by Oliver Sacks
These nineteen case studies are exemplary in their richness and detail, and constitute primary material of enormous value. Along with the rest of the book, they provide a definitive rebuttal of the notion of mental illness as a remorselessly advancing and deteriorating condition and show how, if there can be an effective integration into family and community life (and, behind this, a safety net of hospital care, professionals, and medication where warranted), even those who would seem to be incurably afflicted can, potentially, live full, dignified, loved, and secure lives.
Life Continues
Anybody Out There?
One of the first books I read as a boy was H. G. Wells’s 1901 fable, The First Men in the Moon. The two men, Cavor and Bedford, land in an apparently barren and lifeless crater just before the lunar dawn. Then, as the sun rises, they realize there is an atmosphere—they spot small pools and eddies of water, and then little round objects scattered on the ground. One of these, as it is warmed by the sun, bursts open and reveals a sliver of green. “A seed,” says Cavor, and then, very softly, “Life!” They light a piece of paper and throw it onto the surface of the moon. It glows and sends up a thread of smoke, indicating that the atmosphere, though thin, is rich in oxygen and will support life as they know it.
This was how Wells conceived the prerequisites of life: water, sunlight (a source of energy), and oxygen. “A Lunar Morning,” the eighth chapter in his book, was my first introduction to astrobiology.*
It was apparent, even in Wells’s day, that most of the planets in our solar system were not possible homes for life. The only reasonable surrogate for the Earth was Mars, which was known to be a solid planet of reasonable size, in stable orbit, not too distant from the sun, and so, it seemed likely, having a range of surface temperatures compatible with the presence of liquid water.
But free oxygen gas—how could that occur in a planet’s atmosphere? What would keep it from being mopped up by ferrous iron and other oxygen-hungry chemicals on the surface unless, somehow, it was continuously pumped out in huge quantities, enough to oxidize all the surface minerals and keep the atmosphere charged as well?
It was the blue-green algae, or cyanobacteria, that must have infused the Earth’s atmosphere with oxygen, a process that took more than a billion years. The cyanobacteria invented photosynthesis: by capturing the energy of the sun, they were able to combine carbon dioxide (massively present in the Earth’s early atmosphere) with water to create complex molecules—sugars, carbohydrates—which the bacteria could then store and tap for energy as needed. This process generated free oxygen as a by-product, a waste product that was to determine the future course of evolution.
Although free oxygen in a planet’s atmosphere would be an infallible marker of life, and one that, if present, should be readily detected in the spectra of extrasolar planets, it is not a prerequisite for life. Planets, after all, get started without free oxygen, and may remain without it all their lives. Anaerobic organisms swarmed before oxygen was available, perfectly at home in the atmosphere of the early Earth, converting nitrogen to ammonia, sulfur to hydrogen sulfide, carbon dioxide to formaldehyde, and so forth. (From formaldehyde and ammonia the bacteria could make every organic compound they needed.)
There may be planets in our solar system and elsewhere that lack an atmosphere of oxygen but are nonetheless teeming with anaerobes. And such anaerobes need not live on the surface of the planet; they could occur well below the surface, in boiling vents and sulfurous hot pots, as they do on Earth today, to say nothing of subterranean oceans and lakes. (There is thought to be such a subsurface ocean on Jupiter’s moon Europa, locked beneath a shell of ice several miles thick, and its exploration is one of the astrobiological priorities of this century. Curiously, Wells, in The First Men in the Moon, imagines life originating in a central sea in the middle of the moon and then spreading outward to its inhospitable periphery.)
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IT IS NOT CLEAR whether life has to “advance,” whether evolution must take place, if there is a satisfactory status quo. Brachiopods, lampshells, for instance, have remained virtually unchanged since they first appeared in the Cambrian period, more than five hundred million years ago. But there does seem to be a drive for organisms to become more highly organized and more efficient in retaining energy, at least when environmental conditions are changing rapidly, as they were before the Cambrian. The evidence indicates that the first primitive anaerobes on Earth were prokaryotes: small, simple cells—just cytoplasm, usually bounded by a cell wall, but with little if any internal structure.
Primitive as they are, prokaryotes are still highly sophisticated organisms, with formidable genetic and metabolic machinery. Even the simplest ones manufacture more than five hundred proteins, and their DNA includes at least half a million base pairs. Certainly still more primitive life-forms must have preceded the prokaryotes.
Perhaps, as the physicist Freeman Dyson has suggested, there were progenotes capable of metabolizing, growing, and dividing but lacking any genetic mechanism for precise replication. And before them there must have been millions of years of purely chemical, prebiotic evolution—the synthesis, over eons, of formaldehyde and cyanide, of amino acids and peptides, of proteins and self-replicating molecules. Perhaps that chemistry took place in the minute vesicles, or globules, that develop when fluids at very different temperatures meet, as may well have happened around the boiling midocean vents of the Archean sea.
