David Attenborough's Natural Curiosities Episode Rating Graph

David encounters two examples where Nature has tinkered with the aging process to alarmingly different effect – the first grows old while trapped in a young body while the second looks old from birth but might hold the key to a long life.

Hybrids can be bizarre and they can be deadly. We look at two hybrid animals that owe their existence to human interference – the pizzly bear (a cross between a polar bear and grizzly), which has come into being because of global warming, and the killer bee brought into existence because of the transfer of African bees to South America.

The bodies of some animals stretch and shrink in extraordinary ways. The anaconda can swallow prey twice its own body size - and then wait for over a year until their next meal. The camel’s curious hump can almost double in weight giving it the energy to travel huge distances across deserts. What is the secret behind these expandable bodies?

Orangutans can use tools but such skills remained undiscovered for centuries. They were considered as just clever mimics until discovery in remote Sumatran swamps revealed their true potential. Clever crows also make surprisingly sophisticated tools. How have the curious minds of these two animals helped them become so inventive?

The giant panda gives birth to the smallest baby of any mammal and has to care for and protect it for many months. The kiwi lays one of the largest eggs in the bird world, which produces a very well developed chick. Why don’t pandas give birth to more developed, robust young and why do kiwis produce a single egg that is a quarter of its body mass and almost too big to lay?

Humans are not alone in using medicines against injuries and infection. Some animals protect themselves with natural remedies in the most extraordinary ways. Hippos produce a blood-red “sweat” that acts as a sunblock and helps fight infections, while capuchin monkeys rub themselves with insect-repellent leaves to protect against insect bites.

The Siamese Fighting Fish is so aggressive it will fight its own reflection until it is exhausted. Recent research shows that the fighting behaviour varies and depends on the personality of the fish! Male kangaroos were once pitted against humans in the boxing ring – the most impressive male kangaroos are solid blocks of muscle with a kick that can kill. Why do they fight and what skills must a winner have?