This programme looks at how evolution has overcome the challenges of being as big as an elephant.

Elephants feed on plants with very little nutritional value for 18 hours a day, so evolution has given them vast intestines as well as huge teeth and jaw muscles - and an equally gigantic head. But this produces another problem: how to reach food on the ground.

The solution is the most versatile limb on the planet - the trunk. Capable of everything from picking up berries to ripping a tree from the ground, the trunk is a wonder of evolution. It's a Just So Story for the Darwinian age.