We propose a multi-layered mechanistic framework explaining the rarity of complex life in the Universe through three sequential, causally linked barriers. Buildingon recent work on evolutionary priority effects in phototrophy (Burnetti et al., 2026), Great Oxidation modeling (Horne et al., 2025), and cellular bioenergetics (Lane Lynch around M-dwarfs, retinal-based phototrophy may lock biospheres into low-energy metabolisms. Filter 2 (geochemical trap): oxygenic photosynthesis triggers phos-phorus sequestration; the resulting oxygenation delay depends on tectonic activity and may exceed the star’s main-sequence lifetime. Filter 3 (complexity barrier):high stellar XUV activity forces life into deep-ocean refugia, reducing photosynthetic energy and raising the energetic threshold for genomic complexity. These filters inter-act via cross-filter feedbacks, forming a network rather than a simple chain (Fig. 1). An illustrative calculation for Earth and TRAPPIST-1e yields a ∼20,000-fold dif-ference in the probability of complex life. The framework is falsifiable and offers concrete predictions for next-generation telescopes (HWO, LIFE).
Tema Igoshev (Sat,) studied this question.