This week, we bring you the highlights of the Naked Scientists trip to South Africa. We explore what life is like in the poor regions of Johannesburg, and how the frightening reality of HIV and AIDS offers a silver lining in prevention research. Plus, In a journey through our evolutionary history, we come face to face with the two-and-a-half million year old Taung child, one of the most important human ancestor fossils ever found. Also, we find out why a moon like ours is rare in the universe, how opals get their colours and how mice choose a mate by smelling their wee. And in kitchen science, we learn how to throw your voice huge distances with the aid of a satellite dish.