Network-engineering problems can be solved by surprisingly simple creatures

FROM adhesives that mimic the feet of geckos to swimsuits modelled on shark skin, biologically inspired design has taken off in recent times. Copying nature’s ideas allows people to harness the power of evolution to come up with clever products. Now a group of researchers has taken this idea a step further by using an entire living organism—a slime mould—to solve a complex problem. In this case, the challenge was to design an efficient rail network for the city of Tokyo and its outlying towns.

Slime moulds are unusual critters—neither animal, nor plant nor fungus. If they resemble anything, it is a colonial amoeba. Physarum polycephalum, the species in question, consists of a membrane-bound bag of protoplasm and, unusually, multiple nuclei. It can be found migrating across the floor of dark, damp, northern-temperate woodlands in search of food such as bacteria. It can grow into networks with a diameter of 25cm. …