Evo-devo Computational Comparison of Evolvable Soma Theory of Ageing and Standard Evolutionary Ageing Theories

The relationship between evolution, which drives fitness enhancement, and ageing, which leads to a decline in fitness, remains an unresolved puzzle in biology. Intuitively, random changes—the primary mechanism of evolution—are expected to be more harmful than beneficial, causing widespread detrimental effects on fitness. The Evolvable Soma Theory of Ageing (ESTA) proposes that ageing results from the cumulative impact of these harmful effects, which primarily cause bodily damage, while a few lead to beneficial adaptations that evolution can harness. This work compares ESTA with mutation accumulation, antagonistic pleiotropy, and disposable soma theories, collectively referred to as the Standard Evolutionary Ageing Theory (SEAT). While SEAT views ageing as a byproduct of diminishing evolutionary pressure, ESTA posits that ageing represents in essence evolution in action. Simulations are performed using a developmental system where genes are linked to onset values that determine their expression, and demonstrate that ESTA achieves superior evo-devo efficiency compared to SEAT. Specifically, our results highlight that the core features of ESTA—fitness evaluation distributed across multiple steps, onset-dependent mutation rates and evolvable gene onsets—are critical for its enhanced performance.