chimps, humans and big numbers

The entire chimpanzee genome has been mapped!
Like me, you've probably heard that we share 99 percent of our genes with chimps. Well, it now turns out it's only 96 percent overlap.
The number has changed, but so what? That old "99 percent the same as chimps" has been bandied about in all sorts of contexts, from evolution-versus-creation arguments to animal rights. But without scientific context (like, how much do chimpanzees vary from one to another? or, how much of a real difference can a 4 percent change make?), such numbers are just useless pieces of information.
This is not unlike the Great Eskimo Snow Hoax. Maybe you've heard that Eskimos have 50 words for snow? This factoid is supposed to deliver psychological shock and awe. Well, sorry to shatter your illusions, but they don't. They've got about half a dozen, same as English. (yes, English has more than one word for snow: for example blizzard and sleet). As anthropologist Laura Martin points out, they don't have 50 words for snow, but would it even be that amazing if they did? After all, typesetters have hundreds of names for different kinds of fonts.
The Great Eskimo Snow Hoax appeals to us because it is suggestive of so many things: how differently other cultures see the world, how languages reflect the worldview of the language community, and of course, how strange those crazy Eskimos are.
Another big number out of context: the man who conceived of the X-Files got the idea when he read an article claiming that 3 million americans believe they've been abducted by UFO's. That's an astounding figure, until you realise that it's about 1 percent of the American population. You can find just about anything in 1 percent of the population. For example, one percent of people are schizophrenic. One percent are geniuses. One percent have epilepsy.
He may have thought he'd hit the marketing jackpot, but really, the article was just a trigger that encouraged him to let his creative impulse run free. The truth is, there's a niche market for pretty much anything. But that three million number apppeals to our suspicions about suburban mid-western Americans, about the idea that there are lots of people out there who have some wacky ideas, and for some, leaves uncertainty about whether so many people could be wrong.
But back to chimps. What's so appealing about the ninety-nine percent (now ninety-six)?
Lots. It suggests we should not be too arrogant as a species, that we should treat other animals well, and that we ourselves are really just beasts underneath. Compelling ideas. But like the Eskimo Snow Hoax, if you think about it, the high number is actually rather banal. Chimps and humans both have two arms, two legs, red blood cells, a liver, heart, lungs, spleen, and brain. They have taste buds and eyes and digestive tracts and skin and ears. They feel hot, cold, and pain, they smile and fight and play and congregrate in small societies. They eat many of the same foods as us. Ninety-six percent doesn't seem like a stretch.
Geneticists now believe that it is a single, crucial gene that makes all the difference between us and chimps. Now that's interesting, because it gives us a handle on the underlying structural differences. One gene, not a cluster.
We love to blow our minds with amazing facts, and huge numbers are a great way to do it. However, interpreting those numbers correctly usually requires context, and that context frequently cuts our amazing fact down to size.
To me, the most fascinating thing about the ninety-six percent is not the number itself, but that we know what the number is. This is a testament to years of hard work by many dedicated, smart people. It's also part of the gold vein of information we are discovering about how humans are built.
Humans are the first species to peek behind the curtain. And armed with our knowledge of the process, for better or worse, we are the first to take control of that process, whether by embryo selection, artificial insemination, gene therapy and other procedures just over the horizon. We are on the cusp of actually controlling and altering our own evolutionary path. But most of all, it is a testament to humans' insatiable drive to understand everything... especially ourselves.

footnote:
here's the reference for the Eskimo snow hoax:
Martin, Laura (1986). "Eskimo Words for Snow: A case study in the genesis and decay of an anthropological example". American Anthropologist, 88 (2), 418-23.

the meek shall inherit the universe

Humans, at first glance, do not appear to be well-designed for survival. Our lack of fur, lack of claws or other natural means of attack and defense, slow breeding times, and our lengthy, costly infancy and childhood (when babies and children are resource drains on adults) all should have combined to make us a biological curiosity, inhabiting some exotic location where conditions were just right for our continues survival. In this way, we would have been rather like the frill-necked lizard, or the polar bear, or various deep-sea-dwelling fish.

