This episode 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 one of the wonders of evolution.