or 2100). But the Hawaii team, led by biologist and geographer Camilo Mora, took an alternate approach—they assumed, in the absence of a global mitigation agreement, greenhouse gas levels will keep rising at a steady rate, and used climate models to track how long it would take for weather events that are currently thought of as extreme to become typical.
When they calculated which year this would occur for a range of cities—defining a deviation from the historical record as the first year when a given month’s coldest day is hotter than any day of that month between 1860 and 2005—our dates of climate departure came far sooner than they were expecting.
“The results shocked us. Regardless of the scenario, changes will be coming soon,” Mora said in a press statement. “Within my generation, whatever climate we were used to will be a thing of the past.”
For all locations on Earth, the average year of departure is 2047, but for some places concentrated in the tropics, that date will come much sooner, in the 2030′s, or in some extreme cases, the 2020′s. In just a few decades, in other words, the coldest day you experience in January will be hotter than the warmest days your parents had in January—and the hottest day you get in July (in the Northern hemisphere) will simply be hotter than any day anyone has ever felt in your city to date.
The fact that these effects would be felt soonest in the tropics, according to the simulation, is also surprising. Thus far, most models have predicted that the most abrupt shifts in temperature will occur at the poles.
The new study actually agrees with that fact, but views it from a different perspective, looking at relative changes compared to the historical record rather than absolute changes in temperature. Because the tropics have less variability in temperature to start with, it takes less of a shift to push temperatures there beyond the norm. On the other hand, temperatures will indeed surge most in the Arctic and Antarctic, but there’s already more natural climate variability at those locales to begin with.
This is a huge concern, because wildlife biodiversity is consistently highest at the tropics, and most of the world’s biodiversity hotspots are located there (tropical rainforests, for instance, are estimated to cover less than 2 percent of the Earth’s surface area yet contain roughly 50 percent of its plant and animal species). If, historically, these ecosystems evolved in the presence of relatively little climatic biodiversity, it follows that they might be less capable of coping with swings in temperature and adapting to survive.
It also happens that a disproportionate amount of the people living in poverty worldwide are located in the tropics. “Our results suggest that countries first impacted by unprecedented climates are the ones with the least capacity to respond,” study author Ryan Longman said. “Ironically, these are the countries that are least responsible for climate change in the first place.”
Despite the bad news, the researchers say they embarked on this alternate sort of climate modeling to empower people. “We hope that with this map, people can see and understand the progression of climate change in time where they live, hopefully connecting people more closely to the issue and increasing awareness about the urgency to act,” said co-author Abby Frazier said.
Towards this goal, the group also put out an interactive map that lets you click on any location and see the projected increase in temperature over time, along with two different years: the one in which you can expect a consistently extreme climate if we keep emitting carbon dioxide at current rates, and the one in which you’ll experience an abnormal climate if we figure out a way to stop.
October 8, 2013
In 2011, Felix Liechti and his colleagues at the Swiss Ornithological Institute attached electronic tags that log movement to six alpine swifts. The small birds—each weighs less than a quarter of a pound—spend the summer breeding in Europe, then migrate to Africa for the winter, thousands of miles away.
“We wanted to learn about energy demands during migration. We expected to see how often they fly, how often they stop, that sort of thing,” he said.
But a year later, when three of the birds returned to the same breeding site and the scientists removed their tags to collect the data, the electronic tags revealed something unexpected. “When we looked at the data, we were totally blown away,” Liechti said. “During their non-breeding period in Africa, they were always in the air.”
For more than 200 straight days straight, as revealed by his team’s study published today in Nature Communications, the birds stayed aloft over West Africa. The tags only collect data every four minutes, so it’s impossible to rule out the chance that they touched down occasionally in between these intervals—but every single one of the data points collected for more than six months in a row indicated that, at the time, they were either actively flying or at least gliding in the air.
Ornithologists had previously speculated that a closely related common swift was capable of staying in flight for extremely long periods of time, but this is the first time anyone has collected hard data. The new finding was, in part, enabled by developments in technology—this was the first time that this particular kind of sensor, developed by at Bern University, was attached to birds for research.
Its tiny size allowed the researchers to attach it to relatively small birds without interfering with their free movement. The tags solely collected data on acceleration, the
pitch of the bird’s body (the angle of its body relative to the ground) and light hitting the bird at any given time. From the latter, scientists were able to infer latitude, due to the timing of sunrise and sunset.
