On April 19, 1966, Roberta Gibb became the first woman to (unofficially) finish the Boston marathon. Women were officially allowed to enter the race in 1971, and Boston medaled its first female winner in 1972 — the year that also saw the passage of Title IX — the amendment that prohibits discrimination based on sex in education programs or any program receiving federal funding. This year, 13,751 women crossed the Boston marathon finish line, making the finisher list 45 percent female. In the last 50 years, other sports have also welcomed in women, from weightlifting to rugby to wrestling. And of course, women exercise noncompetitively, lifting weights, holding yoga poses and putting in hours on the track and in the gym.

Women are making up for a historical bias against them in sports. Not surprisingly, there’s also historically been a bias in sports science. “If you went all the way back to the 1950s, a lot of exercise physiology studies about metabolism talk about the 150-pound-man,” says Bruce Gladden, an exercise physiologist at Auburn University in Alabama and the editor in chief of the journal Medicine and Science in Sports and Exercise. “That was the average medical student.” It was a matter of convenience, studying the people nearest at hand, he explains.

Over time, athletes (and convenient student populations) have become more diverse, but diversity in studies of those athletes has continued to lag behind. When Joe Costello, an exercise physiologist at the University of Portsmouth in England, began studying the effects of extreme cold exposure on training recovery in athletes, he found that women were under-represented in the field compared to men. He wondered, he says, “is that the case across the board in sports science?”

Digging through three influential journals in the field — Medicine and Science in Sports and Exercise, the British Journal of Sports Medicine and the American Journal of Sports Medicine — Costello and his colleagues analyzed 1,382 articles published from 2011 to 2013, which added up to more than six million participants. The percentage of female participants per article was around 36 percent, and women represented 39 percent of the total participants, the scientists reported in April 2014 in the European Journal of Sport Science.

“In my opinion, it’s not enough,” he says. The numbers are relatively close to the gender breakdowns in competitive sport, he notes, but participation in noncompetitive exercise and casual running is a lot closer to a 50:50 breakdown, and the studies don’t reflect that.
Despite the gap, Costello’s study did show that women are represented in exercise science studies in general. But I wondered if the trend was improving — and if the type of study mattered. Are scientists studying women in, say, studies of metabolism, but neglecting them in studies of injury? I looked at published studies in two top exercise physiology journals and found that women remain under-studied, especially when it comes to studies of performance. Reasons for this under-representation abound, from menstrual cycles to funding to simple logistics. But with recent requirements for gender parity from funding agencies, reasons are no longer excuses. When it comes to the race to fitness, women are well out of the starting blocks, but the science still has some catching up to do.
Let’s look at the data
I followed Costello’s lead and looked at studies published in Medicine and Science in Sports and Exercise and the American Journal of Sports Medicine, this time looking at the first five months of 2015(the former journals had articles available for free through May 2015; the latter granted me access. The third journal in the previous study, the British Journal of Sports Medicine, would only grant me access on a case-by-case basis). I excluded single case studies, animal studies, cell studies, studies involving cadavers and studies that dealt with coaches’ or doctors’ evaluations. I also excluded studies where the gender breakdown of participants wasn’t given (11 studies that included people didn’t mention the gender of the participants), and studies where there would be no reason to include women (such as those involving prostate cancer recovery).

That left me with 188 studies that included 254,813 participants. Of the 188 studies, 138, or 73 percent involved at least some women. But overall, women made up only 42 percent of participants. While 27 percent of the studies included only men, only 4 percent were studies of only women.

These results were similar to those Costello and his group showed in 2014. But I also wondered what, exactly, those women were being studied for. I took the 188 studies and divided them into six categories:

Studies on metabolism, obesity, sedentary behavior, weight loss and diabetes
Studies of nonmetabolic diseases
Basic physiology studies
Social studies, including uses of pedometers and group exercise
Sports injury
Performance studies.
In studies of metabolism, obesity, weight loss and diabetes (23 total studies), women were included in 87 percent of studies and represented 45 percent of participants, getting relatively close to gender parity. For nonmetabolic diseases (18 studies), 85 percent of studies included women, and they represented 44 percent of participants.
Out of 188 studies, the number of studies involving women ranged from 36 percent in performance to 100 percent in social studies.

In basic physiology studies (11 total studies), including studies of knee and muscle function and studies of people in microgravity, women were included in 45 percent of studies, and represented 42 percent of all participants.

Women were represented in 100 percent of social studies (seven papers) and made up 60 percent of the participants. These included studies such as self-cognition, how well people adhere to wearing activity trackers, and the influence of meet-up groups on exercise. “Women are more likely to take part in [or] be recruited to group training programs than men,” notes Charlotte Jelleyman, an exercise physiologist at the University of Leicester in England.

The most striking differences came when studying performance and sports injury. There were 102 studies of sports injury and recovery, from concussions and elbow and shoulder repair in baseball players to studies of injury in surfers. Women were present in 80 percent of these studies, but made up 40 percent of participants.

I was especially interested in the large number of studies (38 total) on knee and ACL repair. In these studies, women were present in 94 percent of studies, but were only about 42 percent of participants. “That’s a case where you would think there would be more emphasis,” Gladden notes. “ACL injuries are much more prevalent in female athletes.”
Out of more than 250,000 participants in the 188 studies analyzed, the majority were men, particularly in analyses of sports performance and injury.

But the biggest difference came in sports performance — training to get better, recover faster and perform stronger. Of 30 studies, 39 percent involved women, and women made up almost 40 percent of participants. But this result was heavily skewed by a single study of more than 90,000 participants, which examined sex differences in pacing during marathons. When this study was removed, the total number of participants in all performance studies dropped to 4,001. And the percentage of female participants dropped with it — to 3 percent. Scientists may be trying to get at the secrets of the best athletes, but to do so, they are mostly looking in men.

