I don't believe the fertilised egg can be equated with the sort of human life that you and I represent, or our children represent.

I think it's important for scientists to be a bit less arrogant, a bit more humble, recognising we are capable of making mistakes and being fallacious - which is increasingly serious in a society where our work may have unpredictable consequences.

I don't like seeing myself on television and I don't enjoy filming. What I actually enjoy is thinking about how I am going to express something or how we are going to make the visual metaphor.

Carbon dioxide is unusual because it doesn't go through the usual three phases of matter, from solid to liquid to gas, but it goes straight from solid to gas. The volume of the gas is much greater than the volume of the solid. When a solid turns into a gas, we say it sublimes. The process is sublimation.

Man is a competitive creature, and the seeds of conflict are built deep into our genes. We fought each other on the savannah and only survived against great odds by organising ourselves into groups which would have had a common purpose, giving morale and fortitude.

Over the past 20 years, I have presented many science programmes on BBC1. But none is, I think, more socially important, or of more human interest, than this ongoing series of 'Child of Our Time.'

You can't be judgmental about babies. They are all have different needs. I was left with an enduring hatred of cheese because it was forced down me when I was young.