已知最古老的生命

目前已知最古老的生命澳大利亞附近海域的海底熱泉沉積物中發現的大約34.2億年前的微生物化石[1][2][4][5],不過有的學者對此並不認可,認為這些在海底熱泉沉積物中發現的東西並不是微生物化石[6]

目前已發現的最早期生命是在海底熱泉沉積物之中發現的[1][2][3]
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科學界的一些理論認為生命最早應起源於37.7億年前[2][7][7]。也有學者認為生命應起源於42.8億年前,即距今大約44.1億年前海洋形成後數億年間生命就出現了[2][3][8]

胚種論

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一些理論認為地球上最早的生命來自外太空[9][10]。雖然目前沒有直接證據支持這種理論,不過發表於2018年的一項研究在一顆距今大約45億年前落到地球的隕石上發現了水和有機物[11]

遺傳學上的證據

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對現在尚存的細菌以及古菌基因組進行分析並構建系統發育樹英語phylogenetic bracketing能找出一個「最後共同祖先」(LUCA),以及細菌與古菌之間共有的一些基因[12][13]。據分子鐘理論的計算,一些研究表明最後共同祖先大約出現於距今44.77到45.19億年前,因為最後共同祖先一定是從最早期的生命進化來的,所以按照這一理論生命的出現應該至少不晚於至今44.77到45.19億年前[7][14]

參考資料

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  1. ^ 1.0 1.1 Cavalazzi, Barbara; et al. Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment. Science Advances. 14 July 2021, 7 (9): eabf3963. Bibcode:2021SciA....7.3963C. PMC 8279515 . PMID 34261651. doi:10.1126/sciadv.abf3963 . 
  2. ^ 2.0 2.1 2.2 2.3 Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; slack, John F.; Rittner, Martin; Pirajno, Franco; O'Neil, Jonathan; Little, Crispin T. S. Evidence for early life in Earth's oldest hydrothermal vent precipitates (PDF). Nature. 2 March 2017, 543 (7643): 60–64. Bibcode:2017Natur.543...60D. PMID 28252057. S2CID 2420384. doi:10.1038/nature21377 . 
  3. ^ 3.0 3.1 Zimmer, Carl. Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest. The New York Times. 1 March 2017 [2 March 2017]. 
  4. ^ Tyrell, Kelly April. Oldest fossils ever found show life on Earth began before 3.5 billion years ago. University of Wisconsin–Madison. 18 December 2017 [18 December 2017]. (原始內容存檔於2021-02-10). 
  5. ^ Schopf, J. William; Kitajima, Kouki; Spicuzza, Michael J.; Kudryavtsev, Anatolly B.; Valley, John W. SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions. PNAS. 2017, 115 (1): 53–58. Bibcode:2018PNAS..115...53S. PMC 5776830 . PMID 29255053. doi:10.1073/pnas.1718063115 . 
  6. ^ Brasier, Martin D.; Green, Owen R.; Lindsay, John F.; McLoughlin, Nicola; Steele, Andrew; Stoakes, Cris. Critical testing of Earth's oldest putative fossil assemblage from the ∼3.5Ga Apex chert, Chinaman Creek, Western Australia. Precambrian Research. 2005-10-21, 140 (1): 55–102. ISSN 0301-9268. doi:10.1016/j.precamres.2005.06.008 (英語). 
  7. ^ 7.0 7.1 7.2 Staff. A timescale for the origin and evolution of all of life on Earth. Phys.org. 20 August 2018 [20 August 2018]. (原始內容存檔於2020-11-11). 
  8. ^ Dunham, Will. Canadian bacteria-like fossils called oldest evidence of life. Reuters. 1 March 2017 [1 March 2017]. (原始內容存檔於2017-03-02). 
  9. ^ Steele, Edward J.; et al. Cause of Cambrian Explosion - Terrestrial or Cosmic?. Progress in Biophysics and Molecular Biology. 1 August 2018, 136: 3–23. PMID 29544820. S2CID 4486796. doi:10.1016/j.pbiomolbio.2018.03.004 . 
  10. ^ McRae, Mike. A Weird Paper Tests The Limits of Science by Claiming Octopuses Came From Space. ScienceAlert. 28 December 2021 [29 December 2021]. (原始內容存檔於2021-12-29). 
  11. ^ Chan, Queenie H. S. et al. Organic matter in extraterrestrial water-bearing salt crystals. Science Advances. 10 January 2018, 4 (1, eaao3521): eaao3521. Bibcode:2018SciA....4O3521C. PMC 5770164 . PMID 29349297. doi:10.1126/sciadv.aao3521. 
  12. ^ Weiss, M.C.; Sousa, F. L.; Mrnjavac, N.; Neukirchen, S.; Roettger, M.; Nelson-Sathi, S.; Martin, W.F. The physiology and habitat of the last universal common ancestor. Nat Microbiol. 2016, 1 (9): 16116. PMID 27562259. S2CID 2997255. doi:10.1038/nmicrobiol.2016.116. 
  13. ^ Wade, Nicholas. Meet Luca, the ancestor of all living things. The New York Times. 25 July 2016 [8 October 2018]. (原始內容存檔於28 July 2016). 
  14. ^ Betts, Holly C.; Putick, Mark N.; Clark, James W.; Williams, Tom A.; Donoghue, Philip C.J.; Pisani, Davide. Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin. Nature. 20 August 2018, 2 (10): 1556–1562. PMC 6152910 . PMID 30127539. doi:10.1038/s41559-018-0644-x. 

外部連結

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