Peter Ward

Future Evolution

FUTURE EVOLUTION

TIMES BOOKS
Henry Holt and Company, LLC
Publishers since 1866
115 West 18th Street
New York, New York 10011

I would like to thank the following people for various reasons:

And I would like to thank my gallerists Jay Gorney, Karin Bravin, and John Lee,
and especially Rodney Hill. � A.R.

Henry Holt� is a registered trademark of Henry Holt and Company, LLC.

Copyright � 2001 by Peter Ward (text) and Alexis Rockman (images). All rights reserved.

Library of Congress Cataloging-in-Publication Data

Ward, Peter
Future evolution / Peter Ward; images by Alexis Rockman; foreword by Niles Eldredge.
p. cm.

Includes bibliographical references (p. ).
ISBN 0-7167-3496-6 (cloth)
1. Evolution (Biology) I. Title.
QH366.2 .W37 2001
576.8 � dc21

2001003607

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First Edition 2001

Designed by Diana Blume

Printed in Hong Kong

10 9 8 7 6 5 4 3 2 1

CONTENTS

v

IMAGES

vii

* These drawings were created with pigments derived from the medium in which the actual fossils were discovered, provided to the artist by the author.

All images courtesy of Gorney Bravin + Lee, New York. All works were photographed by Oren Slor, New York.

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FOREWORD

BIOLOGICAL FUTURES

Niles Eldredge

Committee on Evolutionary Processes, and Division of Paleontology,
The American Museum of Natural History,
Central Park West at 79th Street, New York, New York 10024

Predict the future? The future of evolution of life on earth-human life, bird life, fungal life? Most of us New Yorkers would say, �Fageddabout it!� We can�t even predict weather with any accuracy more than three days in advance, even with all our global monitoring stations, constant satellite imagery and computer modeling. We go to bed at night, sure that the sun will �rise�, but with no way of knowing if the Dow Jones Industrial Average will rise, stay flat, or plummet. Sure, we can explain what happens ex post facto (�the snowstorm didn�t materialize because high pressure from Canada deflected the low off the Jersey shore�, or �the market fell on disappointing earnings reports in the tech sector�). But predicting such complex systems with any consistency remains an elusive goal, maybe even a fantasy.
So how on earth can we expect to do any better with the future of life � with its millions of species, its myriad ecosystems � projecting what�s going to happen, not this week or next month, but hundreds, thousands, millions of years down the road? Fageddabout it!
But hold on. One of the key ingredients of the scientific endeavor, after all, is predictivity: if an idea is true, we reason, there must be certain observable

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consequences � and if we consistently fail to observe the predicted results, there must be something wrong with the idea itself: we must �reject the hypothesis�. Laboratory experiments � though sometimes done blindly (�let�s see what happens if we mix these two chemicals!�) � are nonetheless usually performed with some expectation in mind of what the results will be: future outcomes, in other words, are predicted.
But even here we encounter difficulties: creationists are fond of pointing out that evolutionary biologists have usually been reluctant to predict what will happen in the evolutionary future, and claim that this failure to render testable predictions of life�s future means that evolutionary biology is therefore not true science. In any event, none of us will live long enough to see if our predictions turn out to be correct.
Not so, say the philosophers: the future state of a system is not what is necessarily meant by predictivity in science; rather, for an idea to be scientific, we must simply make predictions about what we would expect to observe in the natural world if that idea is true. Thus the grand prediction of evolution would be that, if all life has descended (�with modification�, as Darwin himself put it) from a single ancestor, diversifying into separate lineages as the process went along, there should be a single pattern of resemblance linking up all life on earth. More closely related species should look more like each other than more remote kin � but there should be some vestige of common inheritance of features that are found in absolutely all forms of life. That�s in fact what we do see: RNA is present in all life forms; all vertebrate animals have backbones (the very meaning of the group�s name), all mammals have hair.
Then, too, we would predict, were evolution �true�, that in the history of life the simplest forms would have appeared first, the more complex later. That, too, we see, haunting our diagrams of the structure of relationships in the living world, but especially in the sequence of life preserved in the fossil record. Life was nothing but bacteria for its first billion or so years, and nothing but single-celled organisms for its first 2 billion years. Simpler forms of animal life preceded the more complex � and reptiles preceded their famous derivatives, birds and mammals.
So, not only is evolution a legitimately scientific concept, it is also almost certainly true � having had its two grand predictions about what life should look like (both now and in the fossil record) �corroborated� so many times over that there is no residual rational doubt that life as we know it is the product of evolution.
But if we need not predict the future for us to see the scientific nature of the very idea of evolution, is that all we can do? What about those of us who do not

