Part I: Lost In the Cosmos
1: How to Build a Universe
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Although Penzias and Wilson had not been looking for cosmic background radiation, didn’t know what it was when they had found it, and hadn’t described or interpreted its character in any paper, they received the 1978 Nobel Prize in physics. The Princeton researchers got only sympathy. According to Dennis Overbye in Lonely Hearts of the Cosmos, neither Penzias nor Wilson altogether understood the significance of what they had found until they read about it in the New York Times.
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Rather, space curves, in a way that allows it to be boundless but finite.
Part IV: Dangerous Planet
15: Dangerous Beauty
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The event, it is thought, may have carried humans right to the brink of extinction, reducing the global population to no more than a few thousand individuals.
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That means that all modern humans arose from a very small population base, which would explain our lack of genetic diversity. At all events, there is some evidence to suggest that for the next twenty thousand years the total number of people on Earth was never more than a few thousand at any time.
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“But the thing is, most of the time bad things don’t happen. Rocks don’t fall. Earthquakes don’t occur. New vents don’t suddenly open up. For all the instability, it’s mostly remarkably and amazingly tranquil.”
Part V: Life Itself
16: Lonely Planet
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If Earth were perfectly smooth, it would be covered everywhere with water to a depth of four kilometers.
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The Moon’s steady gravitational influence keeps the Earth spinning at the right speed and angle to provide the sort of stability necessary for the long and successful development of life. This won’t go on forever. The Moon is slipping from our grasp at a rate of about 1.5 inches a year. In another two billion years it will have receded so far that it won’t keep us steady and we will have to come up with some other solution, but in the meantime you should think of it as much more than just a pleasant feature in the night sky.
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As you might expect, oxygen is our most abundant element, accounting for just under 50 percent of the Earth’s crust, but after that the relative abundances are often surprising.
17: Into the Troposphere
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Certainly there is no shortage of energy in the world above our heads. One thunderstorm, it has been calculated, can contain an amount of energy equivalent to four days’ use of electricity for the whole United States.
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Jet streams, usually located about 30,000 to 35,000 feet up, can bowl along at up to 180 miles an hour and vastly influence weather systems over whole continents, yet their existence wasn’t suspected until pilots began to fly into them during the Second World War.
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A form of wave motion popularly known as clear- air turbulence occasionally enlivens airplane flights.
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Low- pressure systems are created by rising air, which conveys water molecules into the sky, forming clouds and eventually rain.
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Warm air can hold more moisture than cool air, which is why tropical and summer storms tend to be the heaviest.
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The greatest supercomputer in the world, taking measurements in the most carefully controlled environment, cannot tell you what forms these ripplings will take, so you can imagine the difficulties that confront meteorologists when they try to predict such motions in a spinning, windy, large- scale world.
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What we do know is that because heat from the Sun is unevenly distributed, differences in air pressure arise on the planet. Air can’t abide this, so it rushes around trying to equalize things everywhere. Wind is simply the air’s way of trying to keep things in balance.
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A tropical hurricane can release in twenty- four hours as much energy as a rich, medium- sized nation like Britain or France uses in a year.
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Incidentally, the first, much thinner edition of that atlas, produced in 1896, divided clouds into ten basic types, of which the plumpest and most cushiony- looking was number nine, cumulonimbus.*
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That seems to have been the source of the expression “to be on cloud nine.”
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A fluffy summer cumulus several hundred yards to a side may contain no more than twenty- five or thirty gallons of water—“ about enough to fill a bathtub,” as James Trefil has noted.
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You can get some sense of the immaterial quality of clouds by strolling through fog— which is, after all, nothing more than a cloud that lacks the will to fly.
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Water is marvelous at holding and transporting heat. Every day, the Gulf Stream carries an amount of heat to Europe equivalent to the world’s output of coal for ten years, which is why Britain and Ireland have such mild winters compared with Canada and Russia.
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But water also warms slowly, which is why lakes and swimming pools are cold even on the hottest days. For that reason there tends to be a lag in the official, astronomical start of a season and the actual feeling that that season has started. So spring may officially start in the northern hemisphere in March, but it doesn’t feel like it in most places until April at the very earliest.
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The main agent of heat transfer on Earth is what is known as thermohaline circulation, which originates in slow, deep currents far below the surface— a process first detected by the scientist- adventurer Count von Rumford in 1797.†
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It is remarkable, when you behold an extraordinary natural feature like the White Cliffs of Dover in England, to reflect that it is made up of nothing but tiny deceased marine organisms, but even more remarkable when you realize how much carbon they cumulatively sequester. A
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The fear is that there would be a runaway increase in the Earth’s warming. Unable to adapt, many trees and other plants would die, releasing their stores of carbon and adding to the problem. Such cycles have occasionally happened in the distant past even without a human contribution.
18: The Bounding Main
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Water is strange stuff. It is formless and transparent, and yet we long to be beside it. It has no taste and yet we love the taste of it. We will travel great distances and pay small fortunes to see it in sunshine. And even though we know it is dangerous and drowns tens of thousands of people every year, we can’t wait to frolic in it.
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Thankfully for us, water seems unaware of the rules of chemistry or laws of physics.
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At any given moment only 15 percent of them are actually touching.
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Deprived of water, the human body rapidly falls apart. Within days, the lips vanish “as if amputated, the gums blacken, the nose withers to half its length, and the skin so contracts around the eyes as to prevent blinking.”
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proportions of these salts and minerals in our tissues is uncannily similar to seawater— we sweat and cry seawater, as Margulis and Sagan have put it— but curiously we cannot tolerate them as an input.
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In extreme situations, dehydration will lead to seizures, unconsciousness, and brain damage.
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There are 320 million cubic miles of water on Earth and that is all we’re ever going to get. The system is closed: practically speaking, nothing can be added or subtracted.
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The water you drink has been around doing its job since the Earth was young. By 3.8 billion years ago, the oceans had (at least more or less) achieved their present volumes.
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The average depth of the ocean is 2.4 miles, with the Pacific on average about a thousand feet deeper than the Atlantic and Indian Oceans.
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It took just under four hours to fall 35,820 feet, or almost seven miles. Although the pressure at that depth was nearly 17,000 pounds per square inch, they noticed with surprise that they disturbed a bottom- dwelling flatfish just as they touched down. They had no facilities for taking photographs, so there is no visual record of the event. After just twenty minutes at the world’s deepest point, they returned to the surface. It was the only occasion on which human beings have gone so deep. Forty
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Eventually, not to say improbably, Alvin was constructed by General Mills, the food company, at a factory where it made the machines to produce breakfast cereals.
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The process is not swift— it can take up to ten million years to clean an ocean— but it is marvelously efficient as long as you are not in a hurry.
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For every pound of shrimp harvested, about four pounds of fish and other marine creatures are destroyed.
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Large areas of the North Sea floor are dragged clean by beam trawlers as many as seven times a year, a degree of disturbance that no ecosystem can withstand.
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Despite declining catches, New England fishermen continue to receive state and federal tax incentives that encourage them— in some cases all but compel them— to acquire bigger boats and to harvest the seas more intensively.
19: The Rise of Life
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As Margulis and Sagan note, photosynthesis is “undoubtedly the most important single metabolic innovation in the history of life on the planet”— and it was invented not by plants but by bacteria.
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Others did likewise but then later (much later) migrated to the digestive tracts of beings like you and me.
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One reason life took so long to grow complex was that the world had to wait until the simpler organisms had oxygenated the atmosphere sufficiently.
20: Small World
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In fact, there is no point in trying to hide from your bacteria, for they are on and around you always, in numbers you can’t conceive.
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If the estimates are correct, there could be more life under the Earth than on top of it.
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Instead they grow directly on their food source, which can be almost anything. Fungi will eat the sulfur off a concrete wall or the decaying matter between your toes— two things no plant will do.
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If Woese’s new arrangement teaches us anything it is that life really is various and that most of that variety is small, unicellular, and unfamiliar.
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Most of the real diversity in evolution has been small- scale.
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This is why so many grade- A diseases— malaria, yellow fever, dengue fever, encephalitis, and a hundred or so other less celebrated but often rapacious maladies— begin with a mosquito bite.
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A great deal of sickness arises not because of what the organism has done to you but what your body is trying to do to the organism.
