Humans have thrived like no other species on Earth. We have established habitats on all the continents, mastered agriculture, invented technology, and we are unique in having culture. All that can’t only be due to opposable thumbs, and indeed it isn’t. Our mental faculties distinguish us from other animals, and consciousness—a mental state as dynamic as it is mysterious—is most distinguishing of all. From an evolutionary perspective, consciousness gives humans a powerful advantage by allowing us to plan far into the future. Squirrels store nuts for the winter, but humans imagine further out, planning systems and institutions that protect our security beyond seasonal irregularities. Neuroscientist Dean Buonomano explores how our minds deliver us the goods, and how studying consciousness with consciousness presents some tricky problems. Buonomano’s book on the subject of consciousness and time is Dean Buonomano is the author of Your Brain Is a Time Machine: The Neuroscience and Physics of Time.

Dean Buonomano: So consciousness is one of the deepest questions in science and I think consciousness may very well be the deepest question and one of the deepest mysteries science has ever coped with. And this is one reason, by the way, that neuroscience is a very unique field in all of sciences.

So neuroscience is the only field in which the thing or the organ being studies is also doing the studying. Now this raises a number of potential concerns, right? Is that even possible? Can a device or an organ or a computational system understand itself? And that’s what we’re asking our brains to do when we’re faced with problems such as the nature of consciousness.

And the nature of consciousness is extremely hard to study for neuroscience and scientists because it’s very hard to measure. But some people have proposed or believe that one of the reasons consciousness evolved is to allow us to simulate future scenarios. And this relates to something called mental time travel. So mental time travel is the ability that we have to relive past experiences. So we’ve all spent perhaps inordinate amounts of time daydreaming about the past or reliving things that have happened and giving those things alternate endings and simulating them in the past to see how we can use them in the future.

We also spend a lot of time daydreaming about the future. And importantly our ability to mentally project ourselves into the future is perhaps one of the most valuable things, the most valuable cognitive abilities of our species. I think in many ways future-oriented time travel makes Homo sapiens sapien. It makes Homo sapiens wise because it’s what gives us the ability to engage in endeavors that other animals cannot do. So if you think about something as a signature of our species: making a tool. Making a tool, carving a blade out of an obsidian stone, is something that implicitly requires a thought of the future. It means I’m doing something for something in the future. So I have a purpose for that.

Similarly perhaps one of the most important inventions of humankind is agriculture. This notion of planting a seed today and reaping its benefits or assuring a source of food in the future is one thing that drove our species forward. And that again is something that requires mental time travel, that requires our ability to think in the distant future.