The geological platform for the origin of life on Earth

Resolving the geochemical steps which led to the first living organisms on Earth is perhaps one of the most challenging tasks in science. A prime reason for this challenge is that these steps cannot be reproduced on laboratory benchtops; numerous environmental parameters (including minerals, physicochemical conditions and mixing processes) were present while prebiotic chemistry unfolded, and these factors undoubtedly played significant roles in the final outcome. In this chapter, we argue that any proposed chemical pathway that leads to the formation of a particular biomolecule therefore needs to be placed into the geological context of the early Earth as a whole, a context which was likely very different from the modern Earth in ways that we outline. Further advances in origin of life research will require: (a) identifying key organic synthesis reactions whose requirements can be met by realistic environmental settings; and (b) identifying utility in geochemical reactions that are known to occur abundantly in natural environmental settings. This chapter will show how evidence from Hadean zircons, Archean crustal remnants, computational geodynamic models and observations of other planets can be used to reconstruct the hydrologically and volcanically dynamic geological platform on which prebiotic reaction networks were operating. Within this framework, several geochemical reactions will be highlighted that were likely common and that may have contributed productively to life’s origin. Ultimately, this geological vantage point may help us understand what makes other planets not just habitable but also suitable for independent biogenesis.