Finding a second sample of life on earth

P. C.W. Davies, Charles H. Lineweaver

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


If life emerges readily under Earth-like conditions, the possibility arises of multiple terrestrial genesis events. We seek to quantify the probability of this scenario using estimates of the Archean bombardment rate and the fact that life established itself fairly rapidly on Earth once conditions became favorable. We find a significant likelihood that at least one more sample of life, referred to here as alien life, may have emerged on Earth, and could have co-existed with known life. Indeed, it is difficult to rule out the possibility of extant alien life. We offer some suggestions for how an alternative sample of life might be detected.

Original languageEnglish (US)
Pages (from-to)154-163
Number of pages10
Issue number2
StatePublished - Apr 2005
Externally publishedYes


  • Biogenesis
  • Impact frustration
  • Origin of life

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Space and Planetary Science


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