Abstract

In 2009, Tennie et al. proposed the theory of the Zone of Latent Solutions, defined as the range of behaviors an individual of a species can invent independently, i.e., which it can acquire without any form of social learning. By definition, species limited to their ZLS are unable to innovate and/or transmit behavioral traits outside their ZLS, i.e., they lack traits which go beyond the level of the individual—traits resulting from a gradual cultural evolution over successive transmission events [“cumulative culture”, Boyd and Richerson ]. However, this does not exclude an influence of social learning on the population frequency of these behaviors: social learning can facilitate the acquisition of latent solutions and thus speed up and consolidate their spread within a population. Cultures—defined as behaviors at least influenced by social learning—are therefore still possible. Here, we elaborate on the ZLS account and relate it to the theories of Vygotsky who studied the role of social learning in human culture. We argue that the ZLS is a missing phylogenetic “baseline” of Vygotsky’s Zone of Actual Development. Vygotsky’s neglect of a need for a human “baseline ZAD” may have been due to his interpretation of Köhler’s work on great ape behaviors: Köhler used his observations on individual chimpanzees to draw conclusions about the chimpanzee species as a whole, stating that chimpanzees can only copy what they could have invented themselves, thus coming close to the ZLS concept. Vygotsky—studying the range of behaviors individuals could achieve independently—seemingly did not see that Köhler was suggesting a species “baseline”, upon which Vygotsky’s idea of an individual’s ZAD could develop. As a result, Vygotsky also did not see the need for a ZLS for his own study subjects: humans. Yet, there is no reason to assume that humans lack a ZLS, and in fact we present evidence for a human ZLS for tool-use behaviors.