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want to say �fageddabout it!� when we wonder what the future holds � especially for ourselves, the human beings who have so recently, so thoroughly changed the face of our globe? Is there nothing rational we can say, nothing about what we�ve learned from life�s history that can serve as a basis for reading the future � or at least narrowing down the possibilities?
The exciting answer is �Yes!� � there�s a whole lot we can say, and with confidence. Life�s evolution, though usually portrayed as a string of events that saw the eventual emergence of leopards and hippos through a long lineage stretching back to primordial bacteria, can also be read as a series of patterns repeated so often that we can be sure they will happen again. Specifically, patterns of extinction followed by the appearance of new species have demonstrated without any lingering doubt that nothing much happens in the way of evolutionary change unless environmental disruption shakes life up.
Life can absorb small local disturbances (like fires or tidal waves), and replace its local dead with recruits of the same species brought in from undisturbed, neighboring ecosystems. But larger-scale disturbances � like global climate change, or objects from outer space colliding with the earth � are another matter entirely. Such larger-scale perturbations are often sufficiently devastating that they drive entire species extinct. Sometimes, as in the great mass extinctions portrayed so vividly in the pages of this book, they drive entire families, orders or even classes of animals, plants and microbes extinct. And that�s when evolution kicks in.
Peter Ward, experienced paleontologist that he is, knows all this. He also sees that we are in the midst of another major surge of extinction that is bound to trigger an evolutionary rebound (indeed, he thinks it already has!). I totally agree with him that humans are the root cause of this current spasm of extinction � and that, critically, it is the fate of humanity that will determine to a very large degree the future complexion and composition of life on earth.
So the question becomes: What is our fate? Others who have taken a shot at what life�s future evolution will look like have assumed that the current vector of extinction � meaning ourselves � will disappear completely, leaving all other forms of surviving life to reclaim the planet. The paleontologist and artist Dougal Dixon, in his After Man, made this assumption � and produced a whimsical work of great charm with his imaginary �sand sharks� and other beasts of the future.
Alexis Rockman, whose often brightly colored canvasses just as often project dark themes, has in the course of his career created a vision of life on earth totally informed by the presence of humanity � tin cans and discarded tires forming the

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substrate of an exuberant, ongoing Life. Alexis�s vision dovetails perfectly with Peter�s notion that humanity is going to survive � and that all life�s future will revolve around our presence. The future is already here, with domestication of barnyard animals and the heady days of genetic engineering beginning to unfold before our eyes. A rational supposition � and one very different from Dixon�s bucolic outlook.
I wonder if past cultural extinctions, where technologically advanced and complexly organized societies have disappeared even while their descendants have persisted, living simpler lives, might not also be a source of predicting the future. The current wave of human planetary disruption might cause, not our physical extinction so much as a loss of the �high culture�, � our knowledge � if we do overrun our Malthusian limits. Loss of topsoil, lack of access to fresh water, loss of fisheries, spread of famine, warfare and disease � all the usual apocalyptic visions, all duly acknowledged in these pages � may not drive our bodies extinct, but could very well play hob with our minds, our cultural memories, our knowledge.
It is the exercise itself that is important: the careful development of a view of the future based on what we�ve seen happen in the past, and what is going on right now with the human joker-in-the deck, the wild card that is mimicking the effects of the asteroid that wiped out the dinosaurs 65 million years ago. It is up to all of us to contemplate the effects of our collective lives on the future of life on our planet. Peter and Alexis have combined to develop a stimulating vade mecum, an invitation to each of us to journey along with them as we wrestle with the problem ourselves. And that, of course, is the real point about reading anything.