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We would have much more success with bacteria if we weren’t so profligate with our best weapon against them: antibiotics.
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Remarkably, by one estimate some 70 percent of the antibiotics used in the developed world are given to farm animals, often routinely in stock feed, simply to promote growth or as a precaution against infection.
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Such applications give bacteria every opportunity to evolve a resistance to them. It is an opportunity that they have enthusiastically seized.
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As James Surowiecki has noted, given a choice between developing antibiotics that people will take every day for two weeks or antidepressants that people will take every day forever, drug companies not surprisingly opt for the latter.
21: Life Goes On
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IT ISN’T EASY to become a fossil. The fate of nearly all living organisms— over 99.9 percent of them— is to compost down to nothingness.
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Even if you make it into the small pool of organisms, the less than 0.1 percent, that don’t get devoured, the chances of being fossilized are very small.
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Fossils are in every sense vanishingly rare. Most of what has lived on Earth has left behind no record at all.
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estimated that less than one species in ten thousand has made it into the fossil record.
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The fossil record consequently is almost absurdly biased in favor of marine creatures.
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About 95 percent of all the fossils we possess are of animals that once lived under water, mostly in shallow seas.
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Life: An Unauthorised Biography,
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“The history of life,” wrote Gould, “is a story of massive removal followed by differentiation within a few surviving stocks, not the conventional tale of steadily increasing excellence, complexity, and diversity.”
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Evolutionary success, it appeared, was a lottery.
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With the exception of jellyfish, all animals today are triploblastic.
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Nor is it agreed that the Ediacaran organisms are in any way ancestral to anything alive today (except possibly some jellyfish).
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It is one thing to have one well- formed creature like a trilobite burst forth in isolation— that really is a wonder— but to have many of them, all distinct but clearly related, turning up simultaneously in the fossil record in places as far apart as China and New York clearly suggests that we are missing a big part of their history. There could be no stronger evidence that they simply had to have a forebear— some grandfather species that started the line in a much earlier past.
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And the reason we haven’t found these earlier species, it is now thought, is that they were too tiny to be preserved.
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“The Cambrian explosion, if that’s the word for it, probably was more an increase in size than a sudden appearance of new body types,”
22: Good-bye to All That
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“They simply exist,” Attenborough adds, “testifying to the moving fact that life even at its simplest level occurs, apparently, just for its own sake.”
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It is easy to overlook this thought that life just is. As humans we are inclined to feel that life must have a point.
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But— and here’s an interesting point— for the most part it doesn’t want to be much.
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If you imagine the 4.5 billion odd years of Earth’s history compressed into a normal earthly day, then life begins very early, about 4 A.M., with the rise of the first simple, single- celled organisms, but then advances no further for the next sixteen hours. Not until almost 8: 30 in the evening, with the day five- sixths over, has Earth anything to show the universe but a restless skin of microbes. Then, finally, the first sea plants appear, followed twenty minutes later by the first jellyfish and the enigmatic Ediacaran fauna first seen by Reginald Sprigg in Australia. At 9: 04 P.M. trilobites swim onto the scene, followed more or less immediately by the shapely creatures of the Burgess Shale. Just before 10 P.M. plants
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begin to pop up on the land. Soon after, with less than two hours left in the day, the first land creatures follow.
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Thanks to ten minutes or so of balmy weather, by 10: 24 the Earth is covered in the great carboniferous forests whose residues give us all our coal, and the first winged insects are evident. Dinosaurs plod onto the scene just before 11 P.M. and hold sway for about three- quarters of an hour. At twenty- one minutes to midnight they vanish and the age of mammals begins. Humans emerge one minute and seventeen seconds before midnight. The whole of our recorded history, on this scale, would be no more than a few seconds, a single human lifetime barely an instant. Throughout this greatly speeded- up day continents slide about and bang together at a clip that seems positively reckless. Mountains rise and melt away, ocean basins come and go, ice sheets advance and withdraw. And throughout the whole, about three times every minute, somewhere on the planet there is a flashbulb pop of light marking the impact of a Manson- sized meteor or one even larger. It’s a wonder that anything at all can survive in such a pummeled and unsettled environment. In fact, not many things do for long.
