PTN Webbed Reprint Collection
William H. Calvin
University of Washington
Box 351800
Seattle WA 98195-1800 USA
Email || Home Page || publication list

William H. Calvin

"How to think what no one has ever thought before,"

as it appeared in a chapter of
How Things Are: A Science Tool-Kit for the Mind, edited by John Brockman and Katinka Matson (William Morrow and Co, 1995), pp. 151-163.

copyright ©1995 by William H. Calvin and the editors

How to think what no one has ever thought before

The short answer is to take a nap and dream about something. Our dreams are full of originality. Their elements are all old things, our memories of the past, but the combinations are original. Combinations make up in variety what they lack in quality, as when we dream about Socrates driving a bus in Brooklyn and talking to Joan of Arc about baseball. Our dreams get time, place, and people all mixed up.

Awake, we have a stream of consciousness, also containing a lot of mistakes. But we can quickly correct those mistakes, usually before speaking out loud. We can improve the sentence, even as we are speaking it. Indeed, most of the sentences we speak are ones we've never spoken before. We construct them on the spot. But how do we do it, when we say something we've never said before - and it doesn't come out as garbled as our dreams?

We also forecast the future in a way that no other animal can do. Since it hasn't happened yet, we have to imagine what might happen. We often preempt the future by taking actions to head off what will otherwise happen. We can think before acting, guessing how objects or people might react to a proposed course of action.

That is extraordinary when compared to all other animals. It even takes time to develop in children. By the time a child goes to school, adults start expecting them to be responsible for predicting the consequences: "You should have realized that..." and "Think before you do something like that!" aren't seriously said to babies and most preschoolers - or our pets. We don't seriously expect our dogs and cats to appraise a novel situation, like a fish falling out of the refrigerator, with an eye toward saving it for the dinner guests tonight.

An ability to guess the consequences of a course of action is the foundation of ethics. Free will implies not only the choice between known alternatives, but an ability to imagine novel alternatives and to shape them up into something of quality. Many animals use trial and error but we humans do a great deal of it "off line," before actually acting in the real world. The process of contemplation and mental rehearsal that shapes up novel variations would appear to lie at the core of some of our most cherished human attributes. How do we do that?

Creating novelty isn't difficult. New arrangements of old things will do.

Everyone thinks that mutations (as when a cosmic ray comes along and knocks a DNA base out of position, allowing another to fill in) are where novel genes come from. Nature actually has two other mechanisms which are more important: copying errors and shuffling the deck. Anyone with a disk drive knows that copying errors are the way things are, that procedures had to be invented to detect them (such as those pesky checksums) and correct them (such as the error-correcting codes which are now commonplace). All that's required to achieve novelty is to relax vigilance.

But nature occasionally works hard at mixing up things, each time that a sperm or ovum is made: the genes on both chromosomes of a pair are shuffled (what's known as crossing over during meiosis) before being segregated into the new chromosome arrangement of the sperm or ovum. And, of course, fertilization of an ovum by another individual's sperm creates a new third individual, one that has a choice (in most cases) between using a gene inherited from the mother or the version of it inherited from the father.

Quality is the big problem, not novelty as such. Nature's usual approach to quality is to try lots of things and see what works, letting the others fall by the wayside. For example, lots of sperm are defective, missing essential chromosomes; should they fertilize an ovum, development will fail at some point, usually so early that pregnancy isn't noticed. For this and other reasons, over 80 percent of human conceptions fail, most in the first six weeks (this spontaneous abortion rate is far more significant than even the highest rates of induced abortions).

There are often high rates of infant and juvenile mortality as well; only a few individuals survive long enough to become sexually mature and themselves become parents. As Charles Darwin first realized about 1838, this is a way that plants and animals change over many generations into versions that are better suited to environmental circumstances. Nature throws up a lot of variations with each new generation, and some are better suited to the environment than others. Eventually, a form of quality emerges through this shaping-up process.

When Darwin explained how evolution might produce more and more complex animals, it started the psychologists thinking about thought itself. Might the mind work the same way as Darwin's mechanism for shaping a new species? Might a new thought be shaped by a similar process of variation and selection?

