I want to tell the story of human beings beginning at the beginning, around 5 million years ago. I also want to put that history in perspective, by showing what went before it and why our own history began in the first place. The past 2,000 years of conventional history are effectively the present. The past 40,000 years, when our species truly got into its stride, is only yesterday. The 5 million years that are the main focus of this book are 'the day before yesterday'.
This book is about change - about the rise and fall of landscapes and the evolution of living lineages. I suggest that once you become aware of the idea of evolution, once you begin to feel that things do change, then your perception of everything around you is enhanced. A fourth dimension has been added to your view of the world: that of time. You begin to perceive that an animal or a plant, and the lineage to which it belongs, and the planet itself, are like a flame - not so much a thing as a performance, always becoming something else.
Proper History of Humankind
~ How The World Works
~ The Dance Through Time
~ How We Became
~ What's So Special About Us?
~ The End of Eden
~ What Difference Do We Make?
~ The Next Million Years
# A PROPER HISTORY OF HUMANKIND
How odd it is to suggest,
as historians conventionally do, that the Assyrians, the Egyptians, the
Greeks, the Romans were 'ancient'. They had advanced technologies - building,
engineering, agriculture; they made war, paid taxes, studied the stars,
developed the arts and miscellaneous philosophies, and allowed themselves
to be organised by priests, generals and bureaucrats.
The truth is of course, that the people were not 'ancient' at all. The epithet was applied by 18th century historians who thought that the world itself was new and that the people they called 'ancient' had lived near its beginning.
The particular trick of human beings is not to forget but to accumulate, over time, all the tricks of other people and of previous generations.
I suggest that the true purpose of science is not to change the Universe but to appreciate it. Most true scientists agree that the more subtle their descriptions become, the more mysterious and wonderful the Universe appears.
It is thrilling, this thought: that anywhere you stand might at different times have been at the bottom of the sea, or the top of a mountain; might have been desert or tropical forest or buried three miles under ice; might, like my own native region of London, have been the home of straight-tusked elephants and sabretooths, and your own beleagured and mystic-minded ancestors.
Earth as it stands is a miraculous jewel of a place, an oasis is an astonishingly hostile Universe. But there are other ways for it to be. The planet itself is labile; we cannot take its benignity for granted; it can be a very hostile place indeed.
# HOW THE WORLD WORKS
The key ideas of 'classical' geology and palaeontology were laid down in the 18th and early 19th centuries - including the crucial notion that the world has not always been the way it is now. Thus the traditional commonsensical view of the world - as a landscape created by God according to his mysterious will - was transformed. The Earth came to be seen as a dynamic body, its structure constantly reformed by volcanoes and sediments, and reshaped by winds and rivers and inundating and retreating seas.
There is a range of geological phenomena so extraordinary that extraordinary explanations are demanded. It is perverse of others to object to ideas on the grounds that they are outlandish, when outlandishness is obviously required. The idea that continents do not move defies common sense. It just happens to be the case, as science continues to demonstrate, that common sense, though indispensible, is not to be trusted.
India broke free from Gondwana more than 180m years ago, floated north, collided with southern Asia around 40m years ago, and has been ploughing into Asia ever since. The land in the path of India has risen to form the Tibetan plateau. This plateau has absorbed CO2 - scrubbing much of the CO2 from the atmosphere of the whole world. This has subjected the entire planet to an anti-greenhouse effect - an 'icebox' effect. This, then, the rise of the Himalayas, has been the fundamental cause of Earthly cooling since the Eocene, and all of its ecological and evolutionary consequences.
The world has now become so cold that the temperature hovers on the point of freezing; and at least ten times in the past million years the balance has flipped, ever so slightly, but enough to take us into ice age. The ice sheets on Antartica, North America and Eurasia have at times been as big as modest continents and as deep as mountains. So much water was locked within them that the sea level fell worldwide, sufficiently to join continents and countries that previously were apart - Siberia to Alaska, the islands of Indonesia to mainland Asia, New Guinea to Australia, Britain with mainland Europe - and enough to drain the Mediterranean Sea, not once but several times. That drop in turn also translates into a huge land area; so at the last glacial maximum there was 40 per cent more dry land than there is today.
It has been estimated that an extra forest the size of Arizona could absorb all the 'surplus' CO2 that the world is liable to produce in the forseeable future.
That the Earth has been struck by asteroids in the past is not in doubt. No planet or moon can escape their impact. At the very least they remind us that the Earth is not an island but part of a hostile, or at least indifferent, Universe. The questions are whether those asteroids have really been as influential as some scientists maintain; whether, as some believe, they strike at regular intervals; and, if their impact is regular, when we can expect the next.
Dave Raup and Jack Sepkoski of the University of Chicago suggest that asteroids have been a regular feature of Earth history and were probably responsible in large part not just for the demise of the dinosuars but also for many other episodes of widepsread extinction, including the five great 'mass extinctions'. In fact, they say if you look closer at the fossil record then you find 'minor' mass extinctions occuring at intervals of every 26m years. According to them, it happens that every 26m years the Earth's orbit crosses that of a belt of asteroids which, like the planets, circulates around the Sun. If they are right, then we are due for another impact, and another mass extinction of unprecedented extent, in 13m years time. We will just have to wait and see.
