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William H. Calvin
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The River That Flows Uphill (Sierra Club Books 1987) is my river diary of a two-week whitewater trip through the bottom of the Grand Canyon, discussing everything from the Big Bang to the Big Brain. It became a bestseller in German translation in 1995. AVAILABILITY limited; the US edition is now out of print. There are German and Dutch translations in print.
The River That Flows Uphill
A Journey from the Big Bang
to the Big Brain

Copyright 1986 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).

This is a Deluxe edition in an unusual sense: the photographs and sound files are from Leonard Thurman’s Grand Canyon River Running web pages. What you get on your web browser is assembled, before your very eyes, using text delivered from Seattle (Washington State USA, near the Canadian border), and pictures and sound being sent from Tucson (Arizona USA, near the Mexican border).


Mile 71
Cardenas Creek

THE ENIGMATIC ANASAZI HILLTOP was all the talk at breakfast. Those who stayed the course had to tell the people who slept through it what they'd missed -- the view of Unkar Delta and the rapids seemed to take precedence over the moon. The half-dozen of us who'd gone on to see the hilltop ruin extolled its commanding view and enigmatic nature.

"If you're quick, you can run right up to the ruin and back down again," added Alan, not looking a bit sleepy. "We took the long way last night to see the cliffs. It's only about 40 stories up, and there's a trail in back of camp that starts straight up that ridge line," he said, pointing. Five people actually packed up their black bags in a hurry, left them down by the boats, and set off up the path, promising to return soon. "You can always stop at the 35th floor to admire the river gravels," Alan shouted after them.

While my calendar idea was discussed briefly, what really held the attention of the people eating breakfast in the alcove of tamarisk was the Unkar Delta story. Particularly the boom-and-bust nature of the Anasazi population, controlled by the intermittent droughts.

"That's almost as bad as the deer," Ben said. "A good summer means a lot of starvation the next winter."

"I thought that humans in primitive tribes held their population pretty constant," Abby ventured. "You know, the Kalahari San and the Australian aborigines. Even without modern birth control they average about four years between babies."

"But how?", someone asked.

"Prolonged breast feeding suppresses ovulation, for one thing," Ben volunteered.

"That doesn't work so well if you're well-nourished, I hear," said Rosalie. "Maybe a poor diet holds population growth constant."

"And maybe it's a constant climate," Ben said. "The big population booms occur when a new niche is opened up, as when more food becomes available. Maybe the stability of the native tribes they've studied is just because they haven't experienced big improvements in living conditions."

"Sounds like inflation to me," Rosalie said. "The population explosion as the archetype of monetary inflation! Maybe both are due to a rapid improvement in living conditions."

Abby looked dubious. "You mean that the tribes with stable populations perceive the world as unchanging? While people in an obviously changing world have more children?" "Could be true," said Ben. "Certainly people have fewer children when times are bad."

"That's partly because the infants don't grow up -- infants haven't acquired much immunity to diseases. They're being stressed all the time, and so die more readily if they're malnourished," explained Rosalie.

"But it's also planning," Ben said. "Humans plan. And there are social pressures -- when another baby comes along too soon in an Aboriginal family, the man loses social status, he's blamed for it."

"So if people plan, why do we have such a big population problem?", asked Abby.

Rosalie pointed out that we've strained things badly, leaving very little insurance against fluctuations in climate or natural disasters. It's inhuman. A humane world ought to have no more people than it can support in its worst years; the way it stands, ten good years of weather in a poor country is almost a sure prescription for starvation, because the weather never stays that good during the next decade. As the statisticians say, it regresses toward the mean. Not that we're any smarter: even in our modern civilization we see college-educated people ignoring the obvious -- such as when they build a house in the flood plain of a river, when it's perfectly obvious that it will be flooded out sometime in the next few decades (they expect, I suppose, that the equally gullible taxpayers will either pay to protect them with dams or reimburse them with disaster assistance when the inevitable happens). Yet boom-and-bust cycles may have been common on the frontiers, where living conditions were marginal and fluctuating. The ice ages probably produced a lot of such conditions, running the ratchets of natural selection quite regularly. And, while I'd grown somewhat accustomed to thinking in terms of such stresses every 100,000 years, the Anasazi experience is sobering: it suggests that significant selection cycles could also occur every decade or two for those living on the margins.

THE STANDARD SWINDLE about the population explosion is that it will cure itself once the standard of living is raised even higher in the developing countries. Of course, the rising standard of living is also blamed for these countries' population boom in the first place. Confused? Someone is. Wishful thinking? Probably.

Medicine, or at least public-health measures such as sanitation, is supposedly the cause of the population boom. All of those babies who would have died, the story goes, have been saved from childhood diseases by improved sanitation and modern medicines. You'd think that population growth had been held in check all those millennia by disease. True, there has been a correlation between better medicine and increases in tropical populations during the last three decades, but to look no further back in history than this one recent example is indeed shortsighted. The world's population started booming long before modern medicine, back when there were still open sewers in the city streets. Europe's population boom started about 1600, not 1900. And 1600 was not the start of either modern medicine or improved sanitation.

Puncturing that fallacy only requires a little history, but to understand why the population explosion will remain a serious, continuing disaster requires a few lessons from population ecology. Back to the birds, while we wait for the boats to be packed for our little trip down what Major Powell called "The Great Unknown."

Some animals, such as mosquitos, lay lots of small eggs and merely hope for the best. Nearly all their young will perish. Other animals -- and birds are good examples of this -- put their reproductive efforts into the well-aimed shot rather than the scattergun. Postnatal care is the most obvious way in which such animals "invest" in their offspring. To insure the quality of the offspring raised, some birds also adjust the number of eggs they lay according to what the food supply will bear that season. The snowy owl may raise only one or two eggs some years, ten eggs in others. It depends on the supply of baby food, namely the little arctic mice called lemmings whose availability tends to fluctuate in cycles of about two to seven years. The snowy owl accurately estimates the food supply, and doesn't create a lot of mouths that cannot be fed without making them all weaklings. By spending their reproductive efforts wisely, more snowy owls' offspring reach maturity.

To estimate in advance the resources available during the coming season is rather clever of the owls. People are even more clever than birds at reading the environment, guessing the future, making plans, and implementing them. We have been in the family-planning business for a long time, using primitive versions of contraception and abortion, social rules and sexual taboos, and so forth. Zero population growth may have often been implemented during human history. Look at today's remaining primitive societies and you will often find a stable population rather than exponential growth. They know how many mouths they can feed, and they adjust their reproduction accordingly. Prolonged breast feeding suppresses ovulation, we now know, but that's been utilized for millennia; it's one reason why the average birth spacing is four years in hunter-gatherer tribes.

But then there are the social devices for birth control; to take but one example, almost any form of sexual taboo helps reduce babies. Social rules also limit the total number of babies per mother by effectively decreasing the reproductive span, that period between puberty and menopause. They delay the first pregnancy: marriage is put off through a variety of devices, such as initiation ceremonies, bride prices, getting together a dowry, building a house for the new couple, and so forth. Social rules may have other functions too, but one of their results is to limit total reproduction.

Primitive people also practiced abortion as best they could, usually in the form of infanticide. In many recent societies and probably most ancient ones, families would carefully evaluate the family resources before letting a newborn baby join the family. Even aspects of our physiology facilitate this: lactation is not triggered by giving birth but by suckling, making it possible to delay mother-infant bonding. If there wasn't going to be enough food to go around, child-rearing was often postponed until a later pregnancy. Today we have the technology to make that decision much earlier, long before the brain develops any uniquely human functional abilities (a far better test than the simple-minded and unanswerable "when life begins"). And in most cases, we now have the ability to prevent conception in the first place. But while our technology may be more sophisticated, family planning has been done by both humans and birds for a very long time.

To assume that the recent invention of mass medicine has made any fundamental difference to the number of children raised in any contemporary society is to assign to people the small-egg gambit of a mosquito; it is to assume that women are mere baby factories and their output is a function of what the doctors can keep alive. It is unscientific as well as literally inhuman.
the ecologist PAUL COLINVAUX, 1982

AND SO IF FAMILY SIZE is normally regulated, one cannot intelligently address the population explosion without asking: Just what factors determine the size of the family one can afford? If it is a control system like a thermostat and furnace, just what determines the setting, the family size around which it hovers? Remember, we're not necessarily talking about rational choices here, but also about the intuitive cues that even birds could use as their target family size. What are the target cues which, in particular, the human species follows?

Until modern societies such as India and China, it seems unlikely that family size was ever regulated primarily for the good of the larger community. Social rules, which initially suggest that population growth was controlled for the sake of the community, may be only a way of decreasing the competition, of holding down other people's family size. Instead, each family was probably trying to rear as many offspring as it could. After all, during prehuman evolution, those who maximized their offspring did wind up with more genes in the next generation than those who limited them.

Such "looking after number one," however, results in some appalling suffering and waste by our humane standards. As a result of such maximizing, most species try to raise far more offspring than can survive as adults. To take an omnivore not unlike humans, bears rear many more cubs than can ever grow up. There is only so much adult bear food around, so only a fraction of those cute cubs can ever raise a family themselves; indeed, like most lion cubs, most bear cubs starve after their parents stop caring for them. Stupid? Just natural. The overall effort expended on raising bear cubs (the "reproductive effort") is absurdly in excess of the number of job slots for adult bears. Yet it was a matter of keeping up with the Joneses -- for an individual bear to do less would mean getting fewer copies of her genes into later generations than the bears who raise many cubs to reproductive age. Regulating current clutch size (the number cared for at any one time) is one thing, as it makes for healthier babies, but to limit lifetime numbers (clutch size times the number of seasons as an adult) makes less Darwinian sense. The excess means that natural selection and chance determine which cubs actually survive to reproduce.

