|A book by|
William H. Calvin
UNIVERSITY OF WASHINGTON
SEATTLE, WASHINGTON 98195-1800 USA
The Cerebral Symphony|
Seashore Reflections on the
Structure of Consciousness
Copyright ©1989 by William H. Calvin.
You may download this for personal reading but may not redistribute or archive without permission (exception: teachers should feel free to print out a chapter and photocopy it for students).
Of Arms Races in Church Gardens:
The Sidestep and Evolution's Other Byways
What may be the only Roman Catholic church belltower in which the bells are
named after biologists stands in a garden beside Eel Pond, the landlocked cove
that, ventricle-like, is surrounded by the seaside village of Woods Hole on Cape
Cod. One bell is called Pasteur, the other Mendel, and presumably they
represent an attempt at a modus vivendi between St. Joseph's, the parish they
belong to, and the four great marine biological institutions that stand nearby....
The Bell Tower Garden is just a block from MBL, around the shores of Eel Pond. Two great
bells ring out the Angelus three times a day: morning, noon, and evening (if you hear the bells at
any other time, there's probably a wedding in St. Joseph's Church across the street). Surrounding
the bell tower is a garden, a pleasant place in which to read or write, or just walk around trying to
clear one's head.
The east end of the garden is patterned after the medieval church gardens of flowers and herbs that monks cultivated for their beauty and usefulness. Here grows Digitalis purpurea, which the Catholic Church calls "Our Lady's Glove," and most gardeners call foxglove. It is a medicinal plant, containing digitalis; it is used to treat heart failure, as it strengthens and deepens the beat if given in small quantities (in larger quantities, digitalis is a poison).
And, of course, its usefulness as a poison is what prompted its evolution, what with the perpetual arms race between the plants and the insects. I know that the Catholic gardeners who labor here probably tell the story of the plants in the garden rather differently, but it is also useful to tell the scientific story of them as, in part, deadly devices. Because that story leads to evolutionary mechanisms in general, the emergent properties of compounded mechanisms, and even to consciousness considerations.
To ward off the insects, many plants have developed defenses: sticky flytraps like amber (which have incidentally preserved 50-million year old insects, looking remarkably like modern species in some cases), heart-stopping or hallucinogenic drugs, agents that coagulate the blood (or, like garlic, prevent its coagulation) and all manner of diabolical devices. Except for the grasses (which mostly do without protection) and the fruits (which mostly want to be eaten, so as to have their seeds deposited several days later at some distance away, in the midst of a nice helping of fertilizer), most edible plants incorporate something disagreeable to some species that eats them. Cooking is the best invention yet for inactivating such toxins (the heat breaks up the proteins into shorter segments), though genetic engineering may have something to say on the subject soon (imagine stirring some enzymes into food during preparation that bind to the harmful molecules and render them harmless).
It is surprising in light of this evolutionary perspective that more people don't get sick from eating plants raw. Some "allergies" are probably just normal reactions that many people do not exhibit in florid form, causing them to be viewed as exceptions rather than rules.
But some plant defenses may just have delayed effects on reproductive fitness rather than immediate bad taste or sickness: It now turns out that the Guam and Rota Island variants of Alzheimer-type dementia, Parkinsonism, and amyotrophic lateral sclerosis (a degenerative spinal cord disorder) are probably all due to eating the seeds of the false sago palm (Cycas circinalis L.) pounded into flour, a traditional food that was eaten by some natives when rice was very scarce during World War II. And so researchers are now looking at the more common versions of Alzheimer's dementia, Parkinsonism, and other degenerative diseases to see if they too were triggered by foods. Thus, our environmental-contamination problems (all the lead, radon, carbon monoxide, etc.) may have to be viewed against the natural background of all the accumulated plant toxins that we consume. I do love spicy food, but spices would also top my list of potential neurotoxins that ought to be investigated.
The insects presumably suffered similar tribulations in their hard times when food was scarce and they ate ten times more than usual of a plant toxin. The insects may not have invented cooking, but they have evolved other ways around the defenses: long feeding tubes that allow the insect to sup from a distance, digestive enzymes that inactivate the toxins, etc.