Instead, humans have spread from the African savannah to every continent and every climate on the earth. We do this through a singular ability: engineering. Certainly, we are still fair game for predators in many places in the world, making, as we do, juicy meals full of protein and calcium. However, we have managed to win the predator-prey game with most of our larger predators, and many of the smaller variety too, such as smallpox.
We have spread to every part of the earth and harnessed the resources of minerals, plants, and other animals to further our own survival. The next step are the empty horizons of nearby planets and Moons.
The planet Mars and the moons Io and Europa have been nominated as possible locations of future human settlements. But their current environments are hostile to humans and currently don't support life. Could we transform them before moving in? Possibly. This strategy is known as terraforming. Such a process would probably take hundreds or thousands of years, and would involve causing permanent changes to the atmosphere, melting the polar icecaps on Mars, and fostering plant life.

Robert Zubrin, in Entering Space: Creating a Spacefaring Civilization, makes the case that this is the natural development for the human race. He points out that the period of European colonial expansion was correlated with unprecedented advances in science, arts, and democratisation, and suggests that human conquest of space, by allowing mankind the freedom to experiment and innovate in new environments, will have similarly beneficial effects.

Michael Griffin of NASA says space travel will be dangerous. He predicts that despite the likelihood of death, people will still travel into space. It fulfils the human need for exploration, conquest and hope in a way that travelling to new continents did in the era of European colonization (and at all times that humans have travelled to new parts of the Earth). To back this up, Griffin points out that the risk of dying whilst climbing Mount Everest is 10%, yet people still continue to climb.
But who will leave the comforts of Earth for the perils of space? If history is any guide, people from all walks of life, but they will be disproportionately the poor and dispossessed: people with nothing to lose.
Wealthy European governments and corporations bankrolled European expansion, but it was poor ethnic groups suffering from persecution (the pilgrims), deprivation and famine (such as the Irish) or the victims of the ravages of war (such as the Italians) that moved in large numbers to countries such as America and Australia. On the other hand, extremely hostile locations such as Antarctica are still populated entirely by government run organizations.
Only after a planet or large moon has been terraformed or otherwise deemed fit for human life will true human settlement, in all its messy, tumultuous, mix of despair and hope take place on a large scale. Given the current pace of technological change, and estimates of the huge time frames involved in terraforming, that will not be until several centuries in the future.
But when it does, as before, the poor, or in the Biblical terms, the meek, will once again shape the future, and inherit whatever inviting part of the Universe we happen to find. Unfortunately, the meek have a habit of staging rebellions and declaring independence, so the dream of a galaxy-wide enlightened civilization, ruled by a benevolent centralist government will probably remain a fantasy of Star Wars movies. Instead, humans will continue to do all the things they do here on planet Earth: love, hate, despair, hope, strive, and quarrel. As the old saying goes: all you have is what you take with you.

Citizen Canine: our multispecies society

What species is our society? I'm guessing that your answer is 'humans'. But our society is made up of several species, peacefully co-existing, and working together for mutual benefit. The most prominent of these, after us, is the dog.
Dogs live with us in our houses, or houses of their own. They consume food from the industrialized food chain just like you- canned meat from supermarket, or raw from a butcher. They walk in our parks. They love sports, such as Frisbee, catch, and running around in circles. They make friends with us, and sometimes fall in love with us, and we in turn, fall in love with them. Archaeologists have found people buried with their pets in graves that are up to ten thousand years old.
Dogs aren’t parasites like rats or cockroaches. No, they’ve got careers: drug-sniffer dogs at airports, guide dogs, tracking dogs, police dogs, hunting dogs, cattle dogs, sheep dogs. Some, in the spirit of agrarian communities, grow up doing what their family have done for generations, such as huskies or Australian sheep dogs. Some, such as those that work for law enforcement or aiding the blind or sick, go to elite universities and graduate only after a lengthy series of demanding coursework. Others, with neither family connections, breeding, or elite qualifications, get their work in the general public doing various odd jobs.
These dogs entertain children, care for the old and sick, Often they find themselves as bodyguards for humans conducting daily exercise, or working home security - a comfortable job for a dog, with few demands and lots of perks. Meals, accommodation, health care, and even free holidays are thrown into the deal.
I say this with not a shred of irony. These are real jobs, and the workers - the dogs - really do contribute to the community, and they get paid to do them. Not in money, of course, because biological and social constraints make it impossible for dogs to use money. Their brains, different from ours in key respects, cannot comprehend the intricacies of the monetary system. Money relies on symbolic reasoning, a peculiarly human talent, so instead, they get paid in other ways: food, shelter, protection, and entertainment. These arrangements almost always transcend the pragmatic requirements and result in bonds of friendship and love.

