How did the slime mould cross the maze?
Vol. 24 No. 7 ยท 4 April 2002 From Andrew Coulson It is quite true, as Adrian Woolfson says (LRB, 21 March), that in the cellular slime mould Dictyostelium discoideum individual amoebae assemble together (when the food runs out) into a multicellular slug which migrates and then differentiates into a stalked fruiting body. It would be impressive if such a creature could reasonably be said to have ‘learned’ to ‘navigate simple mazes’. However, Toshiyuki Nakagaki’s studies have shown no such thing. These experiments (described in Nature 407, 470) were actually carried out with the acellular (or ‘true’) slime mould Physarum polycephalum, which is a totally different creature with a totally different life-cycle. In particular, there is no self-organisation of independent individuals into a community with emergent complex properties. The maze experiments used the plasmodium phase of the mould, a multi-nucleate single cell, or syncytium. The ‘maze’ consisted of two successive pairs of alternat
