The Sixth Extinction: An Unnatural History by Elizabeth Kolbert (2014)

Back in the late 1980s and 1990s there was a fashion for popular science books, and I read as many as I could, becoming better informed about the three major subjects which dominated the lists – cosmology, paleontology with an emphasis on human origins, and environmental biology.

Among them were a number of books by E.O. Wilson, particularly the brilliant Diversity of Life (1992), which gives an unparalleled sense of the wonder and diversity of the natural world, and Richard Leakey’s book, The Sixth Extinction (1995). This latter is an often quite technical account of discoveries and debates in paleontology and environmental biology which, taken together, suggest that the rate at which humanity is killing off species of animals, plants, fish and other fauna amounts to a holocaust, a global extermination, which ranks with the other Big Five mass extinction events that have punctuated the 500-million year story of life on earth – hence the title.

Now, 20 years later, comes a book with the same title by American journalist Elizabeth Kolbert. I was interested to compare the books, not only in terms of what’s changed in our understanding and the plight of nature, but in style and approach.

The situation’s got worse, of course. One third of all reef-building corals, a third of all fresh-water molluscs, a third of sharks and rays, a quarter of all mammals, a fifth of reptiles and a sixth of all birds are headed towards extinction. (p.17) (The radio news today informs me that 7 honey bees have placed on the US endangered species list, as colony collapse disorder continues to decimate hives.)

Kolbert approaches the issue through thirteen chapters, each devoted to a specific species, combining its history, her personal trips and visits to museums or rainforests, along with profiles of key contributors to the history of ecology, and ideas in evolution or conservation thrown up by each story.

The chapters

Thus she opens by visiting a research institute in Panama devoted to trying to save the Panamanian golden frog (Atelopus zeteki). It explains how the fungus Batrachochrytium dendrobatadis is wiping it out, along with scores of other frog species around the world – and so the chapter introduces and explains the notion of the historic mass extinctions.

The second chapter considers discoveries in the 1700s of large bones in America and Europe, specifically of what came to be named Mammut americanum, and how it led the French naturalist George Cuvier to develop and publish a theory of species being wiped out in sudden catastrophes (in an essay published in 1812) although the term ‘catastrophist’ (someone who believes the history of life on earth is marked by long periods of stasis broken by sudden catastrophes in which entire faunas are wiped out and entire new ones replace them) wasn’t coined until 1832, by William Whewell, president of the British Geological Society.

Kolbert contrasts Cuvier’s catastrophism with the ‘uniformitarianism’ of the great geologist Charles Lyell, whose epic work on geology inspired and underpins Darwin’s thinking. It was Lyell who for the first time gave a thorough sense of the profound age of the earth and showed how it had been formed over hundreds of millions of years by slow unrelenting forces. It was this rhythm and metaphor which helped the young Darwin grope his way towards a theory that life on earth had also changed in a slow but unrelenting way due to the process he called ‘natural selection’. The key to both is a nice steady uniform speed of geological and biological processes.

We learn this in chapter three, where it is tied into the history of the great auk (Pinguinis impennis) which went extinct in the 1840s. Kolbert takes a trip to Iceland to visit a nature centre and then go by boat out to the remote island where, supposedly, the last breeding pair of great auks were caught and killed before being sold for £9. This chapter is used to point out that Darwin must have known about man-made extinctions because he witnessed them wherever he went on his epic voyage round the world in HMS Beagle (1831-36).

Chapter four tells the story of Luis Alvarez’s discovery of a layer of iridium at the geological boundary between the Cretaceous and Tertiary periods, the so-called Cretaceous–Tertiary (K-T) boundary about 66 million years ago. Along with other scientists he interpreted this as meaning that the end-Cretaceous extinction, which saw about 70% of species wiped out, was caused by an asteroid or meteorite hitting earth. This chapter recounts the fierce opposition from most paleontologists who were wedded to one form or another of Lyell and Darwin’s uniformitarianism, and so harshly criticised Alvarez’s findings when they were published in 1980. As usual, Kolbert ties this account into a trip she took with paleontologists to a secret location in New Jersey where the K-T boundary is easily accessible and where they hunt for ammonite fossils.

Chapter five explains how ‘neo-catastrophism’ has become the new orthodoxy – i.e. that long periods of uniformity punctuated by disasters, have shaped the story of life and the nature of the current biosphere. This is told via a visit to Dobb’s Lyn, a mountainside stream in Scotland in heavy rain to look for glyptolites, followed by a warm dinner at a local B&B. Here the fossil hunters accompanying Kolbert explain the history of the term ‘Anthropocene’, first suggested in 2000 and now widely used.

Just as organisms are divided into kingdoms, phyla, families, genera and species, so geologists divide the entire history of the earth into eons, themselves divided into eras, which are in turn divided into periods, epochs and ages. Thus we are in the the Phanerozoic Eon, which dates from the beginning of multicellular life some 530 million years ago. This eon is divided into three eras: the Paleozoic Era, the Mesozoic Era and the Cenozoic Era, where ‘zoe’ is Greek for ‘life’ and paleo means old (Old Life Era), meso means ‘middle (Middle Life era) and ceno is from ‘koinos’ which means new = new life era.

Each of these eras is sub-divided into periods: the Paleozoic into the Cambrian Period, Ordovician Period, Silurian Period, Devonian Period, Carboniferous Period and Permian Period; the Mesozoic into the Triassic Period, Jurassic Period and Cretaceous Period; and the Cenozoic Era into the Paleogene Period, the Neogene Period and the Quaternary Period. And these periods are further divided into epochs: thus the most recent period, the Quaternary Period, is sub-divided into the Pleistocene and Holocene epochs, the Pleistocene dated 3 million years ago to around 13,000 years ago i.e. until the end of the last ice age; the Holocene dating from around 13,000 years ago to the present day.

Over the last twenty years or so there have been growing calls from some biologists, paleontologists and archaeologists to define the epoch we’re living in as a new geological epoch, the Anthropocene epoch, because human interaction with the environment is creating unprecedented changes to the entire planet.

I already knew from books and articles about the calls for our age to be named the Anthropocene – but I had never properly processed the full implications of the fact that, not only are we driving species instinct at an unprecedented rate now, in the present – but that all future life on earth will only be able to evolve and cope with changing conditions, from the smaller and smaller and smaller starting base that we are creating. It is not just the present or our children’s world that we are diminishing – but all future possibilities for life on the planet – forever.

Right now, in the amazing moment that to us counts as the present, we are deciding, without quite meaning to, which evolutionary pathways will remain open and which will be forever closed. No other creature has ever managed this, and it will, unfortunately, be our most enduring legacy. (p.269)

I had never grasped the deep historical implications of our greed and arrogance and destructiveness.

