The Brains Behind Morality

Patricia Smith Churchland

Self-preservation is embodied in our brain’s circuitry: we seek food when hungry, warmth when cold, and mates when lusty. In the evolution of the mammalian brain, circuitry for regulating one’s own survival and well-being was modified. For sociality, the important result was that the ambit of me extends to include others – me-and-mine. Offspring, mates, and kin came to be embraced in the sphere of me-ness; we nurture them, fight off threats to them, keep them warm and safe. The brain knows these others are not me, but if I am attached to them, their plight fires-up caring circuitry, motivating other-care that resembles self-care. In some species, including humans, seeing to the well-being of others may extend, though less intensely, to include friends, business contacts or even strangers, in an ever-widening circle. Oxytocin, an ancient body-and-brain molecule, is at the hub of the intricate neural adaptations sustaining mammalian sociality. Not acting alone, oxytocin works with other hormones and neurotransmitters and structural adaptation. Among its many roles, oxytocin decreases the stress response, making possible the friendly, trusting interactions typical of life in social mammals. I can let my guard down when I know I am among trusted family and friends.

Two additional interconnected evolutionary changes are crucial for mammalian sociality/morality: first, modifications to the ancient pain system that, when elaborated, yield the capacity to evaluate and predict what others will feel and do, and notably in humans, also what others want, see, and believe. Anticipating events painful to me-and-mine is more efficient when brains can represent others as having sensations and intentions, regardless of assorted contingencies in behavior and background conditions. Cortical and subcortical modifications also led to a greater capacity for remembering specific events – storing for recall the reputations of assorted others; who cannot be trusted, and who can.  Second, especially owing to the expansion of the frontal brain, an enhanced capacity to learn, underscored by social pain and social pleasure, allowed acquisition of the clan’s social practices, however subtle and convoluted. Increased capacity for impulse control is another feature of frontal brain expansion. Social benefits are accompanied by socials demands; we have to get along, but not put up with too much. Hence impulse control – being aggressive or compassionate or indulgent at the right time – is hugely advantageous.