Astronautical Evolution

Stephen Ashworth, Oxford, UK

~ 3 ~

The snakes and ladders model

When the Soviet astrophysicist N. S. Kardashev considered the problem of detecting possible alien civilisations, whether in our Milky Way Galaxy or beyond, he speculated that observable civilisations might exist on any of three possible levels, Kardashev levels I–III, thus:

Level I:Civilisations using all the power available to them on a single planet;
Level II:Those using all the power available in a single planetary system;
Level III:Those using all the power available in a single galaxy.

This scheme has become well known among those interested in the search for extra-terrestrial intelligence. But since societies of less than global stature are undetectable at interstellar distances, Kardashev did not distinguish between them, and so his scheme failed to connect with the conventional study of human history and politics.

Carl Sagan introduced two extensions. Firstly, he subdivided each level into ten sub-levels according to the total power consumption. Starting with level I = 1016 watts, level II = 1026 watts, level III = 1036 watts, each 0.1 of a level represents a change in consumption by exactly one order of magnitude. Then he added a letter to represent a civilisation’s information processing capabilities, starting with A = 106 bits (roughly the information content of spoken language).

On this ranking, our present-day global society comes out as a level 0.7H civilisation (consumes about 1013 watts, processes about 1013 bits of information).

This extended Kardashev classification can now include early industrial and pre-industrial societies. But it introduces a new flaw: it obscures the erratic nature of growth by giving a false impression of smooth continuity from one level to the next.

The reality is that different levels are set off from one another by periods of social and technological revolution, and very few societies in a position to progress from one level to another actually do so.

Like Carl Sagan, I believe that a two-dimensional description of civilisations would be useful. But surely energy consumption and information processing are correlated, together with other factors? They are two different measures of the same dimension. We have not seen societies with nuclear power stations whose physics textbooks only exist in manuscript, nor societies whose digital computers are powered only by clockwork or water mills. Nor do we expect to find any.

Our model should start from the pre-industrial development of an intelligent species such as Homo sapiens, and then move on to its industrial mode, thus making explicit the relationship between them. This study will show how a spacefaring civilisation can grow naturally out of earlier social phases, but will not necessarily do so.

Our picture should also make a clear distinction between three fundamentally different kinds of society: those convulsed by the turmoil of progressive growth, those stable, static or stagnant societies which experience little structural change, and those suffering from slow decline or more rapid collapse.

My claim is therefore that I can describe the proper place in history of any civilisation by specifying both its level of attainment and the direction – growth, stasis or decline – in which it is moving.

The idea of different social levels connected by periods of abrupt growth or decline suggests the image of a game of snakes and ladders.

Imagine the board on which this game is played, with a number of rows of say ten squares each. Each row represents a different level of social development, but (unlike the real game) is disconnected from the rows above and below, forcing each player to move their counter from side to side along a single row, backwards and forwards.

Players only move to a different row after encountering a snake or a ladder: ladders take you up, and snakes down, one level at a time. Peoples move about in this game space, propelled from square to square partly by the throw of the dice, partly by local conditions (landing on the head of a snake or the foot of a ladder).

This, then, is the snakes and ladders model. It expresses in a simple visual metaphor five fundamental ideas about history:

(1)Different levels of organisation of society are possible;
(2)The levels roughly group together related changes in geographical scale, power usage, information, manufacturing and bio-technologies, complexity, and ethical values;
(3)The levels are related to each other in an ordered hierarchy;
(4)Each level offers the risk of decline to a lower level, but also, if conditions are favourable, the opportunity for expansion with the reward of progress to a higher level;
(5)The direction in which a society changes at each level is in no way predetermined: it may be upwards or downwards, or indeed sideways within a single level, and will in each case depend upon the balance of internal and external conditions – cultural, economic, physical, microbiological, astronomical – effective at the time.

In other words, no law of history is claimed: there is no presumption of inevitable progress or decline, but merely a route map of possibilities along which societies may evolve in whichever direction they are impelled by a mixture of internal and external forces, or on which they may settle for a while at a point of temporary stability or stagnation.

Although it does not lay down any law of inevitable change, the snakes and ladders model – like Kardashev’s system – does incorporate a value judgement about what is important. It is a resolutely Western perspective on history and social change.

