Here we have research to support the role of accumulated senescent cells in degenerative aging: "There is good evidence that senescent cells are not benign. But until now, no one has been able to confirm that they exist in appreciable numbers in old animals. ... the Brown team began to study aging animals - baboons living on a research preserve that ranged in age from 5 to 30. In human years, that age range is roughly 15 to 90. ... For replicative senescence, the most important biomarker is telomere dysfunction-induced foci, or TIFs. Presence of these structures signals that the protective chromosome caps called telomeres have dwindled enough to halt cell division. ... What they found: The number of senescent cells increased exponentially with age. TIF-positive cells made up about 4 percent of the connective tissue cell population in 5-year-olds. In 30-year-olds, that number rose as high as 20 percent."