How to grow an arm

Using tiny electrical currents to go from stump to fully functioning appendage

By Rachel Feltman

Updated on Jun 2, 2021 10:32 AM EDT

New Arm
The process is as fast as normal human fetal growth. That means a 25-year-old solder who lost an arm to a roadside bomb would have to wait a decade, until the age of 35, for the arm of a middle-schooler—but one that would be fully functioning. Illustration by Todd Detwiler

This article explains a theoretical limb regeneration process being developed by bioengineer Michael Levin. Read our profile of him here.

man missing an arm
Biodome
Ion Flood
Gene Trigger

This article was originally published in the January/February 2017 issue of Popular Science, under the title “How To Grow An Arm.”