This Horizon Scan articulates Foresight's objective of providing Government and others with challenging visions of possible futures. It is based on scientific evidence of the state of play at the time of writing (September 2004 to May 2005), and builds on this evidence base to look at possible future change. It does not offer predictions, but it does raise issues and possibilities that policy makers and others might wish to consider. Some are more speculative than others. As this report looks out to 2025 and future possibilities, it inevitably challenges current thinking.