Fig. 2

Phylogenies illustrating the concept of homology. a The bones in a whale’s fin and a human’s hand are homologous. Both sets of bones are descended from the same structure in a common ancestor. Illustration adapted with permission from the Understanding Evolution website. b The words seven in English and sieben in German are homologous. They are both descended from the same word in their common ancestral language. Language phylogeny adapted from Campbell (2004)