How to grow an arm

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

By Rachel Feltman

Updated Jun 2, 2021 10:32 AM EDT

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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 — Illustration by Todd Detwiler

Biodome — Illustration by Todd Detwiler

Ion Flood — Illustration by Todd Detwiler

Gene Trigger — Illustration by Todd Detwiler

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