Abstract

H. sapiens stands out from other primates along many social dimensions; however, none seems as prominent and important as the capacity of our species for cumulative cultural evolution or, as Tomasello calls it, “the ratchet.” Although other primate species show evidence of cultural variation, there is little evidence of cumulative cultural evolution, i.e., the gradual accumulation, modification, and refinement of traditions and skills over historical time, in any primate species other than our own. This is clearly an extremely significant component of the human phenotype, responsible for our unparalleled cultural, social, political, and technological achievements. However, it remains extremely controversial what sorts of cognitive capacities are necessary to trigger cumulative cultural evolution and whether any currently proposed candidates are really distinctive of humans. Furthermore, the ratchet raises a bootstrapping problem: before complex skills and technologies are present and necessary for biological success, there appear to be few advantages to high-fidelity social learning; however, without such high-fidelity social learning, it is unclear how traditions capable of generating complex skills and technologies could arise in the first place. In this chapter, we survey relevant empirical research in comparative and developmental psychology, integrating it with a novel theoretical analysis of the bootstrapping problem to defend a hypothesis about the minimal cognitive preconditions on the ratchet.