Neuroscientist Christof Koch, chief scientific officer at the Allen Institute for Brain Science, thinks he might know the answer. According to Koch, consciousness arises within any sufficiently complex, information-processing system. All animals, from humans on down to earthworms, are conscious; even the internet could be. That's just the way the universe works.
What Koch proposes is a scientifically refined version of an ancient philosophical doctrine called panpsychism — and, coming from someone else, it might sound more like spirituality than science. But Koch has devoted the last three decades to studying the neurological basis of consciousness. His work at the Allen Institute now puts him at the forefront of the BRAIN Initiative, the massive new effort to understand how brains work, which will begin next year.
Koch's insights have been detailed in dozens of scientific articles and a series of books, including last year's Consciousness: Confessions of a Romantic Reductionist. WIRED.COM interviewed Koch:
Christof Koch: I grew up Roman Catholic, and also grew up with a dog. And what bothered me was the idea that, while humans had souls and could go to heaven, dogs were not suppose to have souls. Intuitively I felt that either humans and animals alike had souls, or none did. Then I encountered Buddhism, with its emphasis on the universal nature of the conscious mind. You find this idea in philosophy, too, espoused by Plato and Spinoza and Schopenhauer, that psyche — consciousness — is everywhere. I find that to be the most satisfying explanation for the universe, for three reasons: biological, metaphysical and computational.
WIRED: What do you mean?
Koch: My consciousness is an undeniable fact. One can only infer facts about the universe, such as physics, indirectly, but the one thing I'm utterly certain of is that I'm conscious. I might be confused about the state of my consciousness, but I'm not confused about having it. Then, looking at the biology, all animals have complex physiology, not just humans. And at the level of a grain of brain matter, there's nothing exceptional about human brains.
Only experts can tell, under a microscope, whether a chunk of brain matter is mouse or monkey or human — and animals have very complicated behaviors. Even honeybees recognize individual faces, communicate the quality and location of food sources via waggle dances, and navigate complex mazes with the aid of cues stored in their short-term memory. If you blow a scent into their hive, they return to where they've previously encountered the odor. That's associative memory. What is the simplest explanation for it? That consciousness extends to all these creatures, that it's an immanent property of highly organized pieces of matter, such as brains.
WIRED: That's pretty fuzzy. How does consciousness arise? How can you quantify it?
Koch: There's a theory, called Integrated Information Theory, developed by Giulio Tononi at the University of Wisconsin, that assigns to any one brain, or any complex system, a number — denoted by the Greek symbol of Φ — that tells you how integrated a system is, how much more the system is than the union of its parts. Φ gives you an information-theoretical measure of consciousness. Any system with integrated information different from zero has consciousness. Any integration feels like somethingto that system. When it's dissolved, it does not feel that anymore. It's not that any physical system has consciousness. A black hole, a heap of sand, a bunch of isolated neurons in a dish, they're not integrated. They have no consciousness. But complex systems do. And how much consciousness they have depends on how many connections they have and how they’re wired up. WIRED: Ecosystems are interconnected. Can a forest be conscious?
Koch: In the case of the brain, it's the whole system that's conscious, not the individual nerve cells. For any one ecosystem, it’s a question of how richly the individual components, such as the trees in a forest, are integrated within themselves as compared to causal interactions between trees.
The philosopher John Searle, in his review of Consciousness, asked, "Why isn't America conscious?" After all, there are 300 million Americans, interacting in very complicated ways. Why doesn't consciousness extend to all of America? It's because integrated information theory postulates that consciousness is a local maximum. You and me, for example: We're interacting right now, but vastly less than the cells in my brain interact with each other. While you and I are conscious as individuals, there’s no conscious Übermind that unites us in a single entity. You and I are not collectively conscious. It's the same thing with ecosystems. In each case, it’s a question of the degree and extent of causal interactions among all components making up the system.
WIRED: The internet is integrated. Could it be conscious?
Koch: It's difficult to say right now. But consider this. The internet contains about 10 billion computers, with each computer itself having a couple of billion transistors in its CPU. So the internet has at least 10^19 transistors, compared to the roughly 1000 trillion (or quadrillion) synapses in the human brain. That's about 10,000 times more transistors than synapses. But is the internet more complex than the human brain? It depends on the degree of integration of the internet.
For instance, our brains are connected all the time. On the internet, computers are packet-switching. They're not connected permanently, but rapidly switch from one to another. But according to my version of panpsychism, it feels like something to be the internet — and if the internet were down, it wouldn’t feel like anything anymore. And that is, in principle, not different from the way I feel when I’m in a deep, dreamless sleep.
A map of the internet, circa 2005.
IMAGE: THE OPTE PROJECT
WIRED: Internet aside, what does a human consciousness share with animal consciousness? Are certain features going to be the same?
Koch: It depends on the sensorium [the scope of our sensory perception —ed.] and the interconnections. For a mouse, this is easy to say. They have a cortex similar to ours, but not a well-developed prefrontal cortex. So it probably doesn't have self-consciousness, or understand symbols like we do, but it sees and hears things similarly.
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