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Establishing the Criteria for Early Life on Earth

Part of the Topics in Geobiology book series (TGBI, volume 31)

A significant but widely ignored problem in early life studies concerns our reliance upon inductive lines of reasoning. More specifically, there has tended to be too much reliance upon evidence that is ‘consistent with’ microbes, without falsifying or rejecting (sensu Popper, 1959) other possible non-biological scenarios that may likewise be consistent. We have tended to ask ‘what do these structures remind us of’, rather than ‘what are these structures’? Recognition of the need for testing a null hypothesis of a non-biological origin for the earliest fossil evidence therefore forces us to face up to, and overcome, this very human tendency. Arguments of the kind: ‘absence of evidence is not evidence of absence’ are also highly insecure in the high-stakes search for early life, and are incompatible with evolutionary studies of all kinds.

Attempts have been made to establish sets of more rigid criteria that any claims for early life should adhere to. These are here divided into criteria used to demonstrate the antiquity of a given structure and those used to demonstrate the biogenicity of a structure.

Keywords

Agate Sedimentation Geochemistry Fractionation Pyrite 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Recommended Reading

  1. Awramik, S. M., 1976, The relationship between morphology, microstructure and microbiota in three vertically intergrading stromatolites from the Gunflint Iron Formation, Canadian Journal of Earth Sciences 16: 484–449.CrossRefGoogle Scholar
  2. Awramik, S. M., Margulis, L., and Barghoorn, E. S., 1976, Evolutionary processes in the formation of stromatolites. In: Walter, M. R. (Ed.) Stromatolites, Elsevier, Amsterdam, pp. 149–162.CrossRefGoogle Scholar
  3. Brasier, M. D., Green, O. R., and Mcloughlin, N., 2004, Characterization and critical testing of potential microfossils from the early Earth: the Apex ‘microfossil debate’ and its lessons for Mars sample return, International Journal of Astrobiology 3: 1–12.CrossRefGoogle Scholar
  4. Brasier, M. D., Green, O. R., Lindsay, J. F., McLoughlin, N., Steele, A., and Stoakes, C., 2005, Critical testing of Earth';s oldest putative fossil assemblage from the ~3.5 Ga Apex Chert, Chinaman Creek, Western Australia, Precambrian Research 140: 55–102.CrossRefGoogle Scholar
  5. Brasier, M. D., McLoughlin, N., and Wacey, D., 2006, A fresh look at the fossil evidence for early Archaean cellular life, Philosophical Transactions of the Royal Society B 361: 887–902.CrossRefGoogle Scholar
  6. Buick, R., 1984, Carbonaceous filaments from North Pole, Western Australia: are they fossil bacteria in Archaean stromatolites? Precambrian Research 24: 157–172.CrossRefGoogle Scholar
  7. Buick, R., 1988, Carbonaceous filaments from North Pole, Western Australia: are they fossil bacteria in Archaean stromatolites? A reply, Precambrian Research 39: 311–317.CrossRefGoogle Scholar
  8. Buick, R., 1990, Microfossil recognition in Archaean rocks: an appraisal of spheroids and filaments from 3500 M.Y old chert-barite at North Pole, Western Australia, Palaios 5: 441–459.CrossRefGoogle Scholar
  9. Buick, R., Dunlop, J. S. R., and Groves, D. I., 1981, Stromatolite recognition in ancient rocks: an appraisal of irregularly laminated structures in an early Archaean chert-barite unit from North Pole, Western Australia, Alcheringa 5: 161–181.CrossRefGoogle Scholar
  10. Cady, S. L., Farmer, J. D., Grotzinger, J. P., Schopf, J. W., and Steele, A., 2003, Morphological biosignatures and the search for life on Mars, Astrobiology 3: 351–368.CrossRefGoogle Scholar
  11. Grey, K., Hickman, A. H., Hofmann, H. J., Van Kranendonk, M. J., and Williams, I., 1999, Pilbara Archaean stromatolite excursion field guide, Western Australia Geological Survey Record.Google Scholar
  12. Grotzinger, J. P., and Knoll, A. H., 1999, Stromatolites in Precambrian carbonates; evolutionary mileposts or environmental dipsticks? Annual Reviews of Earth and Planetary Science Letters 27: 313–358.CrossRefGoogle Scholar
  13. Grotzinger, J. P., and Rothman, D. H., 1996, An abiotic model for stomatolite morphogenesis, Nature 383: 423–425.CrossRefGoogle Scholar
  14. Hofmann, H. J., 2000, Archaean stromatolites as microbial archives. In: Riding, R. E., and Awramik, S. M. (Eds.) Microbial Sediments, Springer, Berlin.Google Scholar
  15. Hofmann, H. J., 2004, Archean microfossils and abiomorphs, Astrobiology 4: 135–136.CrossRefGoogle Scholar
  16. Lowe, D. R., 1994, Abiological origin of described stromatolites older than 3.2 Ga, Geology 22: 387–390.CrossRefGoogle Scholar
  17. McLoughlin, N., 2006, Earth'Earliest Biosphere: Western Australia, D.Phil. thesis, Oxford University.Google Scholar
  18. McLoughlin, N., Brasier, M. D., Wacey, D., Green, O. R., and Perry, R. S., 2007, On biogenicity criteria for endolithic microborings on early Earth and beyond, Astrobiology 7: 10–26.CrossRefGoogle Scholar
  19. Pope, M. C., and Grotzinger, J. P., 2000, Controls on fabric development and morphology of tufas and stromatolites, uppermost Pethei group 1.8 Ga, Great Slave Lake, NW Canada. In: Carbonate sedimentation and diagenesis in the evolving Precambrian world, SEPM Special Publication 67: 103–121.Google Scholar
  20. Popper, K. R., 1959, The Logic of Scientific Discovery, Hutchinson, London, 480 p.Google Scholar
  21. Schopf, J. W., and Walter, M. R., 1983, Archean microfossils: new evidence of ancient microbes. In: Schopf, J. W. (Ed.) Earth's Earliest Biosphere, Its Origin and Evolution, Princeton University Press, Princeton, NJ, pp. 214–239.Google Scholar
  22. Semikhatov, M. A., Gebelein, C. D., Cloud, P., Awramik, S. M., and Benmore, W. C., 1979, Stromatolite morphogenesis: progress and problems, Canadian Journal of Earth Sciences 16: 992–1015.Google Scholar
  23. Seong-Joo, L., and Golubic, S., 1999, Microfossil populations in the context of syn-sedimentary micrite deposition and acicular carbonate precipitation: Mesoproterozoic Gaoyuzhuang Formation, China, Precambrian Research 96: 183–208.CrossRefGoogle Scholar
  24. Sugitani, K., Grey, K., Allwood, A., Nagaoka, T., Mimura, K., Minami, M., Marshall, C. P., Van Kranendonk, M. J. and Walter, M. R., 2007, Diverse microstructures from Archaean chert from the Mount Goldsworthy-Mount Grant area, Pilbara Craton, Western Australia: microfossils, dubiofossils, or pseudofossils? Precambrian Research 158: 228–262.CrossRefGoogle Scholar
  25. Turner, E. C., James, N. P., and Narbonne, G. M., 2000, Taphonomic control on microstructure in early Neoproterozoic reefal stromatolites and thrombolites, Palaios 15: 87–111.Google Scholar
  26. Walter, M. R., 1976, Stromatolites (Ed.), Elsevier, Amsterdam, 790 p.Google Scholar
  27. Westall, F., and Folk, R. L., 2003, Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone belt: implications for the search for life in ancient rocks, Precambrian Research 126: 313–330.CrossRefGoogle Scholar

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