Human language, as far as we know, is unique in the animal kingdom. There has been long-standing academic debate over whether linguistic communication should be viewed as a biological adaptation or a cultural invention.
On the one hand, the range of human articulation far surpasses that of our nearest living relatives, the great apes (chimpanzees, bonobos, gorillas and orangutans), suggesting that we are evolutionarily adapted for speech. On the other hand, there are thousands of human languages, most of them mutually unintelligible, consistent with the idea of cultural selection. Both views, however, are rooted in the idea that humans are neuroanatomically and cognitively distinct from other animals.
We last shared a common ancestor with the other great apes around 6 or 7 million years ago. Yet our brains were, essentially, ape-sized until around 2 million years ago, and did not reach contemporary proportions until sometime within the past 200,000 years. Material evidence suggests that humans used ochre to make drawings on rocks only within the past 75,000 years; and representational objects began to appear in the archaeological record about 40,000 years ago. Unfortunately, speech and gesture do not fossilize, but if we consider that no ape can speak (beyond a tiny handful of laboriously produced utterances) and if we assume that language requires a brain larger than an ape’s, we can define a window of time between, roughly, 2 million years ago and 40,000 years ago in which spoken language emerged. Based on a range of data from archaeological to neurophysiological, the computational neuroscientist Michael Arbib estimates this window at around 1.5 million to 100,000 years ago. Somewhere in this time span, we became qualitatively distinct from all other animals by any reasonable measure.