September 10, 2013
If, in the midst of a Szechuan pepper-heavy meal, you have the presence of mind to ignore the searing hot pain that fills your mouth, you might notice a more subtle effect of eating the hot peppers: a tingling, numbing sensation that envelops your lips and tongue.
What’s behind this strange phenomenon, scientifically known as paresthesia? Scientists believe that it has something to do with a molecule called hydroxy-alpha-sanshool, naturally present in the peppers.
Research has shown that the molecule interacts with our cell’s receptors differently than capsaicin, the active ingredient in the world’s hottest chili peppers. Capsaicin produces a pure burning sensation by binding to the same sorts of receptors present in our cells that are activated when we’re burned by excessive heat, but the Szechuan peppers’ active chemical appears to act on separate receptors as well, perhaps accounting for the distinctive tingling that can persist for minutes after the burn has gone away.
Now, in a study that required some uncommonly compliant volunteers—they let their lips get brushed with ground Szechuan pepper—researchers found that the peppers produce the tingle by exciting tactile sensors in our lips and mouth. In other words, it seems that apart from tasting the peppers’ spiciness, we feel it too, as though our lips are being physically touched by the chemicals present in the Szechuans.
As part of the study, published today in the Proceedings of the Royal Society B, a group of neuroscientists from University College London gathered 28 people and subjected them to ground Szechuans and small metal vibrating tools. Initially, they ground up the peppers, mixed them with ethanol and water, and brushed them onto the lips of the participants, who reported the level of tingling they felt.
Then, to try figuring the exact frequency of the tingling—a concept that becomes a bit more intuitive if you think of the tingling, or numbness, as the lips being vibrated quickly—they held a small vibrating tool up to the volunteers’ fingers. They could control how fast or slow the tool vibrated, and were asked to set it so that it matched the same feeling as the tingling on their lips. After the Szechuan tingling had time to die down, the vibrating tools were placed on their lips in the same spot, and again the participants could control the vibrating to make it resemble the pepper numbness as closely as possible.
When they looked at the records of the tool’s frequency, they found that the participants consistently set it to vibrate at 50 hertz (another way of saying 50 cycles per second). This consistency across people was telling—specific classes of tactile receptors in our cells are each activated by different frequencies (when touched, they pass along an electric current through nerve fibers, ultimately signaling to the brain that physical contact has occurred), so it supported the idea that touch receptors were involved. Which class of receptor, though, is activated by Szechuan peppers?
The scientists say that frequency of the Szechuan’s numbing sensation fell within the range of vibration typically conveyed by a highly-sensitive type of tactile receptor called Meissner receptors, which cover around 10-80 hertz. Previous work has shown that in human nerve cells cultured in petri dishes, the sanshool molecule caused fibers associated with Meissner receptors to fire, passing along a burst of electricity.
This experiment showed that in the real world, the Szechuans’ active ingredient seems to do the same thing, triggering activity in this set of receptors and causing them to pass along tactile stimuli towards the brain, thereby making our lips feel numb, as though they’ve been vibrated quickly. It’s a strange idea, but not unlike the feeling of spiciness: When you eat the pepper, you’re not actually being burned, but your heat-sensitive receptors are being activated, making it seem that way. In the same way, if you’re daring enough to bite into a Szechuan, the touch receptors in your lips and mouth will be stimulated, and as a result, they’ll go numb in a few minutes.
Rising gas prices and a dangerously low world panda population–what if someone told you that we soon could have one solution to both these problems? If it seems too good to be true, think again; scientists at Mississippi State University are conducting research on the feasibility of using pandas to help solve our biofuel woes, a step that could lead to a bump in conservation efforts and a drop in fuel expense. The secret to the solution? It’s all in the panda’s poop.
When it comes to biofuels, the market is dominated by one word: ethanol, a biofuel made from corn. Though ethanol is the most widely used biofuel, it isn’t necessarily touted as a perfect replacement for fossil fuels–in fact, the benefit of ethanol is been hotly debated since its creation.
The debate goes a little something like this: in order to fill the tank of an SUV with ethanol fuel, you need to use enough corn to feed a single person for an entire year. A 2012 paper published by the New England Complex Systems Institute cites ethanol as a reason for the increasing price of crops since 2005. And even environmental groups steer clear of ethanol, citing the massive amounts of fossil fuel needed to render corn a useable biofuel product and the propensity of companies to buy land in developing countries to grow the lucrative biofuel rather than food for local consumption.
