AND THEY’RE off! Well, some of them. One weak-kneed participant collapsed before the starting line. Another did so a few steps later. A third quickly ran into a railing. Still, the remaining 18 humanoid robots taking part in a Beijing half-marathon on April 19th leapt, skipped or trundled glitchlessly onto a special track in a technology park on the outskirts of the Chinese capital—and into the future. The winner crossed the finishing line in a stately two hours and 40 minutes; five more completed the 21.1km course. Some of the 12,000 human runners (the best of whom covered the distance in just over an hour) looked on, bemusedly.