Limiting clutch size by the projected availability of baby food is not the same thing as limiting total reproduction over a lifetime according to the availability of adult food. The standard rule in population ecology is that the resources devoted to reproduction have no relationship at all to the population size which results. The numbers of offspring reared are often absurdly in excess of the carrying capacity of the environment and there is a lot of starvation. It is the niche size -- the number of bear job slots available -- that determines the population size.

A niche used to be just a recess in the wall of a room, used for housing statues and such. But the ecologist's use of the word connotes something more like a job slot. For example, there are only so many dentist jobs in Flagstaff. To be a dentist requires a combination of skills and opportunities: one has to have inborn ability (nimble fingers) and the acquired training (eight years of college) to be a dentist, but one cannot function as a dentist unless there is also sufficient dental work for one to do. The number of dentist slots depends on the population of Flagstaff and the prevalence of dental disease there (all that good mountain water can be rather low in fluoride, unfortunately). Thus, the concept of niche implies both a set of skills conferred by inheritance and culture, and a set of environmental constraints such as food availability, climate, predators, disease, and the right setting for successful reproduction. Lack any of them, and one doesn't fit the niche, one can't make a living. Few animals can switch niches successfully; surplus dentists can usually find a different job, thus modifying their niche (making silver jewelry for the tourists would be a good bet if a dentist wanted to remain in Flag).

The niche of human hunter-gatherers is determined by skills and resources too; being even smarter than birds, they too limit their clutch size in accordance with family resources. Birds raise a different clutch every year, but humans mostly raise one big "clutch" of various ages due to the long rearing period for each, replacing the ones that die and repeatedly estimating how many extra can be afforded. In contrast to the birds' situation, this means that human clutch size also represents the number of children produced in a lifetime. This may allow the number of adolescents coming into the human breeding pool to approximate the number of job slots opening up, thus allowing most adult humans to reproduce. We have improved on the birds who, like the bears, usually produce more offspring than can ever survive or reproduce.

Whenever a niche broadens, there is room for a bigger population: when the bears learned to fish, there was a bear population boom until the limits of that new niche were reached. And whenever either human skills or environmental resources improve, there has usually been room -- in the past -- for more humans. For a while.

Before Columbus, says the ecologist Paul Colinvaux, the native Americans were likely packed into the Americas just as tightly as their technology allowed. The European settlers had agricultural technology that supported more people on an acre of land; they also had the weapons that allowed successful aggression against the original inhabitants. And so, back home, the European populations boomed. The family planning in the old countries undoubtedly took into account the possibility of emigration to the new world; the new Americans had big families, as there always seemed to be resources for lots more. The European niche had expanded at the expense of the Indians; the world population had a net increase because the Europeans could live at higher density than the Indians. The Anasazi niche also expanded about A.D. 1050 because the rainfall allowed crops to be grown in new places; but their population boom was, alas, in trouble after just a single generation.

Evolution is what it is. The upper classes have always died out; it's one of the most charming things about them.
ONE CONVENIENT RATIONALIZATION for not worrying about the population explosion is that family size drops as middle- and upper-class economic status is attained; it even happened in ancient Rome (though people who cite that usually fail to note that the total Roman census continued to expand). Perhaps better-off parents don't need all those children to make sure someone will support them in their old age, and so forth.

Thus, the soothing story goes, when those developing countries are further along, the problem will take care of itself. This was the prevailing thinking up until the nineteen-fifties (although U.S. President Ronald Reagan found it convenient to revive it, like an old movie, in 1984). As early as 1944 demographer Kingsley Davis called this view into question, warning that if India's population followed the pattern of the West's demographic/economic transition, it would reach 750 million by the year 2025. Davis was considered an alarmist at the time. But his prophecy came true in only half the time: by 1985 India's population had exceeded 750 million, despite decades of birth control programs.

In The Fates of Nations, Paul Colinvaux points out that both rich and poor probably have as many children as they can afford; the reason there may be only two or three children in rich families is that each child requires such major resources. Rich parents' expectations for their children are at least as high as their own attainments. While a physician may earn a lot in comparison to a laborer, the physician may still be able to afford to send only two children to medical school or its equivalent; the laborer without upward mobility, on the other hand, has no such expectations and may be able to afford seven or eight children who get by on mediocre diets and who all sleep in one room rather than in separate rooms. For the poor, children are cheap. They may even contribute by going to work at an early age, providing another wage-earner to help the family.

Both the rich and the poor family may regulate clutch size just as the snowy owl does, but their standards of what is sufficient differ greatly; thus the number of children from each social class that reach reproductive age may be contrary to what income suggests. We might say that the quality of the product is different, but that's our cultural bias speaking, not biology: rich or poor, all of our offspring are competitive for mates unless they're grossly malnourished, and in evolution that's what counted for getting one's genes into further generations in greater numbers than the competition. I might note that, for humans, such competition is not a consideration anymore, as human biological evolution by standard means has probably ended, what with our mobility stirring our very large gene pool.

Once beyond malnourishment, poverty is relative. And as long as the poor don't have great expectations for their children that require the parent to set aside resources, the poor will be able to afford big families. And they'll have them, too. That, says Colinvaux, is why the population explosion won't go away.

Humans are animals that, rather than being born to their niche, learn their niche: we can learn a hunter-gatherer niche or a dentist niche. And at various times in our history, we have greatly expanded the possible niches. Occasionally this occurred when new land opened up for habitation, as when Homo erectus used fire and clothing to survive Peking's climate, as in the European takeover of the Americas, as in the irrigation of the Negev desert by both the ancient Nubians and the modern Israelis. As in when the land around us here on Furnace Flats was opened up to agriculture by the rainfall improving about A.D. 1050.

Usually niche expansion has been aided by technology, creating new jobs as it were, so that more people can be supported. In the developed countries, we have created so many new niches that 10 percent of the people can now feed both themselves and the other 90 percent as well; and while some of the other 90 percent must occupy niches that supply clothing, housing, fertilizer and fuel to farmers, society has a great deal of choice in what else it will emphasize. It could, I suppose, spend the rest of its efforts at bookkeeping and auditing the bookkeepers, keeping track of every transaction with a passion (this seems to be the goal of our tax laws). Assuming that doesn't happen, what fraction of those new "nonessential niches" will go to lipstick or books, to adult education or spectator sports? You are what you pay attention to.

Peoples' perception of a changing niche is, of course, part of what family size is based on. If they see more-of-the-same in the manner of the traditional hunter-gatherer, they will plan their family size differently than poor Mexican peasants exposed to movies and television who therefore hope to slip their children into the United States someday. Or at least Mexico City's teeming tenements. They're just doing what the Europeans did during these last few hundred years.

We were in Guaymas, Mexico, with a guy from Chicago. He was busy denigrating the area, "who could stand to live here, you wouldn't know anything about the world, it is so squalid, etc." I was busy taking pictures of houses perhaps 25 feet square with a 1954 Chevy pickup truck in the driveway and a satellite dish on the roof. An area of perhaps 1,000 people, with about 50 satellite dishes! He said, "What do those dishes do anyway?" I said, "Well, these people can get 130 TV channels in five languages, and subcarrier FM stereo. They have Quebec, Venezuela, Mexico City, all of America, BBC, and they get the Chicago Symphony as clearly as you do." He was stunned. And silent for a while. And then he said, "What do they think when they see all that, and they look at this, where they live?" And I was silent, and Nan was silent, and he was silent. And I can't get rid of the notion that Scarcity and Abundance will have to be dealt with by the materialistic nations (today's equivalent of the monarchies that went down to democracy's force with the advent of the cheap printed word).

WE NOW SEE UNKAR RAPID from a new vantage point, and the waves sure look larger from down here. Unkar's a long rapid, sweeping in a U-shape, cliffs on the left bank and the Anasazi's ancient cornfields on the right. Those fields were used for not much more than one century, mostly during the Anasazi population boom.

We're holding just downstream of the rapid, waiting for the other boats to come through. Once the boats are bailed out, Jimmy repeats a bit of the Unkar Delta story to those who hadn't ferried across yesterday afternoon.

There is an old Anasazi granary on the right bank, just downstream of us. It's not up as high as the cave at Nankoweap, so maybe the rodents got more of the stored grain here.

We're soaking up the morning sun, having heard stories about the big rapids up ahead. This is reputed to be the hardest day on the river, with lots of really big rapids coming up. Besides which the canyon narrows down, and that means lots of shadow, too.

The human population explosion represents hubris.... If we make use of birth control, we can affect the amount of time it takes for the human population to double. At present, this doubling time is shrinking constantly, and the world's population is burgeoning in accordance with a hyperbolic law. The potential for catastrophe is great. The self-regulating mechanism that will, because of the inherent limits of our environment, inevitably go into effect is inhuman.
.....MANFRED EIGEN and RUTHILD WINKLER, Laws of the Game, 1976.
THE POPULATION EXPLOSION might level out, of course, if people's perception of the future was as unchanging as the hunter-gatherer's -- for example, if the society became very rigid, with no chance to rise as in a caste system, with no opportunities for emigration, with barriers everywhere created by a bureaucracy that has to ration strained resources. There are, and have been, some stagnant societies like that.

