It's taken a year longer than it should have, but Nature is finally on the web, though only with the table of contents for the last month plus a few teasers. And Science has just upgraded its web site to include abstracts and a search engine. Both sites are really just place-holders, hollow shells without real meat, as the magazines tiptoe into the web era. Leadership, it isn't.
The Tree of Life || Radiology Case of the Week || The Digital Anatomist || The Whole Brain Atlas || Boids (Flocks, Herds, and Schools) || Découverte d'une grotte ornée paléolithique à Vallon-Pont-d'Arc (Ardèche) || San Francisco's Exploratorium || Grand Canyon River Running || Sleep Medicine || NetVet and the Electronic Zoo || Cosma Rohilla Shalizi 's web pages on physics and everything else ||
Books: Kanzi || The Animal Mind || Language and Species
Depression and manic-depressive illness affect some of our most creative people with
As if global warming wasn't bad enough, it might also trigger another episode of
Department of Reading
There are books from
And if you're interested in psychology, culture, and evolution, don't miss
My 11 books and some of my science articles can be browsed here. Suggestions (your own pages or others) are always welcome.
Short comments but mostly excerpts, in the Whole Earth Review style.
A finalist for nonfiction in The National Book Awards.
From Dan Dennett's preface to Darwin's Dangerous Idea (Simon & Schuster 1995):
Darwin's theory of evolution by natural selection has always fascinated me, but over the years I have found a surprising variety of thinkers who cannot conceal their discomfort with his great idea, ranging from nagging skepticism to outright hostility. I have found not just lay people and religious thinkers, but secular philosophers, psychologists, physicists, and even biologists who would prefer, it seems, that Darwin were wrong. This book is about why Darwin's idea is so powerful, and why it promises – not threatens – to put our most cherished visions of life on a new foundation.
|| William J. Mitchell, City of Bits
(MIT Press, 1995), starts out like this:
"My name is email@example.com (though I have many aliases), and I am an electronic flâneur. I hang
out on the network."
|"The keyboard is my café. Each morning I turn to some nearby machine -my modest personal computer at home, a more powerful workstation in one of the offices or laboratories that I frequent, or a laptop in a hotel room-to log into electronic mail. I click on an icon to open an "inbox" filled with messages from round the world-replies to technical questions, queries for me to answer, drafts of papers, submissions of student work, appointments, travel and meeting arrangements, bits of business, greetings, reminders, chitchat, gossip, complaints, tips, jokes, flirtation. I type replies immediately, then drop them into an "outbox," from which they are forwarded automatically to the appropriate destinations. (Note the scare quotes. "Box" is a very loose metaphor, and I will come back to that later.) If I have time before I finish gulping my coffee, I also check the wire services and a couple of specialized news services to which I subscribe, then glance at the latest weather report. This ritual is repeated whenever I have a spare moment during the day."|
An Unquiet Mind:
(Well, you could have taken the fast links -- and then used the bounce-back buttons)
A Conversation about|
copyright ©1995 by
Throughout history, it has been known that melancholics, though they have little energy, use their energy well; they tend to work hard in a focused area, do great things, and derive little pleasure from their accomplishments. Much of the insight and creative achievement of the human race is due to the discontent, guilt, and critical eye of [melancholics].
Mood disorders such as mania and depression involve inappropriate emotional responses. Thought disorders involve inappropriate thoughts. Schizophrenia, delusional disorder, and a few minor ones constitute the thought disorders – but let's stick to mania for a minute.|
In mania, you see excessive excitement and a lot of impulsive behaviors, but when the mania is mild, such people can be very energetic and get a lot done. Still, they get into trouble from hypersexuality, inappropriate laughing and joking, buying sprees, and reckless driving. They tend to get disorganized as the mania increases, and even more prone to poor judgment. Their speech becomes pressured and they may answer questions at great length. They sometimes even keep talking after their audience has fled the room. Virginia Woolf, when becoming manic, would talk almost without stopping for two or three days. For the first day, she made some sense, but by the third day she was totally incoherent. That's back before lithium salts as a treatment for mania; schizophrenia and mania used to be confused with each other, especially in the United States, until the response to lithium treatment served to better define the two patient populations.
