Have you ever wondered how you would act at the end of the world? Players’ actions in a video game could reveal insights into how an impending apocalypse might affect people’s behaviour.

A team of researchers analysed how players behaved in a beta test of ArcheAge, a massively multiplayer online role-playing game (MMORPG). The players knew that all of their character information and progress would be deleted at the end of the test, which lasted about 11 weeks. This meant the researchers could watch how their actions changed as they got closer to the virtual world’s end.

ArcheAge, made by XL Games in South Korea, lends itself well to behavioural analysis because it is a wide-open “sandbox” game. This means that people have a large amount of freedom to explore a virtual world, rather than having to approach tasks in a linear fashion. In ArcheAge, players can build houses, have parties, learn a trade, spend money, kill people and advance through the ranks of complex guilds.

Researchers analysed 270 million records of player’s actions, with the data anonymised.

Apart from a few outliers who became more murderous towards the end of the test, they found that most players didn’t resort to killing sprees or antisocial behaviour as the game progressed. In fact, they tended to become more social. “They talk more, they hang out more,” says team member at Telefonica Research in Barcelona, Spain.

In general, players abandoned trying to advance their characters or complete quests. “People don’t really go off the deep end, they just stop worrying about the future,” says Blackburn.

Apple trees at the end of the world

This makes sense, says at the University of Southern California in Los Angeles, who studies the effects of video games. “There’s a big difference between planting an apple tree even when you know you’re going to die because then your kids can enjoy it, to the world is going to end and there will be no apple tree for anybody,” he says.

But studying behaviour in virtual worlds has certain limitations, such as that only some of it mimics real-life actions. For example, previous work has found similarities in virtual and real-world economic activity, but when a “virtual plague” was introduced into World of Warcraft, players ran around purposefully infecting each other, which real sick people don’t do.

Nevertheless, the virtual world offers one huge advantage to researchers: there is no real-life Armageddon to study. “You’ve got this immense power and control,” says Williams. “It’s a supercool tool.”

Next, Blackburn wants to use ArcheAge to explore behaviour in the area of criminal justice. The game’s sophisticated justice system, which wasn’t fully implemented in the beta test, includes player-run courts, punishments and jail time for characters.

Reference:

Fading star

A dark life cycle

It was an avoidable massacre. Beekeepers in Dorchester County, South Carolina, saw 48 of their hives killed off on 28 August. The culprit was a pesticide, sprayed from a plane with the aim of killing mosquitoes that can carry the Zika virus.

But South Carolina’s mosquito population isn’t yet known to carry Zika – and even if the virus is present, there are ways to kill the mosquitoes without killing bees.

In response to four local cases of Zika, Dorchester County sprayed a , a neurotoxin which kills adult mosquitoes and other insects. The four people infected all caught the virus before arriving in South Carolina: no one in the state has yet acquired Zika locally.

The aerial spraying killed millions of bees. Commercial beekeeper Juanita Stanley . “Of course this is a tragedy,” says Michael Weyman at Clemson University, South Carolina, which is investigating claims by the beekeepers that the pesticide was misused.

Any actions that cause mass bee deaths are particularly concerning, given the fragility of bee populations in general – a consequence of the mysterious colony collapse disorder.

Bees can be spared by spraying at night instead of in the early morning. Bees don’t fly at night, and Naled only kills insects while they are airborne, says Mark Latham, director of in Palmetto, Florida, an area with commercially important beekeeping. Latham has carried out aerial spraying for 35 years, including of Naled, and almost always sprays at night.

The approach should work even though Aedes aegypti – the mosquito that can carry Zika – is a species active by day.

Spray at sunset

“We can target them effectively with aerial spraying starting just before sunset and for the following 30-60 minutes,” says Latham. “Bees are usually ‘back home’ in their hives well before sunset.”

When sprayed, Naled hangs in the air in the form of tiny droplets, and this is why insects in flight are vulnerable. Once the pesticide settles on the ground or plants, it quickly breaks down and becomes inactive. So spraying at a time when mosquitoes are flying but bees are not is a good way to make the spray safer for bees.

Since the Dorchester County spraying killed honeybees, it probably also killed wild bees and other pollinators, says Aimee Code, the pesticide programme director of the . Honeybee deaths are just easier to notice, because wild bees are mostly solitary.

Other pesticides that kill adult mosquitoes – known as adulticides – are no safer for bees, says Latham. Even pyrethrin, which is produced from chrysanthemums, is toxic to bees. Latham says he uses a lot of larvicides, which kill mosquito larvae and are safer for bees.

“Adulticiding is in a sense a method of last resort, if you haven’t killed mosquitoes when they’re larvae,” he says. Another effective and safe control method for Aedes aegypti is to eliminate the standing water in gutters, birdbaths and backyard pools where the mosquitoes typically breed.

Code does not rule out using adulticides like Naled, but agrees that they should be “really a last resort, when the disease is established”.

For example, they could be used in Florida, where mosquitoes are clearly spreading Zika. What happened in South Carolina “feels like it was more fear-based”, says Code. “We need to plan ahead, not be reactive.”

Strike the invisibility cloak off your wish list. They are impossible to build for human-sized objects, says a new study.

Invisibility cloaks have been a goal for about 10 years, since John Pendry and colleagues at Imperial College London proposed a way to guide light over or around an object using substances with exotic optical properties, called metamaterials.

Ideally, these would work passively – without you needing to pump in extra energy – and for all wavelengths of light.

But now, and at the University of Texas at Austin have showed that a passive invisibility cloak large enough to hide a human – or any macroscopic object – is impossible to build.