Then the plants up the ante, usually with a new toxin. Armaments races started a long time ago.
The social addiction to armaments races is not fundamentally different from individual addiction to drugs. Common sense urges the addict always to get another fix. And so on.the American anthropologist Gregory Bateson, 1979
UNLIKE THE CURRENT HUMAN ARMS RACE, the ancient one between the plants and the
insects is potentially very beneficial to humans. The insects have become a fascinating
repository of knowledge: If one wanted to find a natural anticoagulant to use with stroke patients
who have plugged up an artery, one might try to find a plant that uses a coagulant as its defense,
then find the insects that still successfully feed on that plant and see what anticoagulants they
produce. Some such insect anticoagulants may work only with that particular coagulating agent,
but others may be more generally useful.
Of course, we are exterminating insect and plant species at a prodigious rate, which some future generation is going to want in order to solve such health problems, or the problems of agriculture. They're likely to view our thoughtless destruction of this genetic library about the same way as we view the book-burners of history.
THE PLANTS certainly did not acquire their toxins by foresight, analyzing the situation and then going down to the store and buying the right product. We humans "think things through," and so tend to assume that it is the only way, that some convenient god must have done the thinking for the plant.
But Darwin's explanation of evolution changed all that, made it clear how random variations that yield small advantages can shape up a new function over a long period to give some results similar to insightful planning. We call these "adaptations" to the environment. When some mammals such as whales and dolphins returned to the sea, they gradually lost their hair and gained a new layer of subcutaneous fat that replaced the hair's thermal insulation and also streamlined the waterfoil -- those are adaptations that occurred simply because there were variations in hair and fat, and some variants produced more surviving offspring than others.
Some of us think that humans too went through an aquatic phase (maybe about 7 million to 5 million years ago, just before the savannah phase) where we lost most of our hair and gained an unapelike layer of subcutaneous fat. One likely way of producing such adaptive features would have been via making our living wading around in shallow waters looking for crabs and shellfish, and diving for them offshore in hard times. We certainly do have an unapelike fascination with shorelines, as witness the beaches and waterfront houses around here. And all those boats floating in Eel Pond, just beyond the boundary hedge of the Bell Tower Garden.
And a fascination with shorebirds. It seems that Eel Pond has only one cormorant for most of the summer, with a second one later in the season. The two current inhabitants are certainly friendly: I just saw them sharing a perch on the same buoy. One had its wings spread, the other standing unruffled -- and from the angle I saw them, it looked just as if one had its arm around the other's shoulder. Then they both spread their wings to dry, and managed not to hit one another.
They seem to be the double-crested cormorant, Phalacrocorax auritus; apparently they go south for the winter, though perhaps only as far as New York. Finally, one left its post. This consisted of hopping into the water, swimming a short distance (and looking considerably more buoyant than earlier, when it cruised with only its neck out of the water) and then diving, producing only a few ripples to mark the spot it disappeared. Some cormorants dive from high cliffs when they spot a fish, others simply cruise underwater.
Despite a lack of oil glands of the kind that ducks use to preen their feathers with waterproofing, the cormorants look sleek. Small wonder that the cormorants have to spend so much time above water, drying their wings. On rainy days, when wings take a long time to "reset," they probably can't go fishing as often as on a sunny, warm day. Another little imperfection of evolution: Natural selection may have adaptively streamlined the shape of the cormorant's body, but missed out on waterproofing. Maybe the right variations never occurred; they are, after all, not totally random, but constrained by everything from where chromosomes break easily to the spatial and temporal matchups that occur during development.
But adaptations aren't the only way of changing functionality, though you'd think that was so from reading some of Darwin's latter-day followers ("ultradarwinists"). Yet Darwin himself emphasized two major ways in which species change without natural selection shaping adaptations up: sexual selection (the male peacock's tail was shaped up by female preferences, not environmental peculiarities) and "conversions of function" (where new functions emerge without anatomical change). And he noted that competition within the species may be minor after the discovery of what we now call a "new niche" -- and that may allow a lot of drift away from the preexisting body form and behaviors.
