Before the discovery of evolution there were some strange theories about heredity. Few were as weird as perhaps the most prevalent, the theory of the homunculus. This is the idea that a fully articulated tiny human person was passed in sperm from man to woman for gestation. One would suppose the invention of the microscope would have been the end of this speculation. But it was not. At least two early researchers claimed to have discovered little floating people in the 1600s. The theory of the homunculus is called "preformation" Preformation is dead, but the homunculus lives on as a neuroscientific map of the perception of our bodies' sensations in the brain:
