The Sixth Extinction (10th Anniversary Edition): An Unnatural History

The Sixth ExtinctionI didn’t rush to read Elizabeth Kolbert’s book, The Sixth Extinction, because I imagined it would be a gloomy expose on the unfortunate consequences of way too much half-baked cleverness — and it was. But it’s also a fascinating story about the long saga of life on Earth, and the unclever antics of the latest primate species. It’s an outstanding book.We have soared away into a fantasy world, where godlike humans spend their lives creating brilliant miracles. But when observed in a 450 million year timeframe, from this moment when a new mass extinction is gathering momentum, the wonders of progress and technological innovation lose their shine. Kolbert rips off our virtual reality headsets, and serves us powerful medicine, a feast of provocative news.Today, the frog people are not feeling lucky. They have lived on this sweet planet for 400 million years, but many are now dying, because of a fungus called Bd. This fungus can live happily in the forest on its own, without an amphibian host, so endangered frogs rescued by scientists cannot be returned to the wild. The crisis began when humans transported frogs that carried the fungus, but were immune to it. There was money to be made in the frog business, and so the fungus has spread around the globe.This is similar to the chestnut blight of a century ago. Entrepreneurs profitably imported chestnut seedlings from Asia. The Asian species was immune to the fungus it carried. American chestnut trees were not immune, and four billion died, almost all of them. The fungus persists, so replanting is pointless.North American bats are dying by the millions from white-nose, caused by fungus that is common in Europe, where bats are immune to it. It was likely carried across the Atlantic by a tourist who dropped some spores in Howe Caverns, in New York. By 2013, the die-off had spread to 22 U.S. states and five Canadian provinces.Welcome to New Pangaea! Once upon a time, long before we were born, all seven continents were joined together in a single continent, Pangaea. Over time, it broke apart, and ecosystems on each continent evolved in a unique way. In recent centuries, highly mobile humans have moved countless organisms from one ecosystem to another, both deliberately and unintentionally. The seven continents no longer enjoy the long-term stability provided by isolation.On another front, many colonies of humans have become obsessed with burning sequestered carbon on an enormous scale. This is overloading the atmosphere with carbon, which the oceans absorb and convert to carbonic acid. Carbonic acid is a huge threat to marine life, except for lucky critters, like jellyfish. The world’s coral reefs are dying.Tropical rainforests are treasure chests of biological diversity. Tropical oceans generally are not, because of low levels of nutrients like nitrogen and phosphorus. Coral reefs are the shining exception. They provide habitat for thriving ecosystems, home to more than 500,000 species. This reminded me of beaver ponds, which are also sanctuaries of abundant life.Coral polyps and beavers are excellent examples of reciprocity. They create relationships that are mutually beneficial for many species. Reciprocity is a vital idea that most human cultures have forgotten. Our dominant culture has no respect for the wellbeing of ecosystems. It has a tradition of displacing or exterminating the indigenous species on the land, and replacing them with unsustainable manmade systems.Evolution is fascinating. Rabbits and mice have numerous offspring, because they are vulnerable to predators. Other species have deflected the predator challenge by evolving to great size, like mammoths, hippos, and rhinos. Big critters have long lifespans and low birth rates. This made them highly vulnerable when Homo sapiens moved into the neighborhood.Kolbert imagines that the megafauna extinctions were not the result of a reckless orgy of overhunting. It probably took centuries. Hunters had no way of knowing how much the mammoth population had gradually dwindled over the generations. Because they reproduced so slowly, they could have been driven to extinction by nothing more than modest levels of hunting. An elephant does not reach sexual maturity until its teens, and each pregnancy takes 22 months. There are never twins. Deer are still with us, because they reproduce faster.Sadly, Neanderthals are no longer with us. They lived in Europe for at least 100,000 years, and during that time, their tool collection barely changed. They probably never used projectiles. They have acquired a reputation for being notorious dimwits, because they lived in a stable manner for a very long time, and didn’t rubbish the ecosystem. Homo sapiens moved into Europe 40,000 years ago. By 30,000 years ago, the Neanderthals were gone. The DNA of modern folks, except Africans, contains up to four percent Neanderthal genes.Homo sapiens has lived in a far more intense manner. In the last 10,000 years, we’ve turned the planet inside out. Kolbert wonders if there was a slight shift in our DNA that made us so unstable — a “madness gene.” I wonder if we’re simply the victims of cultural evolution that hurled us down a terrible path. If we had been raised in Neanderthal clans, would we be stable, sane, and happy?Kolbert laments, “The Neanderthals