The most powerful and prominent processes of competition in the real world may not be competition to occupy a fixed set of niches, but processes of specialization and niche elaboration. Hence we don't have to adopt a picture of the world that is all tooth and claw.the American computer scientist Herbert A. Simon, 1983
EVOLUTION is full of surprises. I don't mean the funny-shaped animals, like flounder or angler
fish, that readily evoke an exclamation or laugh. I'm referring to the improbable ways that
evolution has of doing things, the surprising paths taken by evolution that violate all the
stereotyped notions about progress. Sometimes evolution isn't the slow grind, meandering along,
continuously editing random variations into ever-better versions.
Slow but sure is the popular image of darwinism, but evolution really isn't very efficient. It's full of dead ends, which require backing up biologically in order to "make progress." Then there's coevolution, such as arms races. And most surprising of all, biological evolution sometimes takes a sideways leap to tread a novel path.
If all this is news to you, that's a commentary on the sad state of education. Such surprises are seldom conveyed by harassed schoolteachers, coping with creationist snipers and with compromising textbooks that endeavor to mention evolution in as few words as possible, perhaps in an optional section at the rear that is never reached before the end of the school year. Real biologists teach evolution integrated with all of biology, the common thread that unites molecules, microbes, monkeys, and men. Without that thread, biology can become an endless list to be memorized rather than the greatest adventure of all time. To a biologist, nothing makes any sense without evolution having occurred (but such professional opinion also seldom makes it into the laundry-listlike texts). If you've heard of any one of these surprises (none of which is particularly new; even Darwin emphasized the side-steplike "functional change in anatomical continuity"), count yourself lucky or well read.
Most people do, however, have a good working notion of how cultural evolution operates, just from watching the world around them change. And that provides a shortcut (albeit a somewhat hazardous one) to appreciating similar features of biological evolution such as backing up and sidestepping.
** We've seen novel words introduced into the vocabulary -- and their typical fate, though some survive several decades.
** We've seen new products competing in the marketplace, many of them (breakfast cereals, soft drinks) simple variations on a theme in search of an advantage.
** We've seen old species of fasteners (anyone remember the diaper pin?) replaced with tape and velcro. "Bailing wire and sealing wax" seem to have been replaced by battleship-gray duct tape.
** We've seen vestigial features (those nonfunctional buttons on men's sleeves without matching buttonholes; those buttonholes on their lapels without matching buttons) carried over from an earlier age when they were functional, giving us some analogies to the appendix.
** We've seen patent protection to allow the exclusive right to exploit a new invention for seventeen years. There's no such law in biology, but since evolution is a little slow, a new niche (usually a specialized elaboration of an old one) is a wonderful thing: There's little competition for a while, and so the competition between members of the lucky species is greatly reduced, allowing various competitive "rules" to be broken --including ones that may have nothing to do with the new-niche discovery.
** We've seen cultural evolution backing up occasionally to explore a missed opportunity, as when the technology of ever-more-sturdy adhesives was mellowed to create removable notepaper suitable for temporarily posting reminder messages on doors and telephones. And strippable wallpaper, for those who like to redecorate regularly.
** We've seen cultural combinations that arise for one reason prove handy for other (sometimes diametrically opposed) applications. John Calvin imposed on sixteenth century Geneva "a regimen which included getting up very early, working very hard, and always being concerned with good morals and good reading" (the emphasis on Bible reading instead of sacraments promoted education regardless of birth or wealth). Though more fiercely antiscientific than the Church of Rome (the scientist Servetus was burned at the stake in Geneva, in contrast to Galileo's house arrest), the Calvinist combination of educational for all and hard work turned out to be conducive to science in the following century, the Puritans becoming staunch supporters of science.
** We can even see the sidesteps of cultural evolution, new uses for old things: computers invented for number-crunching becoming useful for noncalculating jobs (competing with typewriters and file cabinets, even running assembly lines and wristwatches), the old anti-inflammatory drugs such as aspirin becoming useful for unexpected applications (such as relieving pain and, more recently, preventing blood clots).
