November 29, 2013
A few years ago, University of Maryland PhD student Nathan Jud was routinely examining a batch of ancient plant fossils in the Smithsonian Natural History Museum‘s collections when one in particular caught his eye.
“It looked sort of like a little piece of fern, so I tried to remove a bit of the rock that was covering it to get a sense of what type of fern it was,” he says. “But the more of the rock I would lift off the surface, the more fossil I found buried. What I thought had been one little piece of a leaf actually turned out to be two, connected to each other.”
As he labored to carefully flake the rock without defacing the fossil, he noticed a series of curious characteristics that suggested the preserved plant was no ordinary fern: It had a closed network of veins, rather than a series of branching ones that split off from each other without coming back together, and at its tips, there were tiny structures called glandular teeth, used to shed excess water.
“Eventually, I realized this wasn’t a fern at all, but some kind of early flowering plant,” he says. Its features wouldn’t be at all out of the ordinary in a plant growing outside today. The fact that they occur in a fossil from the Early Cretaceous period, though, is remarkable. At somewhere between 125 and 115 million years old, this fossil, described in a paper Jud published today in the American Journal of Botany, is among the oldest flowering plants ever found in North America.
Flowering plants—which replicate with sexual structures (i.e. flowers) to produce seeds—now dominate the planet, but for the first 300 million years or so of plant existence, beginning around 450 million years ago, the only types of vegetation belonged to older, more primitive families, such as algae, mosses and ferns, which all reproduce with spores rather than seeds, or gymnosperms, which produce seeds but not flowers.
During the Early Cretaceous, some of the first primitive flowering plants began to evolve. Researchers know that the layer in which this new fossil was found dates to this time period due to a few factors: Pollen analysis (which considers the chemical makeup of pollen embedded in the surrounding rock) and as well as study of the surrounding sediment itself. The same layer has previously produced several other flowering plant fossils of a similar age—together, they’re the oldest ever discovered in North America—but this is the oldest example of a eudicot, a group that includes roughly 70 percent of flowering plants worldwide today that share a distinctively-shaped pollen structure.
Compared to the other fossils found in the same layer, this one is especially remarkable for its derived traits, anatomical characteristics that were previously thought to have developed much more recently in flowers. Their existence so long ago suggests that some early plants were actually quite complex.
“When I compared it to living plants, I realized it was remarkably similar to the leaves of a certain group of modern poppies,” Jud says. “I didn’t expect to see a group that seemingly modern in a collection that old.” The fact that these features existed so long ago, both in this plant and other ancient fossils recently excavated in China, tells us that the evolution of flowering plants (which Charles Darwin famously called an “abominable mystery“) did not happen gradually, but instead occurred very rapidly during a narrow time interval in the Early Cretaceous period between when flowering plants first emerged and the date of this fossil.
There’s also a much more recent history of this fossil that’s just as fascinating. Jud did a bit of research and found that it’d been excavated in 1971 by a former Smithsonian curator, Leo Hickey, who went on to Yale and died in February before working with Jud to re-analyze the fossil after all these years. Hickey had found it during a dig at the Dutch Gap, in Virginia, in sediments that were exposed over a century earlier, by freed slaves who were forcibly taken from the Roanoke Island Freedmen’s Colony by Union troops and forced to dig a canal in August 1864.
While digging, they exposed ancient fossil-filled rocks, and a few decades later, in the 1870s and 1880s, scientists worked there to collect fossils and create some of the Smithsonian’s first fossil collections. Later, Hickey and other researchers returned to collect remaining specimens.
Jud honored this recent history in naming the ancient species that this specimen represents. “Potomac refers to the Potomac Group beds where the fossil was found, capnos is a reference to living poppies that are quite similar to the fossil and apeleutheron is the Greek word for freedmen,” he says. “So the new plant will be named Potomacapnos apeleutheron: roughly, ‘freedmen’s poppy of the Potomac.’”
November 14, 2013
When it comes to deforestation, Brazil’s Amazon often tops the list of places to worry about. New maps of global forest loss, however, find plenty of other sites throughout the world that should be of even bigger concern
. Angola, Zambia, Bolivia, Paraguay and Malaysia all have high rates of forest loss, but the situation is perhaps worst in Indonesia, where the rate of deforestation may soon exceed that in Brazil.
On a global scale, the planet lost 888,000 square miles of forest and gained 309,000 square miles of new forest between 2000 and 2012, a team of researchers led by remote sensing scientist Matthew Hansen of the University of Maryland College Park report today in Science. That’s a net forest loss equivalent to all the land in Alaska.
“Losses or gains in forest cover shape many important aspects of an ecosystem including climate regulation, carbon storage, biodiversity and water supplies, but until now there has not been a way to get detailed, accurate, satellite-based and readily available data on forest cover change from local to global scales,” Hansen said in a statement.
