Why flying dogs are rare: A general theory of luck in evolutionary transitions

•Evolutionary transitions involve a discontinuity in fitness.•First steps in evolutionary transitions involve a nonselectionist chance process.•We provide a systematic account of evolutionary transitions that is non-selective.•Our account is based on a second-order regularity of chance events.

There is a worry that the ‘major transitions in evolution’ represent an arbitrary group of events. This worry is warranted, and we show why. We argue that the transition to a new level of hierarchy necessarily involves a nonselectionist chance process. Thus any unified theory of evolutionary transitions must be more like a general theory of fortuitous luck, rather than a rigid formulation of expected events. We provide a systematic account of evolutionary transitions based on a second-order regularity of chance events, as stipulated by the ZFEL (Zero Force Evolutionary Law). And in doing so, we make evolutionary transitions explainable and predictable, and so not entirely contingent after all.