The Phylogenetic Roots of Language

The anatomy of the nonhuman primate vocal tract is not fundamentally different from the human one. Notwithstanding, nonhuman primates are remarkably unskillful at controlling vocal production and at combining basic call units into more complex strings. Instead, their vocal behavior is linked to specific psychological states, which are evoked by events in their social or physical environment. Humans are the only primates that have evolved the ability to produce elaborate and willfully controlled vocal signals, although this may have been a fairly recent invention. Despite their expressive limitations, nonhuman primates have demonstrated a surprising degree of cognitive complexity when responding to other individuals' vocalizations, suggesting that, as recipients, crucial linguistic abilities are part of primate cognition. Pivotal aspects of language comprehension, particularly the ability to process semantic content, may thus be part of our primate heritage. The strongest evidence currently comes from Old World monkeys, but recent work indicates that these capacities may also be present in our closest relatives, the chimpanzees.