Finding a second sample of life on Earth

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

    Research output: Contribution to journalArticle

    58 Citations (Scopus)


    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 coexisted 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
    Pages (from-to)154-163
    Number of pages10
    Issue number2
    Publication statusPublished - 2005


    • origin of life
    • biogenesis
    • impact frustration

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