Discover how salt underpins our civilisation, launched wars, built monuments and sparked revolutions.

The horse has been a revolutionary animal in unexpected ways. It has changed how we speak, what we wear and sets the hidden limit for the size of our most massive empires.

This episode asks why mankind is gold-crazy, and discovers that there's a hard-wired reason we lust after it and a microscopic explanation for why it shines.

This episode reveals how cold has the power to turn men into Barbarians, spark history's longest running war and create the concept of race.

Discover how biology and human emotions affect our desire to build gigantic structures.

Discover what makes planet Earth the perfect planet for flight.