We also see cultural examples of proximate versus ultimate causes: The proximate cause of the triumph of a new sugar-coated breakfast cereal may be our sweet tooth, but the ultimate cause of that triumph is the early primate's adaptation to eating fruit. When we say "smoking causes lung cancer," we are talking of a proximate cause; the ultimate cause has more to do with evolution not having prepared us for long-term insults (if we are going to aspire to live beyond menopause, we'll have to devise our own protections). People are always confusing levels of explanation -- even scientists, as when fin de siècle geneticists claimed that it was mutations, not darwinian selection, that caused evolution -- and so caused the eclipse of darwinism for nearly four decades until everyone agreed that both were involved. There are usually many causes -- whenever you hear a choice posed ("It's either this or that"), remember it could be both or neither.
But, handy though cultural change may be for illustrating the themes of biological evolution, cultural analogies rapidly lead one astray when thinking about the mechanisms of biological evolution. It is downright hazardous to think of biological evolution using mechanistic analogies from cultural change, largely because biology doesn't pass on skills acquired during your life to your offspring.
Cultural evolution is very Lamarckian, but biological evolution isn't: Your muscle-building doesn't get passed on to your child (nor one's sedentary habits; forget whatever you heard about legs becoming shorter because we sit around so much). At least not via the genes, only by the example you later provide for the growing child.
[There is a] need to distinguish two causations underlying all phenomena or processes in organisms. These have been referred to by earlier authors as proximate and ultimate causations. The proximate causes consist of answers to "how?" questions; they are responsible for all physiological and developmental processes in the living organism, and their domain is the phenotype. The ultimate or evolutionary causes consist of the answers to the "why?" questions, and provide the historical explanation for the occurrence of these phenomena. Their domain is the genotype.... Many famous controversies in various fields of biology have been due to a failure of opponents to realize that one of them was interested in proximate, the other in evolutionary, causes.the American evolutionary biologist Ernst Mayr, 1988
THAT ISN'T TO SAY that culture doesn't influence biological evolution: Indeed, because brains
are so innovative, the usual rule is that behavior invents and anatomy changes later. A squirrel
may learn to leap between trees via either invention or copying others (that's culture); only later
do the perils of leaping manage to select the flabby-skinned variants who stick their legs out to
stretch the skin into an airfoil for more efficient gliding. Behavioral innovations thus paved the
way for biological changes in flabbiness. Whoever invented sewing set the stage for later natural
selection for even more nimble-fingered individuals, at least among those trying to survive
winters where drafty clothing was a problem. The environment doesn't somehow "induce"
flabbiness or sewing skills; it only selects from the novel variants thrown up by the combination
of genes and culture.
Given the usual infant mortality, improved mothering skills are probably the cultural innovations that have had the most feedback into the gene pool for the longest time, enhancing those genes that somehow affect the tendencies to care for the child effectively. You can see the importance of a mother's skills in chimpanzees: Jane Goodall's group has shown that the infant mortality for first-time mothers is much higher than for experienced mothers.
Now chimps aren't noted for innovations (Goodall hasn't seen many new cultural traits arise in a quarter-century of following the Gombe chimpanzees), but you can imagine how an innovation in mothering techniques (say, protecting infants from falls, a significant source of infant mortality in chimps) would cause a big increase in the number of offspring reaching maturity from those mothers whose genes somehow helped them to adopt the innovation. Food-finding skills have strong feedback too (especially in those species that care for their young) but pain-relieving skills have probably had little feedback, since they mostly benefit people who are postreproductive. That weak feedback doesn't make pain-relieving skills unimportant: It just says that there isn't strong biological backup, should culture misplace that information.
Cultural evolution is quicker, but less stable, than the older biological ways of innovation. In biology, there are lots of inheritable variations produced (mostly by shuffling the chromosomes as new sperm and ova are made, rather than via new mutations); some variants are edited out by the environment, some are passed on in average numbers, and some are associated with successful novelties. Since there is a long period of time between conception and the attainment of reproductive age (the developmental period) in which there is a lot of childhood-disease and happenstance mortality, culture can readily bias which biological variants survive best. But that doesn't pass on culture, only the propensity to be born with certain abilities that could reinvent the cultural practice.
