Interaction Studies - Volume 19, Issue 1-2, 2018

Evolutionary change occurs most often through the modification of pre-existing structures. What were the pre-existing circuits in our primate ancestors that paved the way for human language, and how did they change in the lineages leading to our present condition? Among the neural modifications that were critical for human language, there are two of special interest: The origin and evolution of the remarkably rich conceptual world that humans share to the exclusion of other primates (which made possible increasingly sophisticated communication systems), and the origin of neural circuitry that underlies various sequential and hierarchical aspects of language, as utilized for example in syntax and word morphology. The fossil record of brain evolution and the archaeological record provide intriguing clues about these processes.

I argue that a critical feature of language that distinguishes it from animal communication is displacement, the means to communicate about the non-present. This implies a capacity for mental travels in time and space, which is the ability to call to mind past episodes, imagine future ones or purely fictitious ones, and locate them in different places. While mental travel in time, in particular, is often considered to be unique to humans, behavioral and neurophysiological evidence suggests that it is evident in some form, at least, in nonhuman animals, including rodents, and may go far back in the evolution of animals that move. The linguistic capacity to share experiences that transcend space and time evolved much more recently, accelerating during the Pleistocene with increasing demands for effective cooperation and long-distance planning. The expansion of mental time travel probably co-evolved with the development of language itself, because the sharing of memories, plans, and stories vastly added to our own individual experiences. From this perspective, the critical period of the Road Map runs from the emergence of the genus Homo around 2 million years ago to the present.

We present a new road map for research on “How the Brain Got Language” that adopts an EvoDevoSocio perspective and highlights comparative neuroprimatology – the comparative study of brain, behavior and communication in extant monkeys and great apes – as providing a key grounding for hypotheses on the last common ancestor of humans and monkeys (LCA-m) and chimpanzees (LCA-c) and the processes which guided the evolution LCA-m → LCA-c → protohumans → H. sapiens. Such research constrains and is constrained by analysis of the subsequent, primarily cultural, evolution of H. sapiens which yielded cultures involving the rich use of language.