In practice, all lessons
drawn from history must be general, for the first, ironical lesson of history
is that nothing, including climate, ever happens in quite the same way
twice. The world was often warm in the past and it will be warm again in
the future, but the weather will be different - because the continents
are not in quite the same place as they were before, and the mountains
are not quite the same height, and the currents of the sea have found a
new position and the Earth is tilted slightly differently. In short, whatever
is happening at any one time is unique.
But the broad lessons are cogent nonetheless. History tells us that the world is capable of extremes, and it tells us too that those extremes are inevitable. Though we may have plenty of time to live our lives and spread our civilizations and species, we all of us live in the gaps between disasters. It tells us, abundantly, not to be too incredulous. It is difficult to believe that the mountains of today must once have been beneath the sea yet this has been commonplace knowledge for at least 200 years. Asteroids are a fact of living in the Universe - and *something* killed the dinosaurs.
# THE DANCE THROUGH TIME - OUR FELLOW CREATURES
We should see evolution not as a mechanism that was designed to lead to us or even - more broadly - as something that happened in the past. It is happening *now*. We are part of it. Like all living things we ourselves have evolved - and we may be transmogrified into other forms, or if we simply go extinct then we can expect that whatever remains will radiate (diverge to form new species) in all kinds of directions. If the only animals left by the time we disappear are rats, cows, chickens and cockroaches then they for several million years will have a field day, their decsendants refilling some at least of the niches now occupied by tigers, elephants, parrots and wasps.
For every present day species of animal there have been thousands in the past. The mammals of today are a shadow of former glories - even though they include some of the most beautiful and extraordinary creatures that have ever lived.
Today there are five species of rhinocerous in one family while the fossil record reveals at least 200 in three families; and whearas the present day rhinos are all tank-like and much of a muchness, some of the ancient rhinos ran like small ponies, some were more hippo-like than the hippos, and one, Paraceratherium, which lived from Pakistan to Yugoslavia in the Oligocene, was built like a massive giraffe, stood six metres at the shoulder, and was the biggest land mammal that has ever lived, dwarfing the biggest elephants.
Creatures of the past
did not necessarily do the things that their modern relatives do today.
Animals are obviously obliged to obey the laws of physics and those that
live on land are especially prone to gravity, so they cannot be any old
size or shape they choose. In practice, indeed, animals in land conform
to a rather small number of basic engineering designs which work, known
A quick survey of present day mammals might suggest that each lineage has more or less commandeered its own particular ecomorph, as if it was somehow destined to take that form and no other. Thus the only existing practicioners of the giraffe-like ecomorph, with Eiffel-Tower necks for browsing from the heights of acacias, as the giraffes themselves.
But giraffes did not invent the giraffe-like ecomorph. While the giant rhino Paraceratherium was being a giraffe the giraffids themselves resembled moose. Others that have played at being giraffes include several long-necked camels.
In short, the notion that dogs are 'meant' to be like dogs and giraffes were destined to be giraffes is giving way to the realisation that anything can be anything - or more precisely, that most big lineages at some time have explored a wide array of ecomorphs and that most ecomorphs have at different times been essayed by a wide array of lineages.
Jared Diamond of the University of California has suggested that Komodo dragons evolved their huge size specifically to prey upon the dwarf elephants of the small Indonesian islands. Most modern lizards are small enought to bask on an elephant's foot. The fact that lizards once preyed upon elephants shows what astonishing possibilities lie just beneath the surface.
The antilocarpids were once chased over the plains by the cheetah-like cats of the North American Pliocene which may or may not have been close relatives of the modern Acinonyx. Thus were enacted scenes precisely like those of modern Africa - but in a different continent and with a different cast. Nature is endlessly inventive yet endlessly reinvents.
Some bears have assumed the habit of dogs and become runners. The giant short-faced bear Arctodus simus was the biggest true land carnivore that ever lived - almost half as tall again and at least twice as heavy as a modern grizzly. It lived in North America from the early Pleistocene around 2m years ago until recent times - a mere 10,000 years ago. It had long legs for running and short jaws for gripping - in fact it was built and perhaps hunted like a giant rottweiler. It must at least have terrified the first human beings in America. Dr Valerius Geist of the University of Calgary has speculated that Arctodus simus and other bears may even have delayed the human invasion of that continent.
