Everyone assumes a lot of things about aging. But it is not necessarily a normal thing. Take lobsters for instance:
http://wiki.answers.com/Q/How_old_do_lobsters_get
As explained in Chapter 5: “Stem Cells” in my book Telomere Timebombs: Defusing the terror of aging, telomerase keeps stem cells alive and so it should come as no surprise that 20% of lobsters’ cells are stem cells. Will you like the book? Well, we got three 4-star reviews and 13 5-star reviews, so the chances are good!