Which came first, the chicken or the egg?

Why do we always find cockroaches on their back? How does medicine know where it hurts? Why do we dream? Why is the Earth still so hot? What came first, the chicken or the egg? Why did Chernobyl explode? How much energy does a seed need to grow? Can we work out how much energy there is in the world? Why do most of us look different? Chris Smith and Clarence Ford answer questions from the students of the International School of Cape Town...