This episode explores how drugs, foods, poisons, cosmetics and assorted bodily malfunctions can produce human skin in all 7 colours of the rainbow (and how Isaac Newton is to blame for us thinking a rainbow has 7 colours in the first place).

Dehydration. Too much water. Too much exercise. Not enough exercise. Apparently almost anything can cause a muscle cramp. This episode explores why your muscles occasionally seize without permission, what your nervous system has to do with it, and whether magnesium actually helps.

How can the hunk of meat in your mouth ‘know’ what the food smeared over it tastes like? This episode explores what actually makes something sweet, sour, salty, bitter or umami, and what maggot-infested cheese, antifreeze and a poisoned Roman emperor have to do with it.

Spoiler alert: yes. A nosebleed may have finished off one of history's most feared warlords. This episode explores why noses bleed so dramatically, the ingenious anatomy hidden inside your nostrils, exactly what to do the next time your nose starts gushing... and one of the strangest nosebleed case reports ever published.

Your blood is always red. So why the bruise rainbow? This episode explores the colourful chemistry of bruises, from love bites and cupping to creatures with blue, green and yellow blood - and what Tiffany & Co.'s famous turquoise packaging has to do with it.

This episode explores the history hidden inside your belly button, from Renaissance arguments over whether Adam had a navel, to the doctor who classified sixty different types of belly button, to the German students who deliberately collected facial scars to improve their marriage prospects.

Classify your own belly button using Thomas Cullen's 1916 guide.

The marathon wasn't designed by sports scientists. It was shaped by an ancient legend, a royal whim, and one spectacularly bad Olympic experiment involving purposeful dehydration, brandy, and rat poison.

A famous biology textbook diagram. A Harvard psychologist called Edwin Boring. And somehow... netball. This episode explores the mad history of the tongue map, and why taste exists in the first place.