Reactions to a recent half-marathon likely fall into two camps. Some will marvel at the sight; others may feel a quiet, uncanny unease beneath the spectacle.

Last month in Beijing, a half-marathon pitted humans against humanoid robots in parallel lanes. The robots, thin arms and legs pumping at high speed, swiftly pulled ahead of the human runners beside them.

A robot named “Lightning” covered the 21-kilometer course in 50 minutes and 26 seconds, outpacing every human entrant and beating the human world record by nearly seven minutes.

At the same event a year earlier, the fastest robot needed roughly two hours and 40 minutes to finish. The leap in speed lays bare just........

© The Asahi Shimbun