At the end of the last Ice Age, humans undertook an epic American road trip — trekking from a northern land bridge into interior of North America. But details about the route and timing of that trip are hotly debated.
Some researchers think that humans followed a so-called “ice-free corridor” along the eastern Rocky Mountains. Studies have suggested, though, that the corridor froze over and became impassable around 21,000 years ago. Now, a bread crumb trail of fossils showing the movement of ancient bison indicates that the corridor may have reopened a few thousand years later, researchers report in the Proceedings of the National Academy of Sciences the week of June 6.
Analyzing DNA samples from 78 bison fossils unearthed in Canada, a team led by Beth Shapiro of the University of California, Santa Cruz, found that genetically distinct northern and southern populations moved north and south along the corridor by 13,000 years ago. That means humans may have also hiked along the slopes of the Rockies at the same time.
These probably weren’t the first humans to head south. Recent archaeological evidence points to early Americans trekking as far as Chile more than 15,000 years ago. But the corridor could have served as a later route, the team argues.
Kids are fascinated by fireflies. So are scientists, who, despite decades of research, are still perplexed by many of the mysteries posed by “lightning bugs.” In Silent Sparks, biologist Sara Lewis explores both the cultural and scientific fascination with these marvelous beetles.
Many creatures can manufacture their own glow, Lewis notes, but fireflies are some of the few that can readily turn their lamps on and off. Not all of the world’s nearly 2,000 firefly species light up as adults. But all of their larvae do, which suggests that the bioluminescence may have first evolved in a dinosaur-era ancestor as a “Don’t eat me! I’m toxic!” signal to predators. Only later would adults have co-opted this glimmer for the mating displays that most people are familiar with. Some of the most impressive firefly shows involve the synchronous flashing of thousands of insects. Each mating season, these Christmas tree–like spectacles draw thousands of tourists to locales as diverse as Tennessee and Malaysia. Although researchers have a fairly good idea of how the fireflies synchronize their flashings — in some species, males continually adjust their flashing rate based on their neighbors’ activity — scientists still haven’t figured out why they do so.
Fireflies aren’t just pretty; they’re useful. For instance, food inspectors monitor food contamination by taking advantage of the chemical reactions that the insects use to signal their mates. These reactions occur only in the presence of ATP, an energy-storing chemical found in all living cells, making the glowing substances a keen detector for food-tainting bacteria such as Salmonella or E. coli.
Silent Sparks is at its best when Lewis describes her own experiences in the field, such as lying on her back on the forest floor while flickering fireflies wafted mere inches above her nose. For readers who would like their own experience, Lewis includes a field guide to the most common species found in the southeastern United States (the hot spot of North American firefly diversity).
So grab a copy of the book, along with a net, jar and kid you love, and relive fond childhood memories while inspiring a few new ones.
In the years after the animated movie Finding Nemo was released by Pixar in 2003, sales of clownfish spiked as fans, little and big, rushed to buy their own “Nemo.” So many Nemos were purchased that the sales actually depleted some wild stocks of the fish. Pressure on those wild populations has since dropped, thanks to efforts to increase captive clownfish breeding. But now there are worries that Nemo’s sequel, Finding Dory, may have a similar effect on Dory’s species, the blue tang — and an even bigger impact on the coral ecosystems in which these fish are found.
Despite concerted efforts, scientists have been unable to convince blue tangs to breed in captivity. That means that every blue tang, every Dory, sold has to be captured from the wild. And a surprisingly large number of those fish are captured with cyanide, new research shows.
Most of the 11 million fish sold in the U.S. aquarium trade come from coral reefs in the Indo-Pacific. In some places, like Hawaii and Australia, there are decent rules and enough enforcement of them that fish can be collected without too much harm to ecosystems. But in others, there aren’t enough laws or enforcers to prevent disturbing, destructive practices, such as fishing with explosives or cyanide.
For the aquarium trade, cyanide fishing is “cheap and easy to do,” says Craig Downs, executive director of the Haereticus Environmental Laboratory in Clifford, Va. A diver adds a pellet of cyanide to a bottle and squirts a bit on a target fish. Or they may use larger quantities pumped down from their boat. The poison quickly stuns the fish, which can then be captured and later sold.
But cyanide is deadly. Coral exposed to cyanide bleaches and dies. Other fish and organisms left behind can die. Even the fish that enter the aquarium trade may die within a few weeks or months of being caught. “If you survive [exposure], you’re messed up for the rest of your life,” Downs says. And while there are laws that should prevent divers from employing this fishing method — and from wholesalers in the United States from being able to purchase fish caught this way — “this practice happens all through the Indo-Pacific,” says Downs. As many as 30 million fish may be caught this way every year, and 90 percent of those may die.