The euphoria and the sometimes infectious cheerfulness of mania is confusing, but the psychiatrist can usually tell manic euphoria from a genuine "good mood" by other symptoms that are clearly pathological, such as uncharacteristically poor judgment and extreme grandiosity.
And, of course, mania usually alternates with depression, to form a bipolar disorder. Mania's association with depression was first noted 1,800 years ago. The bipolar patients are not continuously abnormal, being quite functional in the periods in between their manic and depressive phases – indeed, they may get a lot done. But there is a lot of alcoholism and drug abuse associated with manic-depressive illness.
More often, depression comes by itself. Depressed people sleep poorly (or too much) and feel fatigued, they get little pleasure out of daily activities, they have difficulty concentrating, and they may feel worthless or guilty. A depressed mood might be an appropriate emotion after death of a loved one, but not as a response to the only sunny day of the month in Seattle.
Depression can be very profound, preventing the patient from doing any activity and with a significant risk of suicide. The lifetime rate for attempted suicide in individuals with no history of mental disorder is 1 percent, but for the depressed it is 18 percent, going up to 24 percent in manic-depressives. And 70-90 percent of all suicides seem to be in people with mood disorders. Untreated, about 20 percent of manic-depressives commit suicide.
"Depression is what they used to call melancholy?"
That's the Hippocratic name for it, 2,500 years ago, and Aristotle thought that "those who have become eminent in philosophy, politics, poetry, and the arts have all had tendencies toward melancholia." But mood disorders can be traced back 10,000 years to King Saul in the Old Testament book of Samuel. Saul developed periods of severe depression, guilt, and incapacity; later he became psychotic and attempted to kill his son Jonathan along with David, nemesis of Goliath.
There are lots of examples – St. Augustine, John Keats, William James, Leo Tolstoy, Ernest Hemingway, Sylvia Plath, John Berryman, Ann Sexton, Winston Churchill – quite a few politicians, actually. Poets seem to have the highest rates of mood disorders and suicide. The psychiatrist Nancy Andreasen, who started out as a professor of English literature, did a study of creative writers using modern psychiatric criteria for schizophrenia that showed that the writers had three times the expected rate of mood disorders, and none had schizophrenia; their parents and siblings also had the same rate of mood disorders. Other studies show artists, poets, and writers with eight to ten times the major depression rate for the general population and ten to forty times the rate for manic-depressive illness and its milder variants. So perhaps Aristotle was right.
"So are there really more depressed women than men?"
About twice as many, for depression by itself. But manic-depressive illness is an equal-opportunity disease.
Mood disorders and schizophrenia are relatively common. About 4 percent of the population is suffering from depression at any one time, maybe 10 percent have had a major depression in the last year, with about 20 percent of the general population experiencing an episode sometime during their life. Another 10 percent of the population has had problems with alcohol or abused drugs in the preceeding year. Schizophrenia is only a fraction of a percent on the preceeding-year scale but that disguises a lifetime prevalence between 1 and 2 percent, with about a tenth of the schizophrenics in the hospital at any one time and many of the rest unemployable – so it's expensive, something like $73 billion annually in the United States alone.
INHERITANCE HAS A LOT TO DO with both schizophrenia and mood disorders. A major way to sort out environmental influences from biological ones is through the study of twins separated at birth by adoption into separate homes. If one identical twin has schizophrenia, there's about a 50 percent chance that, when the other twin is located, he too will be schizophrenic. For fraternal twins, the chances are only those of siblings in general – about one in six. The incidence of schizophrenia in the adoptive parents has little influence. The data is similar, though not as strong, for mood disorders.
However, a genetic predisposition does not seem to be the only factor that accounts for these disorders. Even with the identical genetic makeups of identical twins, about half of the identical twins of schizophrenics never develop the disease. So the environment, the accidents of upbringing and exposure to viruses, made the difference between having the genetic predisposition and actually coming down with the disease.