A practical cloak would redirect light perfectly around an object to meet the observer’s eye on the other side, and would have to be about as big as the object meant to be hidden. Borrowing from the field of electrical circuit theory, AlĂč and Monticone showed that the larger the cloak is, the smaller the wavelength of light it can redirect.

“What it means is that only a specific colour can be made invisible,” says AlĂč.

That doesn’t mean you can make an invisibility cloak that could perfectly redirect light for all shades of, say, blue, either. The wavelength of light would have to be even narrower than that emitted by the best laser that can be built. “Essentially it would be impossible,” says AlĂč.

Making things worse

Not only that, but trying to hide that one uber-specific shade of blue might make the object you’re cloaking even more conspicuous. To make that sliver of blue invisible, whatever energy the object would have emitted in that blue wavelength would be transferred to other colours, making it shine brighter in all other parts of the spectrum.

“Whatever scattering you suppress in one bandwidth has to be paid back in other bandwidths,” says AlĂč. “So cloaking may actually make things worse.”

Different kinds of invisibility cloaks could still be possible. But those have challenges, too, and there are no indications that they would be feasible for human-sized objects.

For instance, AlĂč is currently working on an active cloak using materials that can pump energy into the system. But that is only feasible for wavelengths much longer than that of visible light, such as radio waves – and even then the largest object you could cloak is about 30 centimetres in size, AlĂč says.

Another kind of cloak that can bend light would only make objects invisible for certain light intensities. If the light got stronger or weaker, the object would pop back into view.

“I’m not sure that we will get to the point of invisibility for a large object to visible frequencies,” says AlĂč.

“It reminds us of the sad truth that perfect invisibility is still in the realm of fairy tales,” says Jad Halimeh at the Ludwig Maximilian University of Munich in Germany.

Journal reference: Optica, DOI: 10.1364/OPTICA.3.000718

Watching it flow

LEARNING a tonal language like Chinese is notoriously difficult – it’s easy to end up calling your mother a horse. But soon there could be a wearable headset that can help.

The system was created for people with autism who want help with social interactions, but it could be adapted to help with speech or anxiety problems – or even language learning, says at the that designed it.

Called SayWAT, it gives live feedback via Google Glass to the wearer when they are speaking too loudly or in a flat tone – things that can lead to autistic people unintentionally appearing bored or abrasive in conversation.

SayWAT uses Glass’s microphone to record speech, then displays real-time guidance on volume and tone. It shows a volume icon if the user’s voice is too loud and flashes the word “flat” if the user’s voice does not vary in pitch.

Fourteen autistic adults tested the system. Four used SayWAT to talk with non-autistic volunteers, and 10 used it at an employee training session. The simple feedback seemed to help the users modulate their volume, as they crossed the threshold that triggered feedback less often.

“The device gives real-time feedback to the wearer if they are speaking too loudly or in a flat tone“

But the pitch feedback didn’t have the same effect. Boyd says this could be because pitch is more complicated and might need more specific feedback – something one of the volunteers requested. Her team will present the work at the conference for Human-Computer Interaction in San Jose, California, next week.

The technology could be adapted to work on other devices, says Boyd. A smartphone or watch could give haptic feedback to guide speech, for example.

Live speech feedback could help other groups too. “It would certainly be applicable to anyone who had a speech disorder, any sort of anxiety disorder,” says , a computer scientist at the University of Washington.

Real-time feedback when speaking a foreign language is also possible – but hard, says Boyd. Giving live feedback takes a lot of computational power, so the device could only focus on a few aspects of speech at once. But language learners could be alerted when they mess up a specific sound, like tones in Chinese or the Rs in French, for example.

Some autistic people don’t wish to change the way they interact, but for others, the technology seems to fill a need. In the corridor after the experiment, one autistic man told Boyd, “I really, really want to be social, so if there are tools out there that can help me, I want to try them.”

This article appeared in print under the headline “Tone up your conversation”

Updating FAQs

A fish with the briefest of lifespans may just end up teaching us how to live longer. Inhibiting the effects of certain genes turns out to lengthen their lifespan by as much as 15 per cent.

The African turquoise killifish has one of the shortest lifespans of all vertebrates: it reaches the ripe old age of only three to twelve months.

That short life expectancy – as well as the huge variation among individuals – makes it perfect for studying longevity.

Experiments that would take three years in a mouse take just six months in the killifish, says at the Scuola Normale Superiore in Pisa, Italy.

The killifish’s short lifespan stems from its life cycle in the wild. In Zimbabwe and Mozambique, the fish live in pools that only exist in the rainy season. During the dry season, adults die and their embryos go into a suspended state, encased in dry mud, until the pools fill again.

Cellerino’s team looked at differences in gene expression of individual fish that lived to different ages.

The study involved 152 male fish. The team took cell samples from fish at 10 weeks and 20 weeks old and froze them. Once the fish died, they compared gene expression in the shortest- and longest-lived fish.

They found that genes vital to a cell’s energy production are less active in young killifish that go on to be long-lived, and that inhibiting the proteins those genes make with a drug extends lifespan.

Gene expression differed much more at 10 weeks than at 20 weeks, showing that conditions favouring longevity are set during early adulthood. One of the most significant differences was in a group of genes involved in respiration inside mitochondria, cell components involved in generating energy.

When the team inhibited the products of those genes, targeting the so-called mitochondrial respiratory chain complex I with a chemical called rotenone, they prolonged lifespan by up to 15 per cent.

“This study supports the hypothesis that mitochondria, the batteries of the cells, are determinants in the ageing process,” says Joao Passos at the Newcastle University Institute for Ageing, UK. “This and other studies offer us clues about potential interventions to ameliorate the ageing process.”

But inhibiting mitochondrial activity to try to extend lifespan has not yet been tested in mammals such as mice, let alone humans.

Life in the dark

Rare but not protected