Time, money and menstrual cycles
There are many reasons why women might be under-represented in exercise science. One is the same reason that haunts many sex disparities in biological research — the menstrual cycle.

With monthly hormone cycles, “[we] have to test [women] at certain phases,” even if you’re studying something seemingly unrelated, such as knee pain, explained Mark Tarnopololsky, a neurometabolic specialist at McMaster University, who has extensively studied sex differences in exercise. “One has to choose which phase — follicular or luteal phase — so I think when physiologists are limited in their funds, it’s easier to get guys to come in at any time.”

For some types of studies, scientists note that no previous studies have found sex differences. So scientists just study men — with no menstrual cycle to worry about — and apply the results to women. But “it’s not good enough,” says Jelleyman. “Just to say that because it works in men and previous studies have found no sex differences we assume it will work on women too – you have to show it.”
Many scientists worry that cycling hormones means variable data points, so it’s easier to study men and state that the results probably apply to women, too. But that’s a cop out, says Marie Murphy, an exercise scientist at Ulster University in Northern Ireland. “If you revisit [women] in the same phase, they should be no more variable than a man,” she notes. “You return to them 28 days later and that’s easy enough. It’s not a difficult thing to do. But I think if you’re looking for an excuse you’ll find one.”

Using that excuse can mean missing important differences. Before Gibb’s Boston run in 1966, many people — including scientists — viewed distance running and extreme exercise as somehow unhealthy for women, Tarnopololsky explains. After his lab studied differences in metabolism in men and women during endurance exercise, his group found that “Women were at least as good, if not better able to withstand the rigors of the exercise.”

But menstrual cycles aside, studies are expensive, particularly studies involving people. In many cases, simplifying the study population is the only way to complete the work on time and within budget. As a member of the coaching teams associated with elite athletes, Louise Burke, a sports nutritionist at the Australian Institute of Sport, says she takes her research chances where she can find them. For a recent study of male race walkers, “when we decided to do the study I did think we’d have female race walkers,” she says. But she found that the pool of potential female participants was small. “We didn’t have a lot in Canberra,” she recalls. “Of that ones that were of the right caliber, we had people being injured, a couple who were doing a race that wouldn’t make them available.”

And when logistics shoot down one sex in a study, it will be the women who lose out. “Conference organizers are careful and include symposia on sex differences,” says John Hawley, an exercise physiologist at Australian Catholic University. But when it comes to actually doing studies, there can be challenges. Many of Hawley’s studies are invasive, involving biopsies that leave scars. And many women aren’t willing to get scarred for science. “If I go out to a triathlon and say to the females, ‘we’d like to do invasive work,’ they’re like ‘ooh, no biopsies,’” Hawley says. “It’s a legitimate practical issue.”

Finally, there are also cultural reasons that women end up underrepresented. Female athletes don’t get the same TV time as male athletes, and the players don’t get paid as much, even though, as in soccer, the women’s national team is more highly ranked than the men’s. This disparity might also result in [gender] disparity in performance studies, Gladden suggests. “Science unfortunately isn’t immune to those same problems.”

Leveling the playing field
Calls for equality in exercise research continue. In a recent article in The Sport and Exercise Scientist, Murphy looked at the March issue of the Journal of Sports Sciences, and found that the 13 papers in the issue included 852 participants, but only 103 women, a dismal participation rate of only 12 percent.

While Murphy notes that other fields of study may have similar findings, exercise science needs to do better. “It’s quite simple,” she says. “If we want to apply the findings to men and women, we need to test our hypotheses and do our measures in research involving men and women.”

The lack of parity for female research participants “should be alarming,” Hawley says. He notes that while scientists bear some responsibility, “the funding bodies and editors of journals should be asking more serious questions.” Scientists who peer-review each other’s work should also ask hard questions, he says. “Peer review is failing as well….The typical responses [are] ‘unfortunately the budget does not permit females’ (a complete white lie of course), and time and practicalities. It’s not an excuse.”

As is true in many areas of science, as more women join the ranks of scientists studying exercise, they are more likely to include women in their studies. But Murphy notes that it won’t solve the problem. “I don’t think scientists think of it unless they have a particular interest in the area,” she says. “There are really good women researchers [in exercise science], but they study men, and the men study men! We’re not doing ourselves any favors.”

The broader impact of this gender imbalance is that training, fitness and diet recommendations for performance and recovery are based on science that may have only been done in men, and then downsized to fit women. Sometimes it may make no difference. But what if it could? In the end, the road to stronger, better, faster and healthier is one with studies that include everyone. “It is important to show that the general principles of exercise effectiveness are applicable to all populations whether it be males or females, older or younger, ethnically different or diseased populations,” says Jelleyman. “Sometimes it emerges that there are differences, other times less so. But it is still important to know this so that recommendations can be based on relevant evidence.”

Dogs were domesticated at least twice, a new study suggests.

Genetic analyses of a 4,800-year-old Irish dog and 59 other ancient dogs suggest that canines and humans became pals in both Europe and East Asia long before the advent of farming, researchers report June 3 in Science. Later, dogs from East Asia accompanied their human companions to Europe, where their genetic legacy trumped that of dogs already living there, the team also concludes.