Chapter six records Kolbert’s trip to Kastello Aragonese, an islet near Ischia. The island is home to volcanic vents which release a steady stream of CO2 into the sea. Kolbert meets scientists who are researching the impact of rising CO2 levels in seawater: basically it prevents calcifiers, that is all animals which create shells, from being able to do so – starfish, barnacles, clams, oysters, and scores of thousands of other species. Never in the history of the Earth has so much CO2 been injected into the oceans so quickly. Sea life hasn’t time to adapt.

Chapter seven takes this forward via a trip to One Tree Island off the Great Barrier Reef. Here, in a rough and ready research centre, she meets an international team of scientists who say the future for all coral reefs in the world, and all the species they support is ‘grim’. By 2050 they may all be dead. The Chief Scientist of the Australian Institute of Marine Science has said, that he is

‘utterly humbled to have spent the most productive scientific years of my life around the rich wonders of the underwater world, and utterly convinced that they will not be there for my children’s children.’ (quoted p.138)

She times her trip to observe the wonderful and weird sight of the annual ‘spawning’ of the corals. How many more years will it take place?

Chapter eight takes us to the rainforest of Manú National Park in southeastern Peru where scientist Miles Silman shows Kolbert around the 17 plots, each at a different altitude, which he and his assistants have marked out to explore different tropical communities. They were laid out in 2003. It incorporates the research done by Chris Thomas and colleagues from York Uni which estimate that, with worst case rates of global warming, up to 33% of Earth’s species will be exterminated. Back in Silman’s forest, Kolbert describes their research which shows that, as the climate warms up, species are in fact moving up mountains slopes to continue living in the temperature ranges they’re used to. But only so many species can even move (trees are not so mobile) and not many have mountain slopes to move up, but the real killer is speed – scientists think previous changes occurred over millions of years; we are changing the Earth’s climate in a matter of decades.

One of the defining features of the Anthropocene is that the world is changing in ways that compel species to move, and another is that it’s changing in ways that create barriers – roads, clear-cuts, cities – that prevent them from doing so. (p.189)

Chapter nine sees her in the Amazon, visiting some of the squares of rainforest left standing among areas decimated for farmland, as an ongoing scientific experiment. Lots of numbers. There are about 130 million square kilometres of land which are ice free. Of this around 70 million have been drastically remodelled by man; of the remaining 60 million three-fifths is forest. (Another study, by Erle Ellis and Navin Ramankutty divides the world’s surface into 18 ‘anthromes’, or types of human land-use, which says that 100 million have been altered by human hand, leaving 30 million of wildlands – Siberia, northern Canada, the Sahara, Gobi, central Australian desert.)

Kolbert is taken into the rainforest by her hosts to look for birds, incidentally observing the mad profusion of trees, plants and insects, including a huge column of soldier ants (learning that up to 300 species of animals are dependent on soldier ants and the changes they create). At the base she meets Tom Lovejoy, now in his 70s, credited with putting the phrase ‘biological diversity’ into circulation.

Chapter ten The separation of ecosystems on different continents, islands, archipelagos etc has been one of the key drivers of speciation i.e. diversity. Man began to mess that up with his ocean going journeys from about 2,000 years ago as humans sailed out across the Pacific islands, with the Maori arriving 1,000 years ago in New Zealand and devastating its wildlife. But the real ecological mixing began in the Age of Discovery, which was kicked off when Magellan sailed round the world and Columbus discovered America – the introduction of thousands of Old World species to the New World is now referred to as the ‘Columbian Exchange’.

Nowadays human transports are criss-crossing the globe in mind-boggling volumes, transporting flora, fauna and diseases to every last nook and cranny. Kolbert quotes the estimate that in any given 24 hour period some 10,000 species are being moved around the planet just in ships’ ballast water. So it’s no surprise that diseases once restricted to tiny parts of the world can now travel widely, for example the disease killing off the Panamanian frogs we met in chapter one, and the fungus killing bats in Massachusetts – white-nose syndrome – which we meet here. She follows the catastrophic decline in bat populations in Vermont which have collapsed since the fungus was first identified in 2007. In less than a decade bats have gone from flourishing to endangered, and will probably go extinct in the next decade.

Chapter eleven A visit to see Suci, a captive Sumatran rhinoceros at Cincinnati zoo, is the peg for a review of the catastrophic decline of big mammals (elephants, rhinos, lions, tigers, pandas) over the last century. This leads on to a visit to Big Bone Lick, where 19th century naturalists found fossils and bones of huge animals which once roamed North America but which were completely extinct by the 1800s.

It was American ecologist Paul Martin who popularised the Overkill Hypothesis, which is that megafaunas were hunted to extinction wherever prehistoric man went – in Australia 40,000 years ago, in America from 13,000 years ago, in New Zealand 700 years ago and so on. Kolbert presents the counter-arguments of scientists who are not convinced that handfuls of technologically primitive peoples could wipe out entire continents full of big dangerous animals; and then the counter-counter arguments educed from mathematical models, which show that, given enough time, even killing only one big beast a month could wipe out entire species in a few hundred years – which is what appears to have happened.

The conclusion of this line of thinking is that man has never lived in harmony with nature but has massacred large animals and triggered major ecological change wherever he has gone.

Chapter twelve Kolbert visits the centre in the Neander Valley in Germany where Neanderthal Man was discovered (though the cliffs and cave where he were discovered were long ago demolished for construction material). Neanderthal man (Homo neanderathlensis) existed as a branch of the Homo genus for at least 10,000 years from 130,000 to 30,000 years ago. All the evidence is that, wherever populations of the more ‘advanced’ Homo sapiens appeared, Neanderthal man soon after disappeared. As Chris Stringer discusses in his book, The Origin of Our Species, was he pushed or did he jump? Was it environmental change which did for the Neanderthals or some form of warfare with our ancestors or both which led to his extinction?

The chapter is titled ‘the madness gene’ because one scientist contrasts Neanderthals with Homo sapiens – particularly in regard to adventurousness. As far as we can tell Neanderthals made the same stone tools without any development or improvement for 100,000 years, whereas modern man’s culture evolved quickly. The cave paintings in the Dordogne region of France were made by modern man, whereas nothing comparable exists for Neanderthals. Above all, modern man spread far and wide, and the ‘madness’ idea comes in when you consider the urge, the adventurousness, the recklessness of the peoples who set off in primitive ships 2,000 years ago into the vast empty seas of the Pacific with no maps and no guides and no certainty of finding anything but ended up populating Hawaii and all the other Pacific islands, thousands of miles from the mainland. What is that if not reckless adventurism bordering on madness!