lived in Europe for more than a hundred thousand years and during that period they had no more impact on their surroundings than any other large vertebrate. There is every reason to believe that if humans had not arrived on the scene, the Neanderthals would be there still, along with the wild horses and wooly rhinos.”Cultures have an amazing ability to put chains on our mental powers. Kolbert describes how scientists (and all humans) typically struggle with disruptive information, concepts that bounce off our sacred myths. Bizarre new ideas, like evolution, extinction, or climate change, are reflexively dismissed as nonsense. As evidence of reality accumulates, increasing levels of absurd rationalizations must be invented. Eventually, someone actually acknowledges reality, and a paradigm shift is born.For most of my life, human extinction has not been on my radar. By the end of Kolbert’s book, readers understand that our extinction is more than a remote, theoretical possibility. What is absolutely certain is that we are pounding the planet to pieces. Everything is connected, and when one type of tree goes extinct, so do the insects that depend on it, as well as the birds that depend on the insects. When the coral polyps die, the coral reef ecosystem disintegrates.The sixth mass extinction is clearly the result of human activities. The driving forces include the things we consider to be our great achievements — agriculture, civilization, industry, transportation systems. This is highly disruptive information, and everyone is working like crazy to rationalize our nightmares out of existence. Luckily, a number of people, like Kolbert, are beginning to acknowledge reality. Will there be a paradigm shift? Will we walk away from our great achievements, and spend the next 100,000 years living in balance with the planet?

Extinctions happen, Elizabeth Kolbert tells us. There have been five major extinctions, each brought about by one cause or another. Different causes, like climate change, for instance. Or volcanism, manifested by the Siberian Traps and the Deccan Traps. And the bolide impact at Chixchalub, which wiped out all non-avian dinosaurs and numerous other life forms. Catastrophic events that eradicated millions of species over half a billion years. None of it man made. But in the blink of a eye in geological time, humans have been a major force in extinctions, directly or indirectly.Kolbert details the recent rapid demise of toads and frogs in various places around the globe. Turns out it's caused by a fungus. A similar situation, also involving a fungus, is killing off huge numbers of bats in various locations. The fungi travel globally via modern human transportation means, like ships and airplanes. Humans encroach on some species environments by cutting down forests and replacing them with crops and livestock. And we deliberately kill off every last member of a species. Elizabeth doesn't mention the demise of bison in America, which once thundered across our plains sixty million strong. They were killed, often for sport, until only a couple of hundred survived, before laws protected them. And the passenger pigeons, so numerous that a flock of them passing overhead in America took more than an hour to complete a flyover, with millions of birds. The last of them, a female named Martha, died in an American zoo over a century ago.Invasive species are taking over environments and displacing native species. Kolbert discusses the zebra mussel in this regard. But there are so many more examples. Like the pythons that escaped a pet store in south Florida due to Hurricane Andrew and took up residences in the Everglades. By now there are tens of thousands of them, and they are wiping out native animals there.She talks about climate change and its destructive effects on wildlife. It's evil twin is ocean acidification. The pH of ocean water is about 8.2, slightly alkaline. But the pH is dropping, to 8.1, and near thermal vents down to below 8.0. Some species can handle this. Some cannot, like the calcified, animals that use calcium for their structures. Like sea urchins, starfish, limpits, barnacles, for instance.She is big on diversity. We're losing it, she says. But are we? What she doesn't cover is speciation, the opposite of loss of species. I direct her attention to Lake Victoria in Africa, the world's largest tropical lake. In it reside some 500 species of cichlid fish. They maintain their separation by species through different shapes and color patterns and size, and by feeding habits and water depth.She maintains that when humans start inhabiting places where no people ever lived, many native species die off. Like in Madagascar some two thousand years ago when humans first got to the island. In a couple of hundred years the large bird, twice the size of an ostrich, was gone. So too the huge lemur, the size of a gorilla. The same thing happened to animals, especially large one, when humans got to Australia, over fifty thousand years ago. And in New Zealand when people got there a thousand or so years ago. North America too saw it happen when humans from Siberia came across the Bering land bridge about sixteen thousand years ago. Within a few thousand years at most the large animals were wiped out, like the ground sloth, mammoth, mastodon, cave bear, dire wolf, saber tooth cats, among others.The book is a must read.