Rigidity does stop growth. Rigid societies are, of course, police states in addition to everything else. They may eventually become ripe targets for an aggressive neighbor. If we want anything like a free society, with lots of choices and the constant opportunity to better ourselves, we will also have the natural tendency for the population to grow -- in the absence, that is, of some unnatural intervention. Couples, left to themselves, will continue to have as many children as they think they (without regard for their neighbors) can afford; for the poor, that will likely be many more than is needed to replace the dying in both rich and poor segments of the society, for they're unlikely to be influenced by ecologists' warnings printed occasionally in the big city newspapers.

Human societies have choices, however, that other animal societies don't. The choices are the benefits of our ability to discover and accumulate new knowledge, and apply it to simulating scenarios for the future, choosing the better-appearing alternatives. We can choose to apply our medical technology, for example, not to increasing fertility by treating infertile individuals and saving problem pregnancies, but to decreasing fertility -- by improved contraception, by making spontaneous abortions somewhat more likely rather than less likely (they've always been many times more likely than induced abortions: 48 to 78 percent of all conceptions spontaneously abort, most in the first month where they are never noticed because the woman does not miss a menstrual period), by removing barriers to a woman's right to terminate a pregnancy.

Other effective measures include training every woman for a niche other than full-time mothering, so that she always has a choice. However, one should not deprecate the important niche of full-time mother to achieve such ends; a diverse society should include the possibility of some families having no children and others having four. If one's goal is to decrease overall numbers rather than to uniformly decrease the size of everyone's family, and one doesn't let planning get contaminated by eugenics-type considerations (some of us have great faith that the gene pool of the poor is little different from that of the rich), one can avoid many of the most difficult problems posed by a society trying to implement zero population growth.

Our addiction to "growth" is really an addiction to an expanding niche. We often call it "freedom": to be free to choose, to be free of the bureaucratic constraints associated with the rationing of scarce resources, to be free of the repression employed in stagnating police states as those in power protect their own niche. Niche expansion is, in the natural course of things, conducive to a growth in population as well -- individuals will naturally plan to have larger families, just as the Europeans and Anasazi did when things improved.

And, conversely, some people think that more babies mean more jobs. But that's illusory. For some occupations, of course, a baby boom does mean more jobs -- but we must not allow shortsighted "more is better" thinking to dictate our policy. The postwar baby boom has propagated through our society; the decline after the peak reduced the number of jobs for baby-carriage manufacturers, police officers (fewer erratic teenagers), and teachers -- but during the same period, we nevertheless expanded our niches all the same, the industrialized nations' economies having somehow created an enormous number of additional jobs (which is how the percentage of employed women has soared). We must disassociate niche growth from population growth, or the population growth will eventually overwhelm niche growth and its freedoms, just as has happened before in crowded parts of the world.

The alternative to doing something? Default. Zero population growth will instead be attained by perfectly natural but very undesirable methods -- lots of aggression from overcrowding, rigid caste systems, stagnation, police states, and all the rest. To maintain and expand freedom in the world is going to require vigorous action to decrease average family size. To allow the issue to be swept under the rug by shortsighted politicians and special interests is to abrogate our freedoms, to sentence our children to a world for which they will not thank us.

Just remember those young Anasazi of the years 1070 and 1130, whose parents started their population boom before the agricultural economy was really secure enough to guarantee themselves -- much less their children -- a living. They probably starved to death. Taking those kinds of gambles -- with lives -- has been important in the past, but a humane society doesn't have to continue the practice when it can do better. We aren't deer.

[Spinoza's truth] that outside civilization (privilege) we are nothing, mere battered brutes without choices, whereas inside, however unfair that may be, we have hope, including the hope that our good fortune may spread to others.
.....the writer JOHN GARDNER, 1978

THE CANYON, which had been so broad along Furnace Flats, begins to narrow below Unkar Delta. For us it was a sudden transition, as we weren't paying attention to the scenery, arguing as we were about population problems. Our sense of the world closing in on us was mirrored in the canyon walls closing in on the riverbanks.

The tilted Precambrian layers flanking the riverbanks give an abrupt illusion of heading downhill. Steeply. The river is indeed going downhill -- the Colorado's gradient averages about one story every 1.5 river miles -- but when layers ascend from the riverbank level to many stories high within your several-block view downriver, it gives you the distinct impression of being funneled down into an abyss.

The first view of such V-shaped expanding sightlines, just below Unkar, is reinforced after the river takes a turn or two and the walls have really begun to close in. What is going on? The view of the Palisades is lost and we only catch glimpses of the South Rim; the North Rim is completely obscured. This is Shinumo Gorge, and the prominent white bands in the walls are of quartzite, which is much more resistant to erosion than the usual Dox stuff -- hence the narrower canyon.

But we have other concerns: namely, Hance Rapid, the second of the biggies, rated a 9. It drops nearly three stories and it looks BIG. We see hikers camped here; there is a steep trail down from the South Rim. The ride through Unkar was long and wet as we swept in a broad curve to the right around the foot of Unkar Delta. Hance is a straighter shot and another wet ride as we flush through.

Hance Rapid at Mile 76, from Leonard Thurman's Grand Canyon River Running web pages.

We are now ready to start on our way down the Great Unknown. Our boats, tied to a common stake, chafe each other as they are tossed by the fretful river.... We have an unknown distance yet to run, an unknown river to explore. What falls there are, we know not; what rocks beset the channel, we know not; what walls rise over the river, we know not. Ah, well! We may conjecture many things.... Heretofore hard rocks have given us bad river; soft rocks, smooth water; and a series of rocks harder than any we have experienced sets in. The river enters the gneiss! We can see but a little way into the granite gorge, but it looks threatening.
........POWELL EXPEDITION DIARY, 13-14 August 1869
Just below Hance at mile 77 comes another V-shaped illusion as the Bass Limestone emerges steeply from the river. The Canyon profile narrows further and then we are abruptly into the Vishnu Schist. Nothing gradual about this emergence -- just "wham," like entering a black tunnel whose roof has been left off.

The Inner Gorge is like nothing we have seen before. Its Vishnu Schist is finely layered, almost foliated like the Tapeats sandstone on which we rested at the Little Colorado. But at river level it has a polish like marble, that varies from a buff red (where granite has intruded) to an ebony black. The vertical slabs never extend very far before they are distorted, overlain, intruded -- the impression is of a marbled cake, chocolate with swirls of strawberry red. All this runs a few stories high before terminating abruptly. We often see sky beyond the top of this narrow canyon, though at other times there are a few layers of corrugated Tapeats Sandstone capping the marbled walls. This makes it even more like a cake: horizontal layers of Tapeats frosting atop the vertically-swirled marble layer-cake. The river-polishing of the schist extends more than one story above the current river level.

Then, near Mile 79, we come to the first of the inner-canyon rapids, Sockdolager, whose name is not very reassuring once you learn that it supposedly means "knockout punch" in Swedish. The Canyon is so narrow that sandy beaches are infrequent; even if we wanted to stop and look at this rapid, it would be hard to find a place to park. And we are travelling ever so much faster now that the Canyon has squeezed the river into a narrower channel. We are swept in. Through we go, up and down, getting soaked from one side and then the other, splashed from the rear when we don't expect it.

Sockdolager Rapid at Mile 79, from Leonard Thurman's Grand Canyon River Running web pages.

We pass the last of the good campsites for 11 miles, and what a difference -- Vishnu camp at Mile 81 is a little sandy beach on the left, hardly big enough to hold us. Then "wham!" Grapevine Rapid, another biggie.

Once more we bailed, and then looked around, somewhat breathless by now. The canyon walls continue to display one variation after another on marbling. The river too is marbled with swirls of water, the currents milling about, diving under one another. This occasionally sucks one side of the boat down.

And the boatman yells "Highside!" We quickly move to the high side of the boat to counterbalance it, to keep the other side from subsiding into the swirling waters. And I thought that highsiding was going to happen only in rapids -- but there's no rapid in sight! This river is full of surprises.

The schists here form a medium gray background for a series of red, black, and white bands. Early geologists gave names to all the variations on granite and schist: Brahma Schist, Vishnu Schist, and so on. Now the fashion is to just talk about schist, granite, and gneiss, without further subdivision. We neurobiologists understand this immediately -- in the perpetual war between the splitters and the lumpers in science, the lumpers are currently predominating in this descriptive geology. The same thing happens in any branch of science, where different names are initially assigned to every variant in the hope that they will prove useful (as not infrequently happens). But a later assessment may suggest that one name, lumping them all together, is more advantageous and less tiring.

There are many granite intrusions into the schist, streaking the canyon walls like a crisscrossed lace. The schist is metamorphic rock, made from old sedimentary layers of the same general kind we saw during our descent through Marble Gorge and Furnace Flats. These sandstone and shale sediments were pressed and cooked deeper within the Earth at some point, producing the metamorphosis, a transformation of sandstones and shales and limestones into a harder schist that will take a polish. Hotter, more fluid rock from the Earth's mantle -- granite -- managed to push its way up through weak cracks in the schist, while it was still buried deeply, and we now see the result in the form of these crazy laces running every which way. Sometimes they become so extensive that it is hard to find the original schist -- the wall instead looks as if the red-white granite had somehow acquired patches of black schist.

