The well-documented human bias toward agency as a cause and therefore an explanation of observed events is typically attributed to evolutionary selection for a social brain.Based on a review of developmental and adult behavioral and neurocognitive data, it is argued that the bias toward agency is a result of the default human solution, developed Obsolete Parts With Alternative Or Secondhand Available during infancy, to the computational requirements of object re-identification over gaps in observation of more than a few seconds.If this model is correct, overriding the bias toward agency to construct mechanistic explanations of observed events requires structure-mapping inferences, implemented by the pre-motor action planning system, that replace agents with mechanisms as causes of unobserved changes in contextual or featural properties of objects.Experiments that would test this Engine Cold Air Intake model are discussed.