Two pioneers in the field of gene therapy join us to discuss how they're developing modified viruses to deliver healthy copies of genes to save patients afflicted by lethal genetic diseases. We also hear how energy can be harvested from footsteps and heartbeats to power nanodevices, and how a new SWARM of satellites is about to be deployed to study the Earth's magnetic field from space. Plus, in the news, how "ums" and "ahs" can boost a baby's learning power, how mankind talked his way out of Africa and how scientists are recreating schizophrenia in a Petri dish...