3/3 Sue Broom looks at the future of farming in the worlds' cities.
BBC World Service
2/3 Could new types of maize solve food shortages in Africa? Sue Broom investigates.
1/3 In this week's Discovery Sue Broom investigates the science behind tuna aquaculture.
Rory Cellan-Jones explores the future of the world wide web and the science behind it.
Psychologist Kevin Dutton explores how to transform a situation with extreme persuasion.