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Classic Models (Medawar, Williams, Hamilton, Kirkwood)

Simple Summary

  • Idea: Aging is not “on purpose” — it reflects damage accumulation and selection tradeoffs (antagonistic pleiotropy) with finite investment in repair (disposable soma).
  • Predictions: increasing repair generally trades off with reproduction/fitness; rejuvenation is constrained by maintenance budgets; no adaptive lifespan setpoint is required.

Conflicts With Other Theories

  • Epigenetic Information (Sinclair)
    • Sinclair: State reset can yield large gains with limited costs.
    • Classics: Expect visible tradeoffs (e.g., tumor risk, impaired function) or modest gains; big low‑cost wins challenge this view.
  • SENS Damage Repair (de Grey)
    • SENS: Combined repairs can extend max lifespan significantly.
    • Classics: Diminishing returns/toxicity should limit gains; large, safe extensions push beyond budget constraints.
  • Pathogen Control (Lidsky)
    • PC: Longevity gains often trade off with infection ecology.
    • Classics: No intrinsic infection penalty required; tradeoffs are resource‑based. If rejuvenation under pathogen challenge shows no infection downside, that favors Classics; if penalties appear without anti‑pathogen measures, it favors PC.
    • PC highlights lifespan differences that track population structure (dispersal, eusociality, cohorting) — patterns Classics do not naturally predict.
  • Resilience / Criticality (Fedichev)
    • Resilience: Hazard can shift by tuning system dynamics.
    • Classics: Large, low‑cost hazard shifts are surprising without underlying resource tradeoffs.
  • Bioelectric / Morphogenetic Control (Levin)
    • Levin: Pattern cues can rejuvenate without large repair budgets.
    • Classics: Strong, low‑cost gains via pattern cues would strain damage/repair budget framing.
  • Longevity Bottleneck (Various Proponents)
    • Bottleneck: A small number of pathways dominate aging.
    • Classics: Diffuse damage/tradeoffs across systems; single chokepoints are unlikely to explain most aging.

Questions

Sources

  • Foundational: Medawar (1952), Williams (1957), Hamilton (1966), Kirkwood (1977)