Chapter thirteen features the last trip, to San Diego Zoo which has a facility for deep freezing remains of nearly or extinct species – nicknamed the Frozen Zoo. Kolbert views vials full of deep frozen organic matter from various defunct species and wonders – is this what it will come to, will thousands and thousands of life forms survive only as sketches, photos and tubes of frozen gunk? And the reader who has followed her this far on her deeply depressing journey is forced to answer, Yes.

She pays lip service to the good intentions of the millions of nice people who support the Worldwide Fund for Nature or the National Wildlife Federation or the Wildlife Conservation Society or the African Wildlife Foundation and so on and so on. In this she makes what I regard as the classic liberal error of believing most people are like her, or us, educated middle-class, concerned, white people. As the election of Donald Trump and the Brexit vote in Britain should have shown these kind-hearted liberals – most people are not like them. Most people in the West did not go to private school or attend university and didn’t study the humanities and don’t work in white collar professional jobs. Many are struggling to put food on the table or keep a roof over their heads.

And that’s without going further afield into the Developing World where the majority of the population lives in dire poverty, without access to clean water, sewage facilities or nourishing food, and don’t give a damn about the future of the Panamanian frog or the greater mouse-eared bat or the black-faced honeycreeper, let alone the thousands of insect and plant and fungi species Kolbert’s scientists are so concerned about.

There is no great conclusion. Read it and weep. In the book’s last pages she gives a few token reasons for hope and briefly references those sad people who think it will all be OK in the end because humankind can always go off and colonise the moon, or Mars, or other solar systems. Right. She doesn’t even comment on such expensive fatuousness. a) All attempts to live in artificial atmospheres or biomes have failed because we underestimate the complexity of the ecosystem which keeps us alive. b) We can’t even run this planet, what gives anyone the idea we’d do better somewhere else. c) Are we all leaving for Mars, then? All 7 billion of us?

Words and ideas

  • Hibernacula – a place (cave, mineshaft) where creatures seek sanctuary from the winter, often to hibernate.
  • The Latitudinal Diversity Gradient – the closer to the Tropics, the more species are found in ecosystems, thus the tropical rainforest is the most varied and densely speciated environment on earth. There are some thirty different theories why this might be. The Latitudinal Diversity Gradient
  • Psychrophile – a cold-loving fungus.
  • The Signor-Lipps effect – since the fossil record of organisms is generally incomplete, this makes it hard to be confident about the ends or beginnings of taxa or families. In practice it makes what may have been sudden extinction events look long drawn out. The Signor-Lipps effect
  • The Species-Area relationship – the larger an area you sample, the more species you find. The Species-Area relationship

Summary

At first I thought it was a gimmick that each chapter focuses on one particular species and goes to one particular location (sometimes two) where she meets one or more scientists working on a particular aspect of the massive issues raised.

But after a while I realised how cleverly Kolbert was dovetailing into each chapter not only snapshots of current research, but also key moments in the history of the discipline, going back to explain the early theories of a Cuvier or Lamarck, a Darwin or Humboldt, to give her reporting a historical dimension and to explain how theories about life on earth arose and have developed over the past century or two.

And I ended up respecting and admiring the skill with which the narrative moves forward on these multiple levels at the same time – all leavened with a dry American sense of humour and an eye for evocative similes (the thin layers of slate at the K-T boundary which she is shown how to handle, fall apart like the pages of an old book; stroking the tough hide of Suci the rhino is like running your hand over tree bark, and so on.)

If you’re new to the subject, this is an excellent, very readable, fascinating, wide-ranging and first-hand account of work going on all around the world. That said, most of us are by now very familiar with this subject. And all of us know in our hearts that things will only get a lot, lot worse.


Credit

The Sixth Extinction: An Unnatural History by Elizabeth Kolbert was published by Bloomsbury Publishing in 2014. All quotes and references are to the 2015 paperback edition.

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The Sixth Extinction by Richard Leakey and Roger Lewin (1995)

As a recent article by Tim Flannery in the New York Review of Books explains:

Ever since Richard Leakey and Roger Lewin published The Sixth Extinction in 1995, we have known that humanity is extirpating species at a rate unmatched since the demise of the dinosaurs 65 million years ago. Hunting, deforestation, the introduction of nonnative organisms and diseases, and now climate change have increased the rate of species loss to the point that scientists fear for the functioning of entire ecosystems…

In this pioneering book, Leakey and Lewin take us by the hand through recent (in 1995) discoveries in ecology, palaeontology, palaeoanthropology and geology, to present a whole new worldview, a new way of seeing the natural world and our place in it.

1. Human evolution is a random accident

This is that we – human beings – are NOT the product of some ineluctable force driving evolution towards higher and more sophisticated species and, ultimately, towards Mind and Consciousness. We are emphatically not the pinnacle of the universe. The reverse: we are a cosmic accident. We now know that the long fossil record of life on earth has been marked by countless disasters, accidents, extinctions, most of which have no intrinsic or logical rationale, and that we are the incredibly fortuitous outcome of these massively random events.

2. There is no balance of nature

Older naturalists held that there was a Balance of Nature whereby the complete global system of life worked together to keep things – oxygen levels, complex ecosystems – in a careful balance which favoured the optimum thriving of life forms. But the closer we look at the record, the more obvious it becomes that there is no balance of nature. The more we learn, the more we realise that nature is in fact given to chaotic  and random fluctuations. It is also much more complex than we ever suspected.

3. Fluctuation and accident are the norm

Taken together, these two ideas suggest that flux and fluctuation are an intrinsic part of the history of life on earth.

Humans long for predictability, in relation to the world of nature around us and, most particularly, in relation to our own existence and our future. But it is obvious that, in the realm of evolutionary biology and ecology, ours is an unpredictable world and our place in it an accident of history; it is a place of many possibilities that are influenced by forces beyond our control and, in some cases at least, beyond our comprehension. (p.231)

4. Extinction events

The most dramatic embodiment of this fluctuation – and of the workings of chance – are ‘extinction events’. In the 540 million years since multicellular life suddenly arose in what scientists call ‘the Cambrian Explosion’, there have been no fewer than 15 ‘extinction events’. These are relatively short periods in which – for some reason – the fossil record shows that between 15% and 40% of all species went out of existence, never to return.

Among these 15 were five really big extinction events, ‘the Big Five’, in each of which over 60% of all species went extinct. And king of the Big Five is one real monster, the extinction event at the end of the Permian Era, 250 million years ago, when an estimated 95% of all terrestrial species on earth were wiped out!

The more we learn about the extinction events, the more obvious it becomes that we are the lucky survivors of the lucky survivors of the lucky survivors of a whole series of catastrophes, not through any intrinsic merit in our forebears (who, if you go back far enough, were worms) but from sheer dumb luck.

