The scene is a comedy classic. Kevin is about to become 13; full of excitement, he jokes lovingly with his mother and father. But when midnight strikes, he undergoes a Jekyll and HydeFrom a book by Robert Louis Stevenson, used to describe someone who has a good side and an evil side. transformation, turning into a sulky monster. "It's so unfair - I hate you!" he tells his astonished parents.

This is a caricature of what happens in adolescence - but it contains some truth. "The teenage years can feel like a shocking transformation," observes science writer David Robson. It is "a turning inside out of the mind and soul that renders the person unrecognisable from the child they once were."

This includes uncontrollable mood swings, identity crises and hunger for social approval, as well as risk-taking. According to psychologist Terri Apter, they are simply a product of enormous physical changes to the brain.

Compared to other scientific challenges such as outer space, our ignorance of the subject is huge. But in recent years scientists have managed to chart the neuralRelating to the nerves. changes that occur in adolescence.

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. , before getting 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 prune connections into early adolescence.

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

But some parts of the brain develop more quickly than others. The ones linked to reward develop faster than those linked to self-control. This increases impulsive, risky behaviour.

There is also increased activity in the area which encourages friendship - but it can result in worry about what people think of you.

Some of these changes have a positive side. Rebelliousness can change society for the better.

There have certainly been some extraordinary teenagers. In 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 that people in London literally fought for seats to see him.

"With the right support," writes David Robson, "that mental explosion may feel less like a shocking jolt, and more like a burst of fireworks: dramatic, yes, but also creative, awe-inspiring and beautiful."

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.

Jekyll and Hyde - From a book by Robert Louis Stevenson, used to describe someone who has a good side and an evil side.

Neural - Relating to the nerves.

Neurons - Neurons, also known as nerve cells, are cells in the nervous system that use chemical or electrical signals to transmit information throughout the body. 

Plasticity - Easily shaped or adaptable.

Frontal cortex - A region of the brain linked to behaviour, personality and decision making.

Parietal lobes - Includes areas concerned with sensory information.