There is no way for someone purchasing a fish in a pet store to tell if the animal had been exposed to cyanide. “You have to be a fish pathologist” to see the signs, Downs says. But after a fish, human or other organism is exposed to the toxin, it will excrete a cyanide metabolite, thiocyanate, in its urine. And this can be detected in the water in which a captive fish is living.
Recently, Downs and Rene Umberger, director of the nonprofit organization For the Fishes, wanted to get an idea of how many fish sold in pet stores were caught with cyanide. They purchased 89 fish from shops in California, Hawaii, Maryland, North Carolina and Virginia, collected water samples and sent them off to an independent laboratory. More than half came back positive for cyanide exposure, including many of the blue tangs. None of the fish from companies that breed fish in captivity came back positive, though. The results of this initial study will be presented later this month at the International Coral Reef Symposium in Hawaii.
A 2008 report from NOAA estimated that 90 percent of the aquarium fish imported into the United States were captured with cyanide or other illegal methods. And Downs suspects that cyanide use for the fish in his study may be higher than he and his colleague are now reporting. The fish only excrete detectable levels of thiocyanate for a short time after exposure. Plus, initial runs of a more sensitive method for detecting the chemical show that many of the negatives may really be positives for exposure, he says.
He is hoping that this method might be turned into an easy tool that can be used by consumers, citizen scientists and enforcement agencies to quickly detect fish that have been illegally caught with cyanide, which would hopefully drive down the trade.
This doesn’t mean that all saltwater fish are off limits for consumers, though. “If consumers really want to have coral reef fish, then going the cultured route is the way to go,” Downs says. There aren’t many of those fish — only 42 or so species among the more than 1,800 currently traded in the United States — but identifying them is easy. Umberger’s group has a free iOS app, Tank Watch, that lists them all. And even though the app doesn’t list every species that may be in a store, if a species isn’t on their good list, it can be assumed to be bad.
So go ahead and buy Nemo, if you must, but leave Dory and most of her fishy cousins where they belong — in the ocean.
BOSTON — New studies find a rise in drug-resistant urinary tract infections in pets, raising concerns that companion animals may serve as microbe reservoirs that could contribute to the spread of potential superbugs. About four in 10 U.S. households own dogs, which sleep with us, eat off our plates, lick our faces and leave plenty of poop to scoop. Cat ownership is nearly as prevalent.
It’s not clear whether pets are picking up the resistant microbes from their owners, or vice versa, said Cátia Marques, a veterinary medicine doctoral candidate. She presented the research, conducted by scientists from the University of Lisbon in Portugal, June 20 at a joint meeting of the American Society for Microbiology and the Interscience Conference on Antimicrobial Agents and Chemotherapy. More research is needed to answer that question, she said. Either way, scientists worry that companion animals provide another haven for bacteria to mingle and pick up genes that give them resistance to drugs, said Michael Schmidt of the Medical University of South Carolina in Charleston, who was not involved in the new work. “It is a substantial issue,” he said.
Other research has examined human-pet sharing of bacteria, but the subject has been little explored for urinary tract infections, which are extremely common. The new research found a growing resistance in veterinary infections to antibiotics critical for treating human illness. In one study, samples of the bacterium Proteus mirabilis taken over 16 years in Portugal showed a steady climb in the prevalence of resistant strains. An example: Resistance to a class of drugs known as third-generation cephalosporins grew from 2 percent of samples in 2004 to 20 percent today. Other research found worrisome multidrug resistance in infections caused by Klebsiella. In a third study, which tested for resistance in urinary tract infections in pets across Europe, patterns of drug resistance in dogs and cats tracked that of humans, the researchers found.
In humans, doctors have watched warily as resistance to urinary tract infections has grown. In May, scientists reported the discovery of a woman with a urinary infection resistant to colistin, a rarely used drug of last resort (SN Online: 5/27/16). It’s not clear how the patient contracted the resistance, but given colistin’s role as a last-ditch drug, it raised the specter of an unstoppable microbe.
While the new research is broader, it isn’t the first study to raise concerns about the role of companion animals in difficult-to-treat urinary infections. In 2013, German researchers writing in the Journal of Antimicrobial Therapy described finding carbapenem-resistant Escherichia coli and Klebsiella urinary infections in six dogs — a discovery later called a phenomenon “of great concern” in a commentary in the same journal. E. coli and P. mirabilis are the two biggest causes of urinary tract infections. Carbapenem, which the researchers in Portugal did not test for, is also considered a drug of last resort for urinary infections.
