Sir David Attenborough examines the mysteries behind some of nature's most fascinating creatures and plants.

Orangutans are clever tool users but strangely such skills remained undiscovered for centuries. They were considered clever mimics until a discovery in remote Sumatran swamps revealed their true potential. Crows are clever birds that can solve problems, and they too make surprisingly sophisticated tools. How have the curious minds of these two animals helped them become so inventive?

Some animals can do the seemingly impossible. Salamanders can regenerate entire legs and tails to replace ones they've lost, while deer shed their massive antlers and regrow them from a few remaining cells each year. How do these animals regenerate entire body parts and why is it not possible for all animals to do the same? Show less