Understanding the interrelation between culture and biology requires appreciating the mechanisms of biological evolution at least as well as those of cultural change. But the popular notions of biological change are largely myths that mislead most people (and often scientists as well).
NATURAL SELECTION is often mistaken for the whole darwinian process. Darwin pointed
out that in every generation there is a great overproduction of offspring; only a small fraction can
possibly survive to reproduce themselves. Second, all those individuals differ in their genetic
endowment, and some will survive better than others in the environment into which they are
born. And third, some of those individual differences (though not all) are heritable. Hence a
drift to body styles that "fit" the environment (increased fitness, we call it).
While selection plays the role of eliminating the less fit (or giving only the most fit an opportunity to reproduce), the combination of variation and selection, back and forth, is quite creative; it is what is called darwinism. Selection is an optimization process, but without programming; it is simply opportunistic. It only shapes up a local "good enough" optimum, as Darwin noted when he observed that the native flora and fauna of New Zealand, never exposed to much competition in their isolation, had been rapidly replaced by European types brought in by settlers. Darwin saw quite clearly that a fixed type, a Platonic essence, cannot evolve either. Most philosophers, as well as most nonbiologists, have been obsessed with essences and determinism and designers; biology just doesn't work that way.
I have long been an admirer of the octopus. The cephalopods are very old, and they have slipped, protean, through many shapes. They are the wisest of the mollusks, and I have always felt it to be just as well for us that they never came ashore....the American anthropologist Loren Eiseley, 1957
EVOLUTION IS NOT particularly efficient. The eye, often cited as an example of how a series
of adaptations can shape up a truly magnificent instrument, has a number of stunning flaws that
evolution has not succeeded in fixing, not even over hundreds of millions of years. Since
nearsightedness is so maladaptive in a considerable percentage of people, why hasn't better focus
evolved? And squeezing the lens in order to focus -- that is a truly absurd scheme compared to
the way the octopus lens is moved fore and aft, just as in a camera (after about forty-five years,
the human lens cannot be successfully squeezed into a fatter shape, which is why I now have to
wear half-moon reading glasses). I ask you now -- have you ever seen an octopus who had to
wear reading glasses?
And the retina, that hair-thin sheet at the back of the eye containing the first few way stations of the brain's processing machinery: the retina is inside-out by any rational design criterion. The light has to travel through four layers of not-so-transparent nerve cells before ever reaching the photoreceptors that change light into the first neural messages. Imagine what a few layers of grease, smeared over the surface of the film in your camera, would do to the quality of the pictures. The octopus again does things the right way, the photoreceptors pointing out toward the pupil with no biological wiring in the way to blur the image. Vertebrates probably got started doing things the wrong way when the environment was so muddy that a little additional blurring in the eye wasn't noticeable -- and so, like a bureaucratic procedure that can no longer be modified without changing everything else, we're stuck with the blurring and can only try to work around it somehow. Fortunately, a fancier brain can correct for much of the blur -- and since the same neural machinery can be used for other tasks as well, the early wrong-way-round mistake might be said to have engendered some improvements in overall abilities of the brain. (Alas, I cannot think of any bureaucratic equivalents, where starting out with an awkward procedure -- say, for assuring that merchants collect and forward sales tax -- has generated an unexpected bonus in the long run).
Evolution is also not an inevitable consequence of natural selection: Every little bit doesn't count. Just as most pain and suffering have little effect on cultural evolution, so most of the episodes of climatic change have had surprisingly little effect on a species' biological evolution. This is at odds with the popular notion of darwinism: gradually getting better and better. Species may be stubbornly stable (this is why "living fossils" are still with us): even if temporarily perturbed, they can return to their old body forms once the perturbing influence passes.
