Male homosexuality has stumped evolutionary biologists and psychologists for decades. According to evolutionary theory, the highest goal is to pass on one's genes, yet homosexual males will father no direct offspring without the help of surrogates. Moreover, homosexuality seems to be at least partially heritable and is relatively common in developed societies. Why would such an evolutionarily costly trait be so prevalent?
Past studies have suggested that genes related to homosexuality might confer a mating advantage to heterosexuals expressing them, and that female relatives of homosexual males may receive a boost to fecundity. Evidence supporting those notions remains sparse, however.
A study published in August to PLoS ONE provides support for the former contention. Lead author Julien Barthes, along with his counterparts Pierre-André Crochet and Michel Raymond, suggest that a sexually-transmitted gene on the X chromosome may yield higher femininity or attractiveness in women, and thus signal increased levels of fertility. But, as a side effect, when this gene is expressed in a male on his single X chromosome, it can increase the odds that he will be homosexual. The researchers further suggest that social stratification in societies exacerbates the expression of this gene, as women expressing it may be able to rise to a higher social class, possibly by attracting powerful or affluent mates.
To test their hypothesis, the authors conducted an exhaustive review of the archaeological record for evidence of homosexuality in human prehistory. They also perused anthropological accounts to determine how widespread homosexuality is across societies worldwide. They then assessed levels of social stratification in 92 societies (shown below) across the globe and examined how that stratification correlated to the probability that male homosexuality is present.
The researchers could find no conclusive evidence that homosexual behavior was present in human prehistory, before the rise of organized societies. Moreover, their anthropological search revealed that homosexuality does not appear to be a universal trait. In some societies, particularly those that are smaller and more isolated, homosexuality is entirely absent. For example, the Aka people of the Central African Republic don't even have a word to describe same-sex sexual interaction. It is literally unheard of. Finally, the authors did indeed find a link between social stratification and homosexuality. The more highly stratified a society was -- by rank, wealth, or power, for example -- the greater the chance that male homosexuality was present.
The authors' hypothesis is an intriguing one, and would seem to suggest that wealth inequality, which is a key driver of social stratification, may indirectly contribute to male homosexuality. The theory is a fairly novel notion, however, and will need much more evidential support before it can be taken too seriously.
To that end, Barthes and his co-authors invite others to analyze their work.
"Each step toward a better understanding of the evolution and spread of male homosexual preference among humans would contribute to a constructive social debate."
Source: Barthes J, Crochet P-A, Raymond M (2015) Male Homosexual Preference: Where, When, Why? PLoS ONE 10(8): e0134817. doi:10.1371/journal.pone.0134817
Last year, Professor Alex Schiller of Friedrich Schiller University and two of his students, Martin Elstner and Jörg Axthelm, announced that they had created a sugar-based molecular computer. Admittedly not as complex as your average desktop, the "sugar computer" was still just as cool. It was even able to calculate the correct answer to a simple math problem (10 +15), although the task took roughly forty minutes to complete.
There was one thing the computer was missing, however: games. Well, now Schiller and his associates have programmed their sugar computer to play tic-tac-toe. They revealed their success August 7th in the Journal of Chemical Information and Modeling.
Though very different in design, Schiller's sugar computer runs on essentially the same idea that allows normal computers to function.
“The binary logic which makes a conventional computer chip work is based on simple yes/no-decisions,” Professor Schiller explained. “There is either electricity flowing between both poles of an electric conductor or there isn’t.”
In the sugar computer, the poles are replaced by tiny wells interconnected on a rectangular grid. Each well is filled with sugar solution. Two chemicals either make the solution in a well fluoresce or not. This fluorescence is read by logic gates. Computations begin with a basic, wired algorithm.
"If a fluorescence signal is registered, the algorithm determines what goes into the reaction vessel next. In this way signals are not translated and processed in a current flow, like in a computer but in a flow of matter," Schiller's student, Martin Elstner, explained.
Tic-tac-toe is essentially a game of if _____ then ____. When one player makes a move, the other responds based on the data available. This is something that computers can do very well; that's why tic-tac-toe was the first graphical computer game ever created all the way back in 1952.
With their sugar computer, Schiller and his co-author Elstner set up a 3 x 3 grid of wells connected by logic gates that can measure fluorescence. When a human player pipettes a blue nanoparticle solution into one of the wells, the computer responds by making another well fluoresce red.
