Incognito: The Secret Lives of the Brain

by David Eagleman

There’s another reason why the neural pieces and parts won’t be sufficient for a full understanding of human experience: your brain is not the only biological player in the game of determining who you are. The brain is tied in constant two-way communication with the endocrine and immune systems, which can be thought of as the “greater nervous system.” The greater nervous system is, in turn, inseparable from the chemical environments that influence its development—including nutrition, lead paint, air pollutants, and so on. And you are part of a complex social network that changes your biology with every interaction, and which your actions can change in return. This makes the borders interesting to contemplate: how should we define you? Where do you begin and where do you end? The only solution is to think about the brain as the densest concentration of youness. It’s the peak of the mountain, but not the whole mountain. When we talk about “the brain” and behavior, this is a shorthand label for something that includes contributions from a much broader sociobiological system.** The brain is not so much the seat of the mind as the hub of the mind.