We propose a paleoeconomic coevolutionary explanation for the origin of speech in modern humans. The coevolutionary process, in which trade facilitates speech and speech facilitates trade, gives rise to multiple stable trajectories. While a ‘trade-speech’ equilibrium is not an inevitable outcome for modern humans, we find it is a relatively likely scenario given our species evolved in Africa under climatic conditions supporting relatively high population densities. The origin of human speech is not independent of economic institutions—the economics of early human trade can provide additional insight to help explain the physiological emergence of human speech.