The narrower river channel is due to the harder rock. But the same amount of water has to pass each second if it is not to back up. So the river is deeper and faster here, and the swirls abound in this torrent. Often we must pick our way between two back-eddies, each of which would carry us back upriver. The boatman needs a sharp eye to thread a path that keeps us going forward.

It is, in theory, possible for there to be no path downriver whatever, even though that's where the river is flowing. The River That Flows Uphill. If the deep water flowed faster than the surface water, eddies could make the surface water all flow back upstream. The river, from surface appearances, would actually seem to run uphill! And the surface waters are what we have to ride -- we can't just ride the "average" current. Fortunately, we're able find a little surface current heading downriver.

Classical Laws of Thermodynamics, Simplified:
1. You cannot win.
2. You cannot break even.
3. You cannot get out of the game.
Consequently: he who wants to have right without wrong,
Order without disorder,
Does not understand the principles
Of heaven and earth.
He does not know how
Things hang together.
........CHUANG TZU, about 300 B.C.
WE ALSO LIVE in a part of the universe that isn't average, that is going two ways at once. What's true for the whole "average" universe isn't necessarily true for local sections of it, such as the solar system. Instead of things getting more and more disorderly as time goes on, which is the usual conclusion drawn from the second law of thermodynamics (entropy and all that), things locally often get more and more orderly, just as a consequence of a flow of energy.

This river, by flowing downhill, creates whirlpools below the rapids, nice orderly spirals. And the river sorts rocks by sizes, the small ones getting carried along further than the big boulders; the sand settling out of the river earlier than the silt. Many crystals arise when heat dissipates, as in the formation of a snowflake or the quartz crystals we see here and there in the riverbanks. Or the cooling of lava (Gary says we'll see big hexagonal columns of lava down near Lava Falls in another eight days). That's creating order locally as the universe as a whole supposedly runs downhill to chaos.

Inferences about the long run give one a totally erroneous impression of the short run -- and inferences about the whole universe give an erroneous impression about particular localities. The downhill flow of energy can build up order, quite without any help from intelligent beings. Indeed, this tendency towards order may well be what created life and then intelligent life. "Order through fluctuation" is the phrase that characterizes a new school of thermodynamics; this ordering principle was clearly recognized only as recently as 1967, a century after the advent of classical thermodynamics.

There are other ordering principles too. In 1944 the physicist Erwin Schroedinger claimed, for the Law of Large Numbers, the distinction of being the "order from disorder principle," and we're still discovering the implications this "law" has for brain size. For certain things, bigger is really better. But which things?

The canyon is narrower than we have ever seen before; the water is swifter; there are but few broken rocks in the channel; but the walls are set, on either side, with pinnacles and crags; and sharp, angular buttresses, bristling with wind- and wave-polished spires, extend far out into the river.

Falls at Clear Creek at Mile 84, from Leonard Thurman's Grand Canyon River Running web pages.

Mile 84
Clear Creek

I AM HIGH UP the Inner Canyon walls, looking down on the river from an overlook sparsely decorated by a few hardy plants that have gained a foothold in cracks in the rock. All the rock around here is foliated -- sharp, spiky schist and Zoroaster granite, leaf upon leaf of it sticking up almost vertically, and so hard that little erosion is evident. Certainly nothing has blunted the sharp edges. Having found one small place where I can sit without a knife-edge beneath me, I have let the other hikers continue up this unusual side canyon without me. The rain clouds have drifted away and the sun has already dried my clothes. I yawn and rub my eyes, wishing for coffee.

Some leftover notes to take from last night's marathon discussion, which lasted until the middle of the night up at the hilltop ruin, while the lights were out. The Great Totality Discussion: just how did life get started? From a mere dust cloud? As Abby said, surely that is highly improbable.

True. Looking backwards, any particular outcome is always highly improbable. Nonetheless, the percentages are sobering. For example, the earth happens to be in just the right orbit around the sun. If we were always 6 percent closer, our atmosphere would have become dense clouds of carbon dioxide. And we would have had a runaway Greenhouse Effect like the one on Venus -- which traps heat, raising the temperature to 900°C. at the surface. The same effect plagues cars here in the Southwest: the visible light gets in and heats things up to produce infrared radiation instead. The infrared photons, having a longer wavelength than light, can't get out through the glass as well as those shorter wavelengths got in. And so things inside get hotter and hotter if the air cannot mix with that outside.

However, if we were always 1 percent farther away from the sun, the oceans would have frozen solid about when this spiky schist was formed, nearly 1,700-million years ago, two-thirds of the time between the dust cloud that gave rise to the earth and now. That 1 percent is calling it uncomfortably close, especially when there is already a 3 percent annual variation in our distance from the sun as we travel around our elliptical orbit.

And by happy coincidence, the earth is also the right size. What determined the size? Part of the dust cloud formed an eddy and coalesced at just the right distance from the sun, becoming a "planet" with a lightweight crust floating atop a dense core. Had the earth been smaller like the moon, any atmosphere would have escaped from its lighter gravity. And the heat trapped in the core would have dissipated into space rather than generating volcanos. And so the gases trapped inside the earth would not have vented as they happily did, escaping just far enough to help build up a trapped atmosphere, for the expelled water vapor to have condensed into rainfall. And oceans. Life would have had a rough time of it without water and methane.

For hundreds of millions of years the earth was a hot, inhospitable place as volcanism poured out noxious fumes and vapors at an enormous rate. There were no oceans, a scant atmosphere, and a surface barren, pitted, and scarred by fissures and fiery eruptions from within.... But vast amounts of water bound in the rocks as hydrates were being liberated into the atmosphere and remained there as the surface was hot. After a very long time, with the air saturated and the surface of the earth cooling, a new phenomenon took place.
It rained.
It rained, and the rain evaporated, and it rained some more. It poured down on the bare rocky surface and ate the rock and collected in great flat basins.... The acid rain dissolved the rock... and where the water evaporated the salts formed broad, flat salt plains.
.......WILLIAM DAY, Genesis on Planet Earth, 1984
Methane? Don't you mean oxygen? No, methane. This simple odorless molecule, just a carbon atom surrounded by four hydrogens, was essential to the formation of the carbon compounds that all life utilizes to build structures and store energy trapped from the sunlight. And methane, ammonia, and other simple molecules are even found in interstellar space. Molecules of oxygen came much later, mostly given off as a byproduct of light-induced photosynthesis -- which is getting ahead of the story. Not only were there lots of volcanos on the early earth, but there was also lots of lightning. The early earth had severe weather. So the oceans were stirred by storms, tickled by lightning, and had hot lava dripping into them. This is not unlike what one can see fairly often these days on the south coast of the island of Hawaii, as Kilauea spouts a 160-story-high fountain of bright orange lava. The lava spreads in underground tubes to reappear at the coastline, dripping orange into the ocean waves as they crash into the lava cliffs of the shoreline. Except for the present-day oxygen atmosphere and the tourists, it is all rather like a scene 3,700-million years ago.
It was a stark, barren earth over which the sun rose quickly each morning, searing in a black sky in a blaze of intense ultraviolet radiation. The accretion of the unmelted mass of dust, aggregates, and stones which formed the planet had left it looking much like the dry, barren face of the moon. And as the sun followed its diurnal course, it rushed across the sky in a few hours to descend below the horizon just as quickly. For on this airless, waterless, hadean world, the day was only five hours long. Nightfall brought the rise of the moon, an awesome globe so close as to appear to touch the earth's surface as it loomed over the horizon, brightening the asture landscape with its huge glowing face.
.......WILLIAM DAY, Genesis on Planet Earth, 1984
Back in the fifties, California graduate student Stanley L. Miller tried a simple chemistry lab experiment, stimulated by the 1936 ideas of the Russian biochemist A. I. Oparin. Miller took some methane, ammonia, hydrogen, and water. He boiled them, hopefully to simulate conditions on the early earth. Nothing much happened. Then Miller added lightning, in the form of a 60,000-Volt spark between two wires. And in the residue which formed at the bottom of the chamber after a few days, he discovered that an amazing variety of more complex molecules had been formed or, as they say in the biochemistry business, synthesized. Actually, as later investigators found, ultraviolet light will do as well as lightning -- and the early earth had even more of that, since there was then little atmosphere to screen out the ultraviolet in the sunshine. Lots of heat -- which volcanic lava could have easily provided -- will also cause the synthesis.

Among the most important building blocks of life are the amino acids, twenty simple organic molecules which are essential for present-day life. And the ones most easily created in these early earth experiments were exactly those most abundant in life forms today.

If one gently heats a mixture of those individual amino acids, proteins are formed -- long chains whose links are the little amino acid building blocks. These chains fold here and there, like the tire chains in my car trunk. Cross-links also form, tying together adjacent loops of amino-acid chain to make a pretzel out of it (I have often suspected that my tire chains form new crosslinks too, as I try to unravel them with cold fingers). Proteins, all folded up pretzel-fashion, have some amazing tendencies to speed up chemical assembly lines. They act as catalysts, providing lots of little nooks and crannies in which simple molecules can be temporarily trapped. And, if such neighboring "prisoners" can stick to each other with a chemical bond, they'll go into solution stuck together when they are eventually freed from the confines of the protein. Imagine a figure-of-eight pretzel, a small one, laying on a table. You could seat two jelly beans inside the pretzel. And if you wanted to cement two jelly beans together, you'd want a jig -- something like that pretzel, to hold them for awhile until the cement dried. After popping out the linked jelly beans, the pretzel could then serve as a jig again (catalysts aren't used up). Catalysts like proteins not only make chance meetings far more likely than if the constituent molecules were just wandering around in solution, ricocheting off one another, but they also hold those molecules close together long enough for a chemical bond to form between them.