Most random variations on a standard behavior, even if only changing the order of actions, are less efficient and some are dangerous ("look after you leap"). Again, quality is the problem, not novelty per se. Most animals confine themselves to well-tested solutions inherited from ancestors that survived long enough to successfully reproduce. New combinations are sometimes tried out in play as juveniles, but adults are far less playful.

By 1880, in an article in the Atlantic Monthly, the pioneering American psychologist William James (who invented the literary term "stream of consciousness") had the basic idea:

...the new conceptions, emotions, and active tendencies which evolve are originally produced in the shape of random images, fancies, accidental outbursts of spontaneous variations in the functional activity of the excessively unstable human brain, which the outer environment simply confirms or refutes, preserves or destroys -- selects, in short, just as it selects morphological and social variations due to molecular accidents of an analogous sort.

His French contemporary, Paul Souriau, writing in 1881, said much the same thing:

We know how the series of our thoughts must end, but... it is evident that there is no way to begin except at random. Our mind takes up the first path that it finds open before it, perceives that it is a false route, retraces its steps and takes another direction... By a kind of artificial selection, we can... substantially perfect our own thought and make it more and more logical.

James and Souriau were building on the even more basic idea of Alexander Bain, concerning trial and error. Writing in Scotland in 1855, Bain initially employed the phrase trial and error when considering the mastery of motor skills such as swimming: Through persistent effort, Bain said, the swimmer stumbles upon the "happy combination" of required movements and can then proceed to practice them. He suggested that the swimmer needed a sense of the effect to be produced, a command of the elements, and that he then used trial and error until the desired effect is actually produced. This is what a Darwinian process can use to shape up a thought - which is, after all, a plan for a movement such as what to say next.

Surprisingly, no one seemed to know what to do next, to make the link between the basic idea of Darwinian thought and the rest of psychology and neurobiology. For more than a century, this key idea has lain around like a seed in poor soil, trying to take hold. One problem is that it is easy (even for scientists) to adopt a cartoon version of Darwinism - survival of the fittest, or selective survival - and fail to appreciate the rest of the process.

The basic darwinian idea is deceptively simple. Animals always reproduce but all of their offspring don't manage to grow up to themselves have babies - they overproduce. There is a lot of variation in the offspring of the same two parents; each offspring (identical twins and clones excepted) gets a different set of shuffled chromosomes.

Operating on this generated diversity is selective survival. Some variants survive into adulthood better than others, and so the next generation's variations are based on the survivor's genes: some are better, most are worse, but they center around an advanced position because the worst ones tend to die young. And the next generation is, for the average survivor into adulthood, even better suited to the environment's particular collection of food, climate, predators, nesting sites, etc.

We usually think in terms of millennia as the time scale of this process that can evolve a new species. With artificial selection by animal breeders, substantial effects can be produced in a dozen generations. But the process can operate on the time scale of the immune response, as new antibodies are shaped up by success in killing off invading molecules; within a week or two, antibody shapes can be evolved that have a key-and-lock specificity for a foreign molecule. Might the same process suffice for the time scale of thought and action?

It is worth restating the six essentials of a darwinian process a bit more abstractly, so we can separate the principles from the particulars:

Not every process that makes copies of patterns is going to qualify as Darwinian. Photocopy and fax machines make copies of the ink patterns on a sheet of paper, but there is usually no loop.

If you do make copies of copies, for dozens of generations, you will see some copying errors (especially if copying gray scale photographs). Now you've satisfied the first three conditions - but you still don't have competition for a workspace that is biased by a multifaceted environment, nor an advantage in reproduction for certain variants.