It stands, for example, in sharp contrast with a particular religionist worldview in which the single significant factor is the personal relationship of individuals with an imaginary all-powerful alien being, as expressed in their day-to-day behaviour and attitudes. On this view, questions of a civilisation’s technology, geographical scale, power consumption and so on are irrelevant to the important business of the salvation of the soul, being merely part of the material universe, which the imaginary deity is likely to annihilate at any time. In the teachings of leaders such as Jesus Christ, as reported in the Gospels, material prosperity is even held to be an active impediment to true enlightenment.

The idea of ‘lower’ and ‘higher’ levels of development has also come under attack from post-modernist ideas of cultural neutrality – not to mention that extreme reaction against modernism which makes the inverse valuation when it favours a simple rural existence over city life with all its complexities and villainies, its hectic money-making and its obsessive industrial activity. So let us remind ourselves of the place of human history in the real universe.

We are one species among many on Earth: currently a very widespread one, although a global climate change of a few degrees either way – perhaps induced by variations in the heat from the Sun, or by dust collecting in the stratosphere from passing comets or volcanic eruptions – or some internal flaw in our makeup or institutions, producing perverse behaviour and leading to self-destruction – any of these could cause our population to crash. Then different species would dominate the top of the food chain on Earth – although on present showing none would display our zest for innovation for a million years or more into the future.

But suppose that humanity avoids the pitfalls and settles down into a comfortable zero-growth global society, in total harmony with its environment. Its eventual extinction is equally certain. The unpredictable movements of historical forces, the unruliness of human nature – these are always liable to throw up a military or economic crisis, no matter how careful the political safeguards that attempt to suppress them. Meanwhile, the fossils of extinct mammals and reptiles stand as petrified witness to the fact that in the pre-industrial natural order of things no species lasts for ever.

Either way, the million-year wheels of biological evolution, combined with whatever cosmic circumstances visit Earth from outside, will continue to turn slowly but surely, throwing up one new species after another, driving each in turn to ultimate extinction and replacement.

Eventually the Sun will gradually expand into a red giant before fizzling out and leaving a feeble white dwarf star behind. The living Earth will be consigned first to the furnace, then to the freezer. The universe will continue as if Earth had never existed, and all the struggles and sufferings of people throughout history will be deleted from its memory forever. (Unless you believe in an imaginary continuation universe where everyone goes after they die.)

What is the alternative? Clearly, to continue to grow and diversify. The universe is still young. The technobiota is chipping at the shell of its planetary egg.

If we value our unique contributions of culture and creativity to the evolution of intelligence and compassion in the universe, not to mention our collective survival and our children’s future, then we will assert that there are lower levels of social development which give us limited opportunities, and higher levels which give us a wider range of choices, and we want to progress from the lower to the higher, and in so doing are willing to cheerfully undergo the growing pains of our civilisation, be they nuclear or genetic or economic or psychological in character, in furtherance of our collective goals of ever greater prosperity, knowledge, moral judgement and security.

This attitude is fundamental to Western civilisation and culture.

Do not imagine for one moment that I am suggesting there exists any mystical or moral or existential imperative that humanity should continue to grow. Perish the thought! Whether a people or a species turns towards or away from the opportunities in front of it, that is equally the outcome of the sum of all the haphazard impersonal forces acting on it at that moment in time. It is not at all a matter of social morality or divine guidance or mystic destiny, but of practical, system-level evolutionary processes (including any cultural beliefs in manifest destiny, mystical hocus-pocus and such like).

The levels in the snakes and ladders model can be illustrated with an astronaut’s eye view of human history and prehistory.

A detailed discussion of the different levels of human society would compare them in terms of their spatial range, power consumption, characteristic technologies, life-support systems, political, military and police institutions, population size and density, and worldview and ethics. All these diverse factors are broadly correlated together on at least six main levels of development, giving us a summary overview of social change over the ages.

Out of the biological matrix

Before anybody can get onto the snakes and ladders model, haphazard biological evolution must first produce a land-dwelling species with the essential physical attributes necessary for civilisation: a large brain, organs of communication, some kind of social structure, and the specialisation of limbs into legs for walking and arms and hands for carrying and manipulating objects.

The dolphin possesses the first three of these, but is an evolutionary dead end so far as civilisation is concerned, partly because it has no hands, partly because, living permanently in water, it can never master the use of fire. The development of dolphin intelligence must therefore remain at its current, pre-technological, level, unless or until dolphins engender a daughter species which returns to the land, millions of years in the future.

Given the right biological hardware, it becomes possible for it to develop further in parallel with a species’ cultural software, in a process of coevolution.