Ashli Brown, a researcher at Mississippi State University, thinks she’s found the answer to this alternative fuel conundrum. By taking corn byproducts–the husks, the stems and cobs–ethanol could be created without dipping into the edible parts of corn, reducing the chance of a food shortage and price spike. The issue is that to break down these materials, which are extremely high in lignocellulose, or dry plant matter, a special pretreatment process is required. The process is extremely costly and not very time-efficient, using high temperatures, high pressures and acid to break down the dry plant matter before it can become ethanol. To circumvent this problem, Brown and other researchers have been looking for a natural solution–bacteria, which could help with the breakdown of the lignocellulose material.
Biofuel companies have been seeking a natural method to break down plant material for a while; so far, termites have been a favorite for chewing through the woody material. But it turns out there might be a better–and cuter–animal that can help produce biofuel
. The intestines of pandas are remarkably short, a physical attribute which means their intestines have come to contain bacteria with unusually potent enzymes for breaking down their woody diet of bamboo in a short amount of time.
“The time from eating to defecation is comparatively short in the panda, so their microbes have to be very efficient to get nutritional value out of the bamboo,” Brown, the researcher heading the work, said. “And efficiency is key when it comes to biofuel production—that’s why we focused on the microbes in the giant panda.”
The study began more than two years ago, when Brown and a team of researchers began looking at panda feces. In 2011, they identified these super-digesting microbes are present in panda feces, but they had yet to specify the type and amount of microbes present until now. Using the poop from two giant pandas–Ya Ya and Le Le in the Memphis Zoo–Brown and her team performed DNA sequencing on microbes in their samples, identifying more than 40 microbes in the panda feces that could be useful to the breakdown and creation of biofuels.
To grow these microbes on an industrial scale
, Brown believes that scientists could put the genes that produce those enzymes into yeasts--these yeasts could then be mass-produced and harvested for biofuel production. The process would go something like this: Large pits of corn husks, corn cobs, wood chips, and other forms of discarded fibrous material are covered with the genetically altered yeasts. As the microbes digest woody substances, they quickly turn it into sugar, which would then be allowed to ferment. Over time and after filtering out solids and any excess water, you would have ethanol, distilled from woody waste products.
Pandas aren’t the only animal that subsists on a grassy diet, but their physiology makes them a unique candidate for breaking down plant byproducts in a hyper-efficient way. Pandas have the same digestive track as any other bear; unlike cows or other herbivores, pandas don’t have an extra stomach where hard lignocellulostic material is pretreated before being digested. Instead, they have the intestinal system of a carnivore, and yet manage to extract enough nutrients from their herbaceous diet to survive.
“Because their retention time is very short—they’re constantly eating and they’re constantly pooping—in order to get the material for nutrition, they have to be really quick at breaking it down and extracting the sugars,” Brown explained. “Many microbes produce celluloses that breakdown lignocellulostic biomass, but it’s about how efficiently or how effectively they do it.” When it comes to a panda, Brown notes, their microbes are some of the most efficient scientists have seen at breaking down the woody material of a plant.
And Brown thinks that using pandas for their poop could lead to more than a greener economy: it could also lead to increased conservation for the animals, who have seen their numbers in the wild drop to a dangerous 1,600 (though there has been recent luck with breeding pandas in captivity, like the new baby panda at the National Zoo). “These studies also help us learn more about this endangered animal’s digestive system and the microbes that live in it, which is important because most of the diseases pandas get affect their guts,” said Brown.
Brown notes that if the panda becomes valuable to the market for more reasons than its incredibly adorable demeanor, it might spark greater steps toward conservation–a move that could be mutually beneficial to pandas and humans alike.”It’s amazing that here we have an endangered species that’s almost gone from the planet, yet there’s still so much we have yet to learn from it. That underscores the importance of saving endangered and threatened animals,” she said. “It makes us think—perhaps these endangered animals have beneficial outputs that we haven’t even thought about.”
August 30, 2013
History teachers often point out the humor in Greeland’s name. That northerly land, after all, is anything but green. According to the Icelandic Sagas, Eric the Red–exiled from Iceland for the crime of murder–stumbled upon Greenland’s glacial shores in the late 10th century. Though “Coldland” or “Snowyland” would have been more apt, he dubbed the place “Grœnland” in the hopes of luring settlers to the remote outpost with the promise of bountiful forests and fields.