In a sense depression is a view of the world through a glass darkly, and mania is a shattered pattern of views seen through a prism or kaleidoscope: often brilliant but generally fractured. Where depression questions, ruminates, and is tentative, mania answers with vigor and certainty. The constant transitions in and out of the constricted and then expansive thoughts, subdued and then violent responses, grim and then ebullient moods, withdrawn from and then involving relationships, cold and then fiery states – and the rapidity and fluidity of moves across and into such contrasting experiences – can be painful and confusing. Such chaos, in those able ultimately to transcend it or shape it to their will, can, however, result in an artistically useful comfort with transitions, an ease with ambiguities and with life on the edge, and an intuitive awareness of the coexisting and oppositional forces at work in the world. The weaving together of these contrasting experiences from a core and rhythmic brokenness is one that is crucial to both the artistic and manic-depressive experience.
Adapted from Chapter 10 of my book, Conversations with Neil's Brain: The Neural Nature of Thought and Language (Addison-Wesley 1994; softcover April 1995 US$12), co-authored with my neurosurgeon colleague, George Ojemann.
THE CLIMATE'S |
Abrupt Cold Snaps
Have Been Triggered
by Global Warming
copyright ©1995 by
You can also read this in Italian translation at Lo Scienziato in Poltrona: Calvin
Matching wits with the fickle climate is how we became human. Or so I reflect, while waiting for the London-bound flight to depart from New York. "Delayed by unseasonably severe weather," a disembodied voice proclaimed an hour ago. My fellow passengers speculate about whether the greenhouse climate has already arrived.
The last time that the earth warmed up, it was as the last ice age was ending. Both animals and humans were probably doing well because of the North Atlantic's warming trend that had suddenly started 1,500 years earlier (this "Allerød event" was about 14,500 years ago).
This same generation saw things suddenly change, for the worse. One year, the winter rains were scant, and it seemed colder. It wasn't as cloudy as usual in the spring, and the summer was bone dry. The good grazing was exhausted early, and animals started exploring unlikely places in search of food. By the time that the winter snows started, both humans and animals were in poor condition; more than the usual numbers died that winter. Was it just a drought?
The next year was even colder and drier. And the next. The next twenty years saw dramatic changes, far greater than in the "Little Ice Age" of a few centuries ago. German forests died and scrubs characteristic of present-day Siberia took over. It became more dusty as severe storms stirred up the dry topsoil. The herds surely dropped to a fraction of their former sizes. And the human tribes likely did poorly in consequence.
(A few decades ago, modern scientists looked at the accumulated layers of a lake bottom in Denmark. In a deep layer, they saw the sudden introduction of the pollen of an arctic plant called Dryas that had no business being in Denmark, and named this cold snap after it: the Younger Dryas climate.)A millennium later, it ended even more suddenly than it had begun. There was a generation about 11,800 years ago, the great-great-(repeat that 46 more times)-grandchildren of those people who were absolutely sure about the good old days, that experienced the change. They grew up in a cold and dry Europe, and then saw the warm rains suddenly come back over the course of just a few years and melt the ice. The grass prospered, and the remaining grazing animals began a population explosion. It became a boom time for those Europeans who had survived up in the land of hard winters.
It was as if a switch had been turned off. And then back on again. Or perhaps faucet is the apt metaphor, since the key to what happened is the ocean current that keeps Europe warm, the North Atlantic Current (it's not really the Gulf Stream, after all).
Ice core data of Dansgaard et al Nature 1993. Younger Dryas shown in red. Note the two episodes during the warm period 130,000 years ago. Illustration from my Scientific American article (October 1994).
AFTER LEAVING NEW YORK at sunset, our London-bound airplane followed the Gulf Stream to the northeast, up over familiar Cape Cod haunts in the dusk, then just offshore of the Nova Scotia peninsula. We saw the entrance to the Gulf of St. Lawrence, where the overflow from the Great Lakes makes its way out to sea, and saw many fishing boats as we passed over the Grand Banks fishing grounds off the large island of Newfoundland. Finally, during the night, we followed the eastbound Gulf Stream out over the North Atlantic proper.
Before dawn, we flew over the North Atlantic Current, which sweeps northward up toward Iceland. But even after we passed over the current, I continued to see its effects, in the form of rain clouds drifting eastward toward Europe. I saw southern Ireland in the dawn light, great green patches between the storm clouds. Home of the Irish elk, the deer with the giant wingspan – at least for about 1,500 years (the Younger Dryas wiped it out, a good 1,600 years before humans arrived in Ireland).