Similarly, you can have selective survival without the rest of the Darwinian process. You will find more 15-year-old Volvos still on the road than you will Fiats of the same age. But the 15-year-old Volvo doesn't reproduce. Nor do brain cells - though the connections between them (synapses) are edited over time. In the brain of an infant, there are many connections between nerve cells that don't survive into adulthood. But this selective survival (random connections that prove to be useful) isn't proper Darwinism either, unless the surviving connection patterns somehow manage to reproduce themselves elsewhere in that brain (or perhaps through mimicry in someone else's brain). And, even if they did, this pattern copying would still have to satisfy the requirement for a loop where reproduction with new variation is biased toward the more successful.

Selective survival is a powerful mechanism that produces crystals in nonliving matter as well as economic patterns in cultural evolution. Selective survival is a problem for all business enterprises, especially small ones, but it leads - at least in capitalist free-market theories - to a better fit with "what works."

Selective survival of all sorts is sometimes called Darwinian (Darwin was annoyed when Herbert Spencer started talking of social Darwinism). But selective survival per se can even be seen in nonliving systems, as when flowing water carries away the sand grains and leaves the pebbles behind on a beach.

Full-fledged Darwinism is even more powerful, but it requires differential reproduction of the more successful. Economics has some recent examples in fast food franchises, where copies are produced of the more successful of an earlier generation. Indeed they seem to be in a competition with their variants for a limited "workspace." If they close the loop by generating new variations on the more successful (imagine a MacUpscale and a MacEconomy splitting off from one of the chains), they may provide another example of a Darwinian process evolving new complexity.

When people call something "Darwinian," they're usually referring to only part of the darwinian process, something that only uses several of the six essentials. And, so powerful are the words we use, this overly loose terminology has meant that people (scientists included) haven't realized what was left out.

Indeed, the second reason why the Darwinian thought idea wasn't fleshed out earlier is that it has taken a while to realize that thought patterns might need to be copied - and that the copies might need to compete with copies of alternative thoughts. Since we haven't known how to describe the neural activities underlying thought, we haven't been able to think about copying. But copying is a major clue about what the thought process must be like; it's a constraint that considerably reduces the possibilities.

In the early 1950s during the search for the genetic code, molecular biologists were acutely aware of the need for a molecular process that could somehow make copies of itself during cell division. The reason why the double helix structure was so satisfying in 1953 was that it solved the copying problem. In subsequent years, the genetic code (the translation table between DNA triplets and amino acid strings) was worked out. Perhaps we too can identify the cerebral code that represents an object or idea, with the aid of looking at what cerebral patterns can be semiaccurately copied.

Thoughts are just combinations of sensations and memories - or, looked at another way, thoughts are movements that haven't happened yet (and maybe never will). The brain produces movements with a barrage of nerve impulses going to the muscles, whether limbs or larynx. But what determines the details of this barrage?

Sometimes, it is simply an innate rhythm such as the ones which produce chewing, breathing, and walking. Sometimes there is time for lots of corrections, as when you lift a coffee cup and discover that it weighs less than you thought; before it hits your nose, you manage to make some corrections to your arm muscles. But some movements are so quick (over and done in one-eighth of a second) that no feedback is possible: throwing, hammering, clubbing, kicking, spitting (including "spitting out a word"). We call these ballistic movements; they're particularly interesting because they require that a complete plan be evolved before acting. During "get set" you have to produce the perfect plan. A plan for a movement is like the roll for a player piano: 88 output channels, one for each key, and the times at which each key is struck. To hammer or throw indeed requires coordinating close to 88 muscles, so think of a sheet of music as a plan for a spatiotemporal pattern - all of those chords, melodies, and interweaving patterns we call musical.

In 1949, the Canadian psychologist Donald Hebb formulated his cell-assembly hypothesis, stating that evoking a memory required reconstituting a pattern of activity in a whole group of neurons. We now think of Hebb's cell assembly more generally as a spatiotemporal pattern in the brain which represents an object, an action, or an abstraction such as an idea. Each is like a musical melody and, I calculate, takes up about as much space in the brain as would the head of a pin (just imagine that the pinhead is hexagonal in shape).