5. Darwin’s theory of evolution is over-ridden by extinction events

Darwin’s theory of evolution through natural selection is undoubtedly the mechanism by which new species come into being and by which all life forms are continually competing with all others. But in Leakey’s view, Darwin’s theory is only relevant in the relatively stable periods between these global catastrophes. These periods have lasted tens, sometimes hundreds of millions of years – but the history of life on earth is certainly not the slow, steady evolution of more and more sophisticated life forms, as portrayed in older evolutionary theory.

Instead Darwin’s process has been overshadowed time and again – in terms of impact of the history of life on earth – by extinction, catastrophe and random events. In other words, by the accidents and arbitrariness of History.

6. Humans are the most destructive species on the planet

This new emphasis on the importance of destruction, of the really breath-taking mass extinction of life forms, in the long story of life on earth, dovetails with other, recent discoveries about man’s role in nature. For a variety of sources now suggest that Homo sapiens is and always has been, immensely destructive of the ecosystems around him.

  1. For a long time Europeans have thought that when European explorers and colonisers encountered native peoples in places like America, the Pacific islands, Australia and so on, those peoples were living in a blessed ‘harmony’ with nature. Only in recent decades have scientists realised that the supposedly ‘pristine’ environments of all these places had in fact been severely damaged by the arrival of those peoples. One of the most dramatic examples is Hawaii, which looks like a tropical paradise to tourists, but where we have now discovered evidence that the hunter-gatherers who arrived there 1,500 years ago proceeded to burn down much of the rainforest and wipe out most of the larger species, including a majority of the bright songbirds.
  2. This pattern has been replicated wherever humans appeared, most notably in the Americas, where the arrival of the first hunter-gatherers around 12,000 years ago across the then-existing land-bridge from Asia, and their slow spread southwards, coincides exactly with the extermination of the continent’s megafauna i.e. all its large mammals. There is debate about whether other factors were involved as well but the case of New Zealand presents the case with brutal clarity. The Maori only arrived there 1,000 years ago, and promptly cleared much of the rainforest and hunted all the species of flightless birds and large mammals to extinction. So the native peoples which European explorers encountered in the 16th, 17th and 18th centuries were far from living in harmony with nature; they were living amid the ecological devastation their ancestors had wreaked wherever they – wherever humans – went.
  3. In the 1990s (this book was published in 1995) everybody knew that tropical rainforests around the world, especially in the vast Amazon basin, were being destroyed at an unprecedented rate (an acre a minute is one calculation), each acre home to millions of species. Since then the news about endangered species or about the rainforests has been overshadowed by the growing sense of crisis about man-made global warming. This has distracted attention away from the story on the ground, which is the alarming rate at which we are continuing to exterminate species throughout the world by the incessant demands of an ever-growing population. When Leakey wrote this book there were 6 billion people in the world. Now that number is 7.5 billion and climbing. The pressure to destroy natural habitat to convert it to farm or grazing land, along with the relentless polluting of the seas, the rivers and the air, can only escalate.

7. Humans are responsible for the sixth mass extinction event in global history

Having given a thorough account of modern understanding of the 20 or so extinction events which punctuate the fossil record – and especially of the Big Five in which 60%-plus of species went extinct – Leakey’s last chapters introduce us to the final conclusion of their long survey – the idea that we, Homo sapiens, are now having such a destructive impact on the natural world that many if not most environmentalists think we are living through the Sixth Mass Extinction of life on earth.

This is an event so momentous that many geologists and evolutionary scientists think it deserves to be defined as a distinct geological era – the Anthropocene Era – the era in which we human beings are irreversibly destroying the vast majority of life forms on the planet we share with them, on a scale only comparable with the devastation caused by the Big Five extinction events.

We are destroying the world.


Leakey and Lewin

Richard Leakey (b.1944) is a paleoanthropologist and ecologist, born and bred in Kenya, where he made significant discoveries of fossils of early humans, before going on to run the country’s national museums and then become its overall Director of the Wildlife Services.

Roger Lewin (b.1944) is a British prize-winning science writer, a staff member of New Scientist for nine years before going to America to become News Editor for Science. He’s written about 20 books, including three in collaboration with Leakey.

The first two of their collaborations are about Leakey’s work into the origins of the human species, in and around Lake Turkana in the north of Kenya, part of the enormous Rift Valley. Due to the fact that hominids need water, and the mud around rivers and lakes preserves footprints and the bones of dead animals better than the harsh savannah or bare rock, Lake Turkana has been a goldmine for fossil hunters looking for relics of our earliest ancestors. In his early explorations, Leakey’s team discovered Turkana Boy, the most complete early human skeleton ever found, believed to be between 1.5 and 1.6 million years old.

In the late 1980s Leakey’s interest shifted away from paleoanthropology towards wildlife conservation and ecology. This book – itself now quite dated – combines his two areas of expertise to give a thorough and quite academic history of the evolution of life on earth and to situate the evolution of hominids and Homo sapiens within it, before going on to present its Big Issue.

Key dates

  • Age of the universe – 13.772 billion years
  • Age of the solar system – 5 billion years
  • Age of planet earth – 4.6 billion years
  • Simplest life forms – prokaryotes, single-celled organisms which lack a nucleus -3.5 billion years ago
  • Eukaryotic organisms, whose cells contain a nucleus – 1.8 billion years ago
  • 530 million year ago – the Cambrian Explosion, when suddenly a huge diversity of multi-celled life forms and body shapes and sizes emerges in the fossil record
  • The Cretaceous Period, the last and longest segment of the Mesozoic Era, lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event dated at 65.5 million years ago. Period when ‘dinosaurs ruled the earth’.
  • 7 million years ago, approximate parting of the line which led to humans from the lines which led to the great apes
  • 150,000 years ago, evolution of the new species, Homo sapiens
  • 13,000 years ago – end of the last Ice Age triggers the invention of agriculture in the Fertile Crescent, which slowly spreads around the globe and with it the arrival of what we like to call human ‘civilisation’

It’s from the Cambrian Explosion – 530 million years ago – that everything most of us think of as life forms – fish and dinosaurs, plants and trees, then later we mammals – derive. Most of the epochs and periods we hear about – Jurassic, Triassic etc – occur during that 530 million period, most fossils of life forms derive from that period.

The sixth extinction

The central premise of the book, which gives it its title, is that, over the half-billion-year history of multi-celled life on earth, there have been a number of ‘moments’ in the geological record when a significant percentage of the flora and fauna of a certain era seem to have died out very suddenly (in geological terms) – known as ‘mass extinction events’. Having explained the background and possible reasons for them, the book then goes on to point out that we are living through a sixth mass extinction event, in which huge numbers of species are being driven to extinction. There is no doubt at all what is causing it: it is us – humans. Human beings are wiping out the earth’s ecosystems and wildlife.