xii

PREFACE

The ringing phone was one more interruption in a day filled with them, the day just another in the blur of time we call life. I anticipated the mundane. But the telephone�s slight electronic hesitation indicated International, and the caller�s precise Oxbridge accent confirmed England. In this day of E-mail, no one pays for a phone call unless there is a pitch or a catch, so I listened with alacrity.
The smooth-spoken man asked for Professor Ward, showing that European formality so charming and now so extinct in America. After I confirmed that I was I, he launched into the pitch (the catch was yet to come). He explained that he was a producer for the BBC, in charge of a thirteen-hour series about evolution, then early in the planning stages. He wondered if he could ask me a few questions. Sure, I answered, using a word I am sure has never been uttered by a Brit. He explained that the series was about the future � the future of evolution, in fact. I found myself listening much more carefully, having nearly finished the manuscript for this book at the time. He reiterated that he was funded to produce thirteen hours of programming dealing with the animals and plants of the near to far future, with each hour profiling a future time slice, starting in the next few millennia and ending in the far-off future, a billion years from now, when the sun would be brightening to the point of threatening the existence of all life on Earth. We talked a bit further, while I kept exclaiming to myself, �Thirteen hours! What can they possibly put on the screen for thirteen hours?�
And then it was my turn to talk. I explained the thoughts that make up the subject of this book, starting out with the basic assumption that colors all that follows: for the biological life span of the planet, humanity is essentially extinction-proof, and, if we manage to develop effective interstellar travel, completely extinction-proof as long as the galaxy survives. Therefore, any scenario envisioning the future of biotic evolution must do so in a world dominated by humanity � just as our world is today. In such a world the range of possibilities � in particular, the probability of exotic new body plans and life forms that would make good television � is severely limited. Those that do arise will probably be small in size, for humanity

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has carved Planet Earth into a great number of tiny biological islands with our cities, farms, roads, and clear-cuts. Species that arise or evolve on islands usually tend to be small. In other words, there will be no new and exotic large mammals, birds, or reptiles.
From the silence that followed I gathered that I had not delivered the message that this producer wanted to hear. He told me quite succinctly that his program would deal with the future of evolution in the absence of humanity � that surely humans would soon go extinct. To be fair, I find this view almost universal among my acquaintances as well. There seems to be an underlying human belief that Homo sapiens will soon join Tyrannosaurus rex and the dodo in the pile of evolutionary discards � basically a guilt and shame response, I surmise (�Anything as bad as we humans will surely die off soon! Why, we may blow ourselves up next week!�).
�But what could kill off humanity?� I asked. He responded with the familiar litany: war, disease, asteroid impact, famine, climate change. Besides, he added as an afterthought, the future of animals and plants would be so much more interesting without humans � by interesting, I divined that he meant that it would make better television. I asked him to consider my alternative. His answer was that the matter was already decided. The BBC had had a meeting in Bristol, and the decision had been made: humanity would soon go extinct, and the future would be wild � the tentative name of the program. Perhaps a plaque should be mounted somewhere in Bristol inscribed as follows: �On this spot in 1999, executives of the British Broadcasting Company decided the future of the human race � and of all future evolution�.
In one regard Caius Julian of the BBC and I are in accord: The future is wild, and of this I have no doubt. But, in my opinion, not wild in the way that the BBC might think. It is far more likely that the future will be wild in the way that kayak builder and former tree house dweller George Dyson thinks � a digital wilderness of humans ��-evolving with machines, or a wilderness of genetically altered plants escaping from agricultural fields to change the world into a landscape of weeds, or a wilderness of cloned sheep walking amok among their even more staid and normally bred brethren.
There was silence on both ends of the line, and I realized that I had been daydreaming. Finally, it was time for the real pitch: would I consider filling the post of scientific advisor for the series? But we both knew that was a nonstarter now, for my view is that while the future will indeed be wild, many of its evolutionary products will be tame � further domesticated vassals of humanity. The reasoning behind this conclusion, outlined in the ensuing chapters, comes from my lifetime

