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The evolution of human olfactory cognition
Prof Lucia Jacobs
UC Berkeley
Why are humans the only ape with a prominent external nose? To answer this question, we must ask: why do animals have noses? A major selective force in the evolution of olfaction is its role in spatial navigation; navigation and olfaction are intimately connected at the neural level across the animal kingdom, even in humans. In vertebrates, this is reflected in the robust and conserved circuitry linking the hippocampus, a navigational center, with the olfactory system. This relationship between olfaction and navigation may also explain the evolution of the external human nose. The evolution of efficient bipedality and increased space use in Homo led to a new demand for spatial navigation in our genus. Stereo olfaction improves orientation accuracy in diverse animal species. By increasing the physical separation of inputs, the human external nose would enhance stereo olfaction. I further propose that the later variation in nose shape seen in modern humans reflects an adaptive response to the Neolithic transition, when the major function of olfactory cognition shifted from navigation to diagnosis in agricultural societies.