The largest of all living birds is the ostrich and it belongs with the ratites: the only major group of birds that have apparently been flightless from their time of origin in the Palaeocene.The greatest ratites of all were the moas of New Zealand of which there were about 15 species, some smaller than a modern emu but some far taller even than an ostrich. They survived for just a few centuries after the Polynesians arrived on New Zealand to become the Maoris, about a thousand years ago. The moas could dominate New Zealand because those islands had no native mammals. They were preyed upon by a giant eagle, one of the biggest that has ever lived, which was short-winged like the modern harpie eagles that prey upon monkeys in South America, so it could duck through the trees. But the heaviest ratites of all, and hence the most massive birds of all time, were not the moas but the elephant birds of Madagascar. The biggest species stood ten feet tall and weighed half a ton.
Many other birds, besides ratites, have re-evolved flightlessness. Some flightless types became truly formidable, for example the carnivorous diatrymids which flourished briefly from the Palaeocene to the Eocene in Eurasia and North America, and the terrifying phorusrhacids of Patagonia in South America with heads as big as a horse and huge eagle beaks, which survived from the Eocene right through to the Pleistocene. They must have hunted in packs like wolves - or indeed like some dinosaurs - to bring down a galloping litopern in full dash. Diatrymids and Phorusrhacids were relatives of the modern cranes and rails. The moorhen is a rail. Within its tiny breats is the spirit of Tyrannosaurus rex, and within its gene pool is at least some of the potential to release that spirit. It lacks only for opportunity. Perhaps its time will come again.
Taken as a whole the birds may be seen as miniature dinosaurs which could, if only the niches were again vacated, recreate a world ecology very like that of the Mesozoic.
Lions failed to reinvade northern Europe after the ice age not because they are innately tropical animals but because human beings and their farms were already too populous. Lions would now be living in France if it were not for us.
The arrangement that we see now is just the way things happen to be at the moment. We think that animals 'belong' where we happen to have found them but usually they are just passing through. Add the dimension of time, then, and we no longer see a landscape of creatures with each one doing its allotted thing in its allotted space. This radiation of lineages and swapping of roles is an important feature of what Elisabeth Vrba called the 'dance through time'.
Note how mobile the various creatures have been: that many groups have bestridden the entire globe (though usually missing out on Australia) and that where an animal lives today often bears no relationship at all to its place of origin or to its previous excursions. This restless globetrotting is the second aspect of the dance through time.
# HOW WE BECAME
The art of survival is to scrape by in the worst of times and not merely to flourish in the best.
While other mammals have made a virtue of specialization primates have preferred simply to improve on what they were given. But generality leads readily to versatility and the species that has finally prevailed, and in the end transformed the ecology of the whole world, is the one which, more than any other, has exploited this generality most emphatically. We human beings have had such extraordinary success precisely because we have not converted ourselves into horses or bats or lions. As generalists we are able to emulate any and all of them. Thus, we are the animal equivalent of the Turing machine: the universal device that can be turned to any task.
Natural selection favoured physical conservatism and hence generality primarily because the primates elected to stay in the trees.
We can spin our arms through almost all the points not simply of the compass but of a sphere. No other creatures can do this. Only the boneless trunk of an elephant or the tentacle of an octopus or the multi-boned neck of an ostrich has such universal mobility. The signifiance of this hypermobility often goes unremarked yet it can hardly be overstated. For without the mobility of the shoulder - and of the wrist - we could not make proper use of our hands.
Life in the trees demands balance, and hence coordination, in particular of hand and eye. Where the eye prescribes the body must follow precisely, for any failure is severely punished.
That the first australopithecines lived in woodland was crucial to their evolution, and hence to ours. If they had remained in dense forest it is hard to see how they could have evolved at all, for dense forest seems to demand the ecomorph of the chimp. If they had been forced to transpose in one swoop from forest to grassland then surely they would have failed, dying not least by the jaws of lions and hyaenas. But woodland is the perfect country to promote the kind of evolutionary changes that turned the common ancestor, a forest ape, into a hominid. The woodland existence of the australopithecines explains how they evolved their bipedalism: we can envisage them living a double life, half in the trees and half out of them.
On evolutionary grounds it would be surprising if the australopithecines wre not meat-eaters. We know that we eat meat, and that our immediate stone-age ancestors did. We also know, thanks to Jane Goodall, that chimpanzees not only eat meat but are formidable hunters. It would be odd indeed if the lineage that runs from chimp-like common ancestor to australopithecine to Homo had switched away from meat and then switched back again.
The australopithecines perhaps obtained only 10 per cent of their calories from meat, but this putative 10 per cent could have been highly significant. Modern nutritionists generally agree that human beings do not need to eat large quantities of meat. We are perfectly able (and indeed are advised) to obtain the bulk both of calories and of protein from plants. But very few modern nutritionists advocate a vegan diet, with no meat at all. For the protein in plants tends to be of dubious quality. It often lacks particular essential amino acids. Meat protein, by contrast, is 'first class'. Meat also provides minerals such as zinc and vitamins such as B12 which can be difficult to obtain adequately from plants. Australopithecines who ate modest amounts of meat would thereby have increased their ecological range and their survivability our of all proportion to the apparent quantity.