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of walking ancient outcrops and visiting gravesites of the geologic past. This book might be far more entertaining if I took the road of the BBC, or of a visionary named Dougal Dixon, and portrayed an interesting bestiary evolving in a new Eden following the fall of humanity. But I do not think that those paths are anything but fantasy.
This book is a look back and a look forward into worlds past and worlds perhaps to come. How can this vision both backward and forward into time be told? Simple prose will do some of the job, but thousand-words-worth pictures will do it as well, or perhaps better. My partner and frequent inspiration in all of this has been artist Alexis Rockman, my equally dark twin. Our methodology was simple: each morning, to the delight of the stockholders of Ma Bell, we spoke on the phone, holding conversations about art, science, basketball, movies, and new visions of what might come next in the history of life on this planet. Words spoken would speciate into words written and pictures painted, followed by faxes sent across the continent or the oceans, depending on the apogees of life�s travels. Sometimes we sent each other as well; he to live with me and help me buy books, and I to sleep on his miserable couch, buy expensive New York take-out food, and live in his windowless studio where vision becomes visible; I colored his paintings and he shadowed my moods and thoughts about the future of evolution. I am a scientist but he is a naturalist, and therein lies a harmony often ending in cacophony, for the future may not be pretty, and the past has surely been brutal. So here art and science will collide as well, as Alexis Rockman takes these precepts and mediates them into images. It is our collective vision of a bit of the past and more of the future of evolution. His hands were on these keys, and mine on his brushes.
Others have also had an influence: the evolutionary scientists, of course, notably Norman Myers, Martin Wells, Robert Paine, and Gordon Orians; my colleagues in the extinction business, including my Permian companions Roger Smith and the Karoo paleontology field crew; James Kitching, Joe Kirschvink, the crew from the Foundation for the Future, and especially Sir Crispin Tickell; Dr. David Commings, Neal Stephenson, George Dyson, our agent Sam Fleischmann, and our editor John Michel. Thanks to Holly Hodder for books, and to our families for patience.

Here goes �

xv

FUTURE EVOLUTION

The farm.

INTRODUCTION

THE CHRONIC ARGONAUTS

Cambridge lies well east and north of London, nestled in a flat landscape softened by time. The spacious farms surrounding this ancient college city are furrowed in white and brown, for the plows gutter into the white chalk making up this part of the British Isles. The chalk comes from a different time; it is a legacy of a long-ago tropical sea filled with the Cretaceous bestiary of a saurian world, an era when dinosaurs ruled and seemingly had all the time in the world to revel in their hegemony. In the oceans the dominant creatures were many-tentacled ammonites, relations of the modern-day octopus and squid. Now they and their world are but memories in chalk, to be disinterred each plowing season.
Slender lanes lead from the center of Cambridge and its splendid University to both rustic working farms and more genteel estates, many of some age. One such manor house sits amid hedges and spacious gardens going wild; around back a large pond long ago given over to eutrophication reflects back the gray skies and slanting rain, while ancient trees afford some slight protection from the English weather for more zealous players on the croquet pitch. The ivy-covered house, stone cold in the grand English tradition, counts its age in centuries. A huge kitchen is its warmth, but the book-lined study is its heart. Like many old English houses, it is a hodgepodge of rooms and uneven floors, the results of successive

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owners adding on here and there, burrowing amid its warrens, building a wall or tearing one down, marking the centuries with their successive versions of home improvement. Deep in the house�s center a great clock ticks, marking time�s unidirectional progress, while deeper still the ghost of H. G. Wells just might reside.
The current owners are people of the University. Martin Wells is a professor of zoology; his wife Joyce is a financial officer. Martin has had an influential scientific career, one now far nearer its end than its beginning; he started out investigating octopuses in Naples as part of his graduate studies and continued for years after that, probing the consciousness of these arcane kraakens, puzzling over their eyesight and superb reflexes, wondering how their large brains worked. Later he moved on to explore the brains and physiology of other cephalopods, including the most ancient of all, the chambered nautilus.
It was on an expedition to study Nautilus that I first met him. We lived together on an isolated island in the Great Barrier Reef, and sailed the antipodean seas in the sun-drenched tropics to probe the most ancient of living things. I remember thinking then that Martin was slumming a bit in his nautilus studies. His first love remained the octopuses, those creatures that served as models for Martians in the most celebrated book by his grandfather, the English writer and prophet H. G. Wells. The War of the Worlds became famous for its malevolent molluscan Martians. Did H. G. ever talk to his grandson Martin about these octopus-like invaders? Somehow, in all of our long days and nights together, I never asked him; perhaps he told me, but time has erased the memory. Perhaps cephalopod preoccupation runs in the Wells family, an odd recessive gene.
H. G. was a Londoner, not of Cambridge, and he never visited the manor house now serving as the ancestral home. But if anything spiritual of H. G. still exists anywhere, it must be in this house. His memorabilia, the numerous first editions, even the remaining royalties from the great man�s publishing empire make their way here. This was not H. G.�s house during his lifetime, but it is now.
I first came to this place on a cold March day now many years ago and stayed for a week, playing croquet with Martin, drinking his elder flower wine, and plotting new research on our favorite creatures. Here he critiqued and corrected the draft of my first book, a scientific treatise on the nautilus. We talked endlessly amid the playing and drinking, and when late at night I shivered under the piles of covers in my unheated room and listened to the ticking of clocks, it was of H. G. that I thought, imagining his life, and wondering where his inspiration welled from.

