WIRED: How did you come to
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
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.
this idea in philosophy, too, espoused by Plato and Spinoza and
psyche - consciousness - is everywhere.
find that to be the most satisfying explanation for the
universe, for three reasons:
'What is the simplest explanation? That consciousness extends to
all these creatures...'
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
Φ gives you an information-theoretical measure of
Any system with integrated information different
from zero has consciousness. Any integration feels like something.
WIRED: Ecosystems are interconnected. Can a forest be
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,
"Why isn't America conscious?"
After all, there are 300
million Americans, interacting in very complicated ways.
doesn't consciousness extend to all of America? It's because
integrated information theory postulates that consciousness is a
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 ▄bermind 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
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.
Internet has at least 1019 transistors, compared to the roughly
1000 trillion (or quadrillion) synapses in the human brain.
That's about 10,000 times more transistors than synapses.
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.
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
A map of the
Internet, circa 2005.
Image: The Opte Project
WIRED: Internet aside, what does a human consciousness share
animal consciousness? Are certain features going to be the
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.
In every case, you have to look at the underlying neural
mechanisms that give rise to the sensory apparatus, and to how
they're implemented. There's no universal answer.
WIRED: Does a lack of self-consciousness mean an animal has no
sense of itself?
Koch: Many mammals don't pass the mirror self-recognition test,
But I suspect dogs have an olfactory form of
self-recognition. You notice that dogs smell other dog's poop a
lot, but they don't smell their own so much. So they probably
have some sense of their own smell, a primitive form of
Now, I have no evidence to suggest that a
dog sits there and reflects upon itself; I don't think dogs have
that level of complexity. But I think dogs can see, and smell,
and hear sounds, and be happy and excited, just like children
and some adults.
Self-consciousness is something that humans have excessively,
and that other animals have much less of, though apes have it to
some extent. We have a hugely developed prefrontal cortex. We
WIRED: How can a creature be happy without self-consciousness?
Koch:: When I'm climbing a mountain or a wall, my inner voice is
Instead, I'm hyperaware of the world around me.
I don't worry too much about a fight with my wife, or about a
tax return. I can't afford to get lost in my inner self. I'll
fall. Same thing if I'm traveling at high speed on a bike.
not like I have no sense of self in that situation, but it's
certainly reduced. And I can be very happy.
Neural pathways in the brain of a fruit fly.
Image: Hampel et
WIRED: I've read that you don't kill insects if you can avoid
Koch: That's true. They're fellow travelers on the road,
bookended by eternity on both sides.
WIRED: How do you square what you believe about animal
consciousness with how they're used in experiments?
Koch: There are two things to put in perspective.
are vastly more animals being eaten at McDonald's every day. The
number of animals used in research pales in comparison to the
number used for flesh. And we need basic brain research to
understand the brain's mechanisms.
My father died from
Parkinson's. One of my daughters died from Sudden Infant Death
To prevent these brain diseases, we need to
the brain - and that, I think, can be the only true
justification for animal research. That in the long run, it
leads to a reduction in suffering for all of us.
But in the
short term, you have to do it in a way that minimizes their pain
and discomfort, with an awareness that these animals are
WIRED: Getting back to the theory, is your version of
panpsychism truly scientific rather than metaphysical? How can
it be tested?
Koch: In principle, in all sorts of ways.
One implication is
that you can build two systems, each with the same input and
output - but one, because of its internal structure, has
integrated information. One system would be conscious, and the
other not. It's not the input-output behavior that makes a
system conscious, but rather the internal wiring.
The theory also says you can have simple systems that are
conscious, and complex systems that are not.
should not give rise to consciousness because of the simplicity
of its connections. Theoretically you could compute that, and
see if that's the case, though we can't do that right now. There
are millions of details we still don't know. Human brain imaging
is too crude. It doesn't get you to the cellular level.
The more relevant question, to me as a scientist, is how can I
disprove the theory today. That's more difficult.
has built a device to perturb the brain and assess the extent to
which severely brain-injured patients - think of
Terri Schiavo - are truly unconscious, or whether they do feel pain and distress
but are unable to communicate to their loved ones.
And it may be
possible that some other theories of consciousness would fit
WIRED: I still can't shake the feeling that consciousness
arising through integrated information is... arbitrary, somehow.
Like an assertion of faith.
Koch: If you think about any explanation of anything, how far
back does it go? We're confronted with this in physics.
quantum mechanics, which is the theory that provides the best
description we have of the universe at microscopic scales.
Quantum mechanics allows us to design
MRI and other useful
machines and instruments.
But why should quantum mechanics hold
in our universe? It seems arbitrary!
Can we imagine a universe
without it, a universe where Planck's constant has a different
value? Ultimately, there's a point beyond which there's no
further regress. We live in a universe where, for reasons we
don't understand, quantum physics simply is the reigning
With consciousness, it's ultimately going to be like that. We
live in a universe where organized bits of matter give rise to
And with that, we can ultimately derive all sorts
of interesting things:
the answer to when a fetus or a baby
first becomes conscious, whether a brain-injured patient is
conscious, pathologies of consciousness such as schizophrenia,
or consciousness in animals.
And most people will say, that's a
If I can predict the universe, and predict things I see around
me, and manipulate them with my explanation, that's what it
means to explain. Same thing with consciousness.
Why we should
live in such a universe is a good question, but I don't see how
that can be answered now.