Data from just 6 minutes of walking, collected via motion sensors in smartphones, may be enough to predict someone鈥檚 risk of dying in the next five years.

Previous studies have estimated level, measured by wearable motion sensors in devices like fitness watches. Yet despite the growing popularity of smart watches and fitness trackers, they are still mostly worn by an affluent minority.

Most people own smartphones with similar sensors, but calculating mortality risk from activity data they gather is difficult because people don鈥檛 tend to carry their phones all day, says at the University of Illinois Urbana-Champaign.

To find an alternative predictor that is measurable with smartphones, Schatz and his colleagues looked at data from 100,655 participants in the UK Biobank study, which has been collecting information on the health of middle-aged and senior adults living in the UK for more than 15 years. As part of that study, participants wore motion sensors on their wrists for one week. About 2 per cent of the participants died during the following five years.

The researchers ran motion sensor and death data on about one-tenth of participants through a machine learning model, which developed an algorithm that estimated five-year mortality risk using acceleration during a 6-minute walk.

鈥淔or many diseases, specifically heart or lung diseases, there鈥檚 a very characteristic pattern where people slow down when they鈥檙e out of breath and speed up again in short doses,鈥� says Schatz.

They then tested the model using data from the other participants and determined its c-index score 鈥� a metric commonly used in biostatistics to assess accuracy 鈥� was 0.72, which is comparable to other metrics of estimating life expectancy, like daily physical activity or health risk questionnaires.

鈥淭his predictor is as strong as or stronger than traditional risk factors,鈥� says at Johns Hopkins University in Maryland.

While this study used wrist-worn motion sensors, smartphones are also capable of measuring acceleration during short walks, says Schatz, who is currently planning a larger study using smartphones. 鈥淚f people carry phones around, you could do a weekly or daily prediction and that鈥檚 something you cannot get by any other method,鈥� he says.

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IN 2013, the world鈥檚 news media fell in love with Talea de Castro, a Mexican village (population around 2400) in a remote corner of northern Oaxaca. Am茅rica M贸vil, the telecommunications giant that ostensibly served their area, had refused to provide them with a mobile phone service, so the Taleans built their own.

Imagine it: an embattled, predominantly indigenous community besting and embarrassing Carlos Slim, Am茅rica M贸vil鈥檚 owner and the richest person in the world at the time. The full story of that short-lived, home-grown network is more complicated, says Roberto J. Gonz谩lez in his fascinating account of rural innovation.

Talea de Castro was never a backwater. A community that survived Spanish conquest and has resisted 500 years of interference by centralised government may become many things, but 鈥渂ackward鈥� isn鈥檛 one of them.

Globalisation is a homogenising whirlwind of technology, finance and bureaucracy that brings with it new roads, hospitals, schools, entertainment, jobs and medicine. Yet for every outside opportunity seized, indigenous skills are watered down or forgotten. Talea de Castro鈥檚 farmers can now export coffee and other cash crops, but many fields lie abandoned as its youth migrate to the US. The village still tries to run its affairs 鈥� indeed, the entire Oaxaca region staged an uprising against centralised Mexican authority in 2006.

Some traditional Mexican buildings are built partially of mud. It is much easier and cheaper to use 鈥� not to mention a more repairable and more ecologically sensitive material 鈥� than the imported alternatives. Despite this, almost every new building in Talea de Castro is made of concrete.

The village backed another piece of imported tech in 2013: a DIY phone network, assembled by US-born rural development specialist Peter Bloom and Erick Huerta, a Mexican telecoms lawyer. Both considered access to mobile phone networks and the internet to be a human right. Also involved were 鈥淜ino鈥�, a hacker who helped indigenous communities evade state controls, and Minerva Cuevas, an artist best known for hacking supermarket barcodes.

Talea de Castro鈥檚 network ran off an open-source mobile phone network program called OpenBTS. Mobiles within range of a base station could communicate with each other and connect globally over the internet.

Yet the network never worked very well. Whenever the internet went down, the whole place lost its mobile coverage. Recently, the phone company Movistar has moved in with an aggressive plan to provide the region with regular (if costly) coverage. The idea of an autonomous network in Talea de Castro lives on, however, in a cooperative organisation of community cell phone networks that represents nearly 70 villages across several regions in Oaxaca.

Connected is an account of how a rural community takes control over the forces that threaten its existence. The people of Talea de Castro are dispersing ever more quickly across continents and platforms in search of a better life. The 鈥渧irtual Talea鈥� they create on Facebook and other sites to remember their origins are touching, but the fact remains: 50 years of development have done more to unravel a local culture than 500 years of conquest.

