Aging is a cumulative process. It does not matter what theory of aging you adopt, what processes are you following in the end will be an accumulation (positive or negative) of changes, proteins, cells etc.
Most of the time, this ‘accumulation’ will result in a constant decline in organism fitness leading eventually to death.
Aging Researchers discovered that modifying one gene in a bacteria (yeast) and in an invertebrate worm could lead to a great life extension. Because of this and because we want things to be simple we started looking for a single fundamental cause o aging and a single biomarker of aging.
But aging does not have a single cause in the same way a car does not because of a single cause.
Aging is the accumulation of many different damages in many different types of cells, tissues, organs leading to many pathologies.
Aging is the complex sum of all evolving diseases.
Some prof that even with negligible senescence … DAMAGE Accumulation matters the most:
longevity in these animals is not limited by investment in (or capacity for) maintenance and repair of damaged tissues.
The lack of age-related differences in the maintenance of tissue homeostasis and regenerative potential in sea urchin species with different lifespans were unexpected in light of current evolutionary theories of aging, and further study is required to understand the factors underlying the short lifespan of L. variegatus in particular.