IF life is chemical adaptation to a heat cycle, And "The dependence of Tm on base composition is linear increasing 0.4 C for every percent increase in GC content." (ex. 40% GC = Tm 87C. 60% GC = Tm 95C) Then once we know the temperature range of the heat cycle in the environment then, we will know the GC percentage - or vice versa. If we know the GC percentage we would have a major clue to the temperature range then. Comment?