An objective Bayesian analysis of life’s early start and our late arrival
David Kipping
Abstract
Significance Does life’s early emergence mean that it would reappear quickly if we were to rerun Earth’s clock? If the timescale for intelligence evolution is very slow, then a quick start to life is actually necessary for our existence—and thus does not necessarily mean it is a generally quick process. Employing objective Bayesianism and a uniform-rate process assumption, we use just the chronology of life’s appearance in the fossil record, that of ourselves, and Earth’s habitability window to infer the true underlying rates accounting for this subtle selection effect. Our results find betting odds of >3:1 that abiogenesis is indeed a rapid process versus a slow and rare scenario, but 3:2 odds that intelligence may be rare.