Know any teenagers? Chances are they will have a phone on them 鈥� and that is a big mental health problem. At least, that is the impression you get from , saying that one in four teenagers are addicted to their smartphone.

We have seen headlines like this before. This time they are based on a paper finding that 23 per cent of teens are using their phones in a problematic way. An accompanying press release said that this was 鈥渃onsistent with a behavioural addiction鈥�.

The paper also found that those with problematic use were three times more likely to report feeling depressed, anxious or that they weren鈥檛 getting enough sleep. The narrative is irresistible: smartphones are giving our children mental health problems.

But perhaps we should stop and think before we get too alarmed. It is highly debatable whether anyone can be addicted to their phone 鈥� or to using the internet or playing computer games. Some researchers in the field say it is possible, while others say it is meaningless to use the term addiction in this context.

The new paper, which is a summary of 41 previous studies of phone use, doesn鈥檛 shed light on this almost philosophical question, except to confirm that some teens are on their phones an awful lot. I suspect that their families knew this anyway.

The researchers looked at studies that used surveys to assess people鈥檚 behaviour. The most common survey includes several questions that could merely indicate high levels of phone use without it necessarily being a pathological medical condition.

Questions include whether people use their phone for longer than they had intended, whether it had caused them to miss some planned schoolwork, or if they had been told by others they were using it too much.

Can this really identify addiction? Substitute 鈥減hone鈥� for 鈥渂ook鈥� and you can imagine a keen reader answering yes to many of these questions, but we don鈥檛 tend to despair about reading addicts.

When I put this to one of the study authors, Nicola Kalk of King鈥檚 College London, she said the surveys were widely used. She also cited examples of teenagers who spend so much time gaming on their phones that they won鈥檛 even stop to get washed or leave the house.

That certainly would be disturbing behaviour, but this study doesn鈥檛 tell us anything about the number of teenagers in such an extreme state.

Another concern is that the studies included in the review were unrepresentative, says Amy Orben at the University of Cambridge. That is because Kalk鈥檚 team scanned the database of all studies on phone use by using 鈥渁ddictive鈥� as one of the search terms. Studies that found low levels of problematic use may have been overlooked, says Orben.

Kalk and co-author Ben Carter, also at King鈥檚 College London, agree that this is a limitation but say the findings still suggest a pattern that requires further investigation.

The other claim, that phones are making young people depressed, isn鈥檛 supported at all; the studies merely show a correlation between phone use and reported mental health issues, not that phones are the cause.

It is quite plausible that feeling depressed because you don鈥檛 have many school friends makes you more likely to game or talk to people online as way of coping. If that is the case, any parents who respond to the latest headlines by taking their child鈥檚 phone away might be making things worse.

To be fair to Kalk鈥檚 team, they do state in their paper they have only found an 鈥渁ssociation鈥� between phone use and mental health issues, but the fact that this is no proof of causation has been glossed over in much of the media coverage. It is almost as if journalists can鈥檛 resist a good story about teenagers and their phones. You might say we are addicted.

鈥淚 want 5G鈥� in the United States as soon as possible,鈥� . The US president isn鈥檛 the only one buying into the hype around the fifth generation of wireless technology. At last week鈥檚 mobile technology event MWC Barcelona, we were promised blisteringly quick download speeds and a mini industrial revolution powered by zippier data. Naturally, you will have to buy a new phone.

鈥淚t is being positioned as all things to everybody, the Swiss army knife of the mobile world鈥�

Perhaps Trump is worried about being left behind: the world鈥檚 first commercial 5G network is being , while US providers aren鈥檛 expected to launch services until later this year. The technology has聽also become part of the US鈥檚 trade war with China. The Trump administration is extending a ban聽on 5G kit made by Chinese firm Huawei, citing national security concerns. Huawei, in turn, is expected to sue the US government this week to overturn聽the ban.

But hang on. What even is 5G, and what is it going to mean for you? If you have heard about it before, you have probably got some sense that 5G is meant to be faster than 4G, the current mobile internet service that lets us stream video on the go or Instagram our every move.

鈥淚t is being positioned as all things to everybody, the Swiss army knife of the mobile world,鈥� says Simon Forrest at market research firm Futuresource.

In reality, 5G is a collection of different technologies developing at their own pace, some of which won鈥檛 be much faster than existing networks.

In basic terms, there are three main types of 5G, operating at low, medium and high frequencies. The latter is just what it sounds like: an electromagnetic signal broadcast at very high frequencies of over 24 gigahertz. That means data transfer of at least 1000 megabits per second (Mbps), or 50 times as fast as the average 4G speed in the UK.