That muddled genetic legacy may help explain why previous studies have indicated that dogs were domesticated from wolves only once, although evidence hasn’t been clear about whether this took place in East Asia, Central Asia or Europe. The idea that dogs came from East Asia or Central Asia is mostly based on analysis of DNA from modern dogs, while claims for European origins have been staked on studies of prehistoric pups’ genetics. “This paper combines both types of data” to give a more complete picture of canine evolution, says Mietje Germonpré, a paleontologist at the Royal Belgian Institute of Natural Sciences in Brussels, who was not part of the study.

Understanding this domestication process may illuminate humans’ distant past — dogs were probably the first domesticated animal and may have paved the way for taming other animals and plants.

In the study, evolutionary geneticist Laurent Frantz of the University of Oxford and colleagues compiled the complete set of genes, or genome, of an ancient dog found in a tomb near Newgrange, Ireland. Researchers drilled into the hard-as-stone petrous portion of the dog’s temporal bone, which contains the inner ear, to get well-protected DNA, Frantz says.
The researchers don’t know much about what the midsize dog looked like; it doesn’t bear any genetic markers of particular modern dog breeds, Frantz says. “He wasn’t black. He wasn’t spotted. He wasn’t white.” Instead, the Newgrange dog was probably a mongrel with fur similar to a wolf’s.

But the ancient mutt has something special in his genes — a stretch of enigmatic DNA, says Germonpré. “This Irish dog has a component that can’t be found in recent dogs or recent wolves.” That distinct DNA could represent the genetic ancestry of indigenous European prehistoric dogs, she says. Or it could be a trace of an extinct ancient wolf that may have given rise to dogs (SN: 7/13/13, p. 14).
Unraveling the prehistoric mutt’s DNA may help researchers understand dogs’ history. Already, comparisons of the ancient Irish dog’s DNA with that of modern dogs reveal that East Asian dogs are genetically different from European and Middle Eastern dogs, the researchers have found. Other researchers may have missed the distinction between the two groups because they were working with subsets of the data that Frantz and colleagues amassed. Frantz’s team generated DNA data from the Newgrange dog and other ancient dogs, but also used data from previous studies of modern dogs, including the complete genomes of 80 dogs and less-complete sampling of DNA from 605 dogs, a collection of 48 breeds and village dogs of no particular breed.

The distinct genetic profiles of today’s Eastern and Western dogs suggests that two separate branches of the canine family tree once existed. The Newgrange dog’s DNA is more like that of the Western dogs. Since the Irish dog is 4,800 years old, the Eastern and Western dogs must have formed distinct groups before then, probably between about 6,400 to 14,000 years ago. The finding suggests that dogs may have been domesticated from local wolves in two separate locations during the Stone Age.

The ancient dog’s DNA may also help pinpoint when domestication happened. Using the Newgrange dog as a calibrator and the modern dogs to determine how much dogs have changed genetically in the past 4,800 years, Frantz and colleagues determined that dogs’ mutation rate is slower than researchers have previously calculated. Then, using the slower mutation rate to calculate when dogs became distinct from wolves, the researchers found that separate branches of the canine family tree formed between 20,000 and 60,000 years ago. Many previous calculations put the split between about 13,000 and about 30,000 years ago, but the new dates are consistent with figures from a study of an ancient wolf’s DNA (SN: 6/13/15, p. 10). Frantz and colleagues emphasize that their estimate doesn’t necessarily pinpoint the time of domestication. It could indicate that different populations of wolves were evolving into new species at that time. One of those could later have evolved into the ancestor of dogs.
Although the new study indicates there were two origin points for dogs, humans’ canine companions have since mixed and mingled. By comparing mitochondrial DNA, the genetic material inside energy-generating organelles, from 59 ancient European dogs and 167 modern dogs, the researchers determined that East Asian dogs at least partially genetically replaced European dogs in the distant past. Mitochondria are inherited from the mother. Ancient European dogs’ mitochondrial DNA varieties, or haplogroups, differed from those of modern dogs, the researchers found. Of the ancient dogs, 63 percent carried haplogroup C and 20 percent carried haplogroup D. But in present-day dogs, 64 percent carry haplogroup A and 22 percent carry haplogroup B. That shift and other evidence indicate that dogs from the East moved west with humans, and Eastern dogs passed more of their genetic heritage to descendants than Western dogs did.

Archaeological evidence backs up the dual origin story. Dogs as old as 12,500 years old have been found in East Asia. In Europe, dogs date back to 15,000 years ago. But there is a dearth of dog remains older than 8,000 years old in Central Eurasia. That lack possibly rules out this in-between region as a domestication site, despite some genetic evidence from village dogs that says otherwise (SN:11/28/15, p. 8). “The argument in this paper, pointing out a pattern in the archaeological data of an absence of early dog remains in the period [before] 10,000 years ago, should be taken very seriously,” says Pontus Skoglund, an evolutionary geneticist at Harvard University.

He’s not yet won over by the double-domestication hypothesis, though. The researchers admit they can’t yet rule out that dogs were domesticated once, then transported to different places where isolation, random chance and other factors caused them to drift apart genetically.

More ancient DNA may help clarify the still-hazy picture of dog domestication. Says Skoglund: “It’s going to be an exciting time going forward.”

Fire was one of our ancient ancestors’ first forays into technology. Controlled burns enabled early hominids to ward off cold, cook and better preserve game. New evidence places fire-making in Europe as early as 800,000 years ago, much earlier than previously thought and closer to scientists’ best estimate for hominids’ first use of fire, about 1 million years ago in Africa.

