Summary: This week, the world of parasites. We find out what's living in you and on you, how these invaders hijack your immune system and how they can even control the behaviours and body shapes of their hosts. Plus, in the news, the oldest remains of our first human ancestors are uncovered in Ethiopia, scientists weigh a stegosaurus and NASA's Dawn probe reaches the dwarf planet Ceres, but what awaits it there...?
