To begin, an experiment. Start by extracting a couple of thousand of your brain cells. Adult humans have about 86 billion neurons inside our skulls, so you can afford to lose a few, but don’t make a habit of it. Once you’ve acquired your sample, suspend your cells in a sterile solution filled with nutrients, growth factors and antioxidants maintained at asteady temperature of 37°C. Stir it into a slurry.
Over time, the separate cells will connect up with each other. Within a few months, they’ll construct molecular scaffolding so they can self-organise into brain-like, threedimensional structures. When they’ve done this, they generate synchronised electrochemical waves: these follow the same patterns as fetal and neonatal brains.
Is the thing in the solution alive? Is it thinking? Is it … you, in some weird way? Ethics boards agonise over such questions, but for the biologist and neuroendocrinologist Robert Sapolsky, the experiment reveals two profound truths. The first is that it demonstrates emergence, a key concept in the natural sciences: how complex patterns and behaviours emerge from simple systems.
And the second, Sapolsky believes, is that it demonstrates the impossibility of free will. Just as there is no magical self-causing entity interfering with the cells in the solution, causing it to self-organise and generate brain waves, there is no such entity at work inside our own brains. All our actions, for good and evil, are determined by a hierarchy of physical and cultural causes.
Before Sapolsky became a bestselling author, before his career as a professor of biology, neurology and neuroscience at Stanford, before he was a primatologist studying a group of baboons on the Kenyan savannah, Sapolsky was a clinically depressed teenager growing up in an Orthodox Jewish family in Brooklyn, New York, and losing his faith.