Eric the Red’s false advertising, however, may become more appropriate in the not-too-distant future, an international team of researchers report in the journal Philosophical Transactions of the Royal Society B. Climate change is quickly converting once-frozen tracts into potentially hospitable places for trees and shrubs. In some parts of the country, pieces of land have already opened up and only await a few chance seeds to blow in and begin the process of converting the rugged landscape into lush forest.
These findings sprouted up through a computer model the researchers built of Greenland’s predicted climate for the next 100 years. They overlaid that climate model with known data for various North American and European tree species’ ideal habitat niches. Within a century, they found, all 56 species of trees and shrubs they tested would likely be happy to take up residence or expand their reach in Greenland. Greenland, they predict, could start looking a lot more like Alaska or western Canada, though the exact composition of trees and bushes depends upon which species make it there first and take advantage of the new ecological niches.
Currently, only five species of trees or large shrubs occur naturally in Greenland–Greenland mountain ash, mountain alder, downy birch, grayleaf willow, and common juniper–and and those hardy plants grow only in scattered plots in the far south. Field experiments and ambitious gardening projects, however, have confirmed that a range of other species–including Siberian larch, white spruce, lodgepole pine and Eastern balsam poplar–can get a root-hold in Greenland if given the chance. Those species, along with the five other long-established native varieties, may begin to spread as temperatures warm. The team also predicts that invasive species–species not currently found on Greenland–will inevitably find their way to the island as well. How soon this will happen, however, remains a matter of speculation.
Without help, the researchers’ models indicate that some species of trees would take around 2,000 years to find their way to a hospitable patch of Greenland soil. In today’s age of tourism and regular flights between continents, however, the plants will most likely receive some significant, though inadvertent, colonization assistance. Researchers and tourists alike tramp around with all sorts of seeds unknowingly stuck to their shoes. A study conducted in Svalbard, an archipelago north of Norway with a similar ecosystem as Greenland, found 1,019 seeds of 53 species clinging to just 259 travelers’ shoes. Twenty-six of those species germinated in Arctic conditions when given the opportunity. Migratory birds, likewise, have been known since the time of Alfred Russell Wallace and Charles Darwin to bring along seeds stuck to their plumage and feet or passed through their bowels.
On the other hand, humans may just decide to plant the trees themselves. “People often plant utility and ornamental plants where they can grow,” Jens-Christian Svenning a biologist at Aarhus University and co-author of the paper, said in a press release. “I believe it lies in our human nature.”
However, he warns, if Greenland’s greening is left up to the locals, they should proceed with caution. “The Greenlandic countryside will be far more susceptible to introduced species in future than it is today,” he said. “So if importing and planting species takes place without any control, this could lead to nature developing in a very chaotic way.”
Whether human-mediated or not, this ecological shift, the team points out, would be no small change for Greenland. Their models predict the ice-free, tree-friendly patches to total around 400,000 square kilometers. If trees do move in, they could grow a new forest that’s nearly the size of Sweden.
While the idea of more green intuitively seems like a score for the environment, the shift from mossy tundra to towering forest will almost certainly push out some native plant and animal species. On the other hand, Greenlanders may enjoy a break from the monotony of ice, rock and lichen. Forests could bring recreational or economic possibilities, such as hunting and foraging for wood and natural edibles. Additionally, the researchers write, the trees may alleviate some of the erosion issues from quickly-trickling-away glaciers.
For better or for worse, however, just like Eric the Red we probably won’t get to see how the forests ultimately alter Greenland’s ecology. Even with human intervention, the researchers write, those forests probably won’t fully come into their own for centuries.
August 21, 2013
As the inane car insurance commercials suggest, ancient humans were smarter than we give them credit for. They created some of the same words we still use today. They even brewed beer.
Now evidence suggests that they had some culinary flair as well. A new analysis of food residue encrusted on millennia-old pottery shards collected from sites in Germany and Denmark shows that prehistoric humans used the spice mustard seed to season the plant and animal staples that made up the bulk of their diet.
As part of the new study, published today in PLOS ONE, researchers from the UK’s University of York and elsewhere chemically analyzed the residue on ancient pieces of pottery that are part of the collections of a trio of museums—the Kalunborg and Holbæk Museums, in Denmark, along with the Schleswig-Holstein Museum in Germany. The artifacts were originally excavated from three different sites in the same two countries which are between 5,750 and 6,100 years old, an era during which people in the area were in the midst of transitioning from hunter-gatherer to nomadic societies.