Professor Stephen Oppenheimer argues that the dramatic growth in brain size, experienced by a number of early hominid species of genus Homo and Paranthropus between 2.5 and 1.5 million years ago, was driven by their invention of language. It’s good to talk. [14]

The study of our past evolution is confusing, due to a glut of theorising and a scarcity of fossil evidence. But the broad outlines of what happened seem to be clear enough.

Around 6 million years ago, there existed a chimp-like species of African ape which sometimes walked on the ground on its hind legs, though with difficulty, and had a relatively large brain, though not powerful enough for tool-making or language. This species split into two populations, as species do over the millennia. One of the branches has changed very little over the intervening time, and survives today as the modern chimpanzee.

The other branch was forced by local circumstances or by acquired habit to do rather a lot of walking and running on two legs, perhaps using its hands for carrying food, or wielding sticks to fight off predators. Its anatomy therefore evolved to make this easier (those who ran slower tended to get eaten before they had produced offspring). This trend to bipedalism may have been driven by a long period when the climate became cooler and drier, causing the tropical forests to retreat and the wide open savannah to expand.

Around this time too, our ancestors must have begun to adapt to freshwater and coastal environments. They acquired the ability to swim, voluntary control of their breathing, and buoyant subcutaneous fat resembling that of dolphins and seals, and they lost most of their body hair. The agility required for swimming would also have helped them to attain an upright walking posture. The nutrients from eating fish and shellfish would have been especially beneficial to the growth of the brain. [15]

At 4.5 million years ago this branch is known as Ardipithecus, which was partly bipedal but still generally apelike. By 4 million years ago, Ardipithecus had engendered a group of species with much improved bipedal walking ability, but still with chimp-sized brains, known to science as Australopithecus, and to everyone else as ‘Lucy’.

At some point between 4 and 2.5 million years ago, one particular species of Australopithecus (from the fossil remains it is hard to say exactly which one) hit on greater social coordination as a survival strategy. For this, they needed better communication among themselves, and so they began to develop a complex spoken language. The deep thought required for processing verb tenses and conditional clauses created a selection pressure that made their chimp-class 500 cc brains increase in size and processing power.

At 2.5 million years ago, the global climate took a decisive turn for the worse as Earth entered the Pleistocene epoch of fluctuating ice ages (in which we are still living). During especially cold periods huge volumes of water were locked away in the polar ice caps. In Africa this was felt in the form of greatly reduced rainfall, as a result of which formerly rich grassland and forest became uninhabitable desert, making survival much more difficult for all large mammal species, including our ancestors among the australopithecines.

At about this time, the talking species of Australopithecus divided into two groups of daughter species: Paranthropus, which specialised in a vegetarian diet, and Homo, which continued to enjoy a nice juicy steak with their veg. In both cases, their dependence upon speech maintained an evolutionary premium on brain size, which consequently more than doubled over the next million years or so. Surviving fossils of both groups of species show increasing skull sizes as they developed their mental and communication skills.

Our ice age ancestors lived in a Tolkienesque Middle Earth where a number of different more-or-less intelligent species coexisted. The real-life men, elves, dwarves, orcs and hobbits were Homo habilis, ergaster and erectus, Paranthropus boisei and robustus, and late-surviving species from the Australopithecus stable. Later in time, Homo sapiens shared the European forests with Homo neanderthalensis and heidelbergensis.

There were successive expeditions out of Africa to colonise Asia and Europe, starting from about 2 million years ago. Yet, as Professor Oppenheimer reports, genetic analysis has established that every modern human is descended from a small African population living about 190,000 years ago, and every modern non-African is descended from a particular ice age exodus out of Africa 80,000 years ago.

The wanderers appear to have followed the coast – the ‘beachcombing route’ – from the Horn of Africa round southern Arabia and India to Indochina, then southeast to Australasia and northeast to China and Japan, exploiting their ability to swim. When they entered the continents, it was usually by going up river valleys.

All the other human and near-human species became extinct, whether through competition for food, or environmental stress. The neanderthals were the last to disappear, around 28,000 years ago, leaving modern humans as the sole survivors of the diverse flowering of hominid species from 6 million years ago, together with our cousins, the evolutionarily conservative, non-speaking, chimpanzees.

The first stone tools date from 2.5 million years ago, correlating with the start of the period of dramatic increase in brain size.