Communication between dog and man
Communication between the two species is better than you might realise. Dogs can learn the meaning of about fifty human words, far more than any other animal except for certain primates. They certainly understand language far more than cats or horses, two other species with extensive interaction with humans.
People, in turn, can interpret the meaning content of dogs’ barks, and can often find their facial expressions easier to read than other humans. Dogs don’t cloak their feelings in layers of social nuance: they wear their heart on their paw. They can also communicate simple wishes through gestures, such as running back and forth between a human and an object of desire (such as a car, if the dog wants to go for a ride).

Dogs and the law
If we accept that we live in a multi-species society, what are the social policy implications? A radical overhaul of policy would be wrongheaded and possibly counterproductive. Dogs don't have the same rights or obligations as us, and to treat them otherwise would be absurd. Most of our laws don’t apply to dogs. We don't expect dogs to vote, testify in court, or submit income tax returns. We do expect them to obey some laws. Dogs cannot walk freely on roads, destroy property, cause a public nuisance, and are forbidden to commit assault or murder (even on other dogs). Dogs are subject to the death penalty for serious infractions most places on earth. The flip side is that dogs are likewise afforded various protections under the law, at least in most Western democracies: it is illegal to torture or maliciously harm a dog with no reason.
We recognize that the relationship between dogs and their owner-employers resembles a master-slave relationship in many ways. Human slavery is rightly considered an abomination, but interspecies slavery is not immoral for several reasons. Firstly, while communication does occur, it is too limited to negotiate contracts or change of employment. Secondly, even if we could talk to them about these things, it is by no means clear that dogs have the mental apparatus necessary to negotiate them. In fact, the reason they are so useful in society and have found so many niches is that they and we are good at different things. Dogs can track a fugitive for miles based on nothing but scent trail that is invisible to us. With their biologically bestowed sharp teeth, claws, and musculature, they make great bodyguards. However, they don’t do contracts or negotiation. Therefore, the ownership model is the only viable model. But the very fact that they are incapable of advocating on their own behalf is a compelling reason to make sure that the system is ethically sound, as much as can be expected.
Historically, dogs have gotten a good deal because, like humans, they tend to make bad employees when they are unhappy. If they are treated well, feel a sense of community and belonging, and have interesting lives (from their perspective, not ours), then they do their jobs. Looking at it this way, it may be that the system corrects itself.

The future of dogdom
We know that dogs descended from wolves, and from them, diversified into all the dog breeds alive today. In fact, dogs were domesticated over 100 thousand years ago. This must be true because there are too many mutations in the various strains of dogs to have occurred in a shorter time period, such as 14,000 years, as previously thought. These different breeds of jobs have distinct roles and careers. If the past tells us anything about the future, then the trend of diversification is likely to continue. We may find that dog breeds continue to diverge until they become different species.
Because of selective pressure, successive generations will get better and better at all of the things that dogs currently do well: sniffing, tracking, herding, guarding, loving, and combat. Thus, the guard dog, the companion, the sled dog, and the hunting companion may be as different from each other as your average dog differs from a cat. Eventually, these specialised creatures will become distinct species, that we will refer to with specific names, such as sniff-trackers, guardweilers, or fetchers. But for all breeds of dog, communication skills with humans will improve, because regardless of vocation, we like dogs that we can communicate with. It follows that those are the dogs that we will keep, and that will breed the next generation.
Counteracting the trend to diversity is the household pet, the generic dog, which needs to be versatile enough to perform a great variety of tasks. We are likely to ask them to guard our property (a task they take to with gusto), accompany us on walks, play with our children, fetch belongings, and be our companions. And the more versatile the dog, the better the companion. This need for general purpose abilities may act as a counterweight to specialisation, creating a superdog of the future. This creature will be supremely adapted to life in human society, will have levels of skill far beyond the abilities of the dogs of today.
If you wake up and find yourself several thousand years in the future (ignoring the fact that this would be very disorienting), you would be likely to meet such superdogs. They will intelligent, playful, muscular, witty, respectful, and will have the ability, if the need arose, to kill you in an instant.

