Science sleuths Drs Rutherford & Fry take on everyday mysteries and solve them with the power of science. Two cases in this episode concerning the inner workings of our bodies, and not for the faint hearted!

Adam bravely sends off a personal sample to the 'Map My Gut' project at St Thomas' Hospital to have his microbes mapped. Prof Tim Spector reveals the shocking results - a diet of fried breakfasts and fizzy drinks has left his guts in disarray. But help is at hand to makeover his bacterial lodgers.

Science writer Ed Yong, author of 'I Contain Multitudes', reveals how much our microbes weigh. We're just beginning to discover the vast array of vital functions they perform, from controlling our weight, immune system and perhaps even influencing our mood and behaviour.

The average adult human has around 30 trillion red blood cells, they make up a quarter of the total number of cells in the body.

We have dozens of different blood groups, but normally we're tested for just two - ABO and Rhesus factor. Adam and Hannah delve into the gory world of blood and the early history of blood transfusions, to discover why we have blood groups and how they differ around the world.

Featuring interviews with Dr Jo Mountford, from the Scottish National Blood Transfusion Service and immunologist Dr Sheena Cruikshank from the University of Manchester.

If you have any Curious Cases for the team to solve please email [email protected].

Presenters: Adam Rutherford, Hannah Fry

Image: Illustration of red blood cells in a blood vessel. Copyright: Science Photo Library