1 June 2018
Peter Sterling
Department of Neuroscience
Perelman School of Medicine
University of Pennsylvania
Allostasis denotes a broad strategy for regulating physiology and behavior. The brain senses the internal milieu, the external environment, and consults its database to predict what will likely be needed. Then it computes the optimal response and commands every cell in the body. The brain rewards a better-than-predicted result with a pulse of dopamine, thereby teaching us to repeat the behavior. By prioritizing behaviors and dynamically adjusting the flows of energy and nutrients, we can exploit more opportunities and avoid more dangers. Prediction in a complex niche naturally requires greater computational capacity. So, to inhabit the whole planet Homo sapiens enlarged its brain, specialized its hemispheres, and finally specialized individual brains for different skills – while including circuits for cooperation. This design worked brilliantly for 99.999 percent of our species history, allowing H. sapiens to outcompete all other hominids. But now we dial for preferred temperature, food, music – and receive exactly what we predict. Yet allostasis requires rewards that exceed prediction, so we are compelled to intensify: bigger burger, more ice cream, more opioids. Unbounded consumption destabilizes all dynamic systems, from metabolism to climate. Although we cannot return to foraging, we need to reinvent lives richer in positive surprise.