It’s unclear how early Homo species came to master fire, but it was perhaps an attempt at problem solving — capturing a natural phenomenon and harnessing it for use. That tradition has persisted in human cultures. It thrives today among scientists, especially those engaged in problem solving related to society’s most pressing issues.
Take drug addiction, a vexing problem that has grown in urgency in the last decade as more and more people have become dependent on opioids — not only street drugs like heroin but also prescription pain meds like OxyContin and fentanyl. Opioids can be extremely difficult to give up because of their strong addictive pull. So scientists are trying to develop vaccines that would block the effects of heroin and other drugs of abuse, as Susan Gaidos reports. Eliciting a strong immune response, researchers theorize, could stop the drug from reaching the brain, preventing the high that fuels addiction. Success with such biotechnology, now being tested only in lab animals, would offer hope to many battling to stay off drugs.

Another modern scourge is terrorism, and anthropologists like Scott Atran have been exploring the psychological and cultural factors that drive some individuals to extreme acts of violence. There is no technology to prevent people from committing such acts — at least not yet. Basic explorations must always precede any practical use of new knowledge: Hominids could not use fire until they understood its nature and limits — which things burn, which do not; water and sand douse flame, oil and fat fuel it. Mapping terrorism’s contours is just a beginning on a long journey toward developing tactics for undercutting its power.

So it is with many other reports in this issue about basic explorations that may well precede the birth of new technologies. A few favorites:

A report on insights into how the microbial denizens of the gut influence weight gain and obesity. Scientists have now revealed a molecule made by microbes that sends a signal to the brain, influencing fat storage and appetite.

An intriguing study of mice with genetic mutations similar to those found in some people with autism. The findings suggest a role in the disorder for nerve cells involved with touch, as well as a new way to think about autism that may one day identify a target for novel therapies and interventions.

News of a second detection of gravitational waves from LIGO. It’s less dramatic and showy than the first black hole merger detection, announced in February. But it is nonetheless a further sign that a new era, one in which astronomers probe the heavens by watching for violent if subtle wakes in the fabric of spacetime, is upon us.

Feeling good may help the body fight germs, experiments on mice suggest. When activated, nerve cells that help signal reward also boost the mice’s immune systems, scientists report July 4 in Nature Medicine. The study links positive feelings to a supercharged immune system, results that may partially explain the placebo effect.

Scientists artificially dialed up the activity of nerve cells in the ventral tegmental area — a part of the brain thought to help dole out rewarding feelings. This activation had a big effect on the mice’s immune systems, Tamar Ben-Shaanan of Technion-Israel Institute of Technology in Haifa and colleagues found.

A day after the nerve cells in the ventral tegmental area were activated, mice were infected with E. coli bacteria. Later tests revealed that mice with artificially activated nerve cells had less E. coli in their bodies than mice without the nerve cell activation. Certain immune cells seemed to be ramped up, too. Monocytes and macrophages were more powerful E. coli killers after the nerve cell activation.

If a similar effect is found in people, the results may offer a biological explanation for how positive thinking can influence health.

Zika should soon run its course in Latin America.

Within the next couple of years, the epidemic that has battered the region since 2015 will largely be over, researchers estimate in a paper online July 14 in Science.

“If we’re not past the peak already, we’re very close to it,” says study coauthor Neil Ferguson of Imperial College London. After this outbreak winds down, it may be a decade ­— at least — before another large-scale Zika epidemic hits the region.
The new timeline could help vaccine researchers get a jump on future outbreaks, and might make health officials rethink advice to pregnant women trying to avoid Zika-related birth defects. Ferguson’s work also suggests something counterintuitive: Current efforts to kill Zika-carrying mosquitoes might actually make it easier for the virus to reemerge.

“It’s an important and timely analysis,” says infectious disease researcher Oliver Pybus of the University of Oxford. “Policy makers would be wise to read it carefully.”

Brazil reported the first cases of Zika in May 2015. Since then, the mosquito-borne virus has spread to 48 countries. Scientists have now widely accepted Zika as a cause of microcephaly, a devastating birth defect that leaves babies with shrunken heads and brains, as well as other serious problems (SN Online: 6/28/16).

Scientists and health officials have hustled to fight Zika, but they’ve had trouble keeping up. Mosquito-control efforts haven’t helped much, says Ferguson, and a safe and effective vaccine could still be years away. What’s more, advice to postpone pregnancy isn’t always realistic, he says.

Predicting the epidemic’s course could refine current Zika-fighting strategies.
Ferguson and colleagues made a computer simulation of Zika transmission within Latin America, using data from 35 countries that have reported cases. The team factored in such variables as seasonal climate variation, the ease with which Zika jumps from person to mosquito to person, and human travel patterns between countries.

After the current outbreak ends, simulations show that some 30 years could pass before Zika transmission picks up again. Once infected with Zika, people are immune to the virus, Ferguson says, capping an epidemic’s length and buying some time before a resurgence. He can’t say for sure that another major outbreak is still three decades away — but suspects a lull could last at least one decade.

Zika has “been burning through the population,” Ferguson says. “Sooner or later, it starts to run out of people to infect.”

The virus doesn’t need to infect everybody to peter out — just enough to generate herd immunity. At that point, so many people are immune to Zika that it can’t easily spread, protecting those still uninfected.

Killing mosquitoes — a strategy some countries have used to curb Zika’s reach — could actually hinder herd immunity, letting the next epidemic strike sooner, the team’s simulations suggest. With mosquito control that’s only marginally effective, a second wave of Zika hits about five years earlier than with no mosquito control at all, the simulations indicate.

“It makes sense theoretically,” says epidemiologist Mikkel Quam of Umeå University in Sweden. But considering that the cost of herd immunity might be more babies born with birth defects, he says, “any way to reduce infection is worth doing now, even if it means potentially more epidemics in years to come.”

