In article <1993Sep17.111919.5186 at gserv1.dl.ac.uk>,
>I propose (following the original idea from George Martin of Seattle) that it
>is the using up of the proliferative potential which we have in most of our
>bodies that prevents adequate regeneration of damaged cells in any given tissue.
>Thus in older people, I suppose that their tissues cannot maintain themselves
>adequately, because the cells cannot raplace damaged cells efficiently.
>
There is also the very intersting idea that this "finite proliferative
potential" is there for a very good reason. By limiting the number of
cell generations in tissue other than, for example, the gut lining
you provide a very efficient defense against cancer. To be a
"successful" cancer a cell has to knock out this mechanism as well as
the normal controlls on division. If you assume that the two
mechanisms are independant and equally likely to be knocked out by
mutation the chances of you getting cancer in a given period could be
reduced to the square root of the current value if the Hayflick limit
were repealed.
Malcolm McMahon
