Breakthroughs in molecular biology are revolutionizing our understanding of the history and relationships of hominid primates. Orangutans depart from the combined African great ape and human line about 13 mya. The great ape (or gorilla) lineage splits from the combined chimpanzee and human lineage some eight mya. We share over 99 percent of expressed DNA with chimpanzees. This does not mean that we are "descended" from chimpanzees, but rather, that we last shared a common ancestor eight mya.