It is a surprisingly simple idea - to end long-term homelessness, give every person living on the streets a home. It can also be surprisingly effective. Medicine Hat, a city in Canada, recently became the first city to end homelessness in this way. The approach is known as Housing First, and – unlike many other homelessness initiatives – it does not require homeless people to make steps towards solving other issues like alcoholism, mental health problems or drug addiction before they get a home. But is this approach solving the problem, or simply moving it off the streets?(Image: A homeless man with his dog outside a building. Credit to Getty)

For decades researchers, academics and psychologists have wanted to know what kind of person becomes a terrorist. If there are pre-existing traits which make someone more likely to kill for their beliefs – well, that would be worth knowing. In this edition of The Inquiry – part of the BBC World Service Identity Season – we tell the story of that search for a ‘terrorist type’. It’s a story which begins decades ago. But, with the threat from killers acting for so-called Islamic State, finding an answer has never felt more pressing.(Photo: Somali soldiers stand at the scene of car bomb at a restaurant in Mogadishu, 2016. Militant Islamist group al-Shabab claimed responsibility for the attack. Credit: Getty Images)

Gender identity is considered more fluid than ever because of the success of the trans movement. But most trans people, just like everyone else, still identify as either a man or a women. For those who feel they are neither – or both – the male/female distinction does not fit. And for the one in 2000 who are born with indeterminate sex, finding a place in this binary world can be damaging. We hear from Dr Imran Mushtaq, who works with intersex children at Great Ormond Street Hospital in London; bi-gender vlogger Brin Convenient; Tamara Adrian, Venezuela’s first transgender congresswomen (who wants gender erased from official forms); and the writer Mark Gevisser.This programme is part of the World Service Identity Season.(Photo: Transgender transsexual concept. Credit: Thinkstock by Getty Images)

A deadly al-Qaeda attack on an Ivory Coast resort town in March reminded the world that the terror network once led by Osama bin Laden has not gone away. But in recent years it has been eclipsed and diminished by the so-called Islamic State group. IS has attracted not just global attention, but fighters and funds too. So how depleted is the group which in 2001 triggered America’s “global war on terror”? In other words: what happened to al-Qaeda?Presenter: Helena Merriman(Photo: A fighter is seen standing in front of an image of Osama bin Laden, the late head of al-Qaeda, in the town of Rada. Credit: Getty Images)

Most research places Mexico at the top of the chart when it comes to the consumption of sugary drinks – by some estimates, they get through half a litre per person every day. Mexico also has some of the highest rates of obesity and diabetes in the world, exacerbated by their love of sugar sweetened beverages. To understand why, we look at how Coca-Cola became the country’s most popular fizzy drink brand, seen everywhere from sports fields to religious ceremonies. We explore the role the country’s poor water quality plays, and ask whether a tax on sugary drinks is helping Mexicans change their habits.(Photo: A variety of fizzy drinks stocked on a shelf in a shop. Credit: Getty Images)

They are at once the most predictable and unpredictable killers. We know continent-sized slabs of earth are moving beneath our feet. We know they move at a speed that is often harmless - the same rate as our fingernails grow. But sometimes, without warning, they can slip tens of metres in a second - and bring down whole cities. About a million people have died in earthquakes in the last two decades, most in a handful of huge quakes in urban areas. Yet the populations of cities at risk continue to grow. So, how can we quake-proof a city?(Photo: A general view shows excavator vehicles and rescue workers in front of a building which collapsed in the 6.4 magnitude earthquake, in the southern Taiwanese city of Tainan early on 9 February, 2016. Credit: Getty Images)

Pay packets in developed economies have hardly grown in decades. Economic output and the number of people in jobs have both improved since the global downturn. But with income levels failing to rise, ordinary workers aren't feeling the benefit. And for many, the good times were over long before the 2008 financial crash.In this edition of The Inquiry we hear from experts in the three largest economies to have suffered flat wage growth in recent years: Japan, Germany and the US. What lies behind the experience in each country – and can those answers help to explain the wider phenomenon?Presenter: Linda Yueh

The clash between Apple and the FBI is the latest battle in a century-long conflict over the power to keep secrets. The FBI wants Apple to build a “backdoor to the iPhone” so that it can read encrypted data on a locked phone used by one of the San Bernadino attackers. Apple says such a backdoor would be the equivalent of “a master key, capable of opening hundreds of millions of locks”. Creating such a key, Apple says, would “undermine decades of security advancements”. Cryptography was once controlled by the state, which deployed it for military and diplomatic ends. But in the 1970s, long-haired hippy Whitfield Diffie came up with what has been described as the most revolutionary concept in encryption since the Renaissance. Diffie’s invention took the keys away from the state and marked the start of the ‘Crypto Wars’ – the fight for the right of individuals and companies to communicate beyond the gaze of government agencies. The Inquiry tells the compelling story of the ongoing encryption war, taking evidence from expert witnesses including Whitfield Diffie himself. (Photo: Rally support for Apple refusal to help FBI. Credit: EPA Wires)

Bashar al-Assad and his Syrian National Army appear to have the upper hand. The president has the momentum in a civil war that has raged for five years. It is a very different picture from that of 2011, when a wave of popular protests spread through the country and the international community demanded Mr Assad’s resignation as his army brutally crushed demonstrations. At home, he remains in the presidential palace, supported by his inner circle. Russian air strikes and support from Iranian Revolutionary Guards have helped the Syrian leader win key battles. And on the international stage, the threat from so-called Islamic State and the role of jihadi groups within the opposition have caused those countries which wanted him gone to consider whether that remains a viable policy. So, has President Assad won?(Photo: President Assad makes a speech. Credit: AP)

Mosquitoes are the most dangerous animals on the planet. They spread diseases - malaria, dengue and zika – that kill huge numbers of people and cause suffering to many more.So why not eradicate them?It wouldn’t be easy. Scientists in Mali have found the mosquito is a surprisingly formidable foe, able to hide for months and evade capture. Other scientists are working on genetically-modifying mosquito populations so that they can’t breed.But could releasing these re-modelled mosquitoes have unintended consequences? And might we accidentally destroy ecosystems by removing mosquitoes altogether? It turns out this tiny creature presents us with huge practical and ethical problems. Presenter: Michael Blastland(Image: Fumigation against the Aedes aegypti mosquito. Credit AFP/Getty)