Jake Leech’s Reviews > Deep Homology?: Uncanny Similarities of Humans and Flies Uncovered by Evo-Devo > Status Update

"A vivid demonstration of such regulation comes from a cute experiment with chick embryos. When posterior spinal tissue that controls the legs was replaced by anterior spinal tissue that controls the wings, the chicks that hatched moved their legs in unison as if they were trying to flap them in a vain attempt to fly."

This is one of the most horrifying things I've ever read.