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Fortunately, that moment hasn’t happened, but the chances are good that it will. I don’t wish to interject a note of gloom just at this point, but the fact is that there is one other extremely pertinent quality about life on Earth: it goes extinct.
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Quite regularly. For all the trouble they take to assemble and preserve themselves, species crumple and die remarkably routinely. And the more complex they get, the more quickly they appear to go extinct. Which is perhaps one reason why so much of life isn’t terribly ambitious.
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On the other hand, there was a powerful incentive to leave the water: it was getting dangerous down there.
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There was also an omnivorous and unsettling new type of predator on the scene, one so perfectly designed for attack that it has scarcely changed in all the long eons since its emergence: the shark.
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Most animals are tetrapods, and all living tetrapods have one thing in common: four limbs that end in a maximum of five fingers or toes. Dinosaurs, whales, birds, humans, even fish— all are tetrapods, which clearly suggests they come from a single common ancestor.
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The best- known animal of this age was the Dimetrodon, a sail- backed creature that is commonly confused with dinosaurs
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Anapsids gave rise to the turtles, which for a time, perhaps a touch improbably, appeared poised to predominate as the planet’s most advanced and deadly species, before an evolutionary lurch let them settle for durability rather than dominance. The synapsids divided into four streams, only one of which survived beyond the Permian. Happily, that was the stream we belonged to,
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Each of these massive transformations, as well as many smaller ones between and since, was dependent on that paradoxically important motor of progress: extinction.
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Whatever the actual total, 99.99 percent of all species that have ever lived are no longer with us.
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For complex organisms, the average lifespan of a species is only about four million years— roughly about where we are now.
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In the Permian, at least 95 percent of animals known from the fossil record check out, never to return. Even about a third of insect species went— the only occasion on which they were lost en masse. It is as close as we have ever come to total obliteration.
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The Permian event was particularly devastating to sea creatures.
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Grazing animals, including horses, were nearly wiped out in the Hemphillian event about five million years ago. Horses declined to a single species, which appears so sporadically in the fossil record as to suggest that for a time it teetered on the brink of oblivion. Imagine a human history without horses, without grazing animals.
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Moreover, and rather chillingly, according to Bruce Tsurutani of the NASA Jet Propulsion Laboratory, “it would leave no trace in history.”
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One of the reasons it is so hard to produce convincing explanations for extinctions is that it is so very hard to exterminate life on a grand scale.
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Well, first it was positively enormous. It struck with the force of 100 million megatons. Such an outburst is not easily imagined, but as James Lawrence Powell has pointed out, if you exploded one Hiroshima- sized bomb for every person alive on earth today you would still be about a billion bombs short of the size of the KT impact.
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The result was an impact that turned an area of seafloor the size of Belgium into aerosols of sulfuric acid. For months afterward, the Earth was subjected to rains acid enough to burn skin.
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Extinctions seem to have been far less severe in the southern hemisphere than the northern.
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Clearly it helped to be at home in water.
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The KT impact wiped out almost 90 percent of land- based species but only 10 percent of those living in fresh water.
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But once they got going, mammals expanded prodigiously— sometimes to an almost preposterous degree.
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Its family survived in formidable fashion for fifty million years, yet until a skeleton was discovered in Florida in 1963, we had no idea that it had ever existed.
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We are so used to the notion of our own inevitability as life’s dominant species that it is hard to grasp that we are here only because of timely extraterrestrial bangs and other random flukes. The one thing we have in common with all other living things is that for nearly four billion years our ancestors have managed to slip through a series of closing doors every time we needed them
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Stephen Jay Gould expressed it succinctly in a well- known line: “Humans are here today because our particular line never fractured— never once at any of the billion points that could have erased us from history.”
23: The Richness of Being
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The “maidenhair” in maidenhair moss, for instance, does not refer to the hair on the maiden’s head.
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Priapulida (or little “penis worms”).
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Even now nearly a quarter of all prescribed medicines are derived from just forty plants, with another 16 percent coming from animals or microbes, so there is a serious risk with every hectare of forest felled of losing medically vital possibilities.
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compounds at a time in labs, but these products are random and not uncommonly useless, whereas any natural molecule will have already passed what the Economist calls “the ultimate screening programme: over three and a half billion years of evolution.”