The ‘Big Five’ mass extinctions

The Big Five are defined as extinction events in which at least 65% of species were obliterated. The end-Permian is the biggest, in which an estimated 95% of species on earth were wiped out.

  • at the end of the Ordovician Period – 440 million years ago
  • the Late Devonian 365 million years ago
  • the end-Permian 225 million years ago
  • the end-Triassic 210 million years ago
  • the end-Cretaceous 65 million years ago

There is huge debate about the possible causes of these great ‘dying outs’. Climate change? The conglomeration of all the continents through continental drift into one mega-continent? The most dramatic suggestion, first mooted in the 1970s by a team led by Luis Alvarez, is that it was asteroids. They found thin layers of iridium at the archaeological line marking the end of the Cretaceous period, an element which is extremely rare on earth but is found in asteroids. This discovery has been replicated at other end-Cretaceous sites, and then a candidate for the giant crater caused by a monster asteroid was discovered on the coast of Mexico. The idea is simple: monster asteroid hits earth with the power of a million hydrogen bombs, throws up vast amounts of dirt and dust into the air which blocks out the sun, as well as triggering widespread volcanic activity. Result: mass extinctions of life.

There’s a lot of evidence for it, but archaeologists and biologists are an argumentative lot, as this book amply demonstrates, and other scientists have piled in to claim that asteroids might have put only the finishing touches to what other causes – climate change, sea level rises, environmental or atmospheric fluctuations and so on – had started. Others – David Raup and Jack Sepkoski – have pointed out that there have been over twenty extinction events over that half billion year span, of which the Big Five are only the most notable (p.56), and which occur at roughly 26 million year intervals. Only the recurrent arrival of a shower of asteroids could explain this regularity, although more recently doubt has been cast on the evidence for this neat pattern. But there’s no doubting, now, that externally-prompted mass extinctions have been a recurrent feature of terrestrial evolution.

Which gives rise to an immense debate about the deep meaning of the theory of evolution, which can be summarised in the phrase ‘bad genes or bad luck’. Is there an inevitability in the way life has evolved? If we ran the tape of evolution again, would life forms turn out much as we see them around us? Is there a kind of deep logic to the way things would have evolved, to fit the available niches?

Or has the evolution of life on earth been subject to mind-boggling accidents and contingency? Could things easily have turned out wildly differently? Was it the merest luck which led to the various mass extinctions, to the death of the dinosaurs 65 million years ago, to the rise of the mammals and then, right at the end of this string of improbable accidents – to us, reading these words?

These and many related questions are tackled – with the help of quite technical diagrams and explanations – in the first half of the book. It takes a few rereadings to get the timelines clear in your head, and then more rereading to understand what the numerous debates are about.

For example, uniformitarianism is the idea that evolution takes place gradually and slowly over vast periods of time. Darwin had to arrive at his theory by battling essentially religious ideas that species were suddenly created by a Creator God, so he and his followers were vehement uniformitarianists. However, from the birth of geology as a science in the early 19th century, geologists recognised sudden abrupt changes in the record – catastrophic changes in the fossil record which the extinction events seem to support. Broadly this view of evolution is called catastrophism. The American paleontologist and evolutionary biologist Stephen Jay Gould developed his own version of catastrophism, which he called punctuated equilibrium – long periods of stasis interrupted by abrupt changes in earth’s biota, or life systems. Modern thinking about the importance of mass extinction events has led to what some call ‘neo-catastrophism’ i.e. Darwin’s laws work most of the time, except when some external force steps in to overshadow them – be it drastic climate change, asteroids, volcanic activity, sea level changes or whatever.

Man the destroyer

We are but one of millions of species here on earth, products of half a billion years of life’s flow, lucky survivors of at least twenty biotic crises, including the catastrophic Big Five. (p.71)

But these and various other theories and debates about the detail of historical evolution are really just the background, the introduction to the meat of the book, which is a lament for man’s destruction of the natural world. Leakey uses numerous examples to show how modern science has revealed just how much life there is, all around us.

He reports Danish scientists who investigated one square metre of tropical rainforest and discovered 46,000 earthworms, 12 million roundworms and 46,000 insects. Just one gram of this soil contained more than a million bacteria, 100,000 yeast cells and 50,000 fragments of fungi (p.136).

The rape and destruction of the earth which we are causing is mind-blowing. It is estimated that ‘we are losing upwards of 80,000 acres of tropical rainforest daily, and significantly degrading another 80,000 acres every day on top of that. Along with this loss and degradation, we are losing some 135 plant, animal and insect species every day – or some 50,000 species a year.’ (Scientific American)

But all that’s new is the scale: man has always been a destroyer. Between 12,000 and 10,000 years ago 50 or so large mammal species went extinct in North America. The extinctions coincided with the arrival of the first peoples from Asia (across the land bridge across what is now the Bering Straits) and their slow fanning out across the continent. Although some paleontologists prefer climate change or disease as the cause, many think these first human settlers of the Americas hunted its large mammals to extinction. This theory is called the Overkill hypothesis. The case is even clearer in New Zealand, which Maori colonised about 1,000 years ago and where they hunted the large flightless birds to extinction, while the rats they’d brought from Australia wiped out whole systems of ground-roosting birds and other fauna.

‘The notion of man-the-exterminator is secure in New Zealand.’ (p.186)

Same on Hawaii (pp.188-190).

Numbers

How many species are there on earth? Nobody knows. Leakey quotes an early estimate from the 1960s of 3 million. Terry Irwin, in 1982, estimated there may be 30 million species of insects alone in the rainforest canopy. Elsewhere, Leakey quotes estimates of the total number of species as 50 million, and then references Robert May’s speculation from the 1990s that there may be as many as 100 million species. These appear to be the end points, which is why later articles refer to ‘anywhere between 3 and 100 million’.

More recently, a 2011 estimate using a new methodology gives the total number of species in the world as 8.7 million – 6.45 million on land, 2.2 million in the sea. According to this calculation, 86% of all species on land and 91% of those in the seas have yet to be discovered, described and catalogued. But googling the subject, though, one comes across a bang up-to-date estimate from 2016 which says there might be as many as 1 trillion species on earth!

In other words, despite E.O. Wilson’s calls for governments to invest more in finding out how many species we share the world with – a plea from the 1990s quoted in this book (p.123) – we still haven’t a clue how many there are. What we can be confident about is that we are wiping out most of the species we share the earth with before we ever get to discover, identify, record or analyse any of them.

