Academic Journal
The hard steps model and whole Earth-system transitions.
| Τίτλος: | The hard steps model and whole Earth-system transitions. |
|---|---|
| Συγγραφείς: | Watson A; Global Systems Institute, University of Exeter, Exeter, UK. |
| Πηγή: | Philosophical transactions of the Royal Society of London. Series B, Biological sciences [Philos Trans R Soc Lond B Biol Sci] 2025 Aug 07; Vol. 380 (1931), pp. 20240105. Date of Electronic Publication: 2025 Aug 07. |
| Τύπος έκδοσης: | Journal Article |
| Γλώσσα: | English |
| Στοιχεία περιοδικού: | Publisher: Royal Society Country of Publication: England NLM ID: 7503623 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1471-2970 (Electronic) Linking ISSN: 09628436 NLM ISO Abbreviation: Philos Trans R Soc Lond B Biol Sci Subsets: MEDLINE |
| Imprint Name(s): | Original Publication: London : Royal Society, 1934- |
| Ιατρικοί όροι (MeSH): | Earth, Planet* , Evolution, Planetary* , Biological Evolution* , Origin of Life* , Models, Theoretical*, Exobiology ; Extraterrestrial Environment ; Planets |
| Περίληψη: | The hard steps model is a 'toy' mathematical representation of evolution towards complex life on Earth or Earth-like planets. It assumes that, at the longest time scale, the rate of evolution towards increased complexity is governed by unlikely transitions that happen randomly and rarely. Applied to Earth, the model suggests a small number of such transitions in the pathway to 'intelligent observers'-humans. The transitions are usually envisaged as occurring instantaneously, but this ignores the reality that on Earth, the evolution of life and the planetary environment have been inextricably linked. The critical steps should be seen as initiating whole Earth-system transitions that take hundreds of millions of years to complete, as in the events that caused, and followed after, the Paleoproterozoic and Neoproterozoic glacial episodes. These were both caused by, and drivers of, evolutionary advances that were necessary for complex life to arise. I adapt the model to include such delays and show that it then suggests just two or three hard steps to humans. The model predicts that the search for biosignatures in exoplanet atmospheres may find planets with Archean-like atmospheres, but probably will not find the signature of a planet with a Proterozoic or modern Earth-like atmosphere.This article is part of the discussion meeting issue 'Chance and purpose in the evolution of biospheres'. |
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| Grant Information: | Royal Society |
| Contributed Indexing: | Keywords: astrobiology; biosignatures; evolution; exoplanets |
| Entry Date(s): | Date Created: 20250807 Date Completed: 20250807 Latest Revision: 20250809 |
| Update Code: | 20260130 |
| PubMed Central ID: | PMC12329452 |
| DOI: | 10.1098/rstb.2024.0105 |
| PMID: | 40770984 |
| Βάση Δεδομένων: | MEDLINE |
| ISSN: | 1471-2970 |
|---|---|
| DOI: | 10.1098/rstb.2024.0105 |