Have you ever wondered why orangutans have those flappy cheeks, or why mandrills have such colourful faces, or why vultures are bald, or even why hammerheads have hammer-shaped heads? This episode explains it all. It shows unique animals that managed to survive by evolving from the neck up.

In geological terms, humans have only been around for the blink of an eye. However, we've managed to influence the evolutionary path for many animals.

Some of the most interesting adaptations in the animal world are invisible. They are internal adaptations that have helped different animals survive in amazing and unseen ways.

The question of sight can be one of life or death in the animal world. See how some creatures have evolved to see perfectly while others can be nearly invisible.

Some animals cooperate to survive. Some animals even put the welfare of the group above their own reproductive potential. This episode explains how cooperation works in the animal world.

From the shark to the horseshoe crab, meet our planet's 'living fossils' - the creatures that have survived relatively unchanged for millions of years.