| You might be looking in the wrong place.
Ageing and death by old age seems to be regulated by growth harmones coming from a gland in the brain. And it would seem that the bio-clock that pre-determines when the gland will shut down growth harmones can be found in the genes or DNA genetic instructions.
It could be that cell reproduction depends on the amount of harmones produced and as that production slows down the genes are effected in what we call the ageing processes beyond prime time maturity.
Some scientific studies have shown that an active sex life will extend the life span of that individual relative to those less active in later years.
So we might note a "loop-back" of (for lack of a better term) intelligence gathering going on that lets the "gland" know when it is time to shut down some of the harmones.
But that last idea is party based on logical assumptions and remains un-studied in detail (far as I would know).
Cells are replaced about every 6 or 7 years, as far as I know that replacement cycle remains pretty constant over the span of a persons life. But such cells are subject to radical behaviors at times, re: cancer cells.
If you wish to check out some more radical concepts I posted them over in the religion department under the topic "Science & Sin". |