Complex systems exhibit far more spontaneous order than we have supposed, an order that evolutionary theory has ignored. But that realization only begins to state our problem.... Now the task becomes much more trying, for we must not only envision the self-ordering principles of complex systems but also try to understand how such self-ordering interacts with, enables, guides, and constrains natural selection.... Biologists are fully aware of natural selection, but have never asked how selection interacts with the collective self-ordered properties of complex systems. We are entering virgin territory.the American biophysicist Stuart Kauffman, 1984
Progress in science is achieved in two ways: through new discoveries, such as x-rays, the structure of DNA, and gene splicing, and through the development of new concepts, such as the theories of relativity, of the expanding universe, of plate tectonics, and of common descent. Among all the new scientific concepts, perhaps none has been as revolutionary in its impact on our thinking as Darwin's theory of natural selection.the American evolutionary biologist Ernst Mayr, 1988
HOW IS AN EVOLUTIONARY ADVANCE stabilized? Not all are backsliders, at any rate.
And in particular, how are sidesteps stabilized?
Sidesteps often confer some selective advantage (though not always, e.g., music) and when they do, some streamlining occurs -- just as when those ungainly protobirds first started gliding, and then the ones with the more streamlined airfoils got to the food first. This is, of course, why sidesteps are so hard to see "in action": They are obscured by the streamlining that follows their crude beginnings. Language surely has some selective advantage now, even if it got its start via a sidestep from secondary uses of something else (a ballistic movement sequencer is my favorite candidate). And the same argument is made for consciousness.
Biology has this roundabout way of doing things that promotes stability in some cases. Unlike culture, which remodels its structures and transmits acquired characteristics directly to the next generation, biology instead builds upon some mixture of the original blueprints -- while scrapping the old models (such as you and me; "planned obsolescence" was, alas, invented by biology before Detroit adopted it). Information stored in the genes is more secure against catastrophe, though much less can be stored than via culture's methods.
Information "stored" in everyday practices is terribly dependent on having a teacher, and so some techniques are totally lost when an epidemic sweeps through a small group. Documents, and ways to learn from them, do tend to carry along information over the vicissitudes that cause backsliding in preliterate societies -- but just remember what happened to the library at Alexandria, and how the accomplishments of the ancient Greeks were almost completely lost by book-burning. And how most of the documents of the New World were destroyed by the pious Spanish explorer-priests. The folly of a single generation can wipe out culture (and, these days, biology too).
Both cultural and biological evolution "make progress" largely because they happen upon inherent stabilities that reduce backsliding: Jacob Bronowski liked to call this stratified stability to emphasize that there were a series of them, each building upon the foundation provided by a previous one. Language was an early human invention of such major proportions; writing's invention five-thousand years ago built upon this foundation by associating a written symbol with an object, as in hieroglyphics, and later with a speech sound. Writing prevented some of the cultural backsliding associated with word-of-mouth errors and "out of sight, out of mind" forgetfulness. In biology, stratified stabilities occurred with replicating molecules, cell envelopes, sexual recombination, and the invention of brains, to name but a few ways. The formation of a new species by a one-month shift in mating season is a prime example of how to prevent backsliding by subsequent dilution. as I explained for the Grand Canyon squirrels in The River That Flows Uphill.
Understanding how evolution proceeds is not only important for understanding ourselves and from whence we arose, but in assuring that the things which we value in our culture are protected against future backsliding. It looks as if morality has little biological underpinning, and even high cultures (consider how accomplished pre-Nazi Germany was in science, philosophy, theology, history, literature, and the arts -- not to mention technology) seem able to lose some essential ingredients rather rapidly. Any underlying principle concerning how innovations become sturdy foundations, capable of supporting new superstructures, is obviously a matter of much importance if other societies are to avoid such backsliding.
THE BREEZE SWITCHED AROUND AGAIN, and that gaggle of sailboats in Eel Pond just followed it around. Societies are sometimes like that too, ready to follow the wind. But usually we act and think individually, or as members of small groups. Sometimes those groups are particularly effective because of the combinations of individuals. Most of the labs at MBL are groups working together, and they get far more done than they would have accomplished individually; other times, personalities will clash and they'll get little done. Picking your co-workers is very important in science; it's hard to imagine how institutions function when they treat co-workers as interchangeable parts, army-fashion.
