Sticky fingers

Spend time anywhere in southern Europe and it won't be long before you spot a gecko, blithely disregarding gravity, running over walls, ceilings and windows at all angles.

How they do it has been a mystery for centuries, but the secret has now been cracked - and BAE Systems' researchers have made a major advance replicating it.

The answer is in the texture of the gecko's feet. The skin of the underside of each toe isn't sticky or tacky as we understand it, but hairy. Each toe is covered by ridges which are coated in millions of hairs, whose ends are split into a multitude of filaments. Each of these ends in a mushroom-shaped cap called a spatula, less than a micron in diameter. It's these that keep the gecko stuck to the wall, and the force that does it is one of the weakest known to science - van de Waals attraction.