The way in which chimps
obtain meat is highly instructive. Specialist predators employ 'aggression'
as a tactic or indeed as an essential weapon for procuring food. A lion
that contrives to bring down a zebra runs a tremendous risk. The predator
must do as the boxer does: slip the opponent's guard and 'get inside'.
But that takes nerve and never requires hype. The necessary heightening
of mood is achieved by mental preparation and surges of adrenalin. Only
the rapid and committed strike can succeed.
The early australopithecines were not in a general way 'aggressive', any more than a lion or domestic cat is especially aggressive. But like lions and pussy-cats they were able to deploy aggression as a necessary technique for obtaining food. However, unlike lions and other cats which go about their work in appropriately professional silence, the method of the australopithecines was that of the chimpanzee: the creation of mayhem and confusion; the method of gang warfare.
Diet influences social life. Cooperative hunting requires mutual trust. Thus hunting, even on a modest scale, would have consolidated social bonds. It would also, probably, have encouraged division of labour among the sexes. Hunting is always dangerous and men, who are not needed to bear or sucke children are more expendable.
There is an odd sense in which the apparently small dependency on meat is worse for prey species than is total commitment. For the population of a specialist predator must dwindle if it overhunts its prey. But a non-specialist predator, one that can eat many different kinds of animal, or eat both meat and plants omnivorously, is not dependent on any one prey species. When the favoured prey is reduced, it simply changes diet. Amimals like us are able to break the ecological law which says that predators are bound to be rare relative to their prey.
Carnivores have had a tremendous impact upon us. Perhaps they affected the speed and direction of our migrations around the globe. Beyond doubt they helped to sharpen our wits in our long history on the plains of Africa and Eurasia.
# WHAT'S SO SPECIAL ABOUT US
Genetically, the pongid
chimp and the hominid Homo are extremely close - so close indeed that it
may be possible to form hybrids between the two. However, we cannot take
this for granted because the barriers between species do not in fact depend
only upon the overall 'genetic distance' between them but on the possession
or non-possession of genes that create barriers to successful mating. However,
I simply do not know whether hybridisation has ever been attemped between
chimps and humans.
Ecologically and morphologically humans and chimps are quite different creatures. Human beings have invented an entirely new ecomorph, a new form of creature, distinct from all other animals including the apes. Indeed, it would not be entirely foolish, if classification is to reflect the broad reality of life and not simply the niceties of genes, to place human beings in a new kingdom. In some significant ways they are as different from all other creatures as plants are from bacteria.
Many modern biologists are content to simply argue that a species is a group of organisms that is evolving as one discrete unit.
There is more to the notion of 'progress' than most scientists now acknowledge and we have already observed than evolution has an innate tendency to pursue some lines rather than others.
It is absolutely not
true to suggest that animals do not think. It is undoubtedly the case,
however, that human beings think more deeply and broadly than other animals.
When we look at the world about us we perceive many more factors than other animals do, and we are able to respond to any one of the factors in a greater variety of ways. We do not simply take the world at its face value. We have, it seems, an innate tendency to observe the patterns that underlie the behaviour of the things around us, and to infer the rules that produce those patterns.
Of course in form this search for order has culminate in the notion that the whole Universe operates according to universal laws; science being the way of searching systematically for those laws. But long before our species hit on that formal method of inquiry our ancestors perceived, for exampe, that prey animals moved to particular places at particular times.
Here is one of the points at which a quantitative difference gave rise to a qualitative advance, for once a creature begins to understand the rules by which other creatures operate then its power over them increases by leaps and bounds. Anticipation can lead on to manipulation. So, the first of our mental tricks is a great power simply to analyse - what psychologists call 'cognitive ability'.
Although we may deny
that thought in general is linked closely to verbal language, there does
seem to be a strong relationship between consciousness and verbal language.
Through consciousness we know that we are thinking. Through verbal language
we tell ourselves that this is the case.
To describe ideas in words, to point at them, is not a trivial thing to do. In the language of computers this ability enables the thinker to access his own thoughts. More: it enables us t monitor them, and to direct them.
What our language has, and that of other animals apparently does not, is syntax. Underpinning our languages are a few basic rules which enable us to manipulate the sounds - the words - in an infinity of ways; by applying the rules of syntax we can convey an infinity of meanings and infer the right meaning when another speaks.
With our kind of language,
unique among human creatures, we can in principle convey any thought of
whatever degree or detail, however abstract or concrete, from one individual
to another. With the medium of writing we can pass ideas from generation
to generation en masse through indefinite time. But even without the aid
of writing huge amounts of information can pass from parents to child over
vast sweeps of time. We know that some of the folk memories of modern Australian
aborigines are at least 8,000 years old: they tell of once familiar landmarks
that were submerged after the last ice age and have now been rediscovered
by modern divers, just as the native Australians described them.
Through the medium of verbal language all human beings may in principle partake of all the thoughts of all other human beings through all of time. Other animals transmit ideas. But no other animal approaches our degree of collective thought. Each of us has become a neurone in a global brain - a brain that thinks across time as well as space. Our perennial problem is to reap the enormous benefits of such collective thought while retaining our individuality.
