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by William H. Benson

September 3, 2009

     Over the eons, our planet, Earth, has staggered violently between centuries of sweltering heat or brutal chill. Cycles of global cooling followed by global warming have been the predominant pattern of Earth’s geological history. The last Ice Age began to end only about twelve thousand years ago, but at its peak, around twenty thousand years ago, about 30 percent of the Earth’s land surface was under ice, whereas today it is 10 percent. 

     The Wisconsian ice sheet covered much of Europe and North America then, and in certain places was half a mile thick. Standing at its leading point, a person would have gaped in astonishment at a towering wall of glacial ice over two thousand feet high, and life in any form atop those millions of square miles of ice had to have been a struggle.

     The size of the Great Lakes and Hudson’s Bay, as well as the thousands of lakes spread across Canada and Minnesota are evidence that those glaciers were indeed colossal. That it is today water and not ice is a fact that we owe to “global warming.”

     Bill Bryson suggested in his 2003 book, A Short History of Nearly Everything, “that ice will be a long-term part of our future.” Ice, rather than global warming.

     What causes an Ice Age and what reverses it are largely unknowns, even though theories abound, such as that the ellipsis that the Earth follows around the sun changes shape, or that the pitch of the orientation of the Earth to the sun wobbles.

     What is most astonishing is that on this, at times, bitter cold planet, life began, and, according to Bryson, “it happened just once. That is the most extraordinary fact in biology, perhaps the most extraordinary fact we know.”

     Matt Ridley, a biologist, said that, “Wherever you go in the world, whatever animal, plant, bug, or blob you look at, if it is alive, it will use the same dictionary and know the same code. All life is one.” And life’s beginning happened a long time ago.

     A hundred years ago this week, early in September of 1909, at the end of the fossil-finding season, an American paleontologist named Charles Doolittle Walcott stumbled upon the Burgess Shelf 8,000 feet high in the mountains of British Columbia, above timberline in steep country, a hundred miles west of Calgary.

     His was an extraordinary and quite lucky find, for the fossils he found that day were later determined to be extremely ancient, from about 540 million years ago, and originated from what is called the Cambrian Explosion, when life was then quite young.

     The fossils were imprinted upon shale rock, and he noted that they were “bizarrely different,” for there were animals with five eyes, others that were shaped like a pineapple slice, and even others with stilt-like legs. Animal life, it seemed to Walcott, was then exuberant and daring, trying out all kinds of forms, and experimenting,

     The Burgess Shale, wrote Stephen Jay Gould in his popular book Wonderful Life, was “our sole vista upon the inception of modern life in all its fullness.”

     However, the fossils that Walcott found were of the small and innocent-looking variety, such as minute oceanic crabs, but life moved on, drifting toward the big, mean, and fierce variety, the dinosaurs, which ruled the Earth, in a multiple number of forms, for millions of years, while the cycles of hot and cold raged on about them.

     And then, about 65 million years ago, the dinosaurs and about half the world’s species were obliterated, it is believed, by the devastation following an asteroid or a comet striking the Earth, and allowing our age, the Age of Mammals, thus a chance to begin.

     Based upon all of this, Bryson suggested four points: “Life wants to be; life does not always want to be much; life goes on; and life from time to time goes extinct.”

     “It is a curious fact,” wrote Bryson, “that on Earth, species death is, in the most literal sense, a way of life.” Of all the species of life forms that have every lived—an estimated thirty billion to perhaps as many as 4,000 billion—99.99 percent are now extinct. “To a first approximation,” said David Raup at Chicago University, “all species are extinct.”

     The environment’s conditions may change—from glacial ice to burning desert sand, from a sea to a high mountain range, from a temperate climate to a cold and inhospitable one—and yet life continues everywhere on planet Earth, undaunted and daring to be.