Meat Heads

A Scientist Explores the Unparalleled Intelligence of the Human Mind
By James Trefil
John Wiley & Sons, 242 pp.

We are all of us, when you think about it, animals. We’re made of meat. We belch and grunt, we fornicate, we defecate, we age and we die. The strange thing is that we can think about it. Other animals may have consciousness, but only humans, it seems, are aware of thinking about thinking.

But what does that mean and how is it possible? And if it is possible to understand a reasoning self-consciousness  — the capacity that makes us unique – might it be possible to build an artificial one – a machine that knows it is thinking – thereby making us no longer unique? And what then?

This is James Trefil’s line of inquiry in Are We Unique?, a deceptively interesting read. It’s popular science in the best sense, in which hard-won ideas become easy to grasp.

Trefil is the Robinson Professor of Physics at George Mason University and a prolific popularizer of science. He’s no stylist on the order of Stephen Jay Gould, nor does he have the journalist’s eye of, say, James Gleick. His strengths, instead, are his chatty style, his magpie ability to draw on a range of different sciences, and his timing with just the right analogy.

That said, the book starts slowly. At first, the question of whether humankind is unique seems like a slender excuse to deliver separate primers on brain structure, how computers work, and theories of what language is – all well and good, but not very exciting if you’re already up on this stuff.

As the book progresses, though, it becomes apparent that this is necessary background for what is to come. From the examination of animal, human and machine intelligence, Trefil triangulates on a central question: How is it possible for a sack of chemicals to be self-aware?

He starts from the proposition that smarts make all the difference. Even our closest primate relatives – whom we know have emotions and personalities – can’t figure out things that give a human toddler no trouble. Trefil cites an experiment that tests not only a sense of self, but a sense of others’ selves.

Put a chimpanzee in a room with a number of boxes equipped with dispensing levers. There is food in some boxes but not in others. If the chimp presses the right levers, she’ll get a reward. She can’t see into the boxes herself, but she can see a human who can. The human on the other side of the glass points to the boxes containing the food. Does the chimp press the corresponding levers?

As it turns out, yes. Now try this: The chimp can see two people behind the glass. One leaves the room. Only then is the food placed in the boxes. The first experimenter returns. The two humans point at different boxes. Can the chimp figure out which gesture to ignore? Apparently not. A four-year-old human, however, gets it right away.

As bright and alive as chimpanzees are, they are not alive to the world in the way we are, and that has to do with mental sophistication. As for machine intelligence, even the most advanced computers in the world are in no way mentally alive.

But the human brain is in its own messy way just a sack of electrochemical activity. Where does it get off being introspective and imaginative, and developing a sense of identity? Trefil points to a branch of inquiry called complexity theory. The idea is that as physical systems become more complex, they develop unanticipated self-referential aspects. One termite is a dumb critter. A termite colony is an organism greater than the sum of its parts. So too with neurons and ganglia.

If humans became smart as individuals, then, it’s because the human brain evolved in a way other animals’ didn’t. But if what we can perceive is the result of electrochemical architecture, is there an upper limit to human comprehension? Are there things we can’t understand no matter how hard we try?

Trefil believes so, and he places the limit on making a truly artificial consciousness. We’ll never be capable of designing machines that think, he argues, because we can never get a handle on how we ourselves think. We just don’t have the mental equipment. We may be capable of thinking about thinking, but we get an intellectual headache whenever we try. Sure, we can conceive of an inorganic intelligence, but we can no more build one than chimpanzees could.

In one respect, at least, Trefil could not be more wrong. We make thinking entities in our own image all the time. We just make them out of meat, not metal. It’s called childbirth. What starts out as a cluster of cells ends up as a reasoning mind. Consciousness begets consciousness, and no matter that we don’t know

  • Globe and Mail May 10, 1997