Ageing population to become one of the most significant 21st Century transformations: UN

According to the United Nations: "Population ageing is poised to become one of the most significant social transformations of the twenty-first century." Nearly all countries in the world will have more older people by number and also proportion of their population than ever before. Scientists in the United States are predicting that there will soon be drugs that could help defy the ageing process, and so help people live more healthily for longer. The BBC's Fergus Walsh has been to America to meet some 'superagers' and the scientists leading the research