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<p>Recent molecular reconstructions dramatically compress the temporal window available for the origin of life on Earth. Moody et al. (Nature, 2023) dated the Last Universal Common Ancestor (LUCA) to approximately 4.2 Ga—only ~300 Myr after the solidification of Earth’s crust. Geophysical analyses indicate that Earth was volatile-poor and largely anhydrous until the Theia impact event delivered the majority of its surface water reservoirs, further constraining the onset of habitability to a narrow geological interval (Jacobsen. et al. University of Bern Geophysical Report, 2024, Canup in Science 338:1052–1055, 2012). Independent Martian observations from Viking (1976) to Perseverance (2025) have revealed multiple, geographically distributed signatures consistent with ancient metabolic activity (Levin and Straat in J Mol Evol 14:167–183, 1979, Hecht in Science 325:64–67, 2009, Webster in Science 347:415–417, 2015, Giuranna in Nat Geosci 12:326–332, 2019), implying that Mars also achieved habitability and potentially hosted life during the same epoch. The existence of sophisticated antiviral systems in LUCA including restriction–modification complexes, nucleases, and proto-CRISPR elements (Moody. et al. Nature, 2023, Horvath and Barrangou in Science 327:167–170, 2010) necessitates the prior evolution of DNA-based viruses and, therefore, a pre-LUCA biological ecosystem. When these timelines are reconciled with established molecular-clock rates for viral genomic diversification (Wertheim et al. in J Virol 87:7039–7045, 2013, Aiewsakun and Katzourakis in Nat Rev Microbiol 15:210–222, 2017), LUCA-1 (the ancestor of LUCA lacking antiviral defenses) must have originated well before Earth’s hydrosphere formed.These combined constraints produce a logical consequence: independent abiogenesis events on Earth and Mars, each producing complex microbial ecosystems rapidly enough to allow viral–host coevolution, are statistically unlikely within the available time frame. The simplest unifying hypothesis consistent with all data is that life, already genetically and ecologically mature, was transported into the early Solar System, arriving on both planets via panspermia. These findings motivate renewed evaluation of panspermia as a potential unifying explanatory framework for the complexity and early distribution of life in the inner Solar System.</p>

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Implications of Moody et al. for the viability of terrestrial abiogenesis

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  • 发表日期：

    2026年7月6日

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  • Arthur Doucette

摘要

Recent molecular reconstructions dramatically compress the temporal window available for the origin of life on Earth. Moody et al. (Nature, 2023) dated the Last Universal Common Ancestor (LUCA) to approximately 4.2 Ga—only ~300 Myr after the solidification of Earth’s crust. Geophysical analyses indicate that Earth was volatile-poor and largely anhydrous until the Theia impact event delivered the majority of its surface water reservoirs, further constraining the onset of habitability to a narrow geological interval (Jacobsen. et al. University of Bern Geophysical Report, 2024, Canup in Science 338:1052–1055, 2012). Independent Martian observations from Viking (1976) to Perseverance (2025) have revealed multiple, geographically distributed signatures consistent with ancient metabolic activity (Levin and Straat in J Mol Evol 14:167–183, 1979, Hecht in Science 325:64–67, 2009, Webster in Science 347:415–417, 2015, Giuranna in Nat Geosci 12:326–332, 2019), implying that Mars also achieved habitability and potentially hosted life during the same epoch. The existence of sophisticated antiviral systems in LUCA including restriction–modification complexes, nucleases, and proto-CRISPR elements (Moody. et al. Nature, 2023, Horvath and Barrangou in Science 327:167–170, 2010) necessitates the prior evolution of DNA-based viruses and, therefore, a pre-LUCA biological ecosystem. When these timelines are reconciled with established molecular-clock rates for viral genomic diversification (Wertheim et al. in J Virol 87:7039–7045, 2013, Aiewsakun and Katzourakis in Nat Rev Microbiol 15:210–222, 2017), LUCA-1 (the ancestor of LUCA lacking antiviral defenses) must have originated well before Earth’s hydrosphere formed.These combined constraints produce a logical consequence: independent abiogenesis events on Earth and Mars, each producing complex microbial ecosystems rapidly enough to allow viral–host coevolution, are statistically unlikely within the available time frame. The simplest unifying hypothesis consistent with all data is that life, already genetically and ecologically mature, was transported into the early Solar System, arriving on both planets via panspermia. These findings motivate renewed evaluation of panspermia as a potential unifying explanatory framework for the complexity and early distribution of life in the inner Solar System.