Science is constantly changing and deepening our understanding of ourselves and our planet. So is it time to give scientists a more prominent role in the debate about humanity's strategic choices; economic, political and environmental?HARDtalk’s Stephen Sackur speaks to Sir John Sulston, a Nobel Prize-winning molecular biologist who has led a Royal Society study into the global impact of population growth two decades on from the Rio Earth Summit. Can science help the human species change its ways?