The ability to bioengineer new living species lies at the frontier of science. In January 2020, a band of US researchers came a step closer to doing this, using stem cells from an African frog (Xenopus laevis) to create a sort of self-organised blob they called the xenobot, in honour of the frog progeny.

       The paper, which had the obscure name, “A scalable pipeline for designing reconfigurable organisms” (www.pnas.org/content/117/4/1853), credited four scientists from Tufts University, Harvard and University of Vermont with this feat. Stem cells are undifferentiated cells ...