I would try and get across the idea that science is not just about what we know, but about how to investigate what we do not know. What drives scientists like myself is a sense of curiosity, about what we do not understand. Sadly, for young people exposed to science for the first time, science lessons can be mostly about the vast number of facts that we do know. This great weight of facts neither inspires nor engages.

I think the most important scientific insight is that life evolved - beginning as a self-sustaining set of chemical reactions within some membrane, three billion years ago; changing the atmosphere when photosynthesis was invented, perhaps two billion years ago; giving rise to air-breathing, multicellular life, perhaps one billion years ago; and blindly unfolding until humans evolved, with brains sufficient to reveal and contemplate this apparent miracle.

This is important, because it forces us to think critically about words such as 'natural' or 'species'. We now have enormous responsibility for the state of the planet. To discharge this responsibility intelligently we must be well-informed, and we must have no illusions about some Garden of Eden to which we wish to restore the planet. We need to work with the grain of nature, based upon rigorous science and hard-headed realism, rather than utopian fantasy.

What we actually need to do, is to move beyond the patterns of behaviour for which we evolved - maximising our individual reproductive success - and pursue our enlightened self-interest. This involves not over-fishing, pursuing highly productive genetics-based agriculture, sustainable energy for transport, maintenance of tropical forests, and ultimately, reducing the human population size - for a better quality of life for ourselves, and for the species with which we share the planet.