John von Neumann's game theory may be seen as the mathematicisation of Machiavelli and its influence accordingly extends through all human affairs, and as we have seen, into ecology and evolution.
We do not need to develop extraordinary teeth to bring down mammoths, as the sabretooths did, or snouts for digging tubers, like pigs. With brains and hands we can make weapons and tools that can do all of those things, and a lot more besides, in some cases more efficiently than the specialists. Our universal brain and our generalised physique have made us the all-purpose animal that can in principle solve any problem that any environment can present us with, just by thinking about it. Ecologically, therefore, we are as significant as all other animals put together.
The stamina and persistence
of the human animal, and the mobility that enables us to cover 20 miles
and more a day, can clearly form the basis of a hunting strategy that differs
from that of lions or cheetahs but need be no less effective.
However, human beings are not mere lions and we know that from at least 30,000 years ago Homo sapiens were modern people, at least as brainy as we are. They could cooperate to a far greater degree than lions are able to do. The people of the upper Palaeolithic were already part of the collective human intelligence, able to communicate across space and time. Each group could build on the knowledge of other groups.
Homo erectus stopped
at the coast of south-east Asia, but Homo sapiens, arriving much later
in those parts, pressed on further. Modern humans reached Australia at
least 40,000 years ago - that is, at a time when there were still Neanderthals
in Europe. Those first Australians must have arrived by boat, for Australia
and south-east Asia have never been in direct contact.
We know too that within a few more millennia the people of south-east Asia became truly fabulous sailors, for at least by 30,000 years ago they were pressing on into the islands of the Pacific.
Migration out of Eurasis into the Americas had to wait. The first crossing was made not by boat but on foot, across the huge land-bridge of Beringia which appeared conveniently in the late Pleistocene. Most of the conspicuous animals of modern North America made the crossing at that time, including the bison and moose. Human beings followed about 13,000 years ago and then spread steadily south to enter South America about 11,000 years ago.
So by the time we reach the Pleistocene, about 10,000 years ago, human beings had colonised or at least set foot on most of the world's great land masses. Indeed only two large areas remained: Madagascar and New Zealand.
# THE END OF EDEN : FARMING
As with thinking, as with consciousness, as with speech, agriculture seems uniquely human. But when you look more closely you see again that farming is a compound skill, built from components which, taken individually, can be observed in other animals. Our special skill, then, our uniqueness, lies in our versatility - not necessarily to do any particular thing that other animals cannot, but to emulate everything that they do, and then to mix and match.
Since farming is so dominating, since it obviously confers such power, and since it has given at least some of us a life of unprecedented ease, it seems obvious that once that once human beings realised the advantages of farming they would have thanked their gods for the new enlightenment and got down to it with a will. That is how traditional archaeologists envisaged matters. Modern scholarship puts the origin of farming in a very different light.
The earliest hard evidence
of true farming dates from the Middle East of around 10,000 years ago.
The problem is that farming in its early days seemed to offer very little
advantage indeed. In fact more and more evidence suggests that it was ghastly.
The diminution in body size seen in the first domesticated animals is also
seen in the world's first farmers. Along with that general enfeeblement
there is often a bending and thinnng of bone which suggests disorders of
privation from rickets to tuberculosis.
The Old Testament confirms again and again that the life of early farmers was harsh indeed. Clear too in the Old Testament is a yearning for the old days of hunting and gathering. Eden is seen as the lost paradise, and although it was presented as a 'garden' there is no suggestion that Adam and Eve were called upon to cultivate. The bounty was just there. Thus when God expelled Adam from Eden it was with a curse - the curse that Adam must become a farmer.
The general impression is growing then, that farming in its early days was unremittingly harsh; the hunting-gathering days that it replaced, on the other hand, were remembered with affection and nostalgia, albeit in a folk-memory that by the time of Genesis was about 6,000 years in the past. Why should thinking people have abandoned an apparently easy way of life in favour of one which, until the last 20th century AD has remained unremittingly awful?
There are reasons bordering
on the mundane why agriculture took off in the way it did in the Middle
East. Middle Eastern people became committed farmers because they were
pushed into it. And what pushed them into it was the end of the last ice
age, around 8,000 years ago. For with the end of an ice age comes flood.
Water runs off the land and rushed to augment the sea. People who live
near estuaries are caught two ways: by the rivers flooding out, and the
seas surging back in. And many people do live by estuaries.
Thus it is that 500 or so of the world's mythologies includes accounts of flood. The area that gave rise to Sumeria, Assyria and Babylon and is regarded as the birthplace of western civilization is Mesopotamia, which was and is especially flood prone. The particular account of Noah is only one of many such stories from that region. Indeed the same story has been traced to The Epic of Gilgamesh.
