Embryo drawings were used in the 20th century as evidence for the theory of common descent in discussions of biological evolution. They compared embryonal stages of different vertebrates and vastly overemphasized their similarities. These similarities were claimed to be evidence that humans and fish evolved from a common ancestor.
The drawings were originally produced by Ernst Haeckel to illustrate his now discredited theory of Ontogeny recapitulates phylogeny. He was later convicted of academic fraud, but the drawings found their way into biology textbooks nevertheless.
In 2000, Harvard professor Stephen Jay Gould called the continued use of these "fraudulent" embryo drawings the academic equivalent of murder. "We do, I think, have the right," he wrote, "to be both astonished and ashamed by the century of mindless recycling that has led to the persistence of these drawings in a large number, if not a majority, of modern textbooks."
The fact that these now discredited drawings overemphasized similarities between embryonal developments is sometimes used as an argument that no such similarities exist, especially by creationists. This is not the view of modern biology however; it is generally accepted that species with a common ancestor pass through similar stages in their embryonal development, see ontogeny and phylogeny. Modern textbooks usually contain photographs to show the similarities in embryo development among related species, and these similarities, such as gill-like structures, are still seen as evidence of the common ancestry of humans and fish.