In fact, we don’t even know precisely how many species have been identified and catalogued. It appears to be about 1.25 million species – roughly 1 million on land and 250,000 in the oceans – but as many as 700,000 more are thought to have been described by local scientists which have yet to reach the central databases and so be included in global counts…

Value in diversity

How do we preserve nature? Well, in our demystified, instrumental, capitalist world, we have to give it a value, the only thing most people understand. Leakey identifies three types of value:

  1. Tangible benefits we can extract from the environment, such as food, raw materials, medicine.
  2. Maintenance of the environment: we need the full web of life to continue its circulation of gases, chemicals and moisture in order to make the world inhabitable by humans.
  3. Psychological health: most people with the money, prefer to live in the country, people like to visit and roam in the country, patients in hospital with a bed by a window in a green space have better recovery rates than patients in a windowless room. The presence of greenery and nature keeps us psychologically healthy – and that greenery doesn’t exist in the abstract – it is made up of incalculably complex webs of organisms. E.O. Wilson has named this sense ‘biophilia’.

Food and drugs are the obvious ones. The world is dangerously dependent on monocultural varieties of a handful of food crops. If a pest devastated the world’s wheat or rice crops, billions would starve. Wild varieties contain genes we haven’t identified or analysed which would provide important genetic variations which could help develop new varieties, if the worst ever happened.

Similarly, important worldwide medicines have been sourced from wholly unexpected wild plants and flora. Aspirin and penicillin are the two obvious examples, which changed the world and saved hundreds of millions of lives. Who knows what cures for cancer or AIDS may be lurking undiscovered in some of the 250,000 species of plants? And in species we are merrily burning to extinction every day?

Theories and ideas

Even twenty years ago when this book was published, all educated people should have known about the destruction of the rainforests and endangered species. That aspect shouldn’t be news to anyone. I think the real revelation of this book is the extraordinary complexity and difficulty of ecological and biological and archaeological science – the range of areas and levels and expertises which are now brought to bear on the natural world, the complexity of computer models and the plethora of rival theories.

Leakey’s book is in many places quite dauntingly technical. Plenty of paragraphs contain numbered points or aspects or theories which we need to learn and bear in mind. For example, we learn about:

  • Allopatric speciation – or geographic speciation is speciation that occurs when biological populations of the same species become vicariant, or isolated from each other to an extent that prevents or interferes with genetic interchange.
  • Cambrian Explosion – ‘the relatively short evolutionary event, beginning around 541 million years ago in the Cambrian period, during which most major animal phyla appeared, as indicated by the fossil record’ (Wikipedia)
  • Chaos theory as it applies to ecosystems i.e. modern understanding has undermined the notion of a ‘balance of nature’ to reveal that all systems, even without any external influence, tend to boom and bust and be subject to other ‘internal’ pressures which create fluctuations. I.e. every ecosystem, and nature as a whole, is much more chaotic and unstable than had been appreciated.
  • The ‘protective network‘ of an ecosystem which places an ‘activation barrier‘ around it to prevent new species intruding (p.162-3).
  • The rivet-popper hypothesis and the redundancy hypothesis of how ecosystems are degraded. Rivet-popper = each species in a system is like the rivets in a ship – you can remove one or two without noticing but the more you remove the more you weaken the system until it reaches collapse. Redundancy = most species are passengers on a system held together by a few lynchpin systems: you can remove most with no change; but remove the lynchpins and the system collapses. (pp.140-141)

The relative importance of ‘history’ and evolution

One of the big points Leakey makes is that in his time older ideas like ‘the balance of nature’ and even the primacy of natural selection, have been thrown in doubt. Nature now appears to be much more chaotic than previously suspected. And he explains recent work which suggests that the world we see around us is radically contingent. Archaeologists examined the fossil record of animals off the North Atlantic coast over the past 60 million years, a huge duration during which sea levels rose and fell six times. They discovered that mature ecosystems repopulated the dry land once it was reflooded – but each time it was repopulated by a different combination of species. I.e. the reappearance of life was ‘inevitable’ – but which specific species fill all the niches and grow into a tangled web of an ecosystem – it can be different each time. There is nothing intrinsic or inevitable about the flourishing of particular species or combinations of species in ecosystems. Shake the dice and you get a different set.

As Leakey puts it, History matters. Life there will be, but what forms of life and how they combine, even in the same environment, can vary hugely depending on chance factors. Thus Darwin’s theory of evolution by natural selection still gives the best account of how species evolve over time – but in seeking an explanation for the natural world as we see it, the theory of evolution is dwarfed by the random events of what we call ‘history’.

Insights into human history

Obviously Leakey’s main concern is with nature and ecology but for someone like me who knows more about history than I do about biology or ecology, the multiple insights a scholarly book like this gives the reader into the natural world can also shed tremendous light on the deeper meaning of human history.

I’ve just finished Alan Taylor’s epic account of the colonisation of America. In it he emphasises that it wasn’t just European humans who arrived in the New World, but that they brought from the Old World , in order of importance – their devastating new diseases, new plants and new livestock. These spread like wildfire across the virgin continent, the diseases wiping out up to 95% of the native inhabitants of the Americas, while new plants spread like weeds, and livestock drove American rivals extinct.

Quite apart from its ostensible purpose as a warning and a plea, a book like Leakey’s can immeasurably increase our understanding of human history by giving us a deep sense of the mind-boggling complexity of the natural world which human beings have been blundering around, reshaping and destroying, burning and deforesting and planting and mixing up, for centuries – the process we refer to as ‘history’.

It makes us realise what was at stake back then, as well as now. It makes us realise the depth of the damage we have been doing, and for centuries.

Attitude

Obviously the planet is indifferent to individual human opinions, attitudes and stands. Clicking ‘like’ on facebook to a photo of a polar bear or the rainforest isn’t going to change anything. Only a wholesale and comprehensive change to all of our lifestyles, combined with drastic attempts to control and reduce human population, will have any real, practical impact on the problem.

On a personal level, this knowledge does suggest a truer, more accurate understanding of human nature (destructive) and our place in the natural world (destructive) which should have a chastening effect on everything we think and do. It transforms our understanding and it should transform our behaviour.

From time to time Leakey mentions, or quotes other ecologists criticising, humanity’s ‘narcissism’ or ‘arrogance’, each of us infested with thoughts and feelings and desires which a) are ultimately trivial b) obscure to ourselves our fundamental role as destroyers of the environment.

A correct attitude, the accurate honest attitude to the devastation we cause, would be one of modesty, shame and penance.

In a way, understanding these issues better should lead us to a kind of attitude and – ideally – lifestyle, characterised by simplicity and humility. All of us need to consume less, vastly less, than our arrogance and ignorance and selfishness prompt us to.

