Precambrian Surface Temperatures and Molecular Phylogeny

Abstract

The timing of emergence of major organismal groups is consistent with the climatic temperature being equal to their upper temperature limit of growth ( T max ), implying a temperature constraint on the evolution of each group, with the climatic temperature inferred from the oxygen isotope record of marine cherts. Support for this constraint comes from the correlation of T max with the rRNA molecular phylogenetic distance from the last common ancestor (LCA) for both thermophilic Archaea and Bacteria. In particular, this correlation for hyperthermophilic Archaea suggests a climatic temperature of about 120°C at the time of the LCA, likely in the Hadean.