Toshiyuki Nakagaki and colleagues of the Bio-Mimetic Control Research Centre, Nagoya, Japan, show that a single-celled organism can negotiate the shortest way out of a maze.
Pieces of the slime mould Physarum polycephalum placed in a 30 cm2 maze join up and expand to fill all available space.
But when two pieces of food are placed at separate exit points in the labyrinth, the organism withdraws itself from dead ends until its entire 'body' runs between the two nutrients along the shortest possible route. Effectively, it solves the puzzle.
"This remarkable process of cellular computation implies that cellular materials can show a primitive intelligence," the researchers say.
An amoeba goes for the food, and withdraws from dead ends in a maze.