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I prowled the house and perused the many books. One of my interesting discoveries concerned H. G. Wells�s first book of fiction, published in the final years of the nineteenth century. At that time, Wells was surrounded by the same end-of-century hysteria that deluged my own world as the twentieth century (and second millennium) came to a close, and surely then (as now) all eyes gazed forward toward the uncertain future. Those of H. G. certainly did. His first novel remains among his best known, a rather brief story about a man who builds a machine that can travel through time. Given the choice of voyaging either forward or backward in time, he (like Wells) is interested only in the future. His motive is simple: to see the future of humanity. The name of this novel was The Chronic Argonauts. It was later renamed The Time Machine, and literary history was made.
Hollywood and armies of pulp science fiction writers have made this story (and this genre) now instantly recognizable to us. The wonderful 1960 George Pal movie of the same name is still staple fare to those surfing across the television bandwidth late at night. But the movie plot departs significantly from the novel it was based upon, and the novel, now not so widely read, holds a number of surprises. The hero, an unnamed Time Traveler, journeys eight hundred and two thousand years into the future from the site of present-day London, and finds wonders � and horrors. Humans have changed � they have undergone evolution. They have become smaller in stature, and more feminine: the men have no facial hair, their mouths and ears have been reduced in size, their chins are small and pointed, their eyes �large and mild�. And it is not just the people that have undergone what might be called �future evolution�. The Time Traveler finds himself in an ecological habitat very different from the England of today (or of Wells�s yesterday). Wells portrays a world where the very plants have changed. Early in the book, Wells�s protagonist describes this future world in the following fashion:

But the garden is not so weedless, it turns out, for it is the former food crops that have escaped from the gardens and fields of Wells�s time to become the weeds of the future. The Time Traveler also finds that the human inhabitants, the Eloi, are vegetarians. Some of the fruits that they eat are of new varieties. Even the flowers

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are different � and most animals are now gone. Clearly a vast extinction has occurred, and a great deal of evolution has transpired. All is not novel, though, for Wells has populated this future world with some old standbys familiar in our world, including rhododendrons, apple trees, acacias, tree ferns, and evergreen trees, as well as the new types of fruits and vegetables.
The Time Traveler has seemingly landed in a Garden of Eden. The well-known plot quickly refutes that first impression, however, for Wells has populated his future world with a second human species � the Morlocks, a troglodyte race small in size, of apelike posture, with �strange large grayish-red eyes� and white flaxen hair. Wells is quite clear about the affinity of this group of creatures:

The Time Machine was first published in book form in 1895, and later reprinted innumerable times. Yet prior to its book publication it appeared in serial form in the National Review, and that version contained several pages of text omitted from all subsequent book editions. In these pages Wells amplifies his prediction about the fate of animals: by 800,000 years from now, humanity will have killed off almost all of the world�s animals, �sparing only a few of the more ornamental�. Wells is describing a mass extinction produced by the actions of humanity. There is a clear message in this novel written in the late 1890s: the plants, animals, and humans of the future will evolve from their state in the present, but many of the extant species of our world will not have a future: they will be driven to extinction by humanity.
Late in the book, there is a final, terrible prediction. The Time Traveler voyages many millions of years into the future. The sun has turned orange. Plant and animal life is sparse; he finds giant insects to be the dominant inhabitants of the Earth. The human race still exists, but has �devolved� into small creatures that look like rabbits or kangaroos. It is a dark and depressing chapter in a book already dark and hopeless in tone. The future of humanity is not extinction, it is evolution � but it is not a very �progressive� evolution, at least as many of us would like to define human progress. We do not end up as wiser, more beautiful, more refined creatures. Quite the contrary.
H. G. Wells made a number of unambiguous predictions in The Time Machine. First, the book clearly implies that evolution will continue in the future. Second,

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humanity will create a great mass extinction on Earth. Third, the surviving future flora will be filled with agricultural species run riot and turned into weeds. Finally, humanity itself is virtually extinction-proof, though it will evolve. Wells was, of course, a confirmed evolutionist. He passed his college years at the Normal School of Science in London, where he took classes on evolution from Thomas H. Huxley himself. The Time Machine is a science fiction novel, one of the first ever, but above all it is an early and prescient attempt to chart the future of evolution. A century later it is difficult not to concur with its predictions.