At the height of that ice age around 18,000 years ago the sea level dropped by 150 metres, so that there was 40 per cent more dry land than there is now. When the ice age ended, that 40 per cent disappeared beneath the rising sea.
the nature of the game. Farmers have a relationship to their resources
that differs from that of hunter-gatherers and of other animals. They are
limited by the generosity of nature, and can eat only what nature chooses
to provide. But if a farmer wants more food he merely has to work harder.
The crucial logistic point that follows is that hunting and gathering offers only modest reward for extra endeavour, and will stifle whoever is over-ambitious. The hunter has a strictly limited output which in turn defines his sensible input. The farmer has not. The ecological impact of each individual human being is increased tenfold, perhaps a hundredfold - simply because each individual works harder.
The world clearly could support the present human population of 5 billion plus - the cause of the ever present famines lies in politics and not in the physical limits of the world. But we can seriously doubt whether the world could support 10 billion, or 20 billion.
# WHAT DIFFERENCE DO WE MAKE
In the 18th century Jean Jacques Rousseau established the myth of the 'noble savage' who, whatever he lacked in European graces, was supposed to live in harmony with his fellow creatures.
The modern hunter gatherers
who were newly discovered in the centuries before Jean Jacques Rousseau
may seem to have lived in harmony with the creatures that still surrounded
them, but those creatures were only the vestiges of former glories. It
was picturesque, but it was devastation nonetheless.
The hunting and gathering people who survived into modern times clearly protected many of their prey animals by taboos: exactly comparable with the western laws that now protect 'game'.
What Rousseau and his 18th century comtemporaries did not begin to suspect, and what indeed is only now becoming apparent is the sheer scale of destruction that had taken place on tropical islands before the Europeans arrived and recorded the remaining fragments. The travellers undoubtedly encountered pristine flora and faunas on some islands - those that human beings had not previously visisted. But however wondrous they may be, the floras and faunas of islands never approach the sheer opulence of continents - and no one in historical times has ever seen a continental fauna in its proper state of glory. Only Africa, and then only in parts, approaches the pristine states that obtained worldwide until the late Pleistocene.
Ironically, some of the countries that are now regarded as the 'wildest' and most 'natural' are in fact the most degraded. The highlands of Scotland have become a symbol of natural wilderness though they contain effectively nothing but red deer and grouse for shooting - and yet those mountains and valleys would still abound with moose, wolf, lynx, beaver and bear were it not for our nobly savage ancestors and the zeal of Tudor ship builders.
The facts of the matter
are only now coming fully to light. First, a huge number of creatures all
over the world disappeared during the late Pleistocene and continued to
die out en masse well into modern times. Secondly, this die-off coincided
with the spread of human beings around the world, initially from Eurasis
into the Americas and Australia and then into the islands of the Indian
Ocean and Pacific, including Madagascar and New Zealand and those of the
The charge is that the deaths of those extinct animals were casued by the diaspora of modern humans - in other words, that our ancestors, wilfully or inadvertently, killed the creatures. In fact this putative scenario has been called the 'Pleistocene overkill' although it actually extended well beyond the Pleistocene.
But were our ancestors truly responsible for the deaths of the animals with which they once shared the planet?
There is a bias in the pattern of extinction - for large species suffered far more in the putative overkill period than small ones. If climate caused the extinctions then we would expect the small creatures to suffer more. And, although there are problems with dating and sampling (it is difficult or impossible to identify first events), it seems that the extinctions in each particular location generally occured soon after the arrival of human beings.
People arrived in North
America via Beringia some time after 13,000 years ago. Their direct descendants
are still there, now known as 'native Americans'. The large mammals that
survived their coming, and are with us still, span twelve genera. There
are moose, deer, bison, oxen, pumas, wolves and various bears. There are
several 'feral' types as well - domestic animals gone wild, including burros
and mustangs. However, until at least 100,000 years ago North America had
45 genera of large mammals - including giant sloths, spectacled bears,
sabretooths, cheetahs, giant beavers and camels.
Note, finally, that the large mammals that survived the advent of human beings were largely of Eurasian origins. In other words they were accustomed to human beings, having been hunted by them for tens of thousand of years. Many of the survivors, too, are either solitary or given to unpredictable migrations, making them more difficult to hunt in a concentrated fashion.
The big African mammals have been adapting to hominind hunting tactics for 3 million or more years, and their various evasive tactics - including erractic migration - were probably shaped in large part by the hominid presence. But the human beings who first came to the Americas and Australia were fully-fledged hunters with novel tactics, thrown suddenly among creatures who were entirely naive. Human beings and the post-Pliocene Arican fauna had the chance to coevolve side by side.
Because islands cannot
support large mammalian predators, the prey animals no longer find it advantageous
to be really small: after all, mice evolved their exiguousness principally
to be elusive. So while the big mammals become small, the tiny ones tend
to grow larger. Thus Malta once had dwarf elephants and giant dormice;
perhaps, with time, the two would have met in the middle. On the continents
of Europe and Asia such ecomorphs would have made no sense at all. But
islands have their own rules.