When analyzing the food gunk encrusted on the pottery, the team looked specifically at phytoliths, microscopic granules of silica that plants produce and store in their cells after absorbing silicic acid from the soil. Different plants produce slightly different types of phytoliths, so by closely examining them, the scientists were able to figure out which sorts of plants had been cooked in the pottery.
They found that the residue from the insides of the pots had much larger quantities of phytoliths than the outsides, confirming that the granules were indicative of cooking use. When they compared the size and shape of the phytoliths to databases of hundreds of modern plant phytoliths, they most closely matched that of mustard seed. The team also found oil residue from both land animals and marine life, and other plant residues that come from starchier plants—suggesting that these prehistoric people were cooking fish, meat and plants in the pots and seasoning them with the mustard seed.
For the scientists, the most surprising aspect of the find is the pots’ age. Until now, the oldest clear evidence for spice use was the discovery of residue from ginger and turmeric in 4,500-year-old cooking pots linked to the Harappa culture, in Northern India. But the new find shows that humans were using spices more than 1,000 years earlier.
In Northern Europe, this was a time soon after domestic animals, such as goats and cattle, were introduced, dramatically remaking these societies’ lifestyles. Still, at this point, crops were not known to have been domesticated—these people were still centuries away from the fully settled agricultural societies that would eventually dominate.
Previously, experts thought that the use of plants in cooking during this era was solely motivated by a need for calories. But the presence of mustard seed, which provides essentially no caloric or nutritional value, indicates that these prehistoric people valued taste as much as we do.
August 15, 2013
If the last Fuji apple you grabbed from your grocery store’s produce section was mealier and less flavorful than the Fujis you remember from childhood, you’re not alone. Your memory isn’t at fault, and it’s not as though you’re particularly bad at picking apples, either.
The truth, though, is much more distressing than either of those possibilities. In chemically comparing modern-day Fujis with tests on samples during the 1970s, a team of Japanese researchers found that today’s apples are less firm and have lower concentrations of a specific acid that contributes to their taste. Their conclusion, published today in the journal Scientific Reports, is that by making apple trees’ blooming time earlier in the year and raising temperatures during apple maturation, climate change has slowly but surely changed the taste and texture of the apples we hold so dear.
They started off by testing two types of newly harvested apples: Fujis—which happen to be the world’s leading apple cultivar—and the Tsugaru. In Japan, apples are taken seriously (the country produces roughly 900,000 tons of apples annually, amounting to 14 pounds per person), and records on these same parameters have been kept on this apples dating back into the 1980s, and in some cases, the 70s.
When the researchers compared modern-day Fujis and Tsugarus to their predecessors, they found that their firmness and concentration of malic acid, which corresponds with an apple’s taste intensity, had slowly declined over the decades. Additionally, the modern apples were more susceptible to watercore, a disease that causes water-soaked regions in the apple’s flesh to break down internally over time. In other words, today’s apples were consistently mealier, less flavorful, and more disease-prone according to objective measurements such as titrating their juices to determine acid concentration, or using mechanical plungers on the fruit’s flesh to test firmness.
To see if climate change might have played a role, they analyzed the long-term climate trends in the two regions of Japan where the apples were grown (Nagano and Aomori prefectures), and found that during the 40-year period, temperatures had gradually risen by a total of about 2°
C in each location. Records also indicated that, over time, the date on which apple trees in the two regions began to flower steadily crept earlier, by one or two days per decade. The last 70 days before harvest in each locale—i.e. the days during which the apples hung on the trees, ripening in the sun—were also, on average, hotter.
It’s hard to pin the blame entirely on climate change, because the process of growing apples—along with agriculture as a whole—has changed so drastically over the past few decades. A new harvesting technique or machine, for example, could have played a role in the taste decline. But other studies, conducted in closed, controlled chambers, have demonstrated that higher temperatures during the 70-day ripening window can significantly decrease taste and texture. If the case against climate change isn’t airtight, there’s at least strong circumstantial evidence.
And though the way apples taste is certainly a crucial part of modern life, the most distressing part of this whole saga might be the way in which the changes in these apples resemble climate change itself. You might eat hundreds of apples each year, and they might vary widely in quality, taste and texture. Thus, when they slowly, steadily get worse over the course of decades, it’s nearly impossible to discern the change firsthand. In these cases—both apples and climate change itself—there’s really only one option: Look to the data.