According to @2008kydd, humans were able to accelerate the speed of the ratchet effect via “supernatural” niche construction:
I hypothesize that a portion of the variance which explains the unprecedented increase [in the speed of the ratchet effect] is that a small population of hominins learned to control yet another natural resource, altered states of consciousness … The pivot of this model is a supernatural niche comprised of emotional charged schemas that are positioned in a hierarchy of ancestrally sanctioned values.
Two lines of evidence suggest a unique evolutionary footprint among Homo sapiens: (1) the cultural manipulation of biochemistry, especially the dopaminergic system, in the assigning of salience to ideas, and (2) specific cognitive endophenotypes.
In particular, supernatural niche construction allows for representations to be decoupled from reality by binding them together in cognition:
Though the [supernatural niche construction] mechanism accelerates the ratchet effect, it modulates the runaway potential of decoupled representation by means of cognitive binding: indices of experiment such as new ideas are riveted to symbols of experience such as conformist and prestige bias transmitters in the form of supernatural agents.