Re-Evaluating the Probability of the Emergence of Intelligence Using Suitable Terrestrial Data

Bayesian models have been used to infer the prevalence of life and intelligence elsewhere in the universe for several decades. In most, the emergence of intelligent life is judged against the time it took to emerge following the emergence of life as whole. However, such approaches are flawed in that they do not relate the emergence of “intelligent traits” to the absolute requirement for high rates of metabolism to support high levels of cognitive activity. They also make temporal assumptions that are based on fossil evidence, which is incomplete, particularly when one goes back to the Archaean. Instead, we provide a series of analyses, using simple Bayesian modelling to investigate the probability of two processes arising on Earth: endothermy and intelligent behaviours, the latter referred to as abstraction. The emergence of these traits is judged against known prior events, such as the origin of life (OoL); the Great Oxidation Event (GOE) and the Neoproterozoic Oxygenation Event (NOE). Likewise, we evaluate different plausible requirements for the emergence of abstract behaviours. The models show that there is a marginal preference for the requirement of oxygenation at the NOE over other events for the evolution of endothermy. However, such models are not fully able to distinguish preferences for the emergence of abstract behaviours. Finally, using the same approaches, we show that the emergence of Apes from other Primate lineages has a lower than expected probability.