Seen through the scattered clouds, London at six in the morning is glowing in the early morning sunlight, and the streets shine from the spotty showers; a few delivery trucks cast long shadows while driving on the wrong side of the street. The green parks and the tennis courts are empty. But it's the London of William Shakespeare, Isaac Newton, Dr. Johnson, Charles Darwin, Bertrand Russell, and George Bernard Shaw.
And London is a puzzle, since it is 51.5° north of the equator. It is hard to imagine any city in Asia or the Americas, that far from the equator, becoming such a center of culture and commerce. None has, so far: not Calgary, Alberta (where parking meters have electric outlets, so you can keep the car warm enough to restart). Nor Moosonee, the town at the bottom of Hudson's Bay. Or chilly Puerto Arenas at Tierra del Fuego, equally distant from the equator to the south.
Indeed, most of Europe is at Canadian latitudes. Compared to the populous parts of the U.S. and Canada, mostly between the 30° and 45° lines on a globe, the populous parts of Europe are shifted 10-15° to the north, mostly between 40° and 60° latitudes. "Southerly" Rome lies at the same 42° N as does "northerly" Chicago. Paris lies at the latitude of Vancouver, British Columbia, about 49° N. Berlin is up at 52.5° N, Moscow at nearly 56° . Oslo, Stockholm, and Leningrad nestle up just under 60° N, where the sun makes only a brief midday appearance during December – about the same as in Alaska's coastal cities.
The reason that Europe is warm and wet, where Canada is cold and dry, is largely due to the North Atlantic Current and how it differs from similar major currents in the Pacific Ocean. All those rain clouds I saw this morning were caused by the copious evaporation from the warm ocean surface of the North Atlantic Current.
But what if something were to happen to the North Atlantic Current again?
THE BEST-KNOWN CLIMATE CHANGE in the offing is the global warming that is occurring from the greenhouse effect. It isn't minor, as this 1989 summary notes:
Computer-modeled predictions of greenhouse warming suggest that global mean air temperatures may rise by 5° C [9° F] over the next 30 years, with amplified rises of up to 12° C [22° F] in polar regions. This is comparable with the temperature increase from the last glacial period to the present interglacial, and the projected rate of increase is probably greater than at any time since then.The best-known consequence is the rise in sea level that threatens coastal populations. But climate need not change gradually. We now know that, in the past, other climatic changes have flipped on and off, without much of a middle ground. The North Atlantic Current's on-and-off tendencies are only one example of the more general problem of "modes" of behavior.
It has long been known that the climate could, in theory, become trapped in extreme states. The "White Earth Catastrophe" scenario could happen if ice extended over enough of the Earth's surface to reflect a lot of arriving sunlight back out into space: the Earth could freeze and never recover, short of volcanos covering the white surface with some dark lava. And the "Greenhouse Catastrophe" scenario would occur if the carbon locked up in the sediments (not just coal and oil but also that frozen tundra of Arctic regions) were released to the atmosphere in quantities sufficient to form a greenhouse layer of insulation, allowing the atmosphere beneath it (and oceans, and land, and us) to heat up catastrophically.
In the 1980s, the Swiss climatologist Hans Oeschger suggested that, in addition, the earth's climate had several modes of interaction between the oceans, the atmosphere, the biosphere, and the ice sheets. These aren't extreme (indeed, we're in one mode now) but the transitions between them could be uncomfortably sudden. There had been hints of fairly sudden minor transitions. After all, people periodically rediscover that monsoons can simply be omitted some years.
There are drought cycles that repeat every few decades, but some are much shorter: South American fisheries and the bird populations of many Pacific islands are dramatically depressed every half-dozen years by the warming changes in the ocean currents, known as El Niño. Evidence has been accumulating that North American droughts are secondary consequences of equatorial ocean currents turning colder, the so-called La Niña condition. But what Oeschger was talking about was more than minor: he suggested that the climate had major modes, some lasting many centuries. These bistable styles of operation may pose far more of a threat than the slow loss of coastal real estate to rising sea levels.
