In 1924, Spemann and Mangold showed that a small patch of embryonic tissue could induce an entire second body axis - the 'organizer.' This Nature study finds the same master switch in a ctenophore, or comb jelly, one of the earliest-branching animals. Transplanting the blastopore lip of a comb jelly embryo grew a working second mouth and pharynx that fused into a shared stomach, suggesting the organizer is far more ancient than thought - present near the very dawn of animal life.

This episode was generated by AI from the cited research paper.