Plato famously described the human psyche as two horses and a charioteer: One horse represented instincts, the other represented emotions, and the charioteer was the rational mind that controlled them. Astronomer Carl Sagan continued this idea of a three-layer, “triune brain” in his 1977 book The Dragons of Eden.
But leading neuroscientist Lisa Feldman Barrett challenges this idea of the brain evolving in three layers, instead revealing a common brain plan shared by all mammals and vertebrates. The development of sensory systems led to the emergence of the brain, and hunting and predation may have initiated an arms race to become more efficient and powerful predators.
Despite advances in neuroscience and genetics, the question of why the brain evolved remains elusive. But Feldman Barrett’s fascinating exploration of the brain’s evolution offers insights into the most important functions of this complex organ and invites us to think more deeply about the origins of our own intelligence.