Many reptiles too, become giants on islands. Predatory reptiles need far less food than mammalian carnivores and in the absence of mammalian competitors seem to come into their own. Thus Australia - an island continent - once had an impressive suite of land crocodilians and a truly massive goanna.
Until a thousand years
ago New Zealand contained one of the finest suites of creatures that has
ever evolved in any country - one that shows what evolution can do, given
a promising gene pool and a free hand. That fauna largely consisted of
the moas. Now of course they are all gone. Gone, too, from those halcyon
and not-so-far-off days are various rails and the giant short-winged eagle
that preyed upon the moad in what must have been among the most dramatic
confrontations in nature.
In one striking respect the extinctions of New Zealand contrast with the first wave of destruction in the Americas and Australia. On those continents, only the big animals apparently suffered. But the Maoris brought with them the Polynesian rat, which winkled out the small creatures that would have escaped the attentions of humans. It is for similar reasons that the invasions of modern Europeans have often been even more devastating than those of prehistoric peoples.
The Australians with their dingo, around 5,000 years ago were among the first to demonstrate that humans-plus-hangers-on are even worse than humans on their own.
The theoretical case for the prosecution which says that Palaeolithic and recent hunter-gatherers could have killed vast suites of large animals rests of three main points: that large animals are much more vulnerable than they seem; that human beings are even more destructive than they seem; and that surprisingly modest pressure of the kind that humans can bring to bear can all too easily drive sensitive creatures to oblivion.
The big animals that remain to us are, for one reason or another, the least vulnerable. The more vulnerable ones have already gone. In general, the ones that survive now are the ones that were least easy to wipe out. The tough survivors have given a false impression. The creatures that are long gone were far more sensitive than the survivors - and far more typical.
Paradoxically, because we are so versatile, and do not rely absolutely on any one prey species, we can be far more destructive of prey species than a specialist can. Versatile predators can and often do drive some at least of their prey species to total extinction, while they happily subsist on others.
We know from their anatomy and from all other signs - including their weapons and their paintings - that the upper Palaeolithic people were as clever as us. In those days circumstance obliged them to be full time hunters. As people they lacked nothing, and I see no reason to doubt that the practised the crafts of their time as efficiently as their descendants practise those of the present.
Crucially, human beings developed the use of the missile. With a spear, a hunter can deliver a lethal blow without ever running the guantlet of the prey's defences. In short, human beings acquired the ability to hunt large and eminently rewarding prey effectively without risk. No predator in all the rest of nature has ever enjoyed such extraordinary advantage.
In general, human beings are far more disturbing than any other predator. Lions may walk in full view within a hundred yards of antelope without disturbing them. Provided the antelope can keep them in view they know they are safe. But prey animals are not stupid. They know that human beings have missiles and, uniquely, can kill from a distance. So human beings cannot walk openly within a hundred yards of wild antelope. Indeed on walks on agricultural land if you keep your eyes open you can see crows and pigeons take off from trees half a mile away. You normally do not notice them - but they notice you. The safest option is simply to give our species a wide berth.
Why should we doubt, either, that those advanced stone-age hunters preferred some creatures to others - and knew how to advance the cause of those they liked and undermine the ones they did not? And if they decided that some creatures were bad news, why doubt that they might have targetted them? They knew perfectly well - they were modern people after all - that it is the young females that give birth. If an animal is of a kind you feel you would be better off without then you should kill the ones with the swollen bellies. Perhaps they decided too, with even greater sophistication, that they would be better off without large rival predators, and set out to remove the principal prey-base of those predators. Get rid of mammoths and giant sloths and you eliminate sabretooths and the giant running bears.
The pattern of extinction worldwide is exactly what you would expect if human beings had been directly responsible for the animals' demise.
Of course we killed them. Other factors did play a part in the Pleistocene and post Pleistocene extinctions, of course. Climate alone night have done the trick here and there. But the coup de grace, and often the sole operant, was ourselves.
# THE NEXT MILLION YEARS
All times are unique; all times are special. But some are more special than others and the age we live in now is crucial.
Throughout the Cenozoic
most species of mammal lasted roughly a million years and then went extinct
or evolved into something else. There are no innate mechanisms to limit
the span of a species, at least none that are known about, but that is
the way things have tended to turn out. So what are the chances of Homo
sapiens lasting a million years?
There is no a priori reason why our species should survive for so long. On the other hand, there are some very good biological reasons why we might last in recognisable form until the dying of the planet - because in theory there is less cause for us to alter and also less opportunity.
Already, of course, we have had some of that arbitrarily allotted span. But not much. The species Homo sapiens has been anatomically modern for about 100,000 years.
Until human beings were finally obliged to commit themselves more or less fully to agriculture, about 10,000 years ago, the restraints on their population growth were all too obvious. Resourceful as they were they still had to compete with bears, and the supply of mammoths and gazelles was all too fragile. It seems, indeed, that by that time the human population had reached a maximum of 5-10 million. But the final commitment to agriculture removed the restraints.
