Language: From How-Possibly to How Probably

Language confronts the human evolution community with an inescapable challenge. The challenge is inescapable because language is both a unique feature of human social life, no other animal has anything like it, and a fundamental feature of human life and cognition. Famously, explaining the emergence of language is also made difficult by evidential considerations. This chapter proposes a set of constraints specifying an empirically and theoretically constrained model of the evolution of language, and presents a partial and skeletal view of the evolution of language that fits that framework as a 'proof of concept'. A classic morphological example of a lineage explanation is the model of eye evolution in Dane-Erik. Communication depends on a complex mosaic of interacting capacities, so a picture of the evolution of language will necessarily be coevolutionary, with changes in one communication-relevant capacity selecting for changes in others.