Contrasting patterns of Organismal versus Molecular Evolution

    The contrast between biological evolution and molecular evolution since the divergence of the human and chimpanzee lineages. A: More biological change has taken place in the human lineage (y) than in the chimpanzee lineages (x), such that they are traditionally classified in separate families (Hominidae and Pongidae, respectively). B: Protein and nucleic acid evidence indicates that  essentially identical amounts of genetic change have occurred in chimpanzee genes (w) as in human genes (z) since their common ancestor. C: The amount of genetic differences between chimps and humans is less than that between morphologically-identical sibling species of Drosophila. One unit of genetic distance corresponds roughly to an average difference of one amino acid substitution per protein. (Wilson 1976, from King and Wilson, 1975)