EMERGENT PROPERTIES may be one of the major sources of innovation in nature. They
seem rather unpredictable, obeying no regular rules. But sometimes two mechanisms in
combination turn out to have a property that neither had separately.
Some combinations are associated with diminished functionality: For example, having three versions of chromosome 21 rather than the usual two is bad news (trisomy-21 is better known as Down's syndrome). For most of our genes, we have two identical versions -- but for some we are heterozygous, having a different one from each parent. For some genes, such as the Major Histocompatibility Complex, having two different versions from which to choose seems particularly useful (two differing versions probably allows the immune system to fight off a much wider variety of invaders).
And sometimes the particular combination of near-identical genes gives a whole new property, as in the gene combinations that fend off malaria. Most of us have two identical versions (called SS) of a gene that affects the shape of red blood cells and thus their fragility. Some people from Africa have the regular dominant one S and a recessive version called s (so their genotype is called Ss), and others inherit s from both parents (becoming ss). It turns out that the mixed genotype Ss is good news (for the individuals carrying it, but not necessarily their children), and that ss is bad news, namely sickle-cell anemia (the red blood cell membrane tends to rupture, diminishing oxygen-carrying capacity).
In trying to figure out why the s version is still around, given that the people with a double dose of it often die without passing on their genes, biologists discovered that the heterozygous carriers Ss were protected against malaria. And so they were better able to grow up and have children, nurture them along up to reproductive age. Half of the offspring from parents who are both Ss will themselves be Ss, a quarter will be SS (and unprotected against malaria), but a quarter will be ss (and tend to die of sickle-cell anemia).
So the combination of both S and s has this emergent property, of protecting against malaria. The s is surely another one of those random variations that turned out to be less functional than the original S. Most variations are less functional that the original (if they are spectacularly less functional, and thoroughly gum up the works, they may find a role as a toxin in an arms race). But in combination with the original, and then only in places where malaria-carrying mosquitoes live, the combination Ss has an unexpectedly nice function.
HYBRID VIGOR is likely another example of combinations of genes being unexpectedly useful.
When crossing two species to make a hybrid, many more genes become heterozygous. Again,
this is usually bad news: Spontaneous abortions are very frequent in cross-breeding, and so one
may get a false impression of vigor just because the bottom half of a distribution never gets born,
giving the ones that do a higher average. But sometimes the combinations themselves have new
functionality. Like mules (and some of the plants in this carefully tended garden), the hybrids
may be sterile and so continue only by continued crossing.
But mostly hybrid vigor is seen when different subpopulations of the same species come to breed again. The "mixed race" individuals are seldom sterile, and their offspring continue to receive gene mixtures. But like genius, which is probably due to a fortunate combination of genes in a single individual, hybrid vigor is difficult to pass on because the combinations are broken up: When sperm and ova are made, the DNA deck is shuffled first, guaranteeing that you get some genes from each grandparent, not just one or the other's chromosomes. Mostly the chromosomes are broken at natural places during the crossing-over phase of meiosis, such as at the end of one gene's DNA sequence, and many genes move as a group (like sticky cards when a deck is shuffled; this increases the chances of inheriting a group of traits together). But new found combinations of genes, one from each parent, usually do not have a new found stickiness, and so are not reliably passed on together. Thus genius, and many similar inheritability phenomena, is often ephemeral.
The cross-fertilization of ideas is a cliché these days: Suffice it to say that hybrid ideas are easier to form than hybrid species -- and that consciousness, insofar as it generates new alternatives and selects among them, is the supreme example of hybrid vigor.
IF MAJOR INNOVATIONS ARE SURPRISES from new combinations rather than predictable-from-the-environment streamlining, then we have to look at nature rather differently from our
usual mechanistic approaches. There has always been a certain tension between scientists who
reduce everything to properties of the component parts (reductionists), and the people who
emphasize that there are different levels of explanation and that the whole is often more than the
sum of the parts (in the extreme, called holists).
