Our body contains literally trillions of cells. It is absurd to think that among all these cells there will be only a few mutations. Mutations will occur in all cell types all over the body.

What I find really interesting is that the mortality distribution in Gompertz's law may be predicted using the Euler-Lotka equation. This says that the reason we die is because there is an absence of selective pressure for the individual in a species to live longer (link: http://www.genetics.org/content/156/3/927.full.pdf)