This week the second of two programmes about fear, why do some of us like to be frightened? Why, in a darkened cinema, do we enjoy and endure fear, horror and suspense? We'll delve into the human mind to find out.

(Image of Janet Leigh Credit: Associated Press)

In the first of two programmes on fear, we ask what actually fear is and discover it's a surprisingly difficult question to answer. What does fear mean to us and how do we face our fears, imaginary or otherwise? Are our fears universal or culturally specific?

*Image of Fear - Credit Getty Images*

This is the story of what happens when running water comes to town. In a rural backwater in southern Ghana the instillation of a network of standpipes six years ago made life feel more safe and secure.

But very soon land prices shot up and the rich began to move in, connecting their own private taps to the water system and draining the reservoir.

The simple addition of taps has changed this region forever – but what does it mean for the everyday lives of the people that live there?

In the physical, material sense, it's quite rare in nature... But, at the same time, it surrounds us. Babies can't detect it. The Himba tribe of Namibia can't describe it. Pablo Picasso turned to it after a friend committed suicide and in the West it's creative and reliable in the East it's cold and deathly. This week on the Why Factor, we're talking about something different - the colour blue.

Why do different cultures have different coming of ages? For some the advent of adulthood is celebrated by lavish parties, for others, by endurance tests and initiation ceremonies. But they all share a commonality - the symbolic passing of childhood into the adult world which usually confers new rights: legal, political or religious.

But what really changes? And why is adolescence, for many, lasting longer than ever?

(Image: Mexican teenagers pose for photos following quinceanera, a coming of age party. Credit: John Moore/Getty Images)

This week, Mike Williams asks why do we shake hands? All over the world millions of us use this gesture to greet others but where does this everyday ritual come from, and what purpose does it serve?

With the US presidential election just days away, Mike also looks at the role of the handshake in political life - why has it proved to be such a sensitive issue?

(Image: US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) shaking hands. Credit: TIMOTHY A. CLARY/AFP/Getty Images)

Why do we care so much about the hair on our heads? Each year we spend billions of dollars on cutting, shaping and colouring our hair.

It's important for personal reasons, cultural and symbolic reasons too. But why? Find out, as we hear the stories of people who have had their hair taken from them.

Join Mike Williams for The Why Factor.

(Image: A US soldier getting his head shaved. Credit: JOHANNES EISELE/AFP/Getty Images)

At first glance, it seems like a very obvious basic human response - we laugh because we find things amusing. But what is it that actually triggers our laughter, do all of us find the same things funny?

In the edition of The Why Factor, we also look beyond comedy, at laughter in our everyday lives and the role it plays in the relationships between men and women.

(Image: Comedian Omid Djalali. Photo by Thos Robinson/Getty Images)

Mike Williams finds out why armies use one type of bullet, while gangsters use another and what the phrase full-metal jacket tells us about our qualms about killing each other.

The bullet has been at the heart of the world's battles for many centuries. Although the essential idea hasn't changed much since the 15th Century, the way the bullet and its use has evolved is revealing.

He hears from doctors, soldiers and criminals about why such a small object causes so much damage and what it means to shoot someone, and be shot.

In this week's programme Mike Williams looks at why people start smoking. Nearly 50 years after the world first learned that smoking kills, millions are still picking up the habit. He also discovers who was behind one of the most lethal inventions of all time - the cigarette.

(Image: The silhouette of a woman as she smokes. Credit: Danny Lawson/PA Wire)