David Attenborough's Natural Curiosities

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.

The single spiral tusk of the narwhal inspiration for tales of unicorns and the myriad variations on the twist of the snail shell have delighted and fascinated naturalists and artists since the dawn of civilization.

Zebra stripes vary subtly between the different species but there is one group of animals that has evolved colourful patterns of seemingly infinite variety, the butterflies. In this episode David looks at two examples of animal patterns that have bedazzled and baffled science for a long time, and uses modern tools to unlock their secrets.