So a protein can be a matchmaker, helping the "loving couple" to get together in a "loveseat" when chance meetings would be rare. As a result, unlikely couplings become the norm, and formerly rare combinations become commonplace. Different proteins catalyze different chemical reactions because they have different nooks and crannies (some metals, such as platinum, are also good catalysts because of their surface structure).

And the rate at which a reaction happens, the speed of the production line, is controlled by these protein catalysts (usually just called enzymes; those chemical names ending in the suffix "-ase" are usually enzymes). When two production lines run at different rates because of different amounts of enzyme, amazing things can happen. Timing is everything. A plant curves toward the sunlight because the cells grow faster on one side of the branch than the other. Embryos form arms and legs in the same way -- just let two connected groups of cells grow at different rates and they'll form a curved surface. That's how gastrulation occurs: because neighboring cells grow at different rates, a spherical sheet of cells invaginates to form a pouch -- used as a stomach -- that is evolutionarily an important step towards our particular phylum of animals. Faster and slower growth rates are also how the convolutions of the human brain form.

Protein-type enzymes control growth rates, and relative growth rates control form, and form controls function (except on those occasions, also important, when form follows function). It's hard to overemphasize the importance of relative rates, when it comes to living systems.

But that gets ahead of the story again. Stability is the other key concept in this nooks-and-crannies tale. It's the stable which survives fluctuations. It's the stable configurations in the right place that go on to do more interesting things, such as progressing from chance proteins to faithfully replicating proteins, and progressing from that to life itself.

At the time when Yahweh God made heaven and earth there was as yet no wild bush on the earth nor had any wild plant yet sprung up, for Yahweh God had not sent rain on the earth, nor was there any man to till the soil. However a flood was rising from the earth and watering all the surface of the soil. Yahweh God fashioned man of dust from the soil.
.......GENESIS 2:5 (the other version, in contrast to the leadoff seven-day story)
Very old are the rocks.  

The pattern of life is not in their veins.  

When the earth cooled the great rains  

came and the seas were filled.  

Slowly the molecules enmeshed in  

ordered asymmetry.  

A billion years passed, aeons of  

trial and error.  

The life message took form, a spiral,  

a helix, repeating itself endlessly,  

Swathed in protein, nurtured by  

enzymes, sheltered in membranes,  

laved by salt water, armored with  


Shells glisten by the ocean marge,  

Surf boils, sea mews cry, and the great wind  

soughs in the cypress.  

   THOMAS H. JUKES, Molecules and Evolution, 1966  

WE ARE HAVING lunch here at the riverside, in a space so small that many people have perched up on the rocks with their sandwich, almost overhanging those of us with a spot on the sand. The returning hikers are exhilarated; they found a waterfall that shoots horizontally out of the rocks and arches out over the bathers in the creek below. Much farther up the canyon is said to be Cheyava ("intermittent") Falls, which comes out of a cave in the top of the Redwall and cascades down into Clear Creek Canyon, the tallest waterfall in the Grand Canyon. You'd never think that a side canyon began just downriver of us, as this sand beach is only big enough to precariously house a few sleeping bags -- at "low tide." Such is the change made by hard rock. From having breakfast amidst the softest rock in the Canyon, we are having lunch amidst the hardest.

We are in the part of the Canyon that reveals the oldest layers of all. Some are as much as 2,000-million years old, the earth itself being about 4600-million years old. There were bacteria 2000-million years ago, but not much more (yes, there were blue-green "algae," but they're now classed with the bacteria, the lumpers being triumphant).

The steep slabs of schist and Zoroaster granite that flank our little beach wouldn't show any fossils anyway, having been laid down more than 1,000-million years before things started leaving fossils. Furthermore, the schist has been melted and reformed too many times in the depths of the earth, which is why it is called a metamorphic rock. But there are original rocks 3,500-million years old remaining in Australia which show small fossils, looking very much like the fossil stromatolites that we saw yesterday at Carbon Creek. And so it is suspected that life itself got started sometime in the first 1,000-million years of the earth's history.

Even simple cells like blue-green "algae" have much more complex properties than those proteins. They have a way of trapping sunlight and using its energy to create ever more complex chemical compounds that store the energy; they use the energy to build another alga, to reproduce their kind.

But how does one trap sunlight, put it to work? One of the other theories that Albert Einstein published in 1905 -- the same year that he tossed off E=mc2, the special theory of relativity, and his statistical explanation of the Brownian Motion -- was a model for the photoelectric effect. When metal surfaces were illuminated, electrons were kicked loose from the metal and went zooming off, generating an electric current (as in solar arrays for electrical power generation these days). Blue light was better at causing this than red light; often red wouldn't work at all, no matter how intense, but a dim blue light would generate an electrical current.

In each of the 1905 papers, Einstein has totally transcended the Machian view that scientific theory is simply the "economical description of the observed facts." None of these theories, strictly speaking, begins with "observed facts." Rather, the theory tells us what we should expect to observe.
Einstein was able to explain or predict all of the puzzling aspects of this photoelectric effect by postulating that light was packaged into photons, little bundles of energy whose content was inversely proportional to the light's wavelength. This (and Planck's use of quantized energy five years earlier in explaining "black body" heat distribution) was the foundation for what became known as quantum mechanics. Einstein received the Nobel Prize for his explanation of the photoelectric effect, as relativity was still in dispute in 1922. Essentially, the photon of light collided with an electron in the metal and gave it a good kick. This kick, however, caused the kicker to disappear; the vanished photon's energy was simply added to the kinetic energy of the electron.

Fortunately, that doesn't happen to the kicker in football -- but the same thing happens in molecules, especially the ones called pigments (the best-known pigment is chlorophyll). The electron kicked by the photon rattles around for awhile, permitting other chemical reactions to occur. This energy, deriving from the sun 8.5 minutes earlier, when two heavy hydrogens fused together to form a nucleus of helium and packaged their spare binding energy into a photon, is used to build up a storehouse of energy inside the cell. This stored biological energy is available for doing various jobs, rather as our dams store rainwater that can later be dropped into generator turbines to spin them around and generate electricity (cells generate electricity too, in a somewhat more subtle manner).

So simple cells like bacteria take in sunlight and use it to rearrange the atoms inside six molecules of carbon dioxide (CO2) and twelve molecules of water (H2O). They split the oxygen off the water molecules and it becomes six molecules of good old O2, better known as molecular oxygen. However, oxygen is a waste product of photosynthesis. The cell really wants the other product of the reaction, which is a simple sugar, stored energy that will be later used to construct things. Glucose, C6H12O6, is what I eventually get from the many cups of lemonade I've been consuming; it is "quick energy," and just about the only fuel on which the brain will run (glucose, not lemonade!). I drink two cups more.

Brains get rather ahead of the story. What's so important about this simple reaction is the oxygen that is discarded. It eventually gets trapped as a gas in the atmosphere. There wasn't much of an atmosphere in the beginning; life had to build it up. Even today, this simple photosynthesis process in the microscopic plants that float in the oceans (collectively called phytoplankton) contributes 90 percent of the oxygen we breathe. That's one reason why we worry about the health of the oceans.

But other chemical reactions gobble up oxygen. Iron rusts into Redwall-colored iron oxide. Silicon liked oxygen too, producing our sand beach. And back near the beginning, there was a lot of exposed iron on the earth's surface and dissolved in the oceans. For perhaps 2,000-million years, not much oxygen remained in the air, so ravenous was the appetite of the iron and silicon. But eventually, rusting was satiated so that oxygen began to build up in the atmosphere, reaching the 20 percent level that it has today. This helped shelter the earth's surface from the ultraviolet radiation in the sunlight (a molecule containing three atoms of oxygen, called ozone, O3, is especially effective at absorbing UV). This shielding made it possible for life to eventually leave the sea and take up residence on land. Some UV still gets through, of course, which is why everyone has been rubbing on sunscreen lotions today.

The oxygen leveled off at 20 percent because photosynthetic production was then in balance with continuing rusting -- and with oxygen consumption by animals. It is estimated that if photosynthesis stopped making oxygen, we'd run through the 20 percent reservoir in the earth's atmosphere in only 2,000 years. That is not the best imaginable safety margin.

It reminds me of those botany bumper-stickers which read "Have You Thanked a Green Plant Today?" Especially the phytoplankton drifting the oceans, which produce most of what we breathe.

MARSHA, the blossoming teenager who was one of the moon-watchers last night, just teased a boatman about when we were going to have prebiotic soup for dinner. A truly organic soup that would be -- hopefully not stirred by lightning, not while I'm around. With a straight face, he replied: "At dinner, with the clams linguine."