the new space race has begun

The website spacefuture predicts that Space tourism will go through three phases:
1) a pioneering phase, where space travel will be expensive and available to a handful of people,
2) a mature phase as the cost goes down; and
3) a mass phase as space travel becomes available to the general public.
We have entered the pioneering phase.
Russia is making a killing on space tourism: tickets for trips into space are now sold out for the next two years. Tickets to visit a real Russian space station sell for about 21 million US dollars.

Meanwhile, Virgin Galactic has detailed its plans. Virgin, headed by the larger-than-life Richard Branson, will be the first private operater of space tourism. Spaceship one, a prototype, was completed and has made three flights. Another spaceship -"Spaceship two"- is being built in Mojave, California, to take people off the planet and back again for the sheer fun of it. Each flight will have two pilots and six passengers. Tickets will cost $200,000, but Virgin expects that price to drop over time.

Space tourism may ultimately lead to trips to Mars, Jupiter, and beyond, but trips into Earth's stratosphere are not the same as trips to Mars or other planets, and are certainly do not pose the same scientific or engineering hurdles. There is a discontinuity due to the vast distances between the Earth-Moon system and other planets in the solar system. This will require further advances in technology. However increasing demand will drive technological development. Furthermore, the science of space travel is proceeding apace independently of any pressure for tourism.

Australia and America recently agreed to a joint research operation into hypersonics (greater than five times the speed of sound) costing $50 million dollars. The research will be conducted at Woomera, in South Australia. Hypersonics are seen as a key to cheap space launches.
And research on humans living in space continues on the international space station.
Is this a worthwhile endeavor? Should we be putting our efforts towards something more noble, such as eradicating poverty?
These questions are moot: the technology exists, and from here, the movement into space is inexorable. Once technology comes into being, it is historically rare for the technology to then be lost. The typical course is widespread adoption, refinement, and use. That is the way it has been before, and in all likelihood is how space travel will unfold in the future. Man's future in space will mirror his history here on Earth.

colonizing the solar system

We have been given the imperative: we must leave this planet in search of new homes. Michael Griffin of NASA says a species on a single planet will not survive. The risks for space travel are high. People are likely to die, yet we will still do it. Griffin points out that the risk of dying on a climb up Mount Everest is 10%, yet people still continue to climb.
Who will colonize space? Americans? If history is anything to go by, it will be the world's poor and oppressed, searching for a better life.
Groundhog from the newsgroup sci.space.policy noted:

I have been around the world, and your average American is anything but a pioneer. The US citizen in a third world country: complains about the food; drinks only bottled water; can't stand the weather; won't learn the local languages; can't stand the locals; despises anything not blessed by the touch of mom'n'apple pie;pines away if he can't follow Oprah or the Superbowl on satellite TV. The pioneering type ?!!!

His cynicism is funny, but doesn't match with history. The English, you might say, were a pampered lot, living on the wealth of the Empire. Yet they kept on colonising. Of course, their colonies then attracted large numbers of those who were less well off. But it was wealth, power, and expansionism that set the ball rolling.
Furthermore, the image of the pampered American abroad is something of a fiction. Americans can be found not only in the cafes of Sydney and the pubs of London, but on the slopes of the Himalayas, the windswept plains of Mongolia, and the jungles of the Congo. Americans despite their well-comforted ways, managed to cope with the cramped conditions on a vessel to the moon and back. You won't see this adventurous side of Americans if you don't venture out of your own neigbourhood.
Rather than not being poor enough, the most likely impediment to America colonizing space is a lack of enthusiasm for imperialistic conquest. On the occasions the country has tried this, the results have been somewhat less than stellar.

links:
the space settlement FAQ

did life originate in outer space?