Immunity to Zika could pose problems for vaccine development, Ferguson says. By the time researchers have something that’s safe to use, it will be hard to find a group of people to test it in. “This was a problem at the end of the Ebola epidemic as well,” he says.

Still, Ferguson says it’s an opportunity to think creatively. In the future, for instance, researchers could prequalify trial sites and get clinicians on the ground early, so when (and if) Zika hits somewhere else, say southeast Asia, they’re ready to go.

He also thinks his simulation could help health officials more clearly lay out the risks to pregnant women. Though the epidemic in Latin America will last roughly three years, his team estimates, individual outbreaks within the region can taper off after three to six months.

By tailoring recommendations to different locations, officials could limit the period of time they’re advising women to delay pregnancy.

When a honeybee colony gets hot and bothered, the crisis sets tongues wagging. Middle-aged bees stick their tongues into the mouths of their elders, launching these special drinker bees to go collect water. That’s just one detail uncovered during a new study of how a colony superorganism cools in hot weather.

Using lightbulbs to make heat waves in beehives, researchers have traced how honeybees communicate about collecting water and work together in deploying it as air-conditioning. The tests show just how important water is for protecting a colony from overheating, Thomas Seeley of Cornell University and his colleagues report online July 20 in the Journal of Experimental Biology.
Water collection is an aspect of bee biology that we know little about, says insect physiologist Sue Nicolson of the University of Pretoria in South Africa. Collecting pollen and nectar have gotten more attention, perhaps because honeybees store them. Water mostly gets picked up as needed.

Bees often get as much water as they need in the nectar they sip. But they do need extra water at times, such as during overheating in the center of the nest where eggs and young are coddled. When researchers artificially heated that zone in two colonies confined in a greenhouse, worker bees fought back. They used their wings to fan hot air out of the hive. “You can put your hand in the opening of a hive on a hot day and feel the blast of air that’s being pushed out,” Seeley says. Several hundred bees also moved out of the nest to cluster in a beardlike mass nearby. Their evacuation reduces body heat within the nest and opens up passageways for greater airflow, he says.

The bees also had a Plan C — evaporative cooling. Middle-aged bees inside a hive walked toward the nest entrance to where a small number of elderly bees, less than 1 percent of the colony, hang out and wait until water is needed. Heat by itself doesn’t activate these bees, especially since they’re not in the overheating core. Seeley now proposes that the burst of middle-aged bees’ repeated begging for water by tongue extension eventually sends the water-collecting bees into action. They return carrying some 80 percent of their weight in water. “The water carrier comes in looking really fat, and the water receivers start out looking very skinny,” Seeley says. “Over a minute when the transfer takes place, their forms reverse.” Then the receiving bees go to the hot zone, regurgitate their load of water and use their tongues to spread it over the fevered surfaces.

In a water-deprivation experiment, bees prevented from gathering water could not prevent temperatures from rising dangerously, up to 44° Celsius, in their hive. When researchers permitted water-collector squadrons to tank up again, colonies could control temperatures. Even for multitalented bees, water is necessary for cooling, the researchers conclude.

After a severe heat stress, the researchers noticed some bees with plumped-up abdomens hanging inside the colony. “Sometime they would be lined up like bottles of beer in the refrigerator,” Seeley says. Bottled beverages is what they were, he argues, storing water and remaining available if the coming night proved as water-stressed as the day.

“Honeybees continue to amaze,” says Dennis vanEngelsdorp of the University of Maryland in College Park, who studies bee health. “Even after centuries of study, we have something new.”

Boeing Milestones of Flight Hall
Now open
After two years of renovations, some of the museum’s most cherished artifacts — including the Spirit of St. Louis and an Apollo Lunar Module — are now on display alongside new objects, including a studio model of the Starship Enterprise.

National Air & Space Museum, Washington, D.C.
Pterosaurs: Flight in the Age of Dinosaurs
Through October 2
Fossils, life-size models and a virtual flight lab transport visitors back to the time of these ancient fliers.

Natural History Museum of Los Angeles County
DARPA: Redefining Possible
Through September 5
In this hands-on exhibit, see a humanlike robot, prosthetic arm, robotic exoskeleton and other high-tech innovations developed by the U.S. Defense Advanced Research Projects Agency over the last six decades.

Museum of Science and Industry, Chicago

Exercise may not erase old memories, as some studies in animals have previously suggested.

Running on an exercise wheel doesn’t make rats forget previous trips through an underwater maze, Ashok Shetty and colleagues report August 2 in the Journal of Neuroscience. Exercise or not, four weeks after learning how to find a hidden platform, rats seem to remember the location just fine, the team found.

The results conflict with two earlier papers that show that running triggers memory loss in some rodents by boosting the birth of new brain cells. Making new brain cells rejiggers memory circuits, and that can make it hard for animals to remember what they’ve learned, says Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto. He has reported this phenomenon in mice, guinea pigs and degus (SN: 6/14/14, p. 7).
Maybe rats are the exception, he says, “but I’m not convinced.”

In 2014, Frankland and colleagues reported that brain cell genesis clears out fearful memories in three different kinds of rodents. Two years later, Frankland’s team found similar results with spatial memories. After exercising, mice had trouble remembering the location of a hidden platform in a water maze, the team reported in February in Nature Communications. Again, Frankland and colleagues pinned the memory wipeout on brain cell creation — like a chalkboard eraser that brushes away old information. The wipe seemed to clear the way for new memories to form.

