At the high level, without delving into specific mechanisms, the consensus view on aging is that it exists in the shadow of natural selection. The selection pressure that drives the spread of changes in genes, systems, biology in general in any given species operates most strongly on early life reproductive success. This inevitably gives rise to systems that perform well initially, but which fall apart later. Expenditure of resources on long-term maintenance loses out to expenditure of resources on short-term reproductive fitness. Aging is a near universal side-effect of evolutionary competition, a race to the bottom that exists because early life reproductive success wins out over repeated reproductive success for a longer period of time.
That a given aspect of an individual's biochemistry can be beneficial in early life and harmful in later life is known as antagonistic pleiotropy. There are many examples at all scales, ranging from the structure and behavior of the adaptive immune system and its limited capacity for memory, to the well-known trade-off between developmental growth and later risk of age-related disease, to activities of specific proteins such VGLL3. There is a great deal of literature on this topic. Today's open access paper thus treads familiar ground in discussing aging as a side-effect of evolutionary pressures, attempting a modestly different framing of the situation.
Despite decades of research, age-related non-communicable diseases (NCDs) remain prevalent even in populations with healthcare access. The conventional explanation invokes "evolutionary mismatch": modern lifestyles clash with ancestral biology. Yet a paradox persists: even individuals maintaining optimal health behaviours eventually develop NCDs. Hunter-gatherers living in ancestral conditions show moderate signs of atherosclerosis, metabolic dysfunction, and immune senescence past age 60-70. This raises the question, "Why are NCDs so difficult to prevent?"
We hereby propose an alternative framework where many NCDs represent not preventable consequences of modern lifestyle, but rather inevitable costs of adaptive mechanisms that were never "designed" to operate over 70 to 90-year lifespans. This "Adaptive Cost Hypothesis" (ACH) reframes NCDs as manifestations of evolutionary trade-offs largely, though not absolutely, between early-life fitness advantages and late-life pathology-trade-offs subject to sharply attenuated selection because they occur long after reproductive success. Late-life pathology is intrinsic to epigenetically programmed adaptive responses, manifesting even under matched environmental conditions. This is not mismatch. It is the inevitable cost of adaptive mechanisms operating beyond their evolved design duration.
View the full article at FightAging