Modifying the earth's climate with greenhouse warming may well exaggerate such mode-switching – or leave us stuck in the "wrong" mode for centuries, as has happened before. Paradoxically, you can get cold from heat, as the Younger Dryas demonstrates: a warming trend can apparently cause a prolonged cold snap. Most people have a tendency to dichotomize climate change into warming or cooling, and forget that both can happen simultaneously – but in different places.
Ice layers preserved under Greenland's glaciers show that more than 20 regional chills, each lasting centuries, have occurred in the last 130,000 years; two occurred during the Earth's last warm period. The Younger Dryas was simply the most recent and the longest-lasting (about 1,200 years). Though detectable along the east coast of the U.S. and Canada, it was most pronounced in Europe and southern Greenland; you won't see it in the deep ice cores from Antarctica. It was probably triggered, in part, by the dilution of the salt water by all that freshwater glacial runoff. But how were the other 19 cold snaps triggered? Might something like a greenhouse warming provoke another one? Those are the kinds of questions to which we urgently need answers.
SUDDEN REGIONAL COOLING during a global warming trend probably happens because the circulating ocean currents switch into a new mode, as when the North Atlantic Current no longer warms and waters Europe in its customary way. And Europe without the North Atlantic Current would be about like Canada: they both have a comparable amount of fertile agricultural land at similar northerly latitudes. Indeed, Europe gets Canada's air second-hand, a week or so later, as Europe periodically rediscovers whenever a forest fire in Canada makes European skies hazy and sunsets dark red.
You might surmise that Europe's population ought to be something like Canada's 27 million people. But France alone has twice as many people as Canada. Europe, to the west of the Soviet Union, totals more than 500 million people (twice the U.S. population), and there are another 200 million people in the western parts of the Soviet Union that share Europe's climate (the Younger Dryas climate reached as far as the Ukraine). That Europe presently supports about 26 times as many people as Canada is largely attributable to the beneficent influence of the North Atlantic Current, warming all that cold Canadian air crossing the North Atlantic, before it reaches Europe. And thus loading it with a lot more moisture, to be dropped on Europe as rainfall.
What will the "extra" half-billion people of Europe do, should the North Atlantic suffer another hiccup, returning Europe to a Canadian climate? If one could reliably forecast this situation, with a lead time of a hundred years or so, perhaps those Europeans would move elsewhere peacefully or develop a reciprocal symbiotic economy with some Third World countries that could feed them. Yet mode-switching cooling can happen as quickly as the onset of a minor drought, and no one knows how to predict it, much less control it. The first few years, there would be an "economic response": Europeans would buy grain elsewhere and ship it in, cut back on meat. But what would happen in the long run?
Remember how poorly the economic response worked for Ireland in the mid-nineteenth century when the potato crops failed? And what happened during Europe's last Great Depression a half-century ago: Germany's lebensraum excuse for territorial expansion, a professed need for "more living space"? Europe is technologically competent, compared to today's Third World or nineteenth century Ireland, and a starving population isn't going to die quietly. They will move instead. A little glitch in the North Atlantic, similar to those of the past, is the most serious, least avoidable scenario for global warfare that I can imagine.
Whether it is a greenhouse-induced rise in sea level threatening the half-billion people relying on low-lying areas of the Indian subcontinent, or a cooling-and-drying Europe in need of lebensraum for a half-billion people, or the projected return to dust bowl conditions in the American Midwest and the loss of irrigation water in California (whose agriculture already helps feed Eastern Europe and the USSR in their bad years), climatic change is not likely to be peaceful. "Disruptions" is hardly the word for it.
We are very overextended, with far more population than we can support (even in the off-years of our current climate, as those Third World famines have repeatedly demonstrated). Major climate change, whether ice age or greenhouse warming, means a considerable "contraction" in the human population that the planet can support, unless new technologies fix up things very well indeed. An abrupt Dryas-like climate change, however, could easily destroy the stable civilizations that such large-scale innovative technologies require.
|Adapted from the introduction to my book,||
The Ascent of Mind
(Bantam 1990) is my book on the
ice ages and how human intelligence evolved; the
"throwing theory" is one aspect.
The entire text and all illustrations are available on the Web;
also see Wallace S. Broecker, "Massive iceberg discharges as triggers for
global climate change," Nature 372:421-424 (1 December
1994) and his "Chaotic Climate" Scientific American article (November 1995 issue).