Whether humans are giving resistant organisms to their animals or vice versa, the findings emphasize that the battle against resistance needs a global strategy that involves veterinarians along with human doctors and patients, Marques said. “We need to have a common public health approach,” she said.
Schmidt also cautioned that people who are particularly vulnerable to urinary infections, such as pregnant women, take extra care around their pets, especially when cleaning up after them. “If you do have a companion animal and you’re prone to these infections,” he said, “be very strict with your hand hygiene before you eat.”
The world’s known helium reserves just ballooned. Applying gas-finding techniques from the oil industry, scientists uncovered a vast reservoir of more than a trillion liters of helium gas beneath Tanzania. That’s enough to satisfy the world’s helium needs for around seven years, the researchers announced June 28 at the Goldschmidt Conference, a geochemistry meeting being held in in Yokohama, Japan. The find may allay fears that a global helium shortage will hit when the U.S. Federal Helium Reserve — currently the world’s largest helium source — runs dry within the next few years.
While previously known helium reserves were discovered by chance during oil and gas exploration, geologist Diveena Danabalan of Durham University in England and colleagues applied geologic know-how to their helium hunt. Helium accumulates underground during the radioactive decay of unstable elements such as uranium. That helium, though initially trapped, can be liberated when surrounding rock melts during volcanic activity. Using this information as well as seismic imaging of gas-trapping underground formations, the researchers discovered five spots in a volcanic region of Tanzania where water and helium-rich gas bubble to the surface from underground reservoirs.
The researchers predicted that they will be able to find more helium reservoirs and help meet society’s helium needs. Those needs go beyond just making balloons float and voices sound squeaky: Helium is essential for scientific research and a critical component of the cooling systems that allow medical MRI scanners to function.
All systems are go for the Juno spacecraft’s July 4 encounter with Jupiter.
“We couldn’t be more excited about being this close to Jupiter’s doorstep,” said Diane Brown, Juno program executive at NASA Headquarters in Washington, D.C., during a June 30 news briefing.
The scientific instruments have been shut off and the final command sequence for going into orbit around Jupiter has been uploaded to the spacecraft’s computers. On July 4, the probe will fire its main engine for 35 minutes, using it as a brake to slow down and be captured by Jupiter’s gravity. Once in orbit, Juno will spend 20 months figuring out what’s hiding beneath the thick clouds that encase the planet.
Juno has been busy during its final approach. On June 28, it got one more look at Jupiter and three of its moons. And last week Juno monitored changes in interplanetary plasma (see below) as it crossed a magnetic boundary that shields Jupiter from the stream of charged particles blowing from the sun.
Now all scientists can do is wait. “I have mixed emotions,” said mission lead Scott Bolton, a planetary scientist at the Southwest Research Institute in San Antonio. “I’m excited, but I also have tension and nervousness.” Juno has to perform a critical engine burn all on its own while passing through treacherous belts of radiation that encircle the planet. A series of radio tones from the spacecraft will let mission scientists know whether or not it worked.
For the last four decades, Koko, the world’s most famous gorilla, has lived in a trailer in Silicon Valley, the subject of the longest-running project on ape sign language. With a reported vocabulary of hundreds of signs, Koko has appeared to express feelings almost anyone can relate to — a love of kittens, a desire to be a mother.
A new PBS documentary argues that Koko’s remarkable life “challenges what it is that makes humans unique.” The problem, though, is that the film never really makes clear what “it” is. Rather than diving into the question of ape language and dissecting Koko’s abilities, Koko — The Gorilla Who Talks focuses more on the relationship between Koko and researcher Penny Patterson. Patterson began working with Koko in 1972 while a Ph.D. student at Stanford University, with the aim of conducting the first sign language experiment with a gorilla. Koko was an infant, living at the San Francisco Zoo. By 1977, Patterson had negotiated to take ownership of Koko.
After completing her Ph.D., Patterson drifted away from mainstream science, and her relationship with Koko seems to have morphed from researcher and study subject to mother and child. Patterson appears deeply attached to Koko, and she seems to genuinely believe Koko is communicating her thoughts and feelings. Skeptics interpret Koko’s behavior differently. Columbia University psychologist Herbert Terrace, who appears in the film, has conducted his own research on primate communication and intelligence. He suggests Koko is largely mimicking Patterson to receive rewards. Patterson, he argues, has failed to produce any data that prove otherwise. The reality is probably somewhere in between these extremes. It’s difficult for anyone to really know what’s going on inside an animal’s head, but the idea of conversing with animals is deeply appealing. In the end, the film may reveal more about human behavior — our infinite capacity for empathy (SN Online: 6/29/16) and our yearning to bond with others — than it does about the capabilities of Koko or any of our other ape cousins.