"Moves from the human player (marked with blue luminescent nanoparticles) are read out and the gaming strategy determines where to move next. The computer move is finally marked with red luminescent nanoparticles and the turn goes again to the human player," Schiller wrote.
For the game to work on their sugar computer, Schiller and Elstner had to simplify it. The human player is only allowed to make a move on corners or edges, and the computer always gets to go first with a move in the middle well.
Unfortunately, that means the human player can never win, but one has to assume that playing a sugar computer in a rousing game of tic-tac-toe is a reward in its own right.
Source: M. Elstner and A. Schiller. Playing Tic-Tac-Toe with a Sugar-Based Molecular Computer. J. Chem. Inf. Model. DOI: 10.1021/acs.jcim.5b00324
Jupiter is gargantuan. With a mass two and a half times greater than all of the other planets combined and a volume equivalent to 1,321 Earths, the gas giant commands respect. There are some who even credit Jupiter with shaping the Solar System as we know it, altering the orbits of the lesser planets and cajoling careening asteroids.
Incredibly, despite Jupiter's massive influence and impressive resumé, the planet may have formed from mere pebbles just centimeters in size.
The pebble accretion model, as the idea is called, suggests that tiny objects first coalesce together due to drag then gravitationally collapse and form larger objects one hundred to one thousand kilometers in size. These larger objects, now referred to as planetesimals, than draw in all the remaining pebbles and become the cores of larger planets.
Simulations completed last year cast doubt on this interesting theory. They suggested that -- in the context of our solar system -- too many planetesimals would form -- as many as one hundred objects the size of Earth! Since our Solar System only contains eight planets and five recognized dwarf planets, this theory was mostly ruled out.
However, a new simulation carried out primarily by researchers at the Southwest Research Institute and published to the journal Nature suggests that if these pebbles form slowly enough, fewer large planetesimals will emerge.
But what's slow is still pretty fast on cosmic terms. According to the simulation, an object with one Earth-mass would grow in just 400,000 years. This object would then become the core of a gas giant, and start to accumulate dust and gas circulating throughout the nascent solar system.
The research fills in the blanks of how our neighborhood gas giants, Jupiter and Saturn, formed. Roughly 4.6 billion years ago, the Solar System was just a hot cloud of dust and gas. Eventually, some of the gas became so concentrated that it collapsed in on itself, forming the Sun. The rest of the material began to swirl and spin around the growing star, forming what's called a protoplanetary disc. In this roiling environment, pebbles joined together to form Jupiter's core, which then captured hydrogen and helium escaping the protoplanetary disc. Saturn's core likely formed a little bit later. When it did, it too began to snatch up the escaping gases. The rest is cosmic history.
Source: Harold F. Levison, Katherine A. Kretke & Martin J. Duncan. "Growing the gas-giant planets by the gradual accumulation of pebbles." Nature. 20 Aug 2015. doi:10.1038/nature14675
There's a silent war being waged on Wikipedia. Entries on so-called "controversial" scientific topics are persistently edited to reflect ideology, not facts.
While topics like evolution, alternative medicine, climate change, and nuclear power are not scientifically controversial, they are politically controversial. It is for this reason that those topics often fall victim to "edit wars" on Wikipedia, where users alter information to fit their biased beliefs or tarnish the integrity of the page with slanderous statements. Other users respond by correcting the changes.
Adam Wilson and Gene Likens, both based out of the University of Connecticut, were curious just how often this happens. So they downloaded the complete revision histories (dating from 2003 to 2012) of three politically controversial scientific topics -- acid rain, global warming, and evolution -- and compared them to four politically uncontroversial topics -- heliocentrism, general relativity, continental drift, and the standard model in physics. They found that significantly more edits were made to the controversial topics compared to the uncontroversial ones, and far more words were changed per day on average.