By degrees, however—and the process took place with glacial slowness—prokaryotes became more complex, acquiring internal structure, nuclei, mitochondria, and so on. The microbiologist Lynn Margulis has suggested that these complex so-called eukaryotes arose when prokaryotes began incorporating other prokaryotes within their own cells. The incorporated organisms at first became symbiotic and later came to function as essential organelles of their hosts, enabling the resultant organisms to utilize what was originally a noxious poison: oxygen.
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THE TWO PREEMINENT evolutionary changes in the early history of life on Earth—from prokaryote to eukaryote, from anaerobe to aerobe—took the better part of two billion years. And then another thousand million years had to pass before life rose above the microscopic and the first multicellular organisms appeared. So if the Earth’s history is anything to go by, one should not expect to find any higher life on a planet that is still young. Even if life has appeared and all goes well, it could take billions of years for evolutionary processes to move it along to the multicellular stage.
Moreover, all those “stages” of evolution—including the evolution of intelligent, conscious beings from the first multicellular forms—may have happened against daunting odds, as Stephen Jay Gould and Richard Dawkins, in their different ways, have brought out. Gould spoke of life as “a glorious accident”; Dawkins likens evolution to “climbing Mount Improbable.” And life, once started, is subject to vicissitudes of all kinds: from meteors and volcanic eruptions to global overheating and cooling; from dead ends in evolution to mysterious mass extinctions; and finally (if things get that far) from the fateful proclivities of a species like ourselves.
There are microfossils in some of the Earth’s most ancient rocks, rocks more than three and a half billion years old. So life must have appeared within one or two hundred million years after the Earth had cooled off sufficiently for water to become liquid. That astonishingly rapid transformation makes one think that life may develop readily, perhaps inevitably, given the right physical and chemical conditions.
But can one speak confidently of “Earthlike” planets, or is the Earth physically, chemically, and geologically unique? And even if there are other “habitable” planets, what are the chances that life, with its thousands of physical and chemical coincidences and contingencies, will emerge?
Opinion here varies as widely as it can. The biochemist Jacques Monod regarded lif
e as a fantastically improbable accident, unlikely to have arisen anywhere else in the universe. In his book Chance and Necessity, he writes, “The universe was not pregnant with life.” Another biochemist, Christian de Duve, takes issue with this; he sees the origin of life as determined by a large number of steps, most of which had a “high likelihood of taking place under the prevailing conditions.” Indeed, de Duve believes that there is not merely unicellular life throughout the universe but complex, intelligent life, too, on trillions of planets. How are we to align ourselves between these utterly opposite but theoretically defensible positions?
Indeed, life on Earth may have originated elsewhere. We know, from the samples returned by the Apollo missions, that there are early Earth and Martian meteors on the moon in considerable quantities. There must be thousands of Martian meteorites on Earth. The notion of “seed-bearing meteoritic stones” was raised by Lord Kelvin in 1871, and the notion of free spores drifting through space and seeding life on other planets (“panspermia”) was postulated by the Swedish chemist Svante Arrhenius a few years later (an idea revived in the twentieth century by Francis Crick and Leslie Orgel, as well as Fred Hoyle). The idea was considered implausible for more than a century, but is once again a subject for discussion. For now it is evident that the insides of sizable meteors do not get heated to sterilizing temperatures, and that bacterial spores or other resistant forms could, in principle, survive within them, protected by the body of the meteor not only from heat but from radiations deadly to life. Meteors were being flung in all directions during the period of Heavy Bombardment four million years ago. Chunks of the Earth must have been ejected into space then, as well as chunks of Mars and Venus—a Mars and Venus that might, at the time, have been more hospitable to life than Earth itself.
What we need, what we must have, is hard evidence of life on another planet or heavenly body. Mars is the obvious candidate: it was wet and warm there once, with lakes and hydrothermal vents and perhaps deposits of clay and iron ore. It is especially in such places that we should look, and if the evidence shows that life once existed on Mars, we will then need to know, crucially, whether it originated there or was transported (as would have been readily possible) from the young, teeming, volcanic Earth. If we can determine that life originated independently on Mars (if Mars, for instance, once harbored DNA nucleotides different from our own), we will have made an incredible discovery—one that will alter our view of the universe and enable us to perceive it, in the words of the physicist Paul Davies, as a “bio-friendly” one. It would help us to gauge the probability of finding life elsewhere instead of bombinating in a vacuum of data, caught between the poles of inevitability and uniqueness.
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IN JUST THE PAST FEW DECADES, life has been discovered in previously unexpected places on our own planet, such as the life-rich black smokers of the ocean depths, where organisms thrive in conditions biologists would once have dismissed as utterly deadly. Life is much tougher, much more resilient, than we once thought. It now seems to me quite possible that microorganisms or their remains will be found on Mars, and perhaps on some of the satellites of Jupiter and Saturn.
It seems far less likely—many orders of magnitude less likely—that we will find any evidence of higher-order, intelligent life-forms, at least in our own solar system. But who knows? Given the vastness and the age of the universe at large, the innumerable stars and planets it must contain, and our radical uncertainties about life’s origin and evolution, the possibility cannot be ruled out. And though the rate of evolutionary and geochemical processes is incredibly slow, that of technological progress is incredibly fast. Who is to say (if humanity survives) what we may not be capable of, or discover, in the next thousand years?