However, the boatmens' stock answer to all questions about dinner menus is always "Clams Linguine," spoken with a flash of the eyebrows. People took it seriously on the first day of our trip, until the steaks were served. On the second day, inquiries also elicited "Clams Linguine" -- but no clams, no linguine. Clams linguine has been picked up like a buzzword. Asked the name of a strange bird, a passenger who doesn't know the name is now likely to reply knowingly: "Must be Clams Linguine."

"The prebiotic soup is sure a catch-all, isn't it?", remarked Rosalie. "Surely our genetic code -- and that fancy chain of manufacturing processes that goes from DNA to RNA to protein chains -- wasn't the start of life."

"Our clams linguine is a catch-all too," Alan volunteered. "Just wait until you see what we throw into the pot."

"Yes, but in our case the prebiotic soup is a catch-all for ignorance," I said. "It's everything that happened before our present-day genetic code evolved. Surely there were simpler versions of replication that competed with one another, some sort of progression in complexity, back before about 3,500-million years ago."

"The real problem," said Dan Hartline, "is how does self-replication start? Molecules that'll make more of their own kind?"

"Remember what happened to Ben's breakfast dish that first morning on the river," said Rosalie, laughing. "He forgot to wash it, left it setting out in the sun, and the pancake syrup dried up hard. When he went to wash it, he popped the hard syrup out, all in one piece. A perfect copy of the inside of the plastic dish!"

"I suppose that it's possible for a protein to serve as its own mold," I answered, "but I'll bet that the key to their evolution lay in RNA or DNA chains evolving along side, and forming a series of molds for amino acid chains."

"That's what a protein is, just a chain of amino acid molecules?", asked Abby.

"Right. And genes are just chains of DNA base molecules. Except DNA chains don't fold up and form cross-links in quite the fancy ways that amino-acid chains do," I answered. "They like to spiral instead, like a corkscrew. The DNA chains are the master memory for the cell -- they don't do anything except let themselves be copied, making a complementary RNA chain. Which then goes forth from the nucleus of the cell and serves as the instruction tape for the assembly of an amino-acid chain."

"There's a translation scheme -- what's called the genetic code," Rosalie explained. "The first three molecules on the RNA chain determine which of the twenty types of amino acid will form the first link of the protein chain. And the next three RNAs determine the second amino acid type to be tacked onto the first one. As so the protein chain grows. That's fancy, which is why I don't think it was the first scheme tried out."

"Some simpler self-replication scheme probably got started using clay as a catalyst," I said. "Once the rains cause rivers, the particles get sorted by size. And you get clay. Clay is really nice as a matchmaker, its nooks and crannies will catalyze various simple carbon reactions."

"Somebody told me that every cell in my skin contains the information necessary to make my brain," Abby said. "Is that really true?"

"Probably," I answered. "The skin cells that I scraped off today on the knife-edged rocks around here had the complete instructions for how to make a copy of me. Or at least how I was at conception. The ants have probably already carried home those cells I left behind. I sure hope they don't have the requisite technology to translate the code and clone me."

"We'd have to award them the next Nobel Prize if they did," Rosalie joked.

I want you to do one thing in connection with [the Grand Canyon] in your own interest and in the interest of the country... Leave it as it is. You cannot improve on it. The ages have been at work on it, and man can only mar it.

Mile 87

THE WHAAP-WHAP-WHAP SOUND of a helicopter is heard, an unwelcome reminder of civilization's casual pollution of the environment. When seen, it is not the usual chopper from the touristy strip of scenic-flight establishments just outside the South Rim entrance to the park, but a builder's beast of burden: dangling from a cable is a truckload of construction materials. J.B. says that Phantom Ranch at Mile 88 -- literally just around the corner from us -- has been "improved" by the Park Service to include flush toilets, hot and cold running water, and blow dryers as a service to the wilderness hiker. And a heliport as a service to the pilots. At least the bulldozer that used to sit beside the river has disappeared, perhaps helicoptered out, perhaps hidden nearby in case more improvements are desired. Mule power sufficed for earlier construction of the bridges, grumble, grumble.

We can hardly wait to see these millions of dollars in wilderness improvements. We have to stop there -- in the old days, you sped by as fast as you could, some passengers keeping their eyes shut so as not to have such sights disrupt their wilderness experience -- because of a new park service regulation that the float trips check in at the Phantom Ranch ranger station.

Since the 1983 overflow of Lake Powell, when the Park Service received hundreds of long-distance phone calls from worried relatives of river-runners, a new layer of bureaucracy has been added -- you have to stop and give them a trip roster, get cleared for the next stage of your journey. You wouldn't, after all, want a park ranger to have to walk down and post a sign on the bridge to flag the boats down, would you? Next, hikers will likely be required to carry beepers so that they too can be summoned.

Mile 88
Phantom Ranch

WE ARE IN LIMBO, pulled up on the sandy shore here where the Bright Angel fault line crosses the Colorado River. We are as close to civilization as we'll get on this trip, what with all the blatant construction and the two fancy footbridges spanning the river. They connect the trail descending from the North Rim with the two trails that ascend to the South Rim. But the outside world has intruded in a bigger way.

Signs of civilization first appeared on the right bank, an old brick tower with boarded-up openings -- the old river-gauge station that estimated water flow in the Colorado. Then, after a left turn, came the first footbridge. And the uncamouflaged shiny new building complex. It used to be that buildings were hidden, five minutes up the trail, near the guest ranch built before Grand Canyon National Park was created.

A sand bar gave us some trouble as we approached the beach, and we finally walked the boat along it until finding a path to the beach proper. The other boats followed our example. One of the boatmen disappeared to check us in. And then returned, shouting to Howard that there was a message for him to phone the Park Service emergency operator.

Someone started to kid Howard about his patients tracking him down even here. He quietly said that he didn't have patients, that he was a Ph.D. researcher. And everyone then realized that it could only be bad news -- personal bad news.

One of the boatmen has gone up the trail with Howard to show him where the emergency phone is located. Most people are out on the shore, but with their lifejackets still on, waiting. We generally have our backs turned to the signs of the outside world, such as the footbridge. I think we're in shock, having gradually let down the workaday mask we all wear, gradually starting to relax and enjoy this unparalleled experience of being away from civilization, in increasing contact with the world of our ancestors, increasingly coming to grips with the great age of the earth and what a recent arrival humans are.

The boatman comes running back alone and holds a quick conference with the other boatmen. Then leaves again. Gradually word trickles along the beach that Howard's father has had a stroke. And that Howard plans to hike out of the Canyon, up the South Rim trail, this afternoon. Several other boatmen have taken off to try to find the mule skinner. This mule train carries freight, and the idea is to get Howard's black bags hauled up on a mule. Someone else starts putting together some trail food. Dan digs into the bottom of one of his black bags and retrieves his car keys, so that Howard will have a car to drive down to Phoenix as soon as he makes it to Flag, where Dan's car is stored.

Howard arrives back, looking somewhat shaken. He goes with the boatmen to identify his black bags, and they take them off the boat. The boatmen appraise him of the arrangements they've made. And so he sits down to open his black bags, looking for heavier hiking shoes than the tennis shoes he is wearing. Then, river wear exchanged for hiking gear, the boatmen run off with the black bags, down the trail to where the mule train is waiting impatiently.

Howard tells us the Park Service emergency operator had somehow lost the exact message. But that he was able to dial out and get hold of his mother, who said that his father had a stroke four days earlier, just after we set out on the trip. Things seem somewhat stable now, Howard's father is in the hospital being treated for the pain, and will undergo diagnostic tests when he is feeling better. And Howard was able to get a good description of what happened. His father had gone to bed the previous night with a bad headache. But got up at dawn and walked downstairs and started to fix breakfast. He went out to pick up the newspaper, brought it back indoors, and spread it out on the table. Then he found that he couldn't read it.

He obviously wasn't blind. Indeed, he could see and name individual letters, even some two-letter words like "is" and "do" -- but he couldn't make any sense out of longer words, he could read a sentence only with many, many errors. He could speak correctly and had no problem with understanding the doctors. So it wasn't a paralytic stroke or one causing language difficulties in general (known as "aphasia") -- it seemed only to affect his reading. He could even write, taking down dictation when the doctors would read a short paragraph to him. But, asked to read back what he had just correctly written down, he couldn't. Except letter-by-letter.

This relieved Howard considerably, since he knew that it meant his father had had a small stroke. And people with small strokes almost always get better. Rosalie, a neurologist, confirmed his judgment on this, saying that alexia (reading disturbance) alone was quite rare: that usually writing was affected too and that there was some aphasia. That, given his father's pain, it must have been a bleed -- a ruptured blood vessel, releasing blood cells into the brain and irritating its dural covering, the dura being capable of signaling pain (brain tissue itself is not). But no one could agree on exactly what part of the brain was most responsible for reading. Apparently a number of places on the periphery of the known visual cortex can, if damaged, produce a reading disturbance.

Howard added one additional piece of information, that his father seemed to ignore objects on the right side of his visual world. It was odd, because he could see objects there -- if that's all there was to see. But if there were some other object on the left side, competing for his attention, then he'd pay attention to the left-sided object and ignore the waving fingers on the right side. Aha, left hemisphere stroke, said Rosalie and several others simultaneously. That makes sense, alexia usually comes from left-sided strokes. The neglect of objects on the right side will disappear, Rosalie predicted -- it was probably due to the brain swelling that occurs near the damaged area. In a week or so, that would probably decline and the selective-attention problem would fade away. But she wasn't equally confident about whether the reading problem would disappear.