Shetty, a neuroscientist at Texas A&M Health Science Center in Temple, wondered if the results held true in rats, too. “Rats are quite different from mice,” he says. “Their biology is similar to humans.”
Using a water maze similar to Frankland’s, Shetty’s team taught two groups of rats how to find a hidden platform in eight training sessions over eight days. Then rats in just one of the groups exercised on a running wheel. Four weeks later, rats in both groups performed the same in the maze test — despite the fact that running rats had 1.5 to 2 times more newly born brain cells in the hippocampus, a skinny strip of tissue that’s thought to help form new memories.
These results and other memory tests “clearly showed that exercise did not interfere with memory recall,” Shetty says. And it’s likely that exercise doesn’t harm human memories either, he says.

Frankland says it’s possible that Shetty’s rats just learned the water maze too well. Shetty’s team trained their rodents for longer than Frankland’s team did, perhaps etching memories more deeply in the brain.

“The stronger the memory is, the harder it is going to be to erase it,” Frankland says.

But he points out that erasing memories isn’t necessarily a bad thing. “People get hung up on this idea,” he says, but actually, clearing out old info from the brain — forgetting — is important. Without some sort of clearance process, “your memory is going to be full of junk.”

The world is on the verge of a water crisis.

Rainfall shifts caused by climate change plus the escalating water demands of a growing world population threaten society’s ability to meet its mounting needs. By 2025, the United Nations predicts, 2.4 billion people will live in regions of intense water scarcity, which may force as many as 700 million people from their homes in search of water by 2030.

Those water woes have people thirstily eyeing the more than one sextillion liters of water in Earth’s oceans and some underground aquifers with high salt content. For drinking or irrigation, the salt must come out of all those liters. And while desalination has been implemented in some areas — such as Israel and drought-stricken California — for much of the world, salt-removal is a prohibitively expensive energy drain.
Scientists and engineers, however, aren’t giving up on the quest for desalination solutions. The technology underlying modern desalination has been around for decades, “but we have not driven it in such a way as to be ubiquitous,” says UCLA chemical engineer Yoram Cohen. “That’s what we need to figure out: how to make desalination better, cheaper and more accessible.”

Recent innovations could bring costs down and make the technology more accessible. A new wonder material may make desalination plants more efficient. Solar-powered disks could also serve up freshwater with no need for electricity. Once freshwater is on tap, coastal floating farms could supply food to Earth’s most parched places, one scientist proposes.

Watering holes
Taking the salt out of water is hardly a new idea. In the fourth century B.C., Aristotle noted that Greek sailors would evaporate impure water, leaving the salt behind, and then condense the vapor to make drinkable water. In the 1800s, the advent of steam-powered travel and the subsequent need for water without corrosive salt for boilers prompted the first desalination patent, in England.

Most modern desalination plants use a technique that differs from these earlier efforts. Instead of evaporating water, pumps force pressurized saltwater from the ocean or salty underground aquifers through special sheets. These membranes contain molecule-sized holes that act like club bouncers, allowing water to pass through while blocking salt and other contaminants.

The membranes are rolled like rugs and stuffed into meter-long tubes with additional layers that direct water flow and provide structural support. A large desalination plant uses tens of thousands of membranes that fill a warehouse. This process is known as reverse osmosis and the result is salt-free water plus a salty brine waste product that is typically pumped underground or diluted with seawater and released back into the ocean. It takes about 2.5 liters of seawater to make 1 liter of freshwater.

In 2015, more than 18,000 desalination plants worldwide had the annual capacity to produce 31.6 trillion liters of freshwater across 150 countries. While still less than 1 percent of worldwide freshwater usage, desalination production is two-thirds higher than it was in 2008. Driving the boom is a decades-long drop in energy requirements thanks to innovations such as energy-efficient water pumps, improved membranes and plant configurations that use outbound water to help pressurize incoming water. Seawater desalination in the 1970s consumed as much as 20 kilowatt-hours of energy per cubic meter of produced fresh-water; modern plants typically require just over
three kilowatt-hours.

Water, water, everywhere
Desalination plants supply water to more than 300 million people worldwide and experts expect that number to grow. Blue dots in this map represent the more than 500 large desalination plants currently in operation. Each plant produces more than 20 million liters of freshwater daily from seawater and salty groundwater. The number of smaller plants, such as those that provide freshwater on ships or for personal use, is unclear.

Source: DesalData/Global Water Intelligence, the International Desalination Association

There’s a limit, however, to the energy savings. Theoretically, separating a cubic meter of freshwater from two cubic meters of seawater requires a minimum of about 1.06 kilowatt-hours of energy. Desalination is typically only viable when it’s cheaper than the next alternative water source, says Brent Haddad, a water management expert at the University of California, Santa Cruz. Alternatives, such as reducing usage or piping freshwater in from afar, can help, but these methods don’t create more H2O. While other hurdles remain for desalination, such as environmentally friendly wastewater disposal, cost is the main obstacle.

The upfront cost of each desalination membrane is minimal. For decades, most membranes have been made from polyamide, a synthetic polymer prized for its low manufacturing cost — around $1 per square foot. “That’s very, very cheap,” says MIT materials scientist Shreya Dave. “You can’t even buy decent flooring at Home Depot for a dollar a square foot.”

But polyamide comes with additional costs. It degrades quickly when exposed to chlorine, so when the source water contains chlorine, plant workers have to add two steps: remove chlorine before desalination, then add it back later, since drinking water requires chlorine as a disinfectant. To make matters worse, in the absence of chlorine, the membranes are susceptible to growing biological matter that can clog up the works.

With these problems in mind, researchers are turning to other membrane materials. One alternative, graphene oxide, may knock polyamide out of the water.