By comparing the acceleration and pitch data to that of birds under observation, Liechti and the others could match particular data patterns with different types of movement—flying (with flapping wings), passively gliding in the air and resting on the ground. “They stayed in the air for all time they spent south of the Sahara, day and night,” he said. “Sometimes they just glide for a few minutes, so there’s no movement, but the pitch of the body indicates that they’re still gliding in the air.”
It’s still a mystery how the birds are able to physiologically accomplish this feat. The diet aspect is relatively straightforward—they largely feed on airborne insects—but until now, opinions differed over the question of whether birds could sleep while aloft. Sleep patterns in birds are fundamentally different than in mammals, and the difficulty of studying the brainwaves of migrating birds makes it very hard to fully understand how they rest while in motion. But the fact that these swifts never touch down for such a long time indicates that they’re able to rest in midair.
There’s also the deeper (and perhaps more confounding) question of why the birds would bother staying aloft for their entire time in Africa. At this point, it’s pure speculation, but Liechti suggests that diet could play a role. “We observed that the further north they go, the more they stay on the ground at night,” he said. “Additionally, the further north you go, the less insects there are in the air—so it might be related.” He also proposes that staying in air could reduce the risk of predation or perhaps the chance of catching a disease.
Perhaps most exciting is the fact that this finding came after just the first time the new, ultra-lightweight movement sensor was used in avian research. Tagging other sorts of birds that are too small for conventional sensors might tell us similarly surprising things about their movement or migrations habits. “It’s fascinating,” Liechti said, “and it opens up a whole new window for us into these species.”
October 3, 2013
The importance of bees in our food system often goes unappreciated. Just by going about their daily business, these insects are responsible for pollinating three-quarters of the 100 crop species that provide roughly 90 percent of the global food supply. The most recent estimate for the economic value of this bee activity is that it’s worth over $200 billion.
But in recent years, an alarming number of bee colonies across North America and Europe have begun to collapse. As part of the phenomenon, formally known as Colony Collapse Disorder, worker bees fail to return to the hive after their pollen-collecting trips nearby. We still don’t fully understand what’s driving this trend, but the list of culprits likely includes pesticides, viral infections, intensive agriculture and perhaps even the practice of feeding bees high fructose corn syrup in place of the honey we take from them.
New research, though, suggests there may be an overlooked problem: the exhaust fumes produced by diesel-powered engines. As described in a study published today in Scientific Reports, a group of researchers from the UK’s University of Southampton found that the pollution produced by diesel combustion reduces bees’ ability to recognize the scent of various flowers—a key sense they use in navigating and finding food sources.
“Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorize new odors,” Tracey Newman, a neuroscientist who worked on the study, said in a press statement. “Our results suggest that that diesel exhaust pollution alters the components of a synthetic floral odor blend, which affects the honeybee’s recognition of the odor. This could have serious detrimental effects on the number of honeybee colonies and pollination activity.”
To come to the finding, the group used extract from rapeseed flowers to create a scent that mimics the natural smell of several different flowers that the bees normally pollinate. In a sealed glass vessel, they mixed the scented air with diesel exhaust at a variety of concentrations, ranging from those that meet the EPA’s standards for ambient air quality to worst-case scenarios—concentrations of diesel pollutants (specifically the highly reactive NOx gases, nitric oxide and nitrogen dioxide) that greatly exceed these standards but are commonly detected in urban areas.
At all concentrations, just one minute after they added the pollutants, gas chromatography testing revealed that two of the main flower-scented chemicals in the original blend were rendered undetectable, degraded by the nitrogen dioxide. Previously, they’d trained 30 honeybees to remember the flowers’ scent—by rewarding them with a sip of sucrose when they extended their proboscis in response to smelling it—but when the scent had been altered by the exposure to diesel fumes, just 30 percent of the bees were still able to recognize it and extend their proboscis. They confirmed that the NOx gases in particular were to blame by repeating the experiments with isolated versions of them, instead of the whole range of diesel pollutants, and arriving at the same results.
It’s a small study on one bee population using one flowers’ scent, but it’s a concern. That’s because, although the study specifically looked at NOx gases that resulted from the burning of diesel, the gases are also produced by your car’s gasoline-burning engine. When NOx measurements are averaged out, few areas exceed the EPA’s standards, but in many urban locales during periods of high traffic, NOx levels can be much higher—high enough, this testing suggests, to disrupt bees’ ability to smell flowers.