That ultra-fast signal could be useful if you wanted to, say, connect .

But that high frequency means the signal doesn鈥檛 spread out easily over a wide area, because the tightly packed electromagnetic wave is narrower and less free to bend or diffract.

That means lots of mobile masts would have to be dotted around the stadium to connect everyone up 鈥� perhaps 200 to allow 50,000 people to stream HD video at once. This would be too expensive to do across wider spaces such as cities.

The medium frequency variant of 5G, operating at 3 to 6 gigahertz, would offer speeds of around 100 Mbps or more. This is still faster than 4G and the signal would cover a wider area than high frequency 5G.

In Europe, low frequency 5G will broadcast at around 700 megahertz, but may vary elsewhere, and exactly how it will be used is still a matter of debate. Some see it as enabling far-reaching coverage for a 5G network, although data speeds at those lower frequencies might not beat 4G.

Marketing buzzword

So 5G is really a marketing buzzword that masks a complex mix of technologies that could leave people confused when they buy a new phone. Worse still, countries are free to choose from a range of frequencies for their 5G services, so a smartphone that gives you 5G at home might not do so on holiday. Addressing this problem is crucial, , but progress has been slow.

There is an even bigger elephant in the 5G room, though: who actually needs it? William Webb, a former director at UK telecoms regulator Ofcom and author of The 5G Myth, says he has yet to hear a convincing answer. For smartphone users, a significantly faster connection speed may be pointless. If your phone is slow when browsing the web or streaming a movie, it is more likely to be down to limited hardware than network issues.

鈥淎ll of the applications that we use are no longer limited by the connection speed,鈥� he says. 鈥淭hey鈥檙e limited by the processor on the device or the far-end server.鈥�

While you could, hypothetically, use 5G to download vast amounts of data remotely 鈥� an entire TV series, perhaps 鈥� it is unclear that anyone would want to.

That is why some 5G proponents are pinning their hopes on commercial, rather than consumer, applications. Brendan O鈥橰eilly, chief technology officer at Telef贸nica UK, says 5G will fundamentally change the way businesses use data.

Telef贸nica UK, which operates the O₂ mobile network, will be rolling out by the end of the year. These won鈥檛 be networks for smartphone users, but small-scale tests for businesses.

O₂ is already involved with a 5G trial being run at Worcester Bosch. The UK firm has installed a private 5G network in its factory, which churns out more than a quarter of a million boilers every year and has nearly 100 industrial machines at work.

Chief executive Carl Arntzen says the network allows the firm to connect sensors to its machines and monitor them in real time. This allows any slips in quality to be caught before they create problems down the assembly line. Arntzen says the 5G network is intended to handle these huge data streams better than a Wi-Fi or 4G equivalent, but it isn鈥檛 clear if that is actually the case 鈥� it is 鈥渆arly days鈥� for the trial, he says.

Arntzen isn鈥檛 alone in pondering the benefits of high-speed wireless coverage in offices and factories. A found that a majority of companies outside North America felt identifying a business case for 5G was the main challenge facing the technology. Although respondents expected applications to emerge in the next few years, these clearly haven鈥檛 arrived yet.

鈥淵ou could use 5G to download vast amounts of data, but it鈥檚 not clear that anyone would want to鈥�

Another area supposedly ripe to benefit from 5G is healthcare. The Rush University Medical Center in Chicago is . It thinks doing so will save money in the long-run and allow it to connect up older equipment.

Meanwhile, a trial in Liverpool, UK, is testing communications devices in people鈥檚 homes that allow health visits to be carried out remotely. Instead of speaking in the flesh with a health professional, the individual talks into a speaker-shaped smart device equipped with a high-resolution 4K camera.

鈥淚f somebody鈥檚 got a rash on their skin, they can show it to the pharmacist on the video,鈥� says Rosemary Kay, director at E-Health Cluster, which is running the trial.

In this case, the devices themselves lack 5G chips, but instead use Wi-Fi to connect to routers on nearby street lights. Those, in turn, broadcast a 5G signal operated by AIMES, a cloud service spun out of the University of Liverpool. The idea is to provide trial participants, who are often older people with no mobile or internet network connection, a smooth way of transferring lots of data, which is crucial for 4K video.

But Webb says it would probably be simpler to connect those in-home devices with traditional broadband internet and Wi-Fi instead. 鈥淚f they haven鈥檛 got it, frankly, give it to them,鈥� he says. 鈥淭hat is going to be cheaper.鈥�

Don鈥檛, then, believe all the hype. If a mobile internet revolution is afoot, it is certainly looking suspiciously slow. Many would argue we actually already had such a revolution 鈥� it was called 4G.