Hansen’s team began with a collection of more than 650,000 images taken by the Landsat 7 Earth-imaging satellite from 1999 to 2012 and housed in the Google Earth Engine, a cloud-computing platform that was created for just this kind of thing—planetary analyses of environmental characteristics, accomplished at amazing speeds. They tasked the engine to monitor vegetation taller than 16 feet (5 meters) across the globe as it appeared and disappeared through time. The result was a set of highly detailed maps showing forest extent, loss, gain and net change at a resolution of a mere 98 feet (30 meters).
The maps reveal a variety of stories taking place around the world. Tropical forests accounted for nearly a third of global deforestation, as humans stripped forest lands, both legally and illegally. Deforestation in those regions is a particular concern–tropical forests are home to many unique species that can be endangered or lost entirely when their forest homes are destroyed. What’s more, depending on the scale and patchiness of the tree loss, rainfall can either intensify or decrease, either of which can have devastating consequences, such as flood or drought. And the lost vegetation can no longer be a
sink for atmospheric carbon–the carbon stays in the atmosphere and intensifies climate change.
The rate of deforestation recorded by the study varied from nation to nation. Indonesia witnessed a doubling of forest loss in just a decade. In Brazil, by contrast, deforestation slowed from a pace of more than 15,400 square miles per year in 2003 and 2004 to a rate less than half that in 2010 and 2011, confirming that efforts in that country to reduce forest loss, including the combating of illegal logging, are seeing success. Despite the decline, however,
Brazil still suffers a lot of tree loss—the second highest total globally. And when combined with deforestation going on in other nations on that continent, such as Argentina, Bolivia and Paraguay, about half of tropical forest loss occurred in South America, Hansen’s team calculated.
Another way to look at the scope of tropical deforestation is to calculate loss as a percentage of a nation’s total land area. In that ranking, Brazil doesn’t look too bad since it’s a country with a large land area. Malaysia, Cambodia, Cote d’Ivoire, Tanzania, Argentina and Paraguay experienced a much greater loss of forest as a share of all their land.
Determining the extent of forest loss can be helpful for reducing it in the future, the researchers note. “Brazil’s use of Landsat data in documenting trends in deforestation was crucial to its policy formulation and implementation,” they write in their paper. “The maps and statistics we present can be used as an initial reference point for a number of countries lacking such data.”
The maps also reveal the small and large stories of forest growth and loss taking place in other regions around the world, highlighting places such as the American Southeast, where large portions of forest are lost and regrown in short periods of time; the region is a much bigger player in the timber industry than the more famous Northwest U.S. In Alaska, Canada and Russia—home to the world’s greatest extent of forest loss (loss per national area) simply due to that nation’s size—one can see how slowly these high-latitude forests recover from events such as wildfires. The maps even allow the detection of smaller events—such as the mountain pine bark beetle infestation in British Columbia and even a powerful windstorm that leveled forests in southwestern France.
“With our global mapping of forest changes every nation has access to this kind of information, for their own country and the rest of the world,” Hansen said. Whether they follow Brazil’s footsteps and use the data to work towards conserving these important ecosystems will be a question for the future.
November 13, 2013
None of these drinks, though, has anything on the tradition of drinking spicy beverages in Mexico. A new analysis of ancient pottery unearthed from archaeological sites near Chiapa de Corzo, in southern Mexico, shows that people were using chili peppers to make their drinks spicy as far back as 400 BC.
The analysis, conducted by a group of researchers led by Terry Powis of Kennesaw State University, was published today in PLOS ONE. As part of the study, the scientists chemically tested 13 pottery vessels that had been excavated from a series of sites in the area linked to speakers of the Mixe-Zoquean group of languages—closely related to the language of the Olmec civilization—and were previously dated to years ranging from 400 BC to 300 AD.
When they scraped tiny samples out of the inside of each of the vessels, used chemical solvents extract organic compounds, and analyzed them with liquid chromatography testing, they found dihydrocapsaicin and other irritants that serve as evidence that Capsicum species, the taxonomic group that includes spicy chili peppers, once filled five of the vessels. Based on the vessels’ shape and prior archaeological work on the Mixe-Zoquean culture, the researchers believe they were used for all sorts of liquids—likely beverages, but perhaps condiments or sauces.
Previously, research by Smithsonian scientists had shown that chili peppers were domesticated much earlier—perhaps as far back as 6000 years ago—in Ecuador. This new research, however, is the oldest evidence of chili pepper use in
Central North America, and the first known instance of their use in ancient beverages, rather than in solid food.