It follows that diesel fumes could play a role in Colony Collapse Disorder: If bees are less effective at navigating and finding nectar, they might be more likely to get lost in large numbers. Colony collapse is typically characterized by the continual disappearance of worker bees during their travels—so it’s possible that the effects of engine exhaust plays a role.
“Diesel exhaust is not the root of the problem,” said Newman said in a press briefing. “But if you think of a situation where a bee is dealing with viral infections, mites, all the other stresses it has to deal with—another thing that makes it harder for the bee to work in its environment is likely to have detrimental consequences.”
September 30, 2013
That hairless, wrinkly, fanged rodent in the photo above? It’s a naked mole rat, and deep inside its cells, its molecular machinery might hold the secret to living a very, very long time.
“They are an incredibly striking example of longevity and resistance to cancer,” says Vera Gorbunova, a biologist at the University of Rochester who studies the long-lived rodents, which have been shown to survive for up to 28 years—a lifespan eight times that of similarly-sized mice—and have never once been observed to develop cancer, even in the presence of carcinogens.
In recent years, Gorbunova and her husband Andrei Seluanov have looked closely at the species, which lives in underground colonies in East Africa, hoping to figure out how exactly it manages to survive so long. As revealed in new research her team published today in Proceedings of the National Academy of Sciences, their team thinks they’ve found at least part of the answer: naked mole rats have strange ribosomes.
Every one of our cells (and, for that matter, every living organism’s cells) converts the genetic instructions present in our DNA into proteins—which control a cell’s overall operation—through a process called translation. Tiny microscopic structures called ribosomes handle this translation, reading genetic instructions that specify a particular recipe and churning out the protein accordingly.
The ribosomes in almost every multicellular organism on the planet is made up of two large pieces of RNA, a genetic substance similar to DNA. But last year, one of the Rochester lab’s students was isolating RNA from cells taken from the naked mole rats when he noticed something unusual. When he separated the RNA pieces, instead of seeing two distinct pieces of ribosomal RNA, he saw three.
“At first, we thought we were doing something wrong and it’d gotten damaged,” Gorbunova says. “Because for all mammals, you’d see two, but we kept seeing three.”
After a variety of testing confirmed that it wasn’t an experimental error, they decided to look more closely at the potential effects of this unusual structure. Other research had suggested that artificially interrupting the translation process to make ribosomes less accurate could produce poorly-built proteins that accumulate and lead to cell death, which raised the possibility that the mole rats’ unusual ribosomes did the opposite—producing fewer transcription errors and extending lifespan. To test the idea, Gorbunova developed a means of seeing just how accurate the mole rats’ ribosomes were at converting genetic instructions into proteins.
It turned out that, compared to mouse ribosomes, these three-part structures made between four and forty times fewer errors during the translation process. At this point, it’s unclear how exactly that might lead to longer lifespans, but the researchers believe it plays a key role.
Even so, the rodents appear to benefit from other, unrelated mechanisms that allow them to live uncommonly long lives. In June, Gorbunova and Seluanov announced the discovery that the rodents also produce a novel cellular compound that appears to prevent them from getting cancer.
Both of these mechanisms prompt an obvious question: Why are naked mole rats blessed with these anomalous, life-extending characteristics? “It’s not random,” Gorbunova says. “It has to do with the ecology of the species.”
Because the rodents live underground, in ultra-social colonies, she explains, they’re much less prone to random deaths caused by accidents or predation. The fact that the risk of dying randomly is so much lower means that, from an evolutionary standpoint, it makes more sense to invest in cellular mechanisms that might allow the creatures to live longer. Even if a mouse had three-part ultra-accurate ribosomes and cancer-fighting substances, in other words, it’d probably be eaten within a year by a predator anyway, so it never had the chance to evolve mechanisms that would allow it to live to 28.
But the naked mole rats did. Gorbunova and Seluanov want to proceed by seeing whether either of their special mechanisms—longevity or cancer resistance—could be introduced into mouse cells, and whether they might lead to corresponding extensions in lifespan. If they’re successful, they hope that, someday, we might even be able to extend our own lifespans by copying the naked mole rats’ success.
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.”