In this lesson students compare the DNA sequence data for a portion of the rat GULO gene to the corresponding sequence in the inactive GULO gene (pseudogene) in humans, chimpanzees, orangutans, and crab-eating macaques by identifying the shared sequences in their alignment. They compare the pseudogene sequences and note a shared deletion. In addition, students do an alignment for the first 25 codons of the functional human beta globin gene and its pseudogene in humans, gorillas, and chimpanzees, then compare the pseudogenes and again note a shared deletion, as well as two other shared significant differences from the functional human sequence. Such shared deletions provide strong evidence for shared common ancestry (descent with modification), a natural process of macroevolution.