The Future of Evolution

What is the future of evolution? So ambiguous a question invites varied responses. As in The Time Machine, it might be interpreted in terms of outcomes: what will animals, plants, and other organisms be like at some time in the future, perhaps a thousand years from now, perhaps a thousand million years from now? The only certainty is that they will be different. Even in the near future, the mix of species and their distributions, relative numbers, and relationships with one another will have changed, and by the far future the accumulated changes may be breathtaking � or trivial. There can be no doubt that the evolutionary forces that have created the astonishing diversity of species on Earth in the past and into the present will continue creating new species and varieties, resulting in a global biotic inventory of species different from that of today. How different, and in what ways, is open to informed speculation, and is one of the subjects of this book. This particular question was addressed some years ago by author Dougal Dixon in his delightful 1970 book After Man.
Ahead of his time (if still well after H. G. Wells), Dixon echoed Wells in forecasting an imminent mass extinction, prophesying that humanity would eliminate enough of the current biota on Earth to open the faucets of evolutionary change. But here Dixon parted company with the Wells vision, for Dixon posited his new fauna evolving in a world where humanity itself has gone extinct. Dixon predicted that most of Earth�s post-extinction bestiary would evolve from the surviving meek, such as small birds, amphibians, rodents, and rabbits. Dixon�s central assumption is that humanity will biotically impoverish the planet and then have the good grace to go extinct, opening the way for the evolution of many new species. His imagined new biota depends on this central fact � that humans have gone extinct, yet left the Earth in sufficiently good repair to allow wholesale evolution of new forms. The creatures figured show evolutionary convergence: they resemble the animals that might soon be extinct on the present-day Earth. Dixon

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has thus figured animals resembling the many endangered large herbivores, carnivores, and scavengers in the varied biomes represented on the planet today. While great fun, this new fauna (like that portrayed in far less detail in The Time Machine) is a completely untestable vision residing in the realm of fantasy.
The pathway of Dougal Dixon � of imagining a subsequent fauna and flora � is one way of answering the query about the future of evolution on Earth. Yet there is another way that the question might be interpreted. Perhaps it relates not to outcome, but to the evolutionary process itself. It might mean, �What is in store for the varied mechanisms that have resulted in the various species of the past and present?� Might the �rules� governing those processes be changed in the near future � or might they have been changed already in the not so distant past?
The second interpretation of this question seems, at first, patently ridiculous. The processes that introduce novelty and evolutionary change � natural selection, mutation, sexual selection � will continue to modify the gene pools of species, occasionally resulting in the formation of new species, just as they have since life first appeared on the planet at least 3.8 billion years ago. But it may be that while process has not changed, pattern has. This is the point of another English thinker, Dr. Norman Myers of Oxford University. One of the most vocal and prominent conservationists of the late twentieth century, Myers believes that humanity has changed the rules of speciation itself. That controversial view will also be explored in the pages that follow.
Whether or not we have somehow changed fundamental aspects of how or where new species arise, it is an unambiguous fact that very early on, our species learned to manipulate the forces of evolution to suit its own purposes, creating varieties of animals and plants that would never have appeared on Earth in the absence of our will. Large-scale bioengineering was under way well before the invention of written language. We call this process domestication, but it was nothing less than efficient and ruthless bioengineering of food stocks � and the elimination of species posing a threat to those food stocks. Once the new breeds of domestic animals and plants became necessary for our species� survival, wholesale efforts toward the eradication of the predators of these new and stupid animals were undertaken. A carnivore eating humans was tolerable, because the losses were negligible, but a carnivore eating the new human food sources was not, because the losses spread to the entire group.
Our modern efforts at biological engineering are but an extension of our earlier efforts at �domestication�. Until the end of the twentieth century the natural world