Membrane maze
Since its discovery in 2004, graphene has been touted as a supermaterial, with proposed applications ranging from superconductors to preventing blood clots (SN: 10/3/15, p. 7; SN Online: 2/11/14). Each graphene sheet is a single-atom-thick layer of carbon atoms arranged in a honeycomb grid. As a hypothetical desalination membrane, graphene would be sturdy and put up little resistance to passing water, reducing energy demands, says MIT materials scientist Jeff Grossman.
Pure graphene is astronomically expensive and difficult to make in large sheets. So Grossman, Dave and colleagues turned to a cheaper alternative, graphene oxide. The carbon atoms in graphene oxide are bordered by oxygen and hydrogen atoms.

Those extra atoms make graphene oxide “messy,” eliminating many of the material’s unique electromagnetic properties. “But for a membrane, we don’t care,” Grossman says. “We’re not trying to run an electric current through it, we’re not trying to use its optical properties — we’re just trying to make a thin piece of material we can poke holes into.”

The researchers start with graphene flakes peeled from hunks of graphite, the form of carbon found in pencil lead. Researchers suspend the graphene oxide flakes, which are easy and cheap to make, in liquid. As a vacuum sucks the liquid out of the container, the flakes form a sheet. The researchers bind the flakes together by adding chains of carbon and oxygen atoms. Those chains latch on to and connect the graphene oxide flakes, forming a maze of interconnected layers. The length of these chains is fine-tuned so that the gaps between flakes are just wide enough for water molecules, but not larger salt molecules, to pass through.

The team can fashion paperlike graphene oxide sheets a couple of centimeters across, though the technique should easily scale up to the roughly 40-square-meter size currently packed into each desalination tube, Dave says. Furthermore, the sheets hold up under pressure. “We are not the only research group using vacuum filtration to assemble membranes from graphene oxide,” she says, “but our membranes don’t fall apart when exposed to water, which is a pretty important thing for water filtration.”

The slimness of the graphene oxide membranes makes it much easier for water molecules to pass through compared with the bulkier poly-amide, reducing the energy needed to pump water through them. Grossman, Dave and colleagues estimated the cost savings of such highly permeable membranes in 2014 in a paper in Energy & Environmental Science. Desalination of ground-water would require 46 percent less energy; processing of saltier seawater would use 15 percent less, though the energy demands of the new proto-types haven’t yet been tested.

So far, the new membranes are especially durable, Grossman says. “Unlike polyamide, graphene oxide membranes are resilient to important cleaning chemicals like chlorine, and they hold up in harsh chemical environments and at high temperatures.” With lower energy requirements and no need to remove and replace chlorine from source water, the new membranes could be one solution to many desalination challenges.
In large quantities, the graphene oxide membranes may be economically viable, Dave predicts. At scale, she estimates that manufacturing graphene oxide membranes will cost around $4 to $5 per square foot — not drastically more expensive than polyamide, considering its other benefits. Existing plants could swap in graphene oxide membranes when older polyamide membranes need replacing, spreading out the cost of the upgrade over about 10 years, Dave says. The team is currently patenting its membrane–making methodology, though the researchers think it will take a few more years before the technology is commercially viable.

“We are at a point where we need a quantum leap, and that can be achieved by new membrane structures,” says Nikolay Voutchkov, executive director of Water Globe Consulting, a company that advises industries and municipalities on desalination projects. The work on graphene oxide “is one way to do it.”

Other materials are also vying to be poly-amide’s successor. Researchers are testing carbon nanotubes, tiny cylindrical carbon structures, as a desalination membrane. Which material wins “will come down to cost,” Voutchkov says. Even if graphene oxide or other membranes save money in the long run, high upfront costs would make them less appealing.

Plus, those new membranes won’t solve the problems of desalination in less-developed areas. The costs of building a large plant and pumping freshwater over long distances make desalination a hard sell in rural Africa and other water-starved places. For hard-to-reach locales, scientists are thinking small.

A portable approach
In remote Africa, electricity is hard to come by. Materials scientist Jia Zhu of Nanjing University in China and colleagues are hoping to bring drinkable water to unpowered, parched places by turning to an old-school desalination technique: evaporating and condensing water.

Their system runs on sunshine, something that is both free and abundant in Earth’s hotter regions. Using the sun’s rays to desalinate water is hardly new, but most existing systems are inefficient. Only about 30 to 45 percent of incoming sunlight typically goes into evaporating water, which means a big footprint is needed to create sizable amounts of freshwater. Zhu and colleagues hope to boost efficiency with a more light-absorbing material.

The material’s fabrication starts with a base sheet made of aluminum oxide speckled with 300-nanometer-wide holes. The researchers then coat this sheet with a thin layer of aluminum particles.

When light hits aluminum particles inside one of the holes, the added energy makes electrons in the aluminum start to oscillate and ripple. These electrons can transfer some of that energy to their surroundings, heating and evaporating nearby water without the need for boiling (SN Online: 4/8/16).
The researchers have produced 2.5-centimeter-wide disks of the new material so far, which are light enough to float. The black disks absorb more than 96 percent of incoming sunlight and about 90 percent of the absorbed energy is used in evaporating water, the researchers reported in the June Nature Photonics.

The evaporated water condenses and collects in a transparent box containing stainless steel. In laboratory tests, the researchers successfully desalinated water from China’s Bohai Sea to levels low enough to meet drinking water standards. The researchers reckon that they can produce around five liters of fresh-water per hour for every square meter of material under intense light. In early tests, the disks held up after multiple uses without dropping in performance.

Aluminum is cheap and the material’s fabrication process can easily scale, Zhu says. While the disks can’t produce as much drinkable water as quickly as big desalination plants, the new method may serve a different need, since it’s more affordable and more portable, he says. “We are developing a personalized water solution without big infrastructure, without extra energy consumption and with a minimum carbon footprint.” The researchers hope that their new desalination technique will find use in developing countries and remote areas where conventional desalination plants aren’t feasible.