A proper understanding of our place in the world should lead to the virtues praised by monks and nuns of all religious orders: shun the world, shun consumption, shun exploitation, work in humility and honesty to supply our bare needs. Only then, maybe, despite all the evidence to the contrary, might there be a slight possibility of hope that we do not exterminate most life forms on the planet including, of course, many that we depend and rely on for our own existence.

In order to know ourselves as a species and to understand our place in the universe of things, we have to distance ourselves from our own experience, both in space and time. It is not easily done but it is essential if we are truly to see a larger reality. (p.6)


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Guns, Germs and Steel by Jared Diamond (1997)

We can rephrase the question about the world’s inequalities as follows: why did human development proceed at such different rates on different continents? (p.16)

The 1990s saw an explosion in popular science books and this one won prizes (the Pulitzer Prize, over a million copies sold) for its skilful interweaving of a wide range of specialisms – biogeography, archaeology, anthropology, molecular genetics, linguistics and more – to answer an apparently ‘simple’ question. In his introduction Diamond calls it ‘Yali’s Question’, after a New Guinea native he knows (Diamond has spent a lifetime studying the birds of New Guinea) and who once asked him: ‘Why did you white people develop so much “cargo” and bring it to New Guinea and we black people have so little “cargo” of our own?’ where ‘cargo’ stands for the full range of marvellous inventions the white man brought with him.

The jokey sub-title of the book is ‘A short history of everybody for the last 13,000 years’ and that summarises Diamond’s approach – which is to find the answer to Yali’s question way back before the beginning of cities, writing or agriculture. Not in the rise of Europe or mercantilism or sailing ships or science or gunpowder, not in writing or the birth of agriculture does Diamond seek the answer, but goes right back before all this to the end of the last Ice Age (13,000 years ago).

For this is when the human populations, scattered around the continents of the earth, all started in roughly the same state of development – as hunter-gatherer societies. Starting from this point Diamond brings together everything we know from the full range of historical and archaeological disciplines to try and clarify why some of these groups did invent all those things – agriculture, cities, writing, metal tools – while others only got as far as non-literate farming, and others remained stone-age hunter-gatherers. With the result that everyone knows, which is that from around 1500 AD the former spread across the world and conquered or even exterminated the latter – resulting in the ongoing global inequalities we are all familiar with. Why?

Answers

It’s a long, fact-packed and detailed book but the answers are easy to summarise, in fact he gives the game away in the introduction:

History followed different courses for different peoples because of differences among people’s environments, not because of differences among peoples themselves. (p.25)

And on page 87 there is a diagram showing the full implications of this simple proposition.

Schematic overview of the chains of causation leading up to proximate factors (guns, horses, disease) enabling some peoples to conquer other peoples.

Schematic overview of the chains of causation leading up to proximate factors (guns, horses, disease) enabling some peoples to conquer other peoples.

1. The East-West axis of Eurasia. This vast stretch of continuous territory enjoys broadly the same climate and the same length of days. This meant that when farming – the domestication of plants and animals – was developed in one place – Mesopotamia – it was able to spread over vast distances east and west with no significant barriers to its diffusion. Unlike in the Americas or Africa, which have a broadly north-south axis, and are littered with barriers (the Mexico desert, the Congo rainforest) which made it harder for these innovations to spread. And Australia completely cut off from all these developments. Thus pottery and iron smelting reached Sub-Saharan Africa’s Sahel region about 4,000 years ago but pottery only reached Africa’s southern tip about AD 1, and metallurgy hadn’t reached it at all by the time the European invaders came in 1500.

2. Eurasia also happened to have a wider range of both plants and animals than the other continents. Diamond has a long chapter about the benefits of the Old World crops – wheat, oats, barley and so on – their bigger yields, their higher protein content, compared to New World corn or African yams as staple crops. Eurasia also has a larger number of domesticable animals. He lists the 14 ‘big’ (over 100 lbs in weight) mammals which were domesticated before the 20th century, divided into the Big Five (sheep, goats, cow, pig, horse) and the Minor Nine (Arabian camel, Bactrian camel, llama, donkey, reindeer, water buffalo, yak, Bali cattle, mithan). Of the total 14, no fewer than 13 had ancestors in Eurasia i.e. were domesticated here, while only one was available in south America (ancestor of the llama and alpaca) and none existed in North America, Australia or sub-Saharan Africa.

3. Stratified society Once you’ve grasped these two fundamental advantages of Eurasia, the rest begins to cascade like an avalanche. Domesticating plants and animals leads, for the first time in human history, to food surpluses, and of types which can be stored over the winter or during hard times (grain, salted meat). For the first time human beings can be supported by this surplus who don’t themselves directly hunt or gather food. Hence the creation of a class of rulers who control the surplus of the community, along with other non-food-producers; hence a soldier class which fights wars, a priestly class which blesses those wars, and a bureaucracy which enacts the ruler’s wishes and manages everyone else.

4. Technology Once you have people specialising in particular activities – groups and guilds and unions of people all doing the same kind of thing – you will get increasing competition between them, leading to innovations, all sorts of technical inventions and improvements, and to the eventual creation of ‘science’ – the technique of speculating, testing, experimenting and speculating again, all creating a virtuous circle of technological progress. Diamond explains the notion of autocatalysis, a process which speeds up at a rate which increases with time because the process catalyses or facilitates itself. Thus Western invaders were not one or two or three developments ahead of the native peoples they encountered, but ahead in thousands and thousands of ways which the invaded couldn’t even comprehend. Beneficiaries of an exponential curve of discovery, invention and technology.

Diamond uses the incident of Pizarro’s massacre of the Incas and capture of their emperor, Atahuallpa, at Cajamarca on 16 November 1532 to enumerate the advantages the Spanish conquistadors had over the native Amerindians:

  • Horses – non-existent in Central and South America, horses were the central military technology of Eurasia from about 4,000 BC to the First World War, and had the same impact on the Mesoamericans as tanks against infantry.
  • Ocean-going ships – unheard of among the Mesoamericans. Themselves developed over thousands of years and navigable because of…
  • Writing Diamond highlights the way the Incas didn’t know what to expect. Their scouts had said the tiny force of Spaniards (about 160 men) were disorganised and badly armed. Atahualpa expected to overawe them with his army of 80,000. He had no knowledge of travellers from across the sea, no knowledge of horses or armour or guns or steel swords, no knowledge that the Spaniards had come to conquer and plunder. Whereas the Spanish were the heirs of 3,000 years of writing, of records of history, of the rise and fall of empires, countless treatises on the art of war, the maps of the sea and knowledge of winds written by previous sailors which helped them get to Inca territory, and written records of Cortes’s conquest of the Aztecs to model themselves on. The contest was not only one-sided in terms of technology and weapons, but in terms of knowledge.
  • Guns, steel, swords – The Spanish had them to fight against the Aztec and Inca stone-headed clubs and woven armour – with devastating results.
  • Epidemic diseases And lurking behind all these factors, was the Big One, the thing which killed more native peoples than all white men’s guns and swords and cannon put together – the Old World diseases they brought with them and which devastated native peoples completely unprepared for them, what Alfred Crosby named ‘virgin soil epidemics’. Eurasians had lived for millennia among the livestock who are vectors for diseases – chickens, pigs and rats – and been decimated by wave after wave of smallpox, plague and the rest until the survivors had built up sturdy resistance. Non-Eurasians had no defences and no medicines, and so died in hundreds of thousands. In the centuries to come far more native peoples died of the scourge of smallpox than any other cause. And – an important point – the diseases spread faster than the conquerors. All it took was one contact on a beach and a native to return to his tribe which included foraging parties or raiders or traders and Old World diseases could travel like wildfire inland – with the result that the conquerors often encountered cultures and societies which were already fatally weakened by disease before they even arrived. Thus apart from the horses and steel swords, the Spanish had the simple advantage that smallpox had already ravaged the Inca empire, killing the emperor Huayna Capac and his son, and sparking a civil war between the successor Huáscar’s and his half-brother Atahualpa.
  • Domesticated animals and disease One is the spawning ground for the other: ‘The major killers of humanity throughout our recent history – smallpox, flu, tuberculosis, malaria, plague, measles, and cholera – are infectious diseases that evolved from diseases of animals.’ (p.197) I didn’t realise that measles, tuberculosis and smallpox are all derived from illnesses of cattle.

There is a sub-explanation related to Eurasian success in domesticating animals and (unintentionally) creating epidemic diseases from them, namely:

The overkill theory Cro-Magnon man arrived in Australia about 40,000 years ago. At more or less the same time Australia’s megafauna of giant animals (a giant flightless bird, giant lizard, giant kangaroos, a marsupial leopard, etc) went extinct. Coincidence? The overkill theory is that the early human settlers hunted these large animals to extinction; and it can be extended to other regions where the first arrival of humans seems to have coincided with the mass extinction of the largest (tastiest) animals e.g. Siberia, settled roughly 20,000 years ago at about which time the native woolly mammoth and woolly rhino went extinct; or the arrival of humans in North America around 12,000 years ago which coincided with the mass extinction of the large native fauna, elephants, horses, camels, giant ground sloths. The overkill theory is important because it helps explain why the native peoples of these places were at such a disadvantage compared to the Eurasians.

Thus the native peoples of these lands themselves wiped out the native larger animals which a) they might have been able to domesticate b) had they done so, close proximity to them would have given rise to infectious diseases which, over time, would have toughened their immune systems, maybe better preparing them for the arrival of Eurasian diseases, and which might in turn have devastated the Eurasian invaders. But no domesticable large animals – no diseases = defeat.

All this has been laid out in principle in the first 100 pages or so: Diamond then turns to examine each of these factors in greater detail, devoting the lion’s share to the development of agriculture (100 pages) which emerges overwhelmingly as The Main Reason – before moving on to germs (20), writing (24), technology (26) and stratified society (28).

The final section of the book (‘Around the World in Five Chapters’) looks in closer detail at how the West’s advantages impacted – when we invaded them – on Australia and New Guinea, China, Polynesia, the Americas, and Africa.

Summary

Guns, Germs and Steel is an incredibly comprehensive, all-encompassing vision of global history which, from both its sheer scope and its novel biological perspective, not only sheds striking new light on all Western history, but achieves Diamond’s aim of placing the histories of all the other peoples of the world on the same footing, as equal inhabitants of the earth.

Countering prejudices

For Diamond is impeccably politically correct, not from ideology but from wide experience. He has worked in the Tropics and made many friends there, especially in his specialist area, New Guinea. He knows for a fact that many of the ‘natives’ are smarter than the white colonials. His entire approach sets out to undermine the possibility of racism by proving that the eventual ‘triumph’ of European societies was nothing to do with innate or genetic superiority: it was entirely driven by these external accidents of geography and biology.

Fascinating facts

The appeal of these kind of popular science blockbusters is the countless peripheral facts and stories and insights they contain. This book is packed with them. Ones which caught my eye include:

  • If we say the line of human evolution parted from the apes about 5 million years ago, then the last 3,000 years since the invention of writing i.e when we have written records of (a very small number) of our activities, represents just 0.01% of human history. We are fond of poring over this record and writing countless analyses of fragments of it – Diamond’s point is that all the really important stuff, all the events which determined the broad pattern of human history, happened well before then.
  • Writing arose in only three centres – the Fertile Crescent, Mexico and China. All other writing derives from one of these sources. (p.236)
  • The notion of the alphabet – individual signs (letters) standing for distinct sounds (phonemes) arose only once in human history, among speakers of Semitic languages in the area from Syria to the Sinai (p.226).
  • Most biomass (living biological matter) on land is in the form of wood and leaves, most of which we cannot digest. (p.88)
  • New Guinea has by far the biggest concentration of languages in the world, with 1,000 of the total 6,000, divided into dozens of language families. Nearly half of them are spoken by groups of 500 or less. (p.306)
  • ‘Australia is by far the driest, smallest, flattest, most infertile, climatically most unpredictable, and biologically most impoverished continent.’ (p.296)

Terrible epidemics

  • The Indian population of Hispaniola when Columbus arrived in 1492 was around 8 million; by 1535, mostly due to European disease, it was 0.
  • Measles reached Fiji via a Fijian chief returning from Australia in 1875 and killed a quarter of the population. Syphilis, gonorrhea, tuberculosis and influenza arrived at Hawaii with Captain Cook in 1779, followed by a typhoid epidemic in 1804 and numerous minor outbreaks, reducing Hawaii’s original population from around half a million to 84,000 in 1853, the year smallpox arrived and killed 10,000 of the survivors. (p.214)
  • Smallpox arrived in Mexico via one infected slave from Cuba in 1520; the resulting epidemic killed almost half of the Aztecs, including the Emperor Cuitláhuac. By 1618 Mexico’s initial population of about 20 million had fallen to 1.6 million.
  • North American Indians are now thought to have numbered about 20 million when Columbus landed. Two centuries later (c.1692) they numbered about 1 million.

Credit

Guns, Germs and Steel by Jared Diamond was published by Jonathan Cape in 1997. All quotes and references are to the 1998 Vintage paperback edition.

TV series

The book was made into a TV series by Public Service Broadcasting in the USA.

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