Though some manage to shift back and forth, alternating viewpoints for a more complete picture, many scientists work completely within one framework or the other. I was trained in a biophysical approach to neurophysiology, which led me from behavior to look at brains, from neural circuits (such as reflexes) to look at individual nerve cells, from looking at cell properties (such as action potentials) to membranes (where dozens of different channel types combine to produce action potentials). Look even closer, and there are electrical gates and molecular sieves controlling the channels, etc. And so on to quantum mechanics.
MBL specializes in such reductionistic science; delving deeper and deeper has produced a lot of valuable insights in the past and it surely will continue to do so. It is also downright addictive: Let a new technique come along that allows finer resolution, and our fingers get itchy. The surest topic for jamming a lecture hall around here is describing a new type of microscope, or a new computerized television system for improving the traditional images. You sit there and say, "I wish I'd thought of that" and then you add, "I've just got to get one of those setups."
Many psychologists were instead trained in a tradition that said the parts were unimportant, that one could treat the brain as a black box, and there remain many cognitive scientists today who would claim that it really doesn't matter how the brain implements the algorithm or stores the information, that what's really interesting are the combinations that subserve higher-order pattern recognition (what I use to tell a Winslow Homer painting from an Edward Hopper). Philosophers too tend to ignore the machinery and how it evolved; Gilbert Ryle's Concept of Mind manages to avoid the word brain entirely.
However, both psychologists and philosophers have the same tendency to subdivide the problem as physiologists do; they just don't use the natural subdivisions of biology. And so they wind up with separate departments of thinking, feeling, and willing (translated into Freudian terminology: ego, id, and superego). These separate units of mind become enshrined in textbooks as separate chapters on sensation, perception, association, memory, intelligence, reasoning, motivation, imagination, instinct, emotion, personality, etc. When they attempt, if they ever do, to put them all together, they are likely to say something like "consciousness emerges from the sum of all the parts." And the physiologists are likely to jump on them for being vague. Hopefully, we can do better by looking at evolutionary theory and basic neurophysiology, attempting to reformulate the problems in more natural terms.
Still, for all their insistence on "something more" than the "sum of the parts," holists of various stripes (some of which are "more holistier than thou", says Richard Dawkins) have been generally unsuccessful at getting a handle on how emergent properties emerge. Surely there are some rules, if only we can find them. The compounding of mechanisms is the clearest aspect: Evolving two different digestive enzymes for breaking down two different plant foods likely gives rise occasionally to an ability to eat some novel third food. But brains are far better at "new uses for old things" than any other organ of the body, thanks to nerve cells having the propensity to reduce everything to so many millivolts and thus establishing a currency for comparing unlike things. Once the new functionality emerges, it will be streamlined by natural selection, and so when we look at it today, we'll see adaptations and not realize their innovative origins.
I suspect that emergents are the crux of brain evolution, and our brain mechanisms for imagination and choice are highly likely to have been shaped by such secondary uses. But having said that, I still have this physiologist's urge to take it apart and understand the pieces too.
SO MY PRIMAL QUESTION about the homunculus at the center of it all isn't likely to be
satisfactorily answered by a generality about the narrator emerging as some surprise, as a lot of
parts combine to give a new property. Yes, emergents happen; yes, they're probably the real stuff
of brain evolution. But the generality -- even if proved correct -- doesn't save us from
understanding the parts and how they work together to produce the emergent narrator. And that
will surely involve clarifying how they evolved, the primary uses from which the secondary uses
Was it some sort of arms race in cleverness? Or was the arms race primarily for armaments, and the cleverness secondary? No generality is going to answer this primal question, only a long (and very interesting) story.
I have developed a view of the growth of knowledge -- of human knowledge more specifically, but also of animal knowledge -- which differs greatly from nearly everybody else's. According to this view, our knowledge is not in the main derived from experience, not even from experience as I see it: the elimination of bad guesses. Most of our knowledge, and animal knowledge, and even vegetable knowledge, is rather the result of sheer invention.... All organisms are professional problem solvers: before life, problems did not exist. Problems and life entered the world together, and with them problem solving.the Austrian-English philosopher Karl Popper, 1984
|The Cerebral Symphony (Bantam 1989) is my book on animal and human consciousness, using the setting of the Marine Biological Labs and Cape Cod.||AVAILABILITY is limited.