The scene is a TV comedy classic. Kevin is about to become 13; excitedly, he jokes with his mother and father. But the moment midnight strikes, he turns into a sulky monster. "It's so unfair - I hate you!" he tells his parents.

This is, of course, an exaggeration. But it contains some truth. "The teenage years can feel like a shocking transformation," says science writer David Robson.

The changes include mood swings and a greater need to be liked by other people. According to psychologist Terri Apter, they are simply a product of enormous physical changes to the brain.

It is a subject scientists know surprisingly little about. But in recent years they have managed to chart the neuralRelating to the nerves. changes that take place in teenagers.

In babies, the brain builds many connections between neuronsNeurons, also known as nerve cells, are cells in the nervous system that use chemical or electrical signals to transmit information throughout the body. . It then gets rid of those that are not useful. This plasticityEasily shaped or adaptable. makes learning very easy. The frontal cortexA region of the brain linked to behaviour, personality and decision making. continues to build and get rid of connections in the early teenage years.

The brain's frontal and parietal lobesIncludes areas concerned with sensory information. also build up the most important connections. This makes it able to develop many skills.

But some parts of the brain develop more quickly than others. This increases impulsive, risky behaviour.

The part which encourages friendship also works harder - though this can result in worry about what people think of you.

These changes have a positive side. Teenage rebelliousness can change society for the better.

There have been some extraordinary teenagers. 1n 1985, aged 13, mathematician Ruth Lawrence became the youngest Briton to earn a first-class university degree. At the same age, in 1804, the actor William Betty¹ caused such a sensation in London, people literally fought for seats to see him.

Yes: It is relatively easy for us to explore things outside ourselves. What happens inside our own brains is far more challenging, and the adolescent phase is one requiring a great deal more research.   

No: The mysteries of the mind are nothing compared to those of outer space. Trying to discover whether there is life elsewhere in the universe is the greatest challenge for scientists.

Or... The greatest mystery of all is one that no living creature can ever solve - whether there is life after death. There is only one way to find out, and those who embark on it cannot report back.