Any traveler to the Olympics could potentially bring Zika home, but just four countries bear a substantial risk of seeing the virus spread.
Chad, Djibouti, Eritrea and Yemen all have the right ingredients to sustain mosquito-borne transmission, researchers report July 13 in a weekly report of the U.S. Centers for Disease Control and Prevention. Few people typically travel from those countries to places where Zika virus is active, but the Olympics will change that.
To gauge the risk of a single person traveling to Rio de Janeiro for the Olympics, becoming infected and then sparking an outbreak back home, CDC scientist Ardath Grills and colleagues analyzed environmental and population data for 206 countries planning to participate in the Games.
All countries risk importing Zika from Rio, the authors write, but only 19 not currently reporting Zika outbreaks have the susceptible populations and environmental conditions needed to keep local transmission going. And all but Chad, Djibouti, Eritrea and Yemen already have lots of travelers trekking back and forth from Zika-afflicted countries.
For most countries, including the United States, travel to the Olympics doesn’t add much to the risk (SN Online: 6/14/16). (Overall, the number of people planning to travel to the Games — up to an estimated 500,000 — is less than 0.25 percent of the total number of travelers in 2015 to countries with Zika, the researchers estimate.)
The new analysis is based on “worst-case scenarios,” the authors say. It does not change current public health warnings: Pregnant women should steer clear of the Games and people should take steps to avoid spreading the virus via sexual transmission when they return home.
Analyzing a bevy of diverse data, scientists have drawn a new map of the human brain in extreme relief. Their approach demarcated 180 areas in each half of the outer layer of the brain — including 97 regions in each half that haven’t been described before. The high-resolution map will allow scientists to more precisely scrutinize brain regions and see how they change with, for instance, age and disease.
Many previous maps of the brain have been built with just one type of data. The new map, described July 20 in Nature, forms a holistic view of the brain by combining several different types of information. These specs included how areas behaved while doing certain tasks or nothing at all, as well as detailed anatomical data about the shape and thickness of the brain. Using these metrics from 210 healthy people, neuroscientist David Van Essen of Washington University in St. Louis and colleagues found that each hemisphere contains 180 distinct areas (separated by black lines in image). In this view, colors show how tightly linked each area is to other brain areas that handle auditory (red), touch and movement (green) or visual (blue) information.
The discovery of unknown yeasts hiding in lichens from six continents could shake up a basic idea of what makes up a lichen partnership.
For more than a century, biologists have described a lichen as a fungus growing intimately with some microbes (algae and/or cyanobacteria) that harvest solar energy. The fungus is treated as so important that its name serves as the name for the whole lichen.
Biologists have recognized that more than one fungus can show up in lichen close-ups, but their role hasn’t been clear. Now that may be on the brink of changing. Fifty-two genera of lichens collected from around the world include a second fungus — single cells, called yeasts, of a previously unknown order now christened Cyphobasidiales. Toby Spribille of the University of Graz in Austria and colleagues report the finding online July 21 in Science. The first example discovered illustrates why these yeasts might turn out to be more than parasites or mere hitchhikers, says study coauthor John McCutcheon of the University of Montana in Missoula. He and Spribille started the research out of curiosity. They wondered how the yellow, toxin-bearing, thready tangles of lichen called Bryoria tortuosa could have the same fungus and the same algal partner — and thus technically be the same species — as the brown, toxin-poor lichen traditionally called B. fremontii. The researchers looked to see which genes were active in each lichen in hopes that some discrepancy could explain the difference in forms. What the researchers found had nothing to do with the alga or previously known fungus. Instead, ample genetic activity of more abundant yeasts in the toxic B. tortuosa turned out to be the most striking disparity.
After five years of work, the research team now has microscope images of yeast cells embedded in the outer layer, or cortex, of B. tortuosa. Gene-activity results suggest that the yeasts could be what’s making the difference between the forms, maybe even synthesizing toxic vulpinic acid. The yeasts turning up across this widespread class of lichens might explain other mysteries, such as why researchers have largely failed to re-create lichen partnerships in the lab. It’s a bold hypothesis, but lichenologist Robert Lücking of the Botanic Garden and Botanical Museum Berlin-Dahlem takes the idea of yeast partners seriously. “This will be a huge surprise to the lichenological and mycological community,” he says.