Memories are mere spatial patterns frozen in time - that sheet of music waiting for a pianist, or the ruts in a washboarded road, lying in wait for something to come along and interact with them to produce a spatiotemporal pattern in the form of live music or a bouncing car. A Darwinian model of mind suggests that an activated memory can interact with other plans for action, compete for occupation of a workspace. A passive memory, like those ruts in the road, can also serve as an aspect of the environment that biases a competition - in short, both the current real-time environment and memories of past environments can bias a competition that shapes up a thought.

So we have a pattern - that music-like thought in the brain - and we have selective survival biased by a multifaceted environment. How can thoughts be copied to produce dozen of identical pinheads? How can their variants compete for a workspace, the same as bluegrass and crabgrass compete for a back yard? How can the loop be closed?

All of the currently active cerebral codes in the brain, whether for objects like apples or for skilled finger movements such as dialing a telephone, are thought to be spatiotemporal patterns. To move a code from one part of the brain to another, it isn't physically sent, as a letter is mailed. Rather, it has to be copied much like a fax machine makes a copy of the pattern on one sheet of paper onto a new sheet of paper at the remote location. The transmission of a neural code involves making a copy of a spatiotemporal pattern, sometimes a distant copy via the fibers of the corpus callosum but often a nearby copy, much in the manner that a crystal grows.

The cerebral cortex of the brain, which is where thoughts are most likely to arise, has circuitry for copying spatiotemporal patterns in an immediately adjacent region less than a millimeter away. All primates have this wiring, but it is not known how often they use it. The cerebral cortex is a big sheet - if peeled off and flattened out, it would be about the size of enough pie crust to cover four pies. There are at least 104 standard subdivisions. While some areas of cortex might be committed to full-time specialization, other areas might often support sideways copying and be erasable workspaces for darwinian shaping-up processes.

The picture that emerges from theoretical considerations is one of a patchwork quilt, some parts of which enlarge at the expense of their neighbors as one code comes to dominate. As you try to decide whether to pick an apple or an orange from the fruit bowl on the table, the cerebral code for apple may be having a copying competition with the one for orange. When one code has enough active copies to trip the action circuits, you reach for the apple. But the orange codes aren't entirely banished; they could linger in the background as subconscious thoughts.

When you try to remember someone's name, but without initial success, the candidate codes might continue copying with variations for the next half hour until, suddenly, Jane Smith's name seems to "pop into your mind." Our conscious thought may be only the currently dominant pattern in the copying competition, with many other variants competing for dominance (just as the bluegrass competes with the crabgrass for my back yard), one of which will win a moment later when your thoughts seem to shift focus.

The Darwinian process is something of a default mechanism when there is lots of copying going on, and so we might expect a busy brain to use it. Perhaps human thought is more complicated than this, with shortcuts so completely dominating the picture that the Darwinian aspects are minor. Certainly the language mechanisms in our brain must involve a lot of rule-based shortcuts, judging from how children make relatively sudden transitions from speaking simple sentences to speaking much more complicated ones, during their third year of life. It may be that the Darwinian processes are only the frosting on the cake, that much is routine and rule-bound.

But the frosting isn't just writing poetry or creating scientific theories (such as this one). We often deal with novel situations in creative ways, as when deciding what to fix for dinner tonight. We survey what's already in the refrigerator and on the kitchen shelves. We think about a few alternatives, keeping track of what else we might have to fetch from the grocery store. And we sometimes combine these elements into a stew, or a combination of dishes that we've never had before. All of this can flash though the mind within seconds - and that's probably a Darwinian process at work, as is speculating about what tomorrow might bring.

How Things Are is available in your local bookstore.

William H. Calvin is a theoretical neurophysiologist on the faculty of the University of Washington School of Medicine. He is the author of The Throwing Madonna, The River that Flows Uphill, The Cerebral Symphony, The Ascent of Mind, How the Shaman Stole the Moon, How Brains Think, The Cerebral Code and, with the neurosurgeon George Ojemann, Conversations with Neil's Brain: The Neural Nature of Thought and Language.

And, since the article, How Brains Think and The Cerebral Code. || Home Page || Calvin publication list || My Science Surf column || The Calvin Bookshelf || Revised 24 December 1996