Organic compounds have been detected in the depths of the Milky Way galaxy. This is more evidence for the theory that life did not originate on earth. Instead, it is possible that the building blocks of life are spread throughout the universe. This theory is known as panspermia. (You can stop giggling now, it means "seeds everywhere").

Panspermia is an idea that has been around for centuries in various forms, but a recent version is that microbes are the fundamental form of life, and that they are widespread throughout the universe. Evidence for this comes from the near indestructibility of many kinds of microbes. They can be found deep in the ocean, in the freezing terrain of antarctica, and can even survive in space.
It seems a small step, then, to believe that they have travelled to other planets, perhaps on small rocks thrown up by a volcano, or from the impact of a large meteor or comet.

But if that is true, there is no reason that this is the planet where they began. If microbes really are the roving carriers of life, then we might be just another resting place on their journey through the furthest reaches of space.

If you want to believe that there are alien life forms out there that we will one day meet, then this theory gives you less solace than you might believe. It may be that complex life, such as that on Earth, is very rare occurrence. For example, it may happen once in every half a million star systems. If the universe is finite, and if and the probability of complex life is very small, then we might still be the only intelligent life in existence (a discussion of what it would mean for the universe to be finite will have to wait until another day). Alternatively, there may be intelligent species out there, but they may be "a long time ago in a galaxy far away." If so, they are forever unreachable.

what lies beyond

Toward the end of his life, philosopher A J Ayer, a towering intellect of the twentieth century, had a near-death experience, and renounced his lifelong atheism. He admitted publicly that he was no longer sure that there was no afterlife, but his private confession to the surgeon that saved his life was even stronger. He confided to the surgeon that he had "met the supreme being," but would not elaborate.
Last week, Daniel Dennett, author of such books as Consciousness Explained and Breaking the spell: religion as a natural phenomenon and who was recently described as a fundamentalist atheist, had a heart operation and a near-death experience. Friends of Dennett were eager to know whether, like Ayer, he had revised his beliefs. No, no, Dennett insisted, if anything his faith in medicine has simply grown stronger. However...
He now has a new-found affection for the expression Thank goodness. This is because, says Dennett, "There is a lot of goodness in this world, and more goodness every day..."
While he goes on to explain that he is still a confirmed atheist, he says of prayers from his friends:

What, though, do I say to those of my religious friends (and yes, I have quite a few religious friends) who have had the courage and honesty to tell me that they have been praying for me? I have gladly forgiven them

because he realises that that is their way of giving well-wishes.
Still, this newfound interest in goodness sounds to me like a subtle, but substantial, metaphysical shift in position. I would not expect a battle-scarred skeptic like Dennett to become an evangelising Southern Baptist overnight, even after a near-death experience. But I would like to be a fly on the wall next time he has dinner with old pal Richard Dawkins, and tries to explain what this strange new concept of "goodness" is all about.

In a slightly related vein, for some interesting thoughts on atheism from a non-atheist, read Frederick Turner's article, What's good about atheism. (Turner is also the author of several books including Natural Religion).

evolution explained

Scientific American has a nice point by point explanation of evolution, responding to creationist arguments.
Also on the evolution-creation argument, new discoveries have strengthened the case for evolution. Sharon Begley of the Wall Street Journal discusses a discovery of a fossil that seems to fit the criteria for being a answer to the well-known 'missing link' criticism:

paleontologists unveiled an answer: well-preserved fossils of a previously unknown fish that was on its way to evolving into a four-limbed land-dweller. It had a jaw, fins and scales like a fish, but a skull, neck, ribs and pectoral fin like the earliest limbed animals, called tetrapods.

