How can a hamster survive falling from the top of a skyscraper, ants carry over 100 times their own body weight and geckos climb across the ceiling? In the first of this year's Christmas lectures, material scientist and engineer Dr Mark Miodownik investigates why size matters in animal behaviour. He reveals how the science of materials - the stuff from which everything is made - can explain some of the most extraordinary and surprising feats in the animal kingdom.