On that question I’ve consistently said 2029. Both hardware and software are progressing exponentially. If logical thinking were the essence of intelligence, then computers are already superior to us. The areas where humans still have an edge are in our emotional intelligence. Emotion is not some sideshow or distraction to intelligence. Being funny, being sexy, expressing love in a convincing way — those are the cutting edges of human intelligence.

In the book you introduce your “pattern recognition theory of mind.” What does it tell us about how the brain works?

The main focus is on the neocortex, which evolved with mammals. It now comprises 80% of the brain in humans. One of the key themes of the book is that neocortex is neocortex. It all runs the same algorithm. This runs counter to the spirit of a lot of neuroscience, which is based on the idea that different regions of the brain run different algorithms for different functions. The neocortex is actually a module of roughly 100 neurons, and it’s repeated over and over again. We have a total of about 300 million modules, and they are pattern recognizers. They learn to recognize a pattern, and they’re organized in a hierarchy. That hierarchy is built from our own thoughts. So it’s true that you are what you eat, but it’s even more true that you are what you think.

When will the average person have his or her brain connected to and supplemented by computers?

One answer is that we have brain extenders already, even though the vast majority are not physically connected. Humans have always built tools to compensate for our limitations. We now have mental tools to extend our reach. So I can access all of human knowledge in sense with a few keystrokes and so can the kid in Africa with a smartphone. So these are very literally brain extenders.

To answer your actual question, I would say the 2030s. We will have intelligent computerized devices the size of blood cells, and we’ll put them in our blood stream. They’ll go inside our brain and provide gateways to the cloud directly from our brain. And one of the things we’ll do will be to extend the neocortex so that we’re not limited to just 300 million pattern recognizers. Consider the last time we added more neocortex, which is when homo sapiens evolved. That was the enabling factor that permitted the evolution of language and art and science and music and literature. It really came from this additional quantity, which made this qualitative leap possible. So 300 million is a lot in terms of the fact that it made this qualitative leap possible, but it’s also very limiting, and we struggle with that limitation every day. Just confront how long it takes to read a book, let alone how long it takes to learn a new language.

Suppose you want a billion or 10 billion pattern recognizers for a few seconds because you’re doing some kind of complex search. What happens now is it goes out to the cloud. The interesting things that happen on your cellphone or notebook are not happening in that rectangle, they’re taking place in the cloud. And the cloud itself is growing exponentially.

Will increased processing power change the way we think, or just increase our memory and the amount of information we can access?

As adults, we’ve filled up our neocortexes. We’re constantly needing to forget things to free up neocortex to learn new things of any magnitude just because of that physical limitation. Just imagine what the next expansion of neocortex capacity will permit qualitatively. But there are other advantages of a non-biological neocortex. It’s not just additional quantity. Computations can be done faster. Also, information stored biologically is not backed up. We routinely back up everything on our non-biological devices. And you can download new knowledge to it. So we will become a hybrid of biological and non-biological intelligence. We’re not going to be plugged in a la the Matrix. It’s going to be WiFi. And it’s not going to be one thing. You’re not going to get a form: Check here, I want to be enhanced, Yes or No. There’s going to be a million choices. There’s a million choices now just of iPad apps. Go out to the late 2030s and there’ll be some nano-bot software combinations that are very conservative that enhance your immune system and your memory that everyone uses. And there’ll be some more cutting edge things that only certain people use. How many people today opt out of this whole connectedness? Maybe the Amish. So people generally don’t opt out, and there’s going to be different choices.

Is technology changing our brains now in an evolutionary way?

Not biologically. What does happen though is that our neocortex isn’t going to bother using up a lot of its capacity learning things that it knows it can get through its brain extenders. There was a controversy when I went to college about these little devices called calculators. People said, ‘Oh, kids aren’t going to learn arithmetic.’ That turned out to be true. They could probably still add and subtract, but doing long division became a lost skill. But the calculators didn’t go away and Google (GOOG) isn’t going away. And we don’t need to fill up our precious neocortical real estate with lots of facts. The idea of rote learning is obsolete because we carry access to all of these facts and knowledge around with us. We do need to teach people how to use knowledge, how to solve problems and so on. But the brain extenders are not going way. People say, “These things are making us stupider.” If you define intelligence as the ability to remember random facts that might be true. But in fact we are much more intelligent with our brain extenders. These powerful tools are making us smarter, but you have to include them as part of who we are. And in my view they are part of who we are.

A shorter version of this interview appeared in the January 14, 2013 issue of Fortune.

More from The Future Issue

• The future according to Larry Page
• Will.i.am: Corporate America’s hit machine
• Teaching IBM’s Watson the meaning of ‘OMG’
• Iron Man in the factory