In other words, they can keep time, all sorts of time. If there’s one clear message about the neuroscience of timekeeping, it’s that neural circuits can wire themselves in response to regular external stimuli. For example, lesions in the suprachiasmatic nucleus don’t alter the brain’s ability to discern temporal patterns at the scale of seconds: there are different clocks for that. One of which is aptly named period.īut unlike our clocks, which can tell time over a vast range of intervals, the brain has no single clock. Circadian clocks depend on pendulum-like oscillations of the levels of specific proteins. For example, there’s the complicated sounding suprachiasmatic nucleus, a cluster of neurons at the base of the hypothalamus that acts as a master circadian clock. Christiaan Huygens’s high-quality pendulum clocks were the first to keep time more accurately than clocks within the human brain.īuonomano’s book is full of delicious details about the myriad ways in which cells – neurons and other types – tell the time. To indulge in mental time travel, biology first had to figure out how to keep time, not unlike how scientists in the 17th century invented the pendulum clock. Scrub jays, oddly, seem to demonstrate similar abilities, but proof of mental time travel in animals is hard to come by as yet.

This mental time travel is a human capacity, distinguishing us from other animals, hence the book’s title. With memory and cognition, our brains became time machines – we could travel back and forth in time. In fact, that’s really the main evolutionary use for memory, as a storehouse of the information needed to predict the future.

This ability to predict the long-term future is reliant on memory. To do so, the brain needs complicated machinery for keeping time – to predict not just what will happen within microseconds, but what might happen in seconds, minutes, hours, even days, weeks, months and years. But popular accounts of the theory often ignore one dimension of the prediction machinery: time.īuonomano points out that the brain is continuously making real-time predictions, not just of “what will happen next” but also of “when it will happen”.

Whenever we perceive something, theory says that what we perceive is not objective reality, but rather the brain’s best guess as to what’s causing the sensations impinging on the body. The title of the book is derived from the now well-regarded idea that our brains are prediction machines. But to do it, biology first had to figure out how to keep time”īuonomano decides it is time to simultaneously tackle the physics and the neuroscience of time. “But despite its intuitive appeal, presentism is the underdog… in physics and philosophy.”

The time machine book