For myself, since I cannot wait, I turn to science fiction on occasion—and, not least, back to my favorite Wells. Although it was written a hundred years ago, “A Lunar Morning” has the freshness of a new dawn, and it remains for me, as when I first read it, the most poetic evocation of how it may be when, finally, we encounter alien life.
* If Wells envisaged the beginning of life in The First Men in the Moon, he envisaged its ending in The War of the Worlds, where the Martians, confronting increasing desiccation and loss of atmosphere on their own planet, make a desperate bid to take over the Earth (only to perish from infection by terrestrial bacteria). Wells, who had trained as a biologist, was very aware of both the toughness and the vulnerability of life.
Clupeophilia
Anyone on the sixteenth floor of the Roger Smith Hotel in midtown at 5:45 on a recent June afternoon would have seen a puzzling assemblage of people in the corridor: a construction worker from Brooklyn, a mathematics professor from Princeton, a couple from Aruba, a father with an infant strapped to his chest, and an artist from the Lower East Side. It wasn’t immediately apparent what had brought this seemingly random slice of humanity together. Had one come up in the service elevator, though, an unmistakable aroma would have given a vital clue. By 5:59, almost sixty people had gathered in the hallway.
At six, the doors to an event room opened and the crowd rushed in. There, in the middle of the room, lighted, draped, surmounted by a huge glittering block of ice, was an altar: an altar covered with hundreds of fresh herring, the first of the season, just flown in from Holland. This was an altar consecrated to Clupeus, the god of herring, whose annual festival is celebrated in late spring by herring lovers the world over.
Entire books have been published about cod, about eel, about tuna, but relatively little has been written about herring. (There is, however, a delightful book by Mike Smylie, Herring: A History of the Silver Darlings, and a fascinating chapter in W. G. Sebald’s The Rings of Saturn.) But herring have played a great part in human history. In the Middle Ages, they were carefully graded and priced by the Hanseatic League, and supported fisheries in the Baltic and the North Sea—and, later, in Newfoundland and on the Pacific Coast. Herring are one of the commonest, cheapest, and most delicious fish on the planet—a fish that can take an infinity of forms: marinated, pickled, salted, fermented, smoked, or, as with the exquisite Hollandse Nieuwe, straight from the sea. They are one of the healthiest fish, too, full of omega-3 oils, and without the mercury that accumulates in the big predators such as tuna and swordfish. A few years ago, the oldest person in the world, a 114-year-old Dutch woman, said she attributed her longevity to eating pickled herring every day. (A 114-year-old woman from Texas attributed her long life to “minding my own business.”)
There are many species of Clupeidae, with varying sizes and tastes, from the Atlantic herring, Clupea harengus, to the pilchard (much loved in England, and often served in tomato sauce), to the tiny sprat, best smoked and eaten bones and all. When I grew up in England, in the 1930s, we had herring virtually every day: smoked herring (kippers or bloaters) at breakfast, perhaps a herring pie at lunch (my mother’s favorite dish), fried herring roe on toast at teatime, chopped herring at dinner. But times have changed, herring is no longer on every breakfast and dinner table, and it is only on special, joyous occasions that we clupeophiles can come together for a real herring feast.
The great traditions of herring are maintained by Russ & Daughters, a Houston Street emporium that started as a pushcart on the Lower East Side over a century ago and still sells the largest variety of herring in New York City. It was Russ & Daughters that organized the recent herring festival.
There are certain passions—one wants to call them innocent, ingenuous passions—that are great democratizers. Baseball, music, and bird-watching come immediately to mind. At the herring festival, there was no talk about the stock market, no gossiping about celebrities. People had come to eat herring—to savor them, to compare them. In its purest form, this meant seizing the new herring by the tail and lowering them gently into the mouth. The sensation this produces is voluptuous, especially as they slip down the throat.
Guest
s started from the great central table, the altar covered with new herring; washed these down with aquavit; and moved on to satellite tables, where there were matjes herring, herring in wine sauce, herring in cream sauce, Bismarck herring, herring in mustard sauce, herring in curry sauce, and plump schmaltz herring, fresh from Iceland. Oily and briny, schmaltz herring can last for twenty years; taken from the Baltic, they were a staple food (along with black bread, potatoes, and cabbage) of poor Jews throughout Eastern Europe. For my father, born in Lithuania, there was nothing to compare with them, and he ate them daily all his life.
Around eight o’clock, after two hours of eating and drinking, the pace slackened. Slowly, the herring lovers left the hotel, still discussing favorite dishes with fellow travelers as they went. They sauntered slowly up Lexington Avenue. One does not rush after such a banquet; indeed, one’s whole perspective on the world is changed. Some of us, the New Yorkers, will meet again, at Russ & Daughters. But the rest, after they have slept the deep sleep of the consummated herring eater, will start counting the days to next year’s herring festival.
Colorado Springs Revisited