Darwin's Predictions
All animals, including humans, descend from a common ancestor.
Darwin knew the idea that man was just another animal would go over like a lead balloon in Victorian society. But in the Origin of Species, he was unequivocal on this notion, writing that "I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from one primordial form, into which life was first breathed." Evidence supporting this view has accumulated ever since, with arguably the strongest support coming from evo devo. Scientists comparing the genomes of members of the three domains of life—archaea, bacteria, and the eukaryotes (animals, plants, fungi, and protists)—have discovered about 500 genes that all living things share. These "immortal" genes have survived essentially unchanged for over two billion years (including the portion of a protein's sequence seen here, with shared amino acids indicated by shading). Says Brown's Ken Miller: "Despite the extraordinary diversity of life, all living organisms share a nearly identical set of essential genes, reflecting their evolutionary development from a common ancestor."