Thesis #22 – Repairing molecular or cellular damage will provide at most partial amelioration for the problem of de-tuned adaptation with adult age, because cumulative damage will also occur at organ and systemic levels at every physiological level as a result of the de-tuning of adaptation with age.
One of the basic theories of aging that has enjoyed popularity among cell and molecular biologists is that aging is due to cumulative damage at the cellular and molecular level. Taking this particular reductionist theory as gospel, the charismatic Aubrey de Grey has proposed that we can solve the problem of aging simply by repairing all such damage. In his somewhat Panglossian view, there are only seven types of cell/molecular damage, and there are relatively straightforward ways to repair that damage, he says. On the basis of this line of reasoning, de Grey expects that a sufficiently concerted research effort should be able to overcome aging within the next thirty to fifty years.
Even if we take this “aging is cumulative damage” theory on its own terms, well-trained pathologists would naturally point out that cumulative damage can also occur at the organ and systemic levels. Those addicted to running assiduously pound away on their joints if they run regularly on concrete and other paved surfaces. After the early twenties, our joints no longer re-grow cartilage, so such running can literally wear-away the connective tissue that sustains joint function, progressively hobbling us. The acids in our stomach frequently reflux up into our esophagi, eating away at their tissues, leading to degraded esophageal function, which we experience as heartburn and difficulty swallowing. And this list goes on.
Damage occurs at every level of our bodily machinery. Yes, it always involves changes to molecules and cells, but the causes of cumulative damage are not confined to those levels. Furthermore, the widespread turnover of cells and molecules throughout much of the human body suggests that our bodies already have fairly good machinery for dealing with damage at these lower levels: get rid of damaged cells and replace them with new ones that have not yet been damaged.
Thus, even on their own terms, molecular damage theories of aging do not necessarily lead to elegant technological solutions to the problems of aging, because there are many types of damage that may require repair, some well above the level of individual cells functioning in isolation.