For the authors, the study was personal. As experts in acid rain, and frequent visitors to the acid rain entry on Wikipedia, they noticed myriad attempts to "introduce balderdash and factual errors" to the page's content. Particularly memorable was a series of edits which began on November 30, 2011:
At 10:20am, an anonymous editor (identified only by an IP address), removed the introductory paragraph which defined acid rain and replaced it with a statement calling acid rain “a load of bullshit.” This change was quickly reverted, but the next day the paragraph was again deleted and replaced by “Acid rain is a popular term referring to the deposition of wet poo and cats.” Five minutes later this edit was reverted and repeated again, and then reverted again. The following day (December 2, 2011) another sentence was changed from “During the 1990s, research continued.” to “During the 1990s, research on elfs continued,” which remained for over seven hours. Later that day the sentence "AciD Rain [sic] killed bugs bunny” was briefly added. Fifteen minutes later the section title “Chemistry in cloud droplets” was changed to “Blowjobs.”
Wikipedia now has numerous algorithms meant to prevent such obvious cases of vandalism, but some subtle, yet nefarious, edits evade detection.
"For example, less than a month later, the sentences, 'Acid rain does not directly affect human health. The acid in the rainwater is too dilute to have direct adverse effects' were briefly changed to 'Acid rain directly affect [sic] human health. The acid in the water is too concentrated to have indirect adverse effects,'” Wilson and Likens wrote.
Wilson and Likens' study makes an elucidating point, but it does suffer from a few drawbacks. For example, the duo did not analyze the edits themselves to determine if they were valid or invalid. Moreover, it's possible that the increase in edits on controversial topics could simply result from the fact that they are viewed more often. Lastly, the authors neglected to examine edits to Wikipedia pages on vaccines and GMOs, which are certainly the controversies du jour.
Wikipedia is the sixth most visited website in the world. Hundreds of millions look to the encyclopedia for fact-based knowledge. Compromised pages can easily spread misinformation.
To prevent misinformation getting loose, Wilson and Liken offered some advice.
"Users should be aware that content in Wikipedia can be extremely dynamic; two students could obtain, within seconds, diametrically different information on a controversial scientific topic. Educators should ensure that students understand the limitations and appropriate uses of Wikipedia, especially for controversial scientific issues."
Update 8/17: Juliet Barbara of the Wikimedia Foundation has responded to the paper:
"[T]he study simply seems to confirm that the articles chosen as controversial are, in fact, controversial. Although the authors reference anecdotal examples of inaccuracies, they note that it is, in fact, “difficult to assess causality.”"
"Wikipedia has been widely found to be as accurate as traditional sources including Encyclopedia Britannica and the German-language encyclopedia Brockhaus. Automated accounts or “bots” detect and revert vandalism within seconds. Volunteer editors and administrators regularly ensure content meets the site’s policies and guidelines. Vandalism and inaccuracies occur, but thanks to Wikipedia’s open, collaborative model the vast majority of inaccurate content is removed within minutes."
Source: Wilson AM, Likens GE (2015) Content Volatility of Scientific Topics in Wikipedia: A Cautionary Tale. PLoS ONE 10(8): e0134454. doi:10.1371/journal.pone.0134454
The evolution of cooperation remains something of a mystery in biology. The cutthroat individualism at the heart of natural selection seems, at first glance, to run counter to the very notion of sociality. However, groups of organisms that display cooperative tendencies tend to be more successful than those that do not, and hence, natural selection also appears to operate at a level higher than merely that of the individual.
Yet, the question lingers of how this is possible. Sociality often involves complex behavior, such as the division of labor observed in ant colonies. How exacly does that evolve? Researchers who have examined the issue tend to assume that the ability to perform each function -- for instance, foraging for food or tending to offspring -- were present in nonsocial ancestors. According to this paradigm, a solitary insect must be able to do everything, but a social insect will evolve to specialize in just one or a few tasks.
Such hypotheses are difficult to test. But the advent of swarm robotics, which allows researchers to examine the behavior of multiple robots in a controlled environment, has provided insights into evolutionary biology. Now, a team of mostly Belgian scientists has demonstrated, using computer simulated robots, that (1) pre-programmed behaviors are not necessary for division of labor to evolve; and (2) cooperation can evolve entirely on its own.
The authors' simulated robots mimicked the behavior of leafcutter ants. These ants divide the labor of leafcutting into two different jobs: "droppers" that cut the leaves and allow them to drop onto the ground and "collectors" that collect the leaf fragments and take them back to the nest. There are also "generalists" than can do both. (See figure.)
The scientists assessed the performance of teams of four robots. The robots were pre-programmed to be droppers, collectors, or generalists, and they found that the most efficient teams contained exactly two droppers and two collectors. That is not surprising.
