Josiah Zayner cursed under his breath as blood pooled under the thin skin of his subject’s leg. He checked for vital signs: no breathing. “I think I might have got the vein on that one accidentally.”

Zayner, who’d just administered an experimental injection, has a Ph.D. in biochemistry and biophysics from the University of Chicago, but to his patient such credentials were meaningless. The leg in question belonged to a Hyla cinerea, a small green tree frog not more than two inches long. The idea was to inject a genetic cocktail to make the frog’s muscles grow larger. A few hours later, the frog was back to its usually hoppy self, but it was touch-and-go for a while.

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“The idea that a homebrew guy could inject a frog and deduce whether the same therapy would work in a person” is a stretch, says Stanford bioethicist Hank Greely. “If this is a step toward successful DIY gene therapy, it is a very small step on a very long path.”