Mode & tempo of evolution of life on earth and possibly elsewhere

In the 1940s, GG Simpson distinguished evolutionary investigations into research on the mode or manner whereby life evolves, and research on the tempo or timeframe wherein it evolves. The former research avenue focuses on evolutionary mechanisms and processes, the latter on the speed whereby evolution occurs as measured over geological, molecular or decimal time. For many years, scholars took for granted that the mechanism whereby life evolves is natural selection and such was argued to occur gradually. But reticulate evolution, drift, and evo-devo on the one hand, and punctuated equilibria theory as well as the recognition of stasis on the other hand, have brought to light the great variety there exists in the mode and tempo of life’s evolution on earth. In this talk, we will review these major modes and tempos of evolution, and we will analyze the lessons that can be drawn for how life possibly evolves elsewhere.