What is surprising is what happened next. The authors used simulated robots that were not pre-programmed with special leaf cutting or collecting functions. Instead, the robots were only programmed to move toward the leaf, move toward the nest, or move randomly. Additionally, they were given the ability to evolve via mutation and crossover followed by selection. (In this case, selection was based on the number of leaf fragments collected.)
At first, the robots hardly collected anything. But selective pressure worked its magic. After 2,000 generations, most of the robots evolved division of labor spontaneously.
Put another way, robots that were programmed only with basic primal instincts and genetic mechanisms, over time and in the presence of selective pressure, evolved to cooperate. That's pretty impressive.
However, there is one major caveat to the research. The biological relevance of the work largely depends on whether or not their evolutionary algorithm properly resembles reality. Unfortunately, many simplifications had to be made, and the accuracy of various features, such as mutation rates and selection paramaters, are uncertain. Despite that, such systems can provide interesting insights into evolutionary biology, rudimentary though they may be.
Source: Ferrante E, Turgut AE, Duéñez-Guzmán E, Dorigo M, Wenseleers T (2015). "Evolution of Self-Organized Task Specialization in Robot Swarms." PLoS Comput Biol 11(8): e1004273. doi:10.1371/journal.pcbi.1004273
Amber may be nature's finest camera, and scientists just revealed one amazing snapshot.
You can see it above: an entire scorpion, exquisitely preserved in a large drop of fossilized tree resin. According to the researchers who examined the contained critter, the scorpion is a brand new species!
Bibiano Luna-Castro, director of the Amber Museum in Chiapas, Mexico, must have been ecstatic when a native local farmer presented him the fossil, which was unearthed near the Guadalupe Victoria Site in the amber-rich Chiapas Highlands. Fossil scorpions are comparatively rare, especially complete ones! Think about it. A tiny insect can easily fall victim to syrupy tree resin, but a two-centimeter-long critter is much harder to ensnare.
After confirming that the scorpion was indeed a novel species, the researchers dubbed the animal Tityus apozonalli. They tentatively dated the specimen to between 15 and 23 million years old!
The fossil further demonstrates scorpions' long-lasting ties to Mexico. Over 258 species have been found in the country, constituting roughly 13.5% of the arthropod's worldwide diversity.
Source: Riquelme F, Villegas-Guzmán G, González-Santillán E, Córdova-Tabares V, Francke OF, Piedra-Jiménez D, et al. (2015) New Fossil Scorpion from the Chiapas Amber Lagerstätte. PLoS ONE 10(8): e0133396. doi:10.1371/journal.pone.0133396
The first person who discovered pearls must have believed he stumbled across a bit of magic. Pull apart the valves of a living oyster, and a beautiful spherical gem of calcium carbonate may lay inside. Alas, it is not magic. A pearl forms in response to tissue damage, such as by the introduction of a foreign body, and the pearl is the oyster's attempt to wall off the offending object. (A similar process occurs in the lungs of people with tuberculosis.) Today, humans take advantage of this quirk of oyster biology in order to culture pearls on our own terms.
Though the basic biology of pearl formation is understood, many mysteries endure. For instance, small circles, rings, and other imperfections form on the surface of pearls. (See figure.)
This indicates that the pearl rotates during its formation, but this process has never been directly observed because it is rather difficult to witness such a phenomenon inside a living creature. So a team of researchers devised a clever way to investigate pearl rotation. Their results are published in the journal Royal Society Open Science.
The scientists implanted tiny magnetic beads inside of oysters, around which pearls began to form. The oysters were then placed inside of a magnetometer which detected the movement of the magnetic beads. (See figure.)
The figure depicts the formation of two different pearls. For pearl #1, there was no rotation for the first 40 days (figure A), after which the pearl began to rotate (figure B). For pearl #2, there was no rotation for the first 24 days (figure C), after which the pearl began to rotate (figure D). On average, the pearls rotated at a speed of 1.27 degrees per minute, which means a full rotation took approximately 4 hours and 43 minutes.
The team concluded that following an initial period of random movement that can last up to 40 days, the pearl begins a stable rotation which endures for 12-18 months, the time required for a pearl to form.
Finally, the authors added a small, endearing rhetorical flourish: "Nature's ability to generate so amazingly complex structures like a pearl has delivered one of its secrets." A finer statement of the grandeur of pure scientific discovery has rarely been written.