So I expect Howard felt somewhat better, what with all the expert consultations in the bottom of the Grand Canyon. It's quite amazing, how much you can predict just from knowing the details of a stroke patient's symptoms. Every part of the brain generates different symptoms, and they serve as excellent clues. Except for the frontal lobe which, when damaged, may cause little detectable malfunction. Until the damage becomes extensive.

THE HEAT HAS BECOME OPPRESSIVE. Only mad dogs, mules and Englishmen go out in the midday sun (to amend Noel Coward). As soon as we're under way on the river, we'll cool down again. No one seems to know whether to commiserate with Howard over his long, hot, hike or just say nothing. The boatmen explain that they'll save Howard walking the first two miles of the trail by floating him downriver until the trail emerges from the ups and downs in the inner canyon rock and turns to start up the Bright Angel fault line toward the south rim. So we all pile back into the boats and set off into the Colorado again. And have our previous trouble getting across the sand bar.

Once out into the channel, we observed that the waters were very unpredictable around there, many rocks having been washed into the stream by flash floods of recent years along the northern side of the Bright Angel fault line. And so we had a splashy mile until the boats pulled over to the left bank, getting soaked several times despite the lack of real rapids. High up a talus slope, we could see the trail emerging from the schist. All of the broken rock here is because the Bright Angel Fault leaves the river at this point to create Garden Creek, which the trail will follow up to the South Rim.

Howard climbed out, handed Subie his lifejacket, tightened his climbing boots, and thanked the boatmen for arranging things so nicely. At Subie's suggestion, he soaked his clothes with cold river water, for a little evaporative cooling. He also dipped his big canvas hat into the river, filled it up, and lowered his head into it, then stood upright. The water began trickling around the hatband and dripping down onto his face. Subie was delighted, and noted that there was water along the way for refills -- just not to drink out of the creek, since it was contaminated by all the people up above (the Park Service has permitted the South Rim to become a small city). Howard shouldered his day pack, loaded with canteens and trail food, and began hiking out of the Canyon, waving goodby to us.

After we cast off, Subie commented that it was indeed going to be a hot hike. It was nearly 47°C. (117°F) in the shade at Phantom; with the river moving along at a runner's pace, we are reasonably comfortable. The trail is nine miles long, in the sunlight and still desert air of mid-afternoon. And the trail ascends one vertical mile (a good 1,500 meters), from about 1,900 feet to 6,900 feet. About like climbing a 425 story building. The air would, at least, cool down to room temperature by the time Howard reached the South Rim in mid-evening.

Horn Creek at Mile 90, from Leonard Thurman's Grand Canyon River Running web pages. (That motor rig going through is the size of a bus).

Mile 93
Monument Creek
Fifth Campsite

I'D SAY WE WERE still in shock, about how our splendid isolation had been brought up short, about how the real world out there can intrude and pluck someone out of our midst. But we got little opportunity to think about it. Despite the steady diet of big rapids before lunch and the continuous knocking about along several miles of the Bright Angel fault, we next got hit by Horn Creek Rapid (rated a 9) at Mile 90.

Now we are pulled over just upstream of Granite Rapid, having endured today all of seven rapids rated higher than 5. It's a good thing we didn't do this on a cold day. Or in more difficult river conditions -- I think I've been battered around enough for one day. And Granite Rapid, from the roar of it just downstream, may tomorrow live up to its rating of 9.

Instead of getting domestic, as we're wont to do after making camp in the afternoon, many people just sit around with their lifejackets still on, soaking up sun and gradually shedding the river. People who would normally drink one beer consume two or three in silence. And then finally set out to look for a campsite. That's usually the first thing anyone does, competing for the best sleeping spots. Today is different. The silence is palpable, broken occasionally by someone talking too rapidly. It has been a tiring, upsetting day for some people.

Granite Rapid at Mile 93, from Leonard Thurman's Grand Canyon River Running web pages.

BARBARA SPREAD OUT the tarp on the sandy shore. Then she picked up two potato-sized rocks from the collection deposited by the last flood. "Want to see how easy it is to make stone tools?", she asked. Her audience was hunching together under some willow trees, escaping the afternoon sun. "Sure," we said, expecting the anthropologist to sit down on the tarp and tap away delicately. Instead she put on her sunglasses -- in the shade. What?

The two rocks were each the size of big, elongated potatoes. Her grip on each rock was simple: she held it by one half, so that the other half protruded unobscured by her fingers. But she didn't sit down. She stood facing the tarp, away from her audience. And began pounding furiously, hitting the two stones together at waist height, really hammering hard. Chips began flying away from her, a few dropping at her feet. After a minute of this furious performance and its shower of rock fragments, a big piece of rock fell and, lacking enough protruding rock to continue, she stopped.

The size of the audience had miraculously tripled. Nothing like a little action to attract attention. Trust the women to invent a distraction from the gloom.

Barbara took off the sunglasses -- eye protection, evidently -- and picked up some flakes, and passed them around. "See these sharp flakes? You hold onto them just like a razor blade. Not only can you butcher a rabbit with these, but you can get through the tough skin of an elephant or a rhino. Now even hyenas and vultures have a hard time doing that, at least until the big animal has been dead long enough for the skin to rot. You can cut open knee joints with these little flakes -- that makes it easier to carry the meat away, a section at a time, off to a safer place to eat it. Gets you away from the other scavengers. And you can cut muscles loose from bone." She paused. "Anyone lost their knife? Steak knives, anyone?" she said to some stragglers just arriving.

Barbara retrieved the two original stones, or what was left of them. "And these big fragments, which are still large enough to fit comfortably in the palm of your hand -- they're sharp too. You can use them for all the same purposes, but they're safer. You can cut your own skin while holding one of these little flakes with your fingertips. And ancient people didn't have band-aids, either. But the original rocks, minus the fragments, still have a nice smooth surface over the back half. A nice handle." She demonstrated the grip.

"And you can bring a lot more pressure to bear, more safely than with a flake. If you spent ten minutes pounding a number of rocks, you'd have dozens of big fragments to choose from. You'd probably find one that had a comfortable grip. Maybe with an indentation in just the right place for your thumb, so you could pull really hard. Maybe cut through roots when you're out gathering. But I'll bet that they used sticks to dig out the goodies -- and that they carried along a sharp piece of rock flake to resharpen the stick with. That's what the women of primitive tribes do today when they're out gathering."

So when did prehumans start making tools this way, we asked.

"Well, hominids were walking upright more than 4 million years ago -- and looking fairly human too. I mean, if you saw Lucy and family over on the opposite riverbank waving at you, you'd immediately classify them as human -- even though they went out of style nearly 3 million years ago. What else stands upright and waves? It's only if you looked carefully, especially if you saw one from the rear and noticed that small skull behind the face, that you'd start to wonder." Barbara paused. "But they do not find simple rock tools with the early Australopithecines. Only starting at about 2.4 million years ago do you find flaked stones like these."

Scientists are prone to probe for holes in an explanation, even in the afternoon heat. Dan Hartline started in: "I'll bet that I could find flaked stones just like those if I looked carefully around any of the waterfalls. All it should take to make fragments and little flakes is for one stone to be dropped from a great height. It's the kinetic energy of the rocks when you strike them together that breaks open fracture planes." Dan, like many other neurobiologists, started out in physics (well, to be more precise, he and his brothers started out collecting horseshoe crabs from Chesapeake Bay for their father's biology research lab).

Barbara smiled. "Right you are. There's even a geologist up in Utah who found a batch of rocks looking like stone tools. Except the sediments in which they were buried dated back to when the biggest primate around was a tree shrew. Turns out that nodules of chert were eroding out of a high cliff, falling and fracturing. You're also right that it's mostly brute force that makes these fragments -- it doesn't take much skill to pound hard like that, just enough to avoid smashing your own fingers." She examined the side of her thumb. "The main problem with the method is blisters, if you're not in practice."

"So what makes you so sure that rock fragments were made by hominids?"

Barbara nodded, then turned and pointed to the tarp, littered with stone flakes. "See that pattern? A big fan of flakes, plus a little pile where I was standing? Like a fat exclamation mark? When his group excavated a big area, that's the pattern Glynn Isaac found in Kenya, time and again. And there were no cliffs around, not for a long, long ways. They were even able to reconstruct some of the original stones from the fragments. Just think -- with random banging around, you too can create an archaeological site in only one minute!"

"But," interjected Ben, "just how often do they find flakes?" "Some places like Olduvai Gorge in Tanzania," reflected Barbara, "are just littered with stone flakes. I mean, you literally cannot take a step in some places at Olduvai without stepping on a hominid stone tool. That's why Louis Leakey started digging there -- with all those stone tools, he just knew there would be hominid bones if he looked long enough. But it took from 1935 until 1959 -- that's when Mary Leakey found the Zinjanthropus skull and teeth. Olduvai goes back to 2 million years ago before the sedimentary layers run out and you hit rock bottom, but Koobi Fora and Laetoli go back earlier -- and have stone tools as early as 2.4 million years."

I smiled, recalling when I'd met Louis Leakey not too long after that first East African hominid find. He wasn't famous yet, having just come to North America to tour anthropology departments. A physics undergraduate, I'd talked myself earlier that year into a graduate anthropology seminar, never having had an introductory anthro course. Late in the term, my professor, Melville Herskovits, smiled his dapper smile and, with that characteristic twinkle in his eyes, announced that he had a treat for us: Louis Leakey and the casts of the Zinj skull and teeth.