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had never evolved a square tomato, or any of the numerous other genetically altered plants and even animals now quite common in agricultural fields and scientific laboratories. Just as physicists are bringing unnatural elements into existence in the natural world through technological processes, so too has our species invented new ways of bringing forth varieties of plants and animals that would never have graced the planet but for the hand of man. And, like plutonium, the new genes created and spliced into existing organisms to create new varieties of life will have a very long half-life; some may exist until life is ultimately snuffed out by an expanding sun some billions of years in the future. So what is the future of evolution? Some of it is being decided in biotechnology labs at this moment.
Humans have profoundly altered the biotic makeup of the Earth. We have done it in ways both subtle and blunt. We have set fire to entire continents, resulting in the presence of fire-resistant plants in landscapes where such species existed only in small numbers prior to the arrival or evolution of brand-bearing humans. We have wiped out entire species and decimated countless more, either to suit our needs for food or security or simply as an accidental by-product of our changing the landscape to favor our new agricultural endeavors. We have changed the role of natural selection by favoring some species that could never otherwise survive in a cruel Darwinian world over others of estimably greater fitness. We have created new types of organisms, first with animal and plant husbandry and later with sophisticated manipulation and splicing of the genetic codes of various organisms of interest to us. The presence of humanity began a radical revision of the diversity of life on Earth � both in the number of species present and in their abundance relative to one another.
It is not just modern humans in gleaming laboratories that have instituted this biotic change, or even the primitive farmers that caused the evolution of the now familiar domesticated animals beginning 10,000 years ago. Hunters have also significantly participated in creating evolutionary change that will echo through time for thousands or tens of thousands of years still to come. We have not only created new ways of producing animals and plants through brutal unnatural selection, but we have manipulated the most potent force of evolutionary change � the phenomenon of mass extinction. Humanity has created a new mass extinction � which I will show to be now largely over � that is different from any that has ever affected the planet.
A central thesis of this book is that the most consequential aspects of the new mass extinction of species so direly predicted to be awaiting us in the wings of the near future have, in fact, already occurred, at least among those creatures that contribute most importantly to the makeup of the terrestrial biosphere. One of the tenets

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of the modern evolutionary theory known as macroevolution is that mass extinction is a potent source of new species once the forces that brought it on have ebbed. According to this theory, the elimination of a majority of species (characteristic of the direst mass extinction events) opens up opportunities for new evolutionary varieties to fill the rolls of the missing. The end result is that novelty reappears on the planet. Many evolutionists have theorized that over the next several centuries humanity will directly or indirectly create just such a situation. In contrast to this position, I argue that, at least for the most important terrestrial animals, this has already happened.
The elimination of large mammals during the last 50,000 years has profoundly affected the evolutionary mix of the planet, and should create the opportunity for a new evolutionary fauna to arise � much like new plant growth following a forest fire, but in this case composed of entirely new types of species. Just such recoveries followed the two greatest mass extinctions of the past: the Permo-Triassic extinction 250 million years ago, which ended the Paleozoic Era of life and ushered in the Mesozoic, and the Cretaceous-Tertiary extinction 65 million years ago, which ended the Mesozoic and created the conditions leading to the Cenozoic Era.
The first of these mass extinctions caused a changeover from a terrestrial world dominated by mammal-like reptiles to one dominated by dinosaurs, while the second opened the way for the Age of Mammals with the complete extinction of the dinosaurs. These and other catastrophic mass extinctions in the Earth�s past were invariably followed by periods when the Earth was inhabited by a relatively low number of species, known as recovery faunas. These depauperate recovery faunas were in turn succeeded by a newly evolved group of dominant organisms, often composed of taxa different from those that dominated prior to the mass extinction.
So too with the extinction of the Ice Age megamammals, which I see as simply the opening (yet most consequential) act of a mass extinction continuing into the present day. This �modern� mass extinction has been profiled in a slew of recent books and articles, such as Ehrlich and Ehrlich�s Extinction, my own The End of Evolution, Niles Eldredge�s The Miner�s Canary, Leakey and Lewin�s The Sixth Extinction, and David Quammen�s The Song of the Dodo. If the past is a key to the present and future, we can expect the emergence of some new Age � an age of new varieties of mammals, or an Age of Birds, or perhaps an Age of animals of a body plan yet to be evolved.
Or maybe not. There are some doomsayers who suppose that there will not be good news after the bad news, or at least any time soon after the bad news. According to this school of thought, there will indeed be a new age: an Age of Weeds, or

