The UN forecasts that the world's population will reach 11 billion by the end of this century - a 50% increase. But can the Earth feed that many mouths? We ask the head of the UN's population division John Wilmoth, and professor of international development Gordon Conway, whether Thomas Malthus was right that humanity will eventually multiply beyond the capacity of our planet to support us.
Also in the programme, three of our correspondents report on the demographic challenges facing their particular corners of the globe. Is Africa's baby boom a blessing or a curse? Has China peaked too soon? And can industrialised countries such as Germany afford to grow old gracefully? Some countries potentially stand to reap a 'demographic dividend' - we ask demographer Dr Amlan Roy of Credit Suisse to explain precisely what that means.