The disks are worth pursuing, says Haddad at UC Santa Cruz. “I say let’s try it out. Let’s work with some villages and see how well the tech works and get their feedback. That to me is a good next step to take.”

Desalinating water by evaporation has a downside, though, Voutchkov says. Unlike most methods for removing salt, evaporation produces pure distilled water without any important dissolved minerals such as calcium and magnesium. Drinking water without those minerals can cause health issues over time, he warns. “It’s OK for a few weeks, but you can’t drink it forever.” Minerals would need to be added back in to the water, which is hard to do in remote places, he says.

Freshwater isn’t just for filling water bottles, though. With a nearly endless supply of salt-free water at hand, desalination could bring agriculture to new places.

Coastal crops
When Khaled Moustafa looks at a beach, he doesn’t just see a place for sunning and surfing. The biologist at the National Conservatory of Arts and Crafts in Paris sees the future of farming.

In the April issue of Trends in Biotechnology, Moustafa proposed that desalination could supply irrigation water to colossal floating farms. Self-sufficient floating farms could bring agriculture to arid coastal regions previously inhospitable to crops. The idea, while radical, isn’t too farfetched, given recent technological advancements, Moustafa says.

Floating farms would lay anchor along coastlines and suck up seawater, he proposes. A solar panel–powered water desalination system would provide freshwater to rows of cucumbers, tomatoes or strawberries stacked like a big city high-rise inside a “blue house” (that is, a floating greenhouse).
Each floating farm would stretch 300 meters long by 100 meters wide, providing about 1 square kilometer of cultivable surface over only three-hundredths of a square kilometer of ocean, Moustafa says. The farms could even be mobile, cruising around the ocean to transport crops and escape bad weather.

Such a portable and self-contained farming solution would be most appealing in dry coastal regions that get plenty of sunshine, such as the Arabian Gulf, North Africa and Australia.

“I wouldn’t say it’s a silly idea,” Voutchkov says. “But it’s an idea that can’t get a practical implementation in the short term. In the long term, I do believe it’s a visionary idea.”

Floating farms may come with a large price tag, Moustafa admits. Still, expanding agriculture should “be more of a priority than building costly football stadiums or indoor ski parks in the desert,” he argues.

Whether or not farming will ever take to the seas, new desalination technologies will transform the way society quenches its thirst. More than 300 million people rely on desalination for at least some of their daily water, and that number will only grow as needs rise and new materials and techniques improve the process.

“Desalination can sometimes get a rap for being energy intensive,” Dave says. “But the immediate benefits of having access to water that would not otherwise be there are so large that desalination is a technology that we will be seeing for a long time into the future.”

This article appears in the August 20, 2016, Science News with the headline, “Quenching society’s thirst: Desalination may soon turn a corner, from rare to routine.”

Manchester, England, is not the birthplace of graphene — the atom-thin, honeycomb-like layer of carbon known for its wondrous properties and seemingly limitless applications. But the city is the material’s main booster and, according to the University of Manchester, the official Home of Graphene. That’s because it was there that Andre Geim and Kostya Novoselov figured out that you could isolate the elusive material from graphite (the “lead” in pencils) with repeated dabs of sticky tape.
The two-dimensional material also proved to be a peerless electrical conductor and superstrong, earning the two Manchester scientists the 2010 Nobel Prize in physics. So when the city played host to the EuroScience Open Forum conference late last month, it made sense that Geim, graphene and the material’s many evolving applications took center stage. At the local science museum’s new exhibit about graphene, I learned that Geim is the only Nobelist who has also been honored with an Ig Nobel (which has fun celebrating seemingly useless research in science). He contends many are more familiar with his Ig Nobel–winning device to levitate a tiny frog than with his work on graphene.

Notably, graphene comes up in both of the feature stories in this issue, adding some heft, perhaps, to Mancunian claims. In Thomas Sumner’s cover story “Quenching society’s thirst,” about the growing interest in desalination to meet the globe’s escalating need for freshwater, graphene oxide has a potentially starring role. New membranes made from this material may help increase the efficiency of separating salt from water. Cost and efficiency, Sumner reports, remain the biggest obstacles to the widespread use of desalination.

Graphene can serve as analogy and inspiration in physicists’ efforts to create solid metallic hydrogen, another theorized wonder material, which Emily Conover describes in “Chasing a devious metal.” “It’s a high-stakes, high-passion pursuit that sparks dreams of a coveted new material that could unlock enormous technological advances in electronics,” Conover writes. Solid hydrogen, which has been made, takes on a graphenelike structure when squeezed to high pressures. Solid metal hydrogen might be a superconductor at room temperature, an exciting prospect. Despite significant progress, so far no one has been able to create it.

Local celebrity or not, graphene did share the spotlight with other science superstars at the EuroScience meeting. The gene-editing tool CRISPR got lots of attention. In a review of the historic detection of gravitational waves, Sheila Rowan of the University of Glasgow offered a bevy of questions that gravitational astronomy might be able to answer in the coming years: Where and when do black holes form? What does that tell you about the large-scale formation of galaxies? Is general relativity still valid when gravity is very strong (such as near supermassive black holes)? A session on the human microbiome generated even more questions, as scientists described efforts to use microbial species as telltale signs of diseases such as cancer. And a debate about how to prevent food allergies left most agreeing that more data are needed. As answers come in on all of these and many more fascinating topics, you can be sure that Science News will be there to report on them.