Source: Yannick Gueguen, Yann Czorlich, Max Mastail, Bruno Le Tohic, Didier Defay, Pierre Lyonnard, Damien Marigliano, Jean-Pierre Gauthier, Hubert Bari, Cedrik Lo, Sébastien Chabrier, Gilles Le Moullac. "Yes, it turns: experimental evidence of pearl rotation during its formation." R. Soc. Open Sci. Published 15-July-2015. DOI: 10.1098/rsos.150144
It is generally accepted as gospel truth among climate scientists and science writers that the world must immediately and drastically reduce carbon emissions in order to prevent apocalyptic climate change. Though RCS's editorial stance toward apocalyptic climate change is one of skepticism -- largely because doomsday prophets, be they the scientific or religious type, have always been wrong -- we freely admit that a catastrophic outcome is a possibility and radical measures may be necessary. (At this time, however, we believe that the best policy is the gradual lowering of carbon emissions through the implementation of a carbon tax.)
Whatever combination of climate solutions the world decides to implement, a new analysis in Environmental Science & Technology reminds us that all policies bear costs and unintended consequences. In the case of greenhouse gas reductions, the unintended consequence may be an increased risk of global hunger.
While it is true that climate change itself in the long run will likely lower crop yields (and hence increase the risk of hunger), ironically the very act of responding to climate change could also increase the risk of hunger. The authors demonstrated this by combining a crop model with an economic model that predicted how climate change and climate policy conspire to affect factors such as crop yields and the cost of food, energy, and land. Using these outputs, the authors were able to compare the risk of hunger in two different scenarios: (1) The Business as Usual (BaU) scenario, in which no climate policy is enacted, and (2) Stringent Mitigation, in which drastic measures are implemented to reduce greenhouse gas emissions.
Even if no climate change occurs, a rather rosy assessment, the authors predict that 90 million people will be at risk of hunger by the year 2050. (Data not shown.) Assuming that climate change occurs and the world continues with Business as Usual, about 2 million additional people will be at risk of hunger. (See bar labeled "World" and "BaU"). This would be entirely due to a decrease in crop yields (green color). However, in the Stringent Mitigation scenario, in which crop yields only decrease slightly, about 14 million additional people will be at risk of hunger. (See bar labeled "World" and "Mitigation.") What is going on?
Climate change policies aimed at reducing emissions may focus on growing more crops for biofuel. That would decrease the available food supply (thus, increasing food prices), as well as increase competition for farm land (which would further increase prices). Higher food prices will increase hunger, and this increase is represented by the blue color.
The biggest impact on hunger comes from mitigation costs (red bar). Replacing fossil fuels with more expensive energy sources or implementing pricey technological fixes such as carbon capture and storage will increase electricity prices. This, in turn, lowers real wages, the effects of which disproportionately impact developing countries. Those in poverty will be forced to choose between eating and keeping the lights on.
Despite their gloomy forecast, the authors conclude that some type of climate change mitigation is still necessary. Yes, this may put more people at risk of hunger compared to inaction, but doing nothing also has its own set of negative consequences, including sea level rise, ocean acidification, increasing the likelihood of extreme weather, and damaging ecosystems. In other words, we're damned if we do, and damned if we don't.
Source: Tomoko Hasegawa, Shinichiro Fujimori, Yonghee Shin, Akemi Tanaka, Kiyoshi Takahashi, and Toshihiko Masui. "Consequence of Climate Mitigation on the Risk of Hunger." Environ. Sci. Technol. 49 (12): 7245–7253. Publication Date (Web): May 18, 2015. DOI: 10.1021/es5051748
The deadliest tsunami in world history struck southeast Asia on Boxing Day 2004 following a behemoth 9.1-magnitude earthquake. Several years later, in March 2011, another tsunami hit Japan, again following a 9.0-magnitude quake. It is not a surprise, then, that geophysicist Gerard Fryer considers earthquakes to be the most common cause of tsunamis. But, they are not the only cause. Landslides are the second most common cause, such as the ones that generated tsunamis in Lake Geneva and Doggerland, a now submerged region of land in the North Sea that once connected Britain to mainland Europe.