Any policy of conservation that does not take full account of the reasonable needs of the human species. The human activity that affects the planet most is that of food production. So we need to devise systems of food production that meet our own needs and at the same time leave room for our fellow species.
Intensive agriculture is not innately polluting, and if agriculture is practised truly intensively, and cleanly, then it is benign precisely because it releases land for other purposes including the conservation and creation of wilderness. The current 'set-aside' policy in Europe shows this principle in action. In truth it is extensive agriculture that needs to justify its existence, amd it can do so only if it does indeed benefit particular wildlife. This can be the case - as in the south of England, where traditional grazing of sheep preserved the short grass of chalk download, and allowed a suite of ice age species to survive that otherwise would have been swamped by advancing forest.
The 'traditional' British landscapes are 'man-made', the landowners can claim much of the credit, and at its best in the Scottish highlands and the English lowlands that landscape is indeed glorious. I chauvanistically suggest that there is none more beautiful in the world. Yet this is the glory of devastation. The green lush fields of England were once covered by open oak forest from border to border. In fact Britain retains less of its pristine forest than any other country in Europe. We also retain fewer of our large animals.
So long as we live in a world in which the only things that are truly valud are those that have a discernible price it is worthwhile at least at attach some prices. I often wonder, whimsically, why people pay thousands for Faberge eggs and tread on beetles. Looked at closely, and objectively, the beetle is more beautiful.
The issue here, however
is that of bona fide neodarwinian evolution: whether it is possible to
change the overall gene pool of human beings to such a significant degree
that our descendants can properly be considered a different species. The
short answer, on purely theoretical grounds, is Yes. It is obvious after
all, that the human gene pool is changing. Even so, we cannot argue that
such fluctuations truly represent 'evolution'. The loss of alleles, sad
though it is, is genetically marginal.
The raw material for evolution, genetic variation, is there. But the key ingredient is missing. Natural selection is simply not acting forcefully or consistently on that variation. The loss of alleles is random - at least, we cannot argue that particular alleles are being lost because they are disadvantageous. Finally, and I think crucially, the human population is just too big to change significantly by neodarwinian mechanisms.
People seem to confuse 'progress' with 'destiny'. 'Progress' in general is likely to happen. 'Better' creatures are bound to appear through the chance process of mutation, and having appeared they are likely to succeed. Furthermore, some lines of development are more likely than others. Animals must obey the rules of engineering, which are founded in the laws of physics, and in practice only a limited range of body forms, or ecomorphs, is feasible.
But we cannot in the least predict which particular creatures are liable to evolve. It would never have been possible to predict that life on Earth would have produced Homo sapiens, or indeed the hominids as a whole. More generally, there is no reason whatever to suppose that intelligence of human proportions would ever have appeared among any lineage.
Natural selection can realise only a subset of the theoretical possibilities, and it will realise only a small proportion of that subset on this Earth before the Earth itself finally dies. But we simply do not know what could evolve before this planet dies, because we simply do not know the potential of present-day life. We cannot tell, by looking at existing life, exactly what life is capable of. We really do not understand enough about the properties of matter to stage categorically that the abilities of present-day creatures represent the full repetoire of possibility. There could be many surprises in store.
# IN OTHER'S WORDS
History as its most
subversive - history that both terrifies and inspires.
- Washington Post
# THE GEOLOGICAL TIME SCALE
to 544 mya) * mya = million years ago
Hadean (4500 to 3800 mya)
Archaean (3800 to 2500 mya) Bacteria
Proterozoic (2500 to 544 mya) Continents, Oxygen
Vendian (650 to 544 mya)
Phanerozoic (544 mya to today)
Paleozoic Era (544 to 245 mya)
Mesozoic Era (245 to 65 mya)
Triassic (245 to 208 mya)
Jurassic (208 to 146 mya)
Cretaceous (146 to 65 mya)
Cenozoic Era (65 mya to today)
Tertiary (65 to 1.8 mya)
Paleocene (65 to 54 mya)
Eocene (54 to 38 mya)
Oligocene (38 to 23 mya)
Miocene (23 to 5 mya)
Pliocene (5 to 1.8 mya)
Quaternary (1.8 mya to today)
Pleistocene (1.8 mya to 11,000 years ago)
Holocene (11,000 years ago to today)
# RECENT ERAS
[ Quaternary Period
- Cenozoic Era ]
Pleistocene : 1.8 m -> 10,000 BC
Holocene : Present
[Tertiary Period -
Cenozoic Era ]
Pliocene : 5m -> 1.8m
Miocene : 26m -> 5m
Oligocene : 38m -> 26m
Eocene : 54m -> 38m
Palaeocene : 65m -> 54m
# PREHISTORIC TIMESCALE
Lower Paleolithic Age
250,000 - 90,000 BP
Middle Paleolithic Age 90,000 - 30,000 BP
Late Paleolithic Age 30,000 BP - 7000 BC
Neolithic Age 7000 - 4800 BC
* BP = Before Present
* BC = Before Christ
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