Any reader who has grown up with a pet dog cannot have failed to notice that the effects of advancing age in dogs are not very different from those apparent in aging grandparents, except that in calendar time they appear more rapidly. Although domesticated animals may present a special case compared with wild animals that hardly survive to the age of sexual maturity, a few wild animals do survive and they also exhibit these common effects of human aging. Very close to human sympathies are the observations of elderly chimpanzees by naturalists who, having followed their stable groups for many years, write that the rare creature that has successfully survived the challenges of the wild exhibits the same thinning hair, slow movements, and sagging and wrinkled facial skin as the elderly human (Hill et al. 2001). And given the laboratory studies of hearing in old monkeys (Bennett et al. 1983) and examinations of cochlear pathology in postmortem studies of aged pet dogs (Shimada et al. 1998), this wrinkled and slowly moving chimpanzee and the graying and arthritic dear old pet must both suffer from poor hearing as do elderly humans.