Relatively minor causes of tsunamis include volcanic eruptions and meteor strikes. Surprisingly, rare weather phenomena can trigger a tsunami, and new research concludes that it was an atmospheric perturbation that caused a series of meteorological tsunamis ("meteotsunamis") that struck locations all over Europe in late June 2014. The oddest thing about the meteotsunamis is that they occurred during nice weather.
The figure above depicts three factors that conspired to cause the meteotsunamis: (1) Warm, dry air coming in from Africa at a height of ~5,000 feet (see first column); (2) A strong jetstream at ~16,000 feet blowing from the southwest (see second column); and (3) Atmospheric instability (see blue areas in third column). As this weather system moved eastward, so did the occurrence of meteotsunamis (see circles in third column).
The meteotsunamis, some as high as 3 meters (10 feet), hit coastal areas all over Europe. The authors propose that ocean waves generated by air pressure changes and amplified by resonance were to blame. They also suggest that tsunami warning systems should monitor not only earthquakes, but also freak weather conditions. That appears to be a very sensible idea.
Source: Jadranka Šepić, Ivica Vilibić, Alexander B. Rabinovich & Sebastian Monserrat. "Widespread tsunami-like waves of 23-27 June in the Mediterranean and Black Seas generated by high-altitude atmospheric forcing." Scientific Reports 5, Article number: 11682. Published: 29-June-2015. doi:10.1038/srep11682
"The ant colony is a heavily guarded, nearly impenetrable fortress rich with bountiful resources. Intruders attempting to infiltrate the ant society are immediately discovered via chemical cues, overtaken and dismantled. Nothing gets by, except for the few highly specialized, that have evolved the necessary chemical, morphological and behavioural tools to hack the complex recognition and communication system of the ants. Flying under the ant radar represents a huge boon that not only grants free access to the bounty of the colony—including the ants themselves—but further provides a safe and well-protected harbor to develop and live."
University Roma Tre's Professor Andrea Di Giulio and his team of co-authors set the scene remarkably well in their paper recently published to PLoS ONE. The focus of that paper? A group of conniving beetles that somehow manages to infiltrate ant colonies and parasitize the ants without eliciting any retaliation whatsoever. Ladies and gentlemen, meet the ant nest beetle.
There are more than 800 species of ant nest beetle (Paussus), and though almost all of them bear little resemblance to ants, they all manage to live out their lives in ant colonies, feeding on ant eggs, larvae, and even adults by piercing their mandibles into the abdomen of their unsuspecting victims and sucking out the nutritious innards. You might think that nefarious actions like these would provoke an angry response, but the sly beetles have evolved two clever traits that allow them to evade detection.
First, the beetles secrete chemicals that mimic those produced by ants, allowing them to blend in. Second, as Di Giulio and his team just discovered, the beetles produce distinct acoustic signals via organs on their bodies that imitate the signals of workers, soldiers, and even the queen herself!
"The use of highly sophisticated communication systems is the key attribute that enables ants to act as a superorganism, thereby facilitating their dominance of terrestrial ecosystems," the researchers write. By essentially hacking into these networks, ant nest beetles are able to elicit incredible control over their unwitting hosts.
To uncover ant beetles' deception, the researchers placed both ants and beetles into tiny sound chambers with super sensitive microphones and recorded the distinct acoustic signals that they emitted. They found that the beetles produced at least three different signals, matching those produced by each of the different ant castes: worker, soldier, and queen. The researchers then played distinct ant signals, white noise, silence, and the recorded beetle sounds for small groups of ants enclosed in chambers and observed their behaviors. While the control sounds -- white noise and silence -- elicited few behaviors, the beetle sounds elicited antennation at similar or even higher rates than the ant recordings. This is remarkable, as antennation -- basically touching something with the antennae -- is widely regarded as a welcoming, friendly behavior, similar to a handshake.
Even more fascinating, the ant nest beetle sounds and the queen sounds were the only signals to induce guarding behavior, "a posture similar to that adopted when [ants] attend queens or objects of great value to their society," the researchers write.
"Our data suggest that, by mimicking the stridulations (sounds) of the queen, Paussus is able to dupe the workers of its host and to be treated as royalty."
Source: Di Giulio A, Maurizi E, Barbero F, Sala M, Fattorini S, Balletto E, et al. (2015) The Pied Piper: A Parasitic Beetle’s Melodies Modulate Ant Behaviours. PLoS ONE 10(7): e0130541. doi:10.1371/journal.pone.0130541