In 1694, the Dutch microscopist Nicolaas Hartsoeker published drawings that showed miniature mini-humans in sperm, replete with head, hands, and feet all tucked origami-like into the sperm’s head, that he had apparently observed under the microscope. The riddle for cell biologists was to prove how a creature as complex as a human could emerge from a fertilized egg if there wasn’t a preformed template already present inside it.
