Does life's rapid appearance imply a martian origin?

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The hypothesis that life's rapid appearance on Earth justifies the belief that life is widespread in the universe has been investigated mathematically by Lineweaver and Davis (Astrobiology 2002;2:293-304). However, a rapid appearance could also be interpreted as evidence for a nonterrestrial origin. I attempt to quantify the relative probabilities for a non-indigenous versus indigenous origin, on the assumption that biogenesis involves one or more highly improbable steps, using a generalization of Carter's well-known observer-selection argument. The analysis is specifically applied to a Martian origin of life, with subsequent transfer to Earth within impact ejecta. My main result is that the relatively greater probability of a Martian origin rises sharply as a function of the number of difficult steps involved in biogenesis. The actual numerical factor depends on what is assumed about conditions on early Mars, but for a wide range of assumptions a Martian origin of life is decisively favored. By contrast, an extrasolar origin seems unlikely using the same analysis. These results complement those of Lineweaver and Davis.

Original languageEnglish (US)
Pages (from-to)673-679
Number of pages7
JournalAstrobiology
Volume3
Issue number4
DOIs
StatePublished - Dec 1 2003
Externally publishedYes

Keywords

  • Carter
  • Mars
  • Origin of life
  • Probability theory
  • Transpermia

ASJC Scopus subject areas

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

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