Biologists are to begin a 10 year international project to map the multitude of different kinds of cell in the human body. The average adult is built of 37 trillion cells and if you look in a text book, it will say there are about 200 distinct varieties of cells. But this is a grand underestimate. There could in fact be 10,000. The Human Cell Atlas project aims to identify every type and subtype of cell in every tissue of the body - a massive endeavour which, the cell mappers argue, will have profound benefits for medicine.

Adam Rutherford also talks to zoological archaeologist Angela Perri whose research is aimed at discovering when our ancestors first started to use dogs as 'hunting' technology. Her work involves joining hunts with dogs in the modern day as well as traditional archaeological field work.

He also explores the science behind exploding smart phone batteries and the new international climate agreement to rid the world of hydrofluorocarbons.