Louis Leakey was a real presence -- comparable, in my experience at the time, only to Harry Truman (around whom I had worked for a week a few years earlier, when I was a fetch-and-carry photographer's assistant at Life magazine and he had just finished his Presidential memoirs). I don't know which was the more impressive, the large and muscular Louis Leakey or the massive Zinj skull with the peaked sagittal crest like a gorilla's. Louis was pleased as punch, cradling that skull in his large hands, replying to the excited questions which indicated that everyone in the room realized that a new era had just begun in paleoanthropology. What I didn't realize then was the 24 years he'd spent, on and off, in Olduvai Gorge paying his dues. And 1959 was the same year he persuaded Jane Goodall to study chimpanzees at Gombe. A good year.

"I wonder if pounding rocks got started from hammering open hard nuts?", asked Jackie. "That's what chimps do. They take a rock, place the nut on a hard surface, and pound away quite skillfully. And the female chimps are the experts -- they tackle nuts so hard that they sometimes break open the rocks instead. Sure looks to me like a perfect setup for accidentally producing rock flakes and then discovering what they're good for. But that's precision hammering, not the brute-force hammering you just used."

Marsha perked up. "You mean that women might have invented tools, rather than the men?"

"At least the female chimps," Barbara replied. "They're certainly the most frequent tool-users, and the most skillful. All of the chimps -- male and female -- try their hand at making sticks for termite-fishing. They strip the leaves off the stick, thus violating Ben Franklin's definition of man as the toolmaking animal. Then the chimps push the prepared stick into a termite nest. The termite defenders attack the stick, grabbing on. And the chimp slowly withdraws the stick and licks off the termites, rather like the Darwin's finch. The female chimps spend many more hours at this task than the males. However, it is in hammering that the big differences between females and males show up: more than 92 percent of difficult nut-cracking is done by females, even though males engage in the simpler tasks. And she doesn't hit her own fingers, either."

"And so, once you take up eating nuts, you develop the skills to make lots of tools too," Ben ventured. "That could have been what started the technology roller-coaster."

Barbara began gathering up the flakes from the tarp, throwing them far out into the river to avoid having anyone step on them. "You know," she said, "once this crude rock-hammering was invented, a basic tool kit was developed by about 1.5 million years ago. But there weren't many improvements in it for the next million years -- maybe the tool-users' behavior altered, but the tools that have been recovered didn't undergo any fundamental change until about 300,000 years ago. More than a million years with little change. Progress was very slow. Think about that." She shook the sand off the tarp.

Silence. "Okay, so why?"

"So whatever did they need fancier tools for? Glynn Isaac used to say that the question isn't why nothing changed for so long, but rather why it changed when it did. Maybe they tried to live in colder climates and needed sewing needles to fasten up animal hides? No one knows yet."

The most powerful drive in the ascent of man is his pleasure in his own skill. He loves to do what he does well and, having done it well, he loves to do it better.
......the polymath JACOB BRONOWSKI, 1973

AFTER DINNER, Rosalie sat down on the rock ledge next to Marsha, who was busy rubbing something against a flat stone. I was sitting nearby and eavesdropped. "Indian arts and crafts?", asked Rosalie.

Marsha looked up with an engaging grin. "This is the way the Anasazi women made necklaces for themselves." She brushed her blond curls back and then held up a small bead for Rosalie to see. "These are juniper nuts."

"So how are you going to make a hole through them for stringing?"

"That's what's so nice about these nuts. If you grind off both ends, the middle core drops out. You just blow out the dust. See? Perfect hole." Marsha fished a handful of finished beads from her jacket pocket and displayed them on the rock's flat surface. "Then you roll them around to make them round."

Rosalie admired them. "Where did you find juniper nuts around here?"

"Brought them with me," laughed Marsha. "That is to say, I forgot that they were in my jacket pocket. I picked them up last week, on the ground outside the archaeological museum at Mesa Verde. After seeing that exhibit there on the Anasazi and their life styles. They had real necklaces on display, beautiful things."

"Did the Anasazi women color the beads?", asked Rosalie.

"Well, I remember that they got some of them to turn black. All they had to do was wear them awhile and their sweat would stain the nuts black. I thought that I'd wear a necklace for a few days and see how it works."

"So were there any other colors in the Anasazi necklaces?"

"I don't remember. I suppose not, for everyday necklaces, because the sweat would just turn them black sooner or later. But maybe I could get some of the Redwall color, that stuff that washes down from the Supai layer, to stick awhile. Maybe I'll try that."

"Did the museum exhibit say anything about the Anasazi using the beads on strings for counting things?", asked Rosalie.

"You mean like an abacus?", answered Marsha. "Sliding the beads back and forth to count? I don't remember that?"

"No, not in that manner. What I'm thinking of is the Aztec scheme of keeping tax records and the like on knotted strings, You know, where the number of knots and their spacing records how many bushels you've paid. They could have done the same thing with beads on a necklace. I was just curious whether the Anasazi had any such schemes." Rosalie tossed a stone into the river.

"Gee, I don't think there was anything in the museum about that," said Marsha. "That's a neat idea. You know, they could wear a necklace whose beads spelled out 'This necklace cost a thousand dollars' rather than wearing diamonds!"

Rosalie laughed. "That might take a lot of beads, a sentence that long."

"It's just a couple of dozen letters."

"But how many different colors of beads would you need?", Rosalie asked.

Marsha thought for a few seconds. "I suppose that twenty-six different colors of bead, one for each letter of the alphabet, is a bit much. How about Morse Code? I could use long and short beads."

"I'll bet a necklace that long would reach your waist," Rosalie estimated. "How about a code with maybe four letters in its alphabet? Four different colors of beads."

"You mean like DNA, the genetic code? It spells everything out with just four different types of letter -- you know, the RNA bases G, C, A, and U." Marsha held the nut that she was rubbing up to the sky, then blew the dust out of the center hole and looked again. "There aren't too many words that I can spell with just those letters."

"You just have to use a two- or three-letter sequence from that four-letter alphabet to stand for each English letter," replied Rosalie. "Like GCA stands for B, GCG for E, and so on. Remember how the genetic code works?"

"I remember. It uses groups of letters too."

"How many letters in the amino-acid alphabet?"

"Oh, you mean like twenty-six letters in English?" Marsha stared at the beginning of sunset downriver. "Isn't it twenty? The DNA is telling the cell what proteins to make, and there are twenty different amino acids that serve as the building blocks of the protein, strung out in a chain. Isn't that right?"

"You've got a good memory. So how many letters of DNA does it take -- you know, to tell the cell which one of those twenty amino acids to tack onto the end of the protein chain under construction?", asked Rosalie, with a raised eyebrow and a grin.

"I think it's three," said Marsha. "Three consecutive bases tell the protein assembly line which one of the twenty amino-acid possibilities comes next."

"Could you get by with only two DNA bases?"

Marsha looked puzzled.

"Well," continued Rosalie, "how many possible ways are there, of arranging two beads on the string there, if each one can be of four different colors?"

"I see. Well, the first bead can be one of any four colors. If the first one is black, the second one can be any of four colors. So that's four possible pairs. If the first one is white, the second one can be.... I guess that's four plus four plus four plus four. Sixteen. Sixteen different pairs."

"Right you are," Rosalie answered. "So with a pair of DNA bases, you could specify only sixteen different types of amino acids."

"But that's not enough, so you have to use triplets so that you can count to at least twenty! Oops!" Marsha exclaimed, having spilled the beads from her lap onto the sand. Both she and Rosalie bent down to gather them up. I tossed over several that had landed on my foot.

"I wish that these nuts came in four different colors, instead of just dirty and clean," Marsha mused. "Then I could make a necklace that told how to construct a real protein."

"Well, this one could be U, for unfinished," Rosalie laughed, holding up a nut with only the ends ground off but without its nut shape rounded into a bead yet. Marsha had smoothed most of the other nuts by rolling them around between two flat rock faces.

"And this polished bead is sort of auburn," observed Marsha. "We've got an A!"

"G for green? Oops, no green nuts here. What else is there?"

"Well, as soon as the sweat goes to work on these, they ought to get pretty dark," Marsha noted, then fished around in her pockets again. "Here's the color that I got by rolling it around in my hot, sweaty hand. On the bus up from Flag."

Rosalie looked at the bead in the soft evening light. "Not really black, Good thing, too. We don't need a B. What colors start with G, or with C?"

"How about chocolate?", Marsha exclaimed.

"Okay. The sweaty ones are C, chocolate stands for cytosine."

Marsha counted. "Now we've got U for unfinished, A for auburn, C for chocolate. Back to G. Of course, the other problem is that I only see three different kinds of beads in this collection here." She brightened. "We could always paint some. Got any green nail-polish?"

"Sounds ghastly."

"I suppose that no one else has any, either. Maybe gray? I could rub them against the gray stones! I remember now, that's what happened at Mesa Verde when I was rubbing the nuts against the rocks there!"

Rosalie clapped her hands with delight. "G is for gray. Good old guanine." They looked around for a gray rock. "You know, I think that it's getting a little dark out here. And everyone seems to have finished brushing their teeth by the river."

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