This app will stop working on 3rd April 2017. But you can still listen to BBC iPlayer Radio via your browser by visiting bbc.co.uk/radio
The extraordinary and hidden histories behind everyday objects and actions
Whether a toothy grin, a megawatt beam or a faint curve of the lips, why do we smile?
What is hypochondria, and why don’t we take this misunderstood malaise more seriously?
Does torture actually work, and can its use ever be justified?
Why do some people choose to be frozen at death, hoping to be brought back to life?
The Why Factor asks why some people believe in conspiracy theories and whether it matters
Why do we feel regret – is it right to live with it, or should we get over our mistakes?
In the countries where it’s legal, why do people choose to bear arms?
Why do some people take the law into their own hands?
From shopping lists to to-do lists – why do we make lists and what do they say about us?
Could you forgive the person who killed your child or who raped or tortured you?
Why does driving bring out the worst in some people?
Why did this type of aggressive behaviour evolve? And what purpose does it serve?
Why do we understand so little about female sexual pleasure?
Why do cities make us rude? What makes us behave so badly in urban areas?
Why are so many people obsessed with discovering their family origins?
Why do some people fill their homes and their lives with stuff?
Why do we make judgments about people without even realising?
Mike Williams asks why scientists and courts are so worried about eye-witness testimony
Why do we donate organs and will we still need to in the future?
Why do we write farewell letters? And how do we find the words to say goodbye?
Why do we feel so many different emotions when someone close to us dies?
Is it ever right to take a life? Mike Williams explores the dilemmas of assisted death.
Why are we so fascinated with the superheroes which populate our comic books and movies?
What explains the success of the Hula-Hoop, Rubik’s Cube and Pokemon Go?
Why is it that we find some voices more annoying than others?
What do our voices reveal about ourselves?
People are often labelled as shy, but introversion is very much misunderstood. Why?
The strange success of pets on the internet. Why?
What lies behind our often overwhelming fear of harmless animals?