Did language evolve in multilingual settings?

Accounts of language evolution have largely suffered from a monolingual bias, assuming that language evolved in a single isolated community sharing most speech conventions. Rather, evidence from the small-scale societies who form the best simulacra available for ancestral human communities suggests that the combination of small societal scale and out-marriage pushed ancestral human communities to make use of multiple linguistic systems. Evolutionary innovations would have occurred in a number of separate communities, distributing the labor of structural invention between populations, and would then have been pooled gradually through multilingually mediated horizontal transfer to produce the technological package we now regard as a natural ensemble.