Here is an interesting paper by João Pedro de Magalhães.
Programmatic features of aging.
João's allegory is good for introducing people to this concept.
If an organism's development is seen as building a house, then developmental processes (which could have a physiological, cellular, or molecular basis) are all the construction workers who perform tasks like laying the bricks, plastering the walls, and carpeting the floors. One would expect these workers to follow a blueprint that would tell them when to stop. But imagine that the blueprint only tells some of the workers when to start and the pace at which to perform their tasks. Provided these are well timed, the workers can construct a functional house with everything in place at a given time, but what happens next? The bricklayer may continue laying bricks after the house is finished, which at first is only a minor inconvenience until living space is substantially diminished, and even the structural integrity of the house is threatened. Likewise, ever-increasing layers of carpets will eventually prevent doors from opening, and ultimately, nobody will be able to get in or out of the house. The programmatic features of aging that originate in development are like instructions to construction workers that tell them the pace at which they must work to build a house that reaches its functional peak, much like reproduction, but do not tell them when to stop and thus eventually their essential tasks early in the house's construction become detrimental and ultimately destroy the house. When looking across species, the pace at which the house is built is inversely proportional to its functionality, and crucially, it will be directly proportional to how quickly it will decay and crumble.
A critical paradigm of aging research is caloric restriction (CR), which was interestingly initially discovered by Clive McCay and colleagues as a test of the hypothesis that stunted growth extends life span (45, 46). Given that CR delays growth and development, it has been hypothesized that CR works, at least in part, by delaying the progression of the genetic program (4, 21). The fact that CR can extend life span even if started well after maturity is irrelevant to the shortsighted watchmaker hypothesis. Going back to the house construction analogy, CR slows down the construction workers and hence the house's functional decline, independent of whether they have finished the house, though of course an earlier slowing down will lead to a greater extension in functionality.
I wonder if continual prostrate growth (beyond what is necessary) in males is also a developmental program that has at least minimal negative effects (incontinence) as people age.
Besides this within this topic, if you have some questions for João Pedro de Magalhães, you can post them here (an upcoming podcast).
