Discover 3

March 2018^ DISCOVER^45

FROM LEFT: TED KINSMAN/SCIENCE SOURCE; DENNIS KUNKEL MICROSCOPY/SCIENCE SOURCE (2); ALISON MACKEY/DISCOVER

Hameroff came to believe the micro-

tubule plays a defining role in anesthesia

effects — in consciousness. He points to

the single-celled paramecium as evidence.

“The paramecium has no central nervous

system,” he says. “No brain, no neurons,

but it swims around, finds food, finds a

mate and avoids danger. It seems to make

choices, and it definitely seems to process

information.”

How? Or more to Hameroff ’s point,

where? In what part of the paramecium

does this crude kind of cognition take

place? Hameroff believed he could find

the answers in the paramecium’s only

internal structure: microtubules, the

paramecium’s cytoskeleton. And since

these are nanoscale structures, he also

began thinking that quantum phys-

ics might play a role. But throughout

the 1980s, his research got nowhere

in terms of public recognition. Then,

one night in 1990, he sat down to read

Penrose’s book The Emperor’s New

Mind, a surprising best-seller that winds

through physics, cosmology, mathemat-

ics and philosophy before marking a

final, slam-bang stop at consciousness.

In his concluding pages, Penrose

wonders how firing neurons generate

experience. He opines that quantum

physics might be necessary to understand

consciousness.

But where in the body — an inhos-

pitable place for delicate quantum

perturbations — could such happenings

take place? Hameroff felt an immediate

connection to Penrose. And of course, he

thought microtubules held the answer.

From afar, the two seemed like an

odd pairing: Penrose is one of the more

respected scientists of the last half-

century, and his work in cosmology and

general relativity has garnered him high honors. Hameroff

was a relative unknown, shouting about an obscure

biological structure. But within a few years, they were

co-authoring papers together, and drawing the scorn of a

generation of fellow scientists.

DATA ARRIVES

In sum, Orch-OR proposes that consciousness originates

from microtubules and actions inside neurons, rather

than the connections between neurons. Whack a tennis

ball with a racket, and afterward you can use traditional

physics to predict where it is at any particular point.

But in the quantum realm, such expectations go out the

window. Movements are unknown until they’re observed,

according to the traditional interpretation of quantum

mechanics. Physicists refer to this final observation, which

determines what happened, as a wave “collapsing” into

a single state.

In quantum systems inside the neuron, Hameroff and

Penrose argue that it’s each collapse of the wave function

that yields a conscious moment.

Hameroff and Penrose were guilty of invoking one mys-

tery to solve another: We don’t understand consciousness,

and we don’t understand quantum physics, so maybe they

explain each other?

So Orch-OR was and remains vulnerable to attack —

and many do so with tremendous gusto. Two decades

ago, neurophilosopher Patricia Churchland and physi-

cist Max Tegmark were among those who launched

outright broadsides. Hameroff and Penrose responded,

and Hameroff published a list of 20 testable predictions

yielded by Orch-OR.

However, the greater theory serves as something of a

distraction from some of Hameroff ’s ideas: that quantum

physics might play a non-trivial role in human cognition

and consciousness, and that microtubules — activity inside

the neuron — could house these quantum happenings.

“If you would have speculated in this direction, say,

10 years ago, you would have been labeled a crackpot,”

says Google’s Neven.

But researchers recently have found quantum effects

are important for certain biological processes, like photo-

synthesis. When a photon strikes an electron in a leaf, the

Single-celled organisms like this paramecium appear to process

information even without a brain or neurons. Hameroff thinks

microtubules might explain how.

Microtubule bundles

line the cilia — tiny,

hairlike structures

— of a paramecium,

shown here both

from the side and

in cross section.

Microtubule

cross sections

Cilia

Cell wall