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perhaps a Depauperate Age. The most prominent of these thinkers is Norman Myers, who brings up an intriguing and disturbing point: What if the processes and places that have restocked the biodiversity cupboard in the past can no longer operate because of the way that humankind has reshaped the surface of this planet? In the past the tropics have repeatedly reseeded the Earth with species. But it is these same tropical regions, and especially the tropical rainforests, that are being most radically affected by burgeoning human populations. Thus Myers believes that there will not be much of a new recovery fauna for many millions of years into the future � if ever.
Yet there is a third alternative. What if we are already in the midst of the new Age? What if the dominant organisms of the new evolutionary recovery fauna have already evolved? In the pages below I will try to show that a newly evolved recovery fauna is indeed already among us, composed of new types of mammals and birds unknown on Earth even 15,000 years ago: cows, sheep, pigs, dogs, cats, chickens, pigeons, barnyard ducks and geese, and fluffy Easter bunnies, among others: the familiar domesticated animals that serve as our companions and food sources. This is not to say that there will be no further extinctions in the centuries to come as humanity continues to enlarge its numbers and its hold on the Earth. But the subsequent species losses will have very little further evolutionary effect on the planet, and will occur mainly among terrestrial species of little evolutionary importance � species that will probably not be replaced as long as humanity exists.
My final proposition is that of all large animals (and certainly among large mammals) on Earth, save for the bacteria inhabiting the deep microbial biosphere of the Earth�s upper stony crust, our species is the most extinction-proof, unless a very low probability traumatic event, such as a very large asteroid or comet impact or an all-out nuclear war, comes along. Yet even in the latter case there is still a high probability that some few of our resourceful species will emerge from some bomb shelter and return to our rabbity breeding ways. This is not to say that our species will be happy, but exist we will � and as long as that happens, there will not be a new age of anything except a continued Age of Humanity.
Even in such a world there will be future evolution, and there will be new varieties of animals and plants. The current use of plants and animals with altered genomes � transgenics � ensures that the future will look different from the present, especially if one appreciates the beauty of ragweed, or can appreciate pesticide-resistant horseflies. The future may be one of runaway giant pumpkin vines and other escaped, altered agricultural crops. It will certainly be interesting.

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This book is not about cause. It is about effect. I will describe in some detail the major mass extinctions that have already occurred, but while most treatments of mass extinction focus on causes, that is irrelevant to the arguments in this book � it hardly matters whether an extinction was brought about by climate change, meteor impact, or human activity. All achieve the same effect � our story.

Eight propositions to be defended, then:

It is likely to continue well into the future. But its most consequential phase � the destruction of large mammals and birds � is already finished, and it happened (at least by human standards of time) a very long time ago. It resulted in the extinction of the dominant terrestrial organisms, the large megamammals that populated most of the land surface until the last phases of the Ice Age and into the present. This new mass extinction now preys upon the small, the endemic, and the wild species such as salmon and cod that are harvested as human food. But mostly it preys on animals and plants living on biotic islands � either real islands surrounded by water or the artificially produced habitat islands that our highways and croplands are creating. What we witness now is a highly significant yet almost invisible diminution of the smaller species on Earth, for the larger animals are already gone.

To date, it has affected mainly large land animals, island birds, and rare tropical species, although data emerging in recent decades suggest that its highest extinction rates may be shifting to tropical plant communities and perhaps tropical marine coral reefs. It is certainly causing the depletion of wild food stocks of land and marine animals. The reduction of fishery stocks is causing a wholesale elimination of major populations that may not kill off entire species (due to fish farming), but will leave the planet biotically impoverished nevertheless. Global terrestrial

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biodiversity will fall to end-Paleozoic levels because of continued extinction and the functional removal of traditional barriers to migration.

In this case, that recovery fauna is already largely in place, and consists mainly of domesticated animals and plants, as well as �weedy� species capable of living amid high populations of humans.

Many of these new species will be the result of jumping genes, as DNA from organisms created under laboratory conditions by biotechnology firms escapes into the wild. Others will be mainly small species adapted to living in the new world of spreading cities and farms. The new animal and plant species will thus evolve in the niches and corners of a world dominated by Homo sapiens. The rules of speciation have changed: few large animals will evolve as long as humanity exists in large numbers, and as long as our planet remains dividend into innumerable small islands.

Yet we are also malleable by the evolutionary forces of natural selection, and we may be seeing rapid evolution within our species at the present time, as evidenced by an increase in the incidence of potentially heritable behavioral disorders (attention deficit hyperactivity disorder, Tourette�s syndrome, clinical depression). There will also be what might be called �unnatural selection� as some segments of humanity acquire the use of neural connections to sophisticated memory storage devices. The future evolution of humanity will entail integration with machines � or perhaps we are but the midwives of the next global intelligence: machine intelligence.

Prophecy is perilous business. But there are some clues, mainly from the fossil record, about how the future of evolution may proceed. These clues and their implications are the subject of this book.

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CONTENTS