Neil Shubin of the University of Chicago said that it is "both fish and tetrapod."
Creationists have argued that this new discovery doesn't satisfy them at all. It is simply the discovery of a new species. Where are the links between fish and this species, or between it and land-dwelling animals? Where is the evidence that it in fact led to new land-based species?
This, of course, uncovers the futility of the whole evolution-creation debate. Creationists complain that that there is no 'missing link.' But, in a bizarre variant of Zeno's paradox, whenever such a link is found, new links are called for to link the links, and new evidence demanded. Unless paleontologists unearth a fossil for every variant of every species that ever existed (which is impossible), missing links will abound- not because the theory is wrong, but because fossils are haphazard and rare.
The creationists have moved the goalposts after the goal is scored, and called 'No goal'. This situation really does expose the lie that the debate is one founded on empiricism or rationality.
The mapping of the chimpanzee genome was more than just a cause for champagne. It provided the opportunity for some very specific, new tests of evolution. Mutation rates are a cornerstone of evolutionary theory. Well, it turns out that evolution really needs mutations to occur at a certain rate in order to work properly. Once you know what the rate should be, you can calculate what proportion of mutations you should find for any particular population size. Now that the chimp genome is known, the mutation/population ratio could be examined. Would it be in keeping with the predictions of the theory of evolution? I know you're on the edge of your seat. Maybe evolution got proven wrong! No, when the numbers were crunched, the mutation rate was in proportion to the chimpanzee population size as predicted by the theory. So evolution passed again.
The response from creationists? None. This is because mathematical modelling is not on their radar. Compare the silence to the typical response you'd get from a rival camp of scientists. Imagine there are scientists who believe, not in evolution, but in a revamped Lamarkism. They would work around the clock to show that their own theory predicted exactly the same numbers. And for good measure, they'd show that Lamarkism predicted a whole bunch of other stuff. The gauntlet would be down. That's how rival scientific theories fight it out.
But evolution isn't up against a rival scientific theory. It's up against an anti-scientific theory that chooses, as one method of attack (but only one of many), to try to criticize science on its own terms. Productive scientific debate is not on the agenda.

does the past exist?

Recently I argued that time travel into the future just doesn't make sense, given a reasonably cogent understanding of what "the future" is. It may be that traveling into the past is just as absurd. Jason of Jason's tech blog poses a question:

what makes you think the past exists?
I mean, sure, we lived through it, and will agree on much of what occurred there, but why should it still exist once we’ve passed it? We can’t predict the future because of quantum uncertainty. That same uncertainty would make it impossible to “predict” (or reconstruct) the past, even given perfect current data (also impossible, due to quantum uncertainty).
In loose analogy with computer terms, where is the data written? The program ran, but what makes you think anyone saved the run? All the information in the universe is describing the present state of the universe. There isn’t room for the information of past states to exist.

The question does the past exist? is a snappy attention grabber, but it's not really at the heart of Jason's question. His point is that the past may be unrecoverable for the same reasons that that the future is unknowable: quantum uncertainty. To put it another way, we can't know the past because it doesn't exist any more.
I previously described the past as fixed, and the future as fluid, but if you can't know the past completely, then how fixed is it, really? Both future and past trail off to infinity with increasing uncertainty. And the future is at least partly knowable: I can tell you when the moon will rise in twenty years time, what the map of earth will look like (the same as it is today), and the approximate population of Tokyo. I can even guess some of the headlines of the day: "school leavers sit final exams", "election day approaching", "tragic murder in suburbia".
But the two differ in symmetry in certain interesting ways. For example, the law of entropy says that disorder has a directional slope from past to future. And from a human perspective, unless you are Gil Grissom investigating a crime scene or a historian reconstructing an ancient battle, you do not typically entertain multiple versions of the past in your mind. By contrast, we constantly juggle alternative scenarios of the future.
As with the future, we cannot know the past perfectly, but this does not mean it doesn't exist. Electrons exist in probability clouds, and we're happy to declare that electrons exist. The same applies to the past. To the extent to which it has form at all, it exists.

digging up the past

Syria:
French Archaeologists have found an 11 thousand year old building near Ja'de on the banks of the Euphrates river. The large size of the building suggests it was some kind of community building. There are multicolored geometrical paintings on the walls. Exactly what went on in this large hall is lost forever.
Cyprus:
British archaeologists have found 120 ancient stone anchors off the coast of Paphosin the eastern Mediterrainean Sea, originating from the bronze age (ie, 2500-1125BC). The most likely explanation is that the anchors are at a location where there was once a port. It seems that all that remains of the hopes, dreams, achievements and failures of an ancient society is a pile of anchors at the bottom of the sea.
Bulgaria:
A 4000 year old skull has been found in Bulgaria... with a perfectly shaped hole, leading to the conclusion that primitive brain surgery was conducted on the skull's owner. Sometime between the 3rd century BC and the twentieth century, the ability to conduct brain surgery was lost and rediscovered, as if for the first time.
Mexico:
Mexican archaeologists excavating in Mexico city hit a massive buried stone slab. As they unearthed it, they realised that it was a giant idol to the Aztec earth god, Tlaltecuhtli. While digging continues, speculation has risen that the slab may actually be a doorway to a long-forgotten chamber beneath an ancient temple.