Interestingly, the researchers originally began the project looking for evidence of the ancient use of cocoa beans in beverages. But their testing didn’t reveal any traces of cocoa left behind in the vessels, suggesting that the tradition of spicy drinks came first, and chocolate flavoring was only added to such drinks later on.
Other contextual evidence also suggests that the spicy drink of in Mixe-Zoquean culture differed significantly from the spiced hot chocolate enjoyed in Mexico today. Three of the vessels were found buried in the tombs of elite-status individuals, while the other two were excavated from temple-like structures. This context, they say, suggests that the beverages might have been used in ceremonial and ritual circumstances.
The authors note that this doesn’t rule out the possibility that the beverages were commonly drunk as well—a more thorough survey of vessels would need to be conducted to know for sure. Additionally, the researchers speculate that rather than a flavoring, chili peppers might have been ground up into a paste and coated on the walls of vessels as an insect and vermin repellent. If that was indeed the case,then bless the serendipity of whoever put liquidy chocolate into one of those vessels and created the wonder that is spicy hot cocoa.
October 22, 2013
If you traveled to the town of Kalgoorlie, in Western Australia, then headed about 25 miles north, you’d eventually reach a grove of large eucalyptus trees, some more than 30 feet tall, scattered across a dusty, arid landscape. Examining the dirt at your feet would reveal no trace of the gold deposits that lie roughly 100 feet underground, due to the thick layers of clay and rock that sit atop the precious metal.
But, scientists recently learned, if you peered closely enough at the eucalyptus trees—specifically, using X-rays to detect nanoparticles—you’d find that there’s gold in them thar leaves. As detailed in a study published today in Nature Communications, a group of researchers from Australia’s Commonwealth Scientific and Industrial Research Organisation has shown that plants can absorb gold particles deep underground and bring it upward through their tissues—a finding that could help mineral exploration companies mine for gold.
“In Australia, we’re faced with this problem of trying to explore through thick layers of sediments and weathered rock to reach valued minerals,” says Melvyn Lintern, an Earth scientist and lead author of the study. “At the same time, we’d previously heard from mining engineers that, in some places, they’d found eucalyptus roots going down to 30 meters [98 feet] or deeper in the mines.” With this observation in mind, and the knowledge that plants can absorb and transport minerals from the surrounding soil and bedrock all the way up to their leaves, Lintern and his colleagues were struck with an idea: Why not test eucalyptus leaves to see if they could indicate underground gold deposits?
To do so, they visited two Australian sites with known gold deposits deep underground (as revealed by exploratory drilling) that were covered by thick layers of rock and on top of which grew tall eucalyptus trees. When they tested leaves that grew on or had fallen from the large trees in both areas, they indeed found minute traces of gold—up to 80 parts per billion, compared with the 2 parts per billion they found in leaves that had grown 650 feet away from the underground deposit.
Other researchers had detected gold particles in plants and leaf litter before, but it was unclear whether they’d been transported all the way from underground deposits. “We were concerned that the gold might have been occurring as dust particles on the outside of these leaves, so it was important for us to locate the gold within the plant,” says Lintern.
His team did so by analyzing the leaves in even further detail (using a specialized X-ray microprobe located at the Australian Synchrotron research facility) and confirmed that the gold particles were located within the plant’s vascular tissue, indicating that they were moving naturally within the leaves. They also conduced greenhouse experiments and found that eucalyptus saplings, grown in soil laced with similar levels of gold, absorbed it and transported detectable levels into their leaves. These separate streams of evidence, they say, shows that the wild eucalyptus trees were indeed sucking up gold from deep underground.
“The eucalyptus acts like a hydraulic pump,” using its roots to suck ground water upward, crucial in an arid environment, Lintern says. “The plants, of course, are searching for water, not gold, but it just so happens that there’s gold dissolved in it.”
The fact that the gold has been found in the leaves, in fact, might be evidence that the eucalyptus is actively trying to get rid of it—after all, it’s a toxic heavy metal—by transporting it to its extremities. Additionally, the gold particles in the leaves were often found located near calcium oxalate crystals, theorized to be part of the removal pathway for toxic chemicals.
Lintern’s group plans to conduct further research into which plants are capable of transporting gold particles in this way and what environmental factors affect the rate of uptake. Mining companies in Canada, he mentions, have already toyed with the idea of using plants as mineral indicators, so this first scientific evidence for the process is likely to accelerate adoption of the method.
“Essentially, we’re tapping into a natural process,” Lintern says. In an age when most of the readily accessible gold near the planet’s surface has been mined, it makes sense to harness the natural mineral exploration plants are already engaging in when they drive their roots deep into the ground. Doing so might even reduce the number of exploratory mines we’re forced to drill—and consequently, lead to less environmental destruction of these plants’ habitats as a result of mining.
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.”