These things remind me of that chilling poem by Percy Shelley, Ozymandias.

OZYMANDIAS of EGYPT
I met a traveller from an antique land
Who said:—Two vast and trunkless legs of stone
Stand in the desert. Near them on the sand,
Half sunk, a shatter'd visage lies, whose frown
And wrinkled lip and sneer of cold command
Tell that its sculptor well those passions read
Which yet survive, stamp'd on these lifeless things,
The hand that mock'd them and the heart that fed.
And on the pedestal these words appear:
"My name is Ozymandias, king of kings:
Look on my works, ye mighty, and despair!"
Nothing beside remains: round the decay
Of that colossal wreck, boundless and bare,
The lone and level sands stretch far away.

- Percy Shelly, 1818

dreaming of an apocalypse

There are certain ideas that tap into the deep primal currents of the human mind, ideas that simultaneously fascinate and appall. The end of the world is such an idea. Humanity lives and relives its own demise in endless variations through fantasy, fiction, science, religion, and prophecy.
In Revelation 20, a thousand-year period of prosperity is foretold. For this reason, people that focus on the imminent end of the world are sometimes called millenarists.
A nation where millenarial thinking is strongly embedded in the culture is South Africa. The obsession with the end of the world can lead to unhealthy trends in politics, as the people look for a great leader, a prophet, or other messianic figure. This is sometimes referred to as the Nongqawuse syndrome, after the tragic events of 1856 and 1857:

Then, a 16-year-old girl, Nongqawuse, had a vision on the banks of the Gxarha River. She saw the departed ancestors who told her that if people would but kill all their cattle, the dead would arise from the ashes and all the whites would be swept into the sea. The message was relayed to the Xhosa nation by her uncle, Mhalakaza. Although deeply divided over what to do, the Xhosa began killing their cattle in February 1856. They destroyed all their food and did not sow crops for the future. Stored grain was thrown away. No further work was to be done. Days passed and nights fell. The resurrection of the dead Xhosa warriors never took place.

The result was starvation and death on a collossal scale.
It might beggar belief that an entire nation could become so enthralled with the visions of a teenage girl that they could destroy their livelihood. However, such scenarios have been replayed time and again since those events. Perhaps the best known incident is the tragedy of Heavens Gate and the Order of the Solar Temple, otherwise known as Jonestown. Even among the general public, we have had a string of disaster scenarios take hold of the public imagination, including a best-seller in the 1980's called "The great depression of 1990", Time Magazine's cover story in the 70's about "the coming ice age," the threat of total destruction from plutonium in space launches, AIDS, SARS, ebola, bird flu, nuclear winter, the 'population bomb', black holes, and my personal favorite (because I was totally sucked in), the Y2K "millenium" bug.
Global warming is the latest threat to our survival. While I do not intend to question the science or the reality that the Earth is warming, I wonder if the more extreme predictions of impending doom and destruction are driven partly by our need to indulge in millenarial thinking.
Of course, catastrophes do happen. Europe's population was halved by the bubonic plague. American Indian populations were virtually wiped out by the arrival of Europeans (although, unlike the Aztecs, the biggest killer of the indians was the introduction of European diseases for which they had no immunity). And the dinosoars met their demise when a giant meteor crashed into Siberia and spewed massive amounts of pollution into the atmosphere. Yes, species and civilisations do meet their demise - in the long run, it is inevitable. The price of survival is eternal vigilance. However, as South Africa shows, apocalyptic predictions can become a destructive obsession that, in the worst case, can become a self-fulfilling prophecy.

other links:
cranky professor
The Dead Will Arise: Nongqawuse and the Great Xhosa Cattle-Killing Movement of 1856-7