Chimpanzees are able to use sticks as tools, but not to manufacture stone tools, which are the first rung on the ladder of material wealth. In a recent experiment, an attempt was made to teach a male bonobo (or pigmy chimpanzee) how to chip sharp flakes from a stone, using a 2.5 million year old technique. Despite the fact that the bonobo had spent many years in human company, had acquired some understanding of spoken English, could communicate back with a computer keyboard, and needed a tool with a cutting edge in order to open food parcels, he never mastered the technique. [16] This supports the view that the 500 cc chimp brain is just below the capacity (for that size of body) needed to embark on tool-making.

There was nothing inevitable about our ancestors acquiring unusual mental powers and manual skills through the coevolution of brain, language and hand.

If circumstances had been slightly different, all the species of Homo could have died out and the world taken over by a vegetarian Paranthropus civilisation instead. Or all the australopithecines could have become extinct before they ever embarked on mental development. Or those that did might have subsequently encountered a new set of evolutionary pressures which reversed the trend in brain size.

Then again, intelligence could have evolved a long time earlier. Certain species of dinosaur among the dromaeosaurids and troödontids had about the same size and weight as we do. They stood on their hind limbs and used their front ones to catch food. Their front paws had an opposable thumb, allowing them to grip objects just as we do. They had a relatively large brain, about 100 grams in weight rather than the few grams typical of other dinosaurs. Given millions of years of conditions causing them to evolve towards greater intelligence, they, not us, could have been the first to build libraries, compose symphonies, launch nuclear submarines and debate rights and duties.

But it was not to be. Their further development was abruptly cut off by the mass extinction of 65 million years ago, apparently caused by the impact of a 10 km asteroid off what is now the Yucatán peninsula of Mexico, combined with enormous volcanic eruptions on the opposite side of the globe in what is now India.

Even without that double catastrophe, it is impossible to guess whether any of those dinosaur species would have encountered the narrow range of environmental conditions capable of stimulating their intellectual growth. It is more likely that they and their successors would have died out before that ever happened – especially since, in terms of increasing their brain size, they had much further to go than the australopithecines.

Level 1: The stone age order

The early humans of between 1 and 2 million years ago, Homo erectus, possessed brains not much smaller than our own, and had many of the capabilities which came to distinguish modern man. They used fire, though it is impossible to say when they first became able to make it. They possessed stone tools such as axes and scrapers for skinning and cutting up large animals, and were able to systematically use tools to make tools. They left behind the earliest constructed dwellings and the earliest wooden spear and wooden bowl.

The evolution of anatomically modern man, completed by the last warm interglacial period around 130,000 years ago, was accompanied by signs of further distinctively human activities: the wearing of animal skins for clothing, ritual and ceremony surrounding the burial of the dead, warfare between tribes, and the striking cave art of south-west Europe, Africa and Australia.

It must have been the discovery of how to make fire that most clearly distinguished early modern man’s significance and future potential. Here was a way to warm himself when it was cold and light up his surroundings when it was dark; here was a way to drive off the most ferocious beasts; here was a way to cook food and refine metal; here was the key to future industrial revolutions as yet undreamt of.

The first level on the snakes and ladders model is therefore that of stone age nomadic tribes supporting themselves by a gatherer-hunter-scavenger lifestyle.

‘Innovation’ is not a buzzword in this type of society. The stone age pattern of life can continue almost indefinitely, the only modifying forces being the slow machinations of biological evolution and climatic variation. Homo erectus lived for over a million years without seeing much change, and after they had become extinct Homo sapiens continued at first with the same lifestyle. The stone age way of life survived into the 20th century in a few places, as exemplified by those Eskimos, Australian Aborigines, Kalahari Bushmen and Amazon and New Guinea tribes who had avoided, until then, being drawn into the culture of progress.

We can only guess at their mental world. Historian Alan Taylor provides a glimpse of what the worldview of stone age peoples may have been in his comparison of the cultures of the pre-Columbian inhabitants of North America and their European colonisers. [17]

Level 2: The local order

The end of the last ice age brought change at a faster rate in the form of the neolithic revolution, some 12–7,000 years ago. For the first time, tribal communities of the still young human species experienced a dramatic change of lifestyle.

The second level, organised on a local scale, is conventionally defined by the revolutionary invention of agriculture, both crop farming and animal husbandry, firstly in the Fertile Crescent of the Near East, a little later in China, Central America and the New Guinea highlands. The pattern of parallel development at widely separated locations suggests a common environmental factor in the global warming from ice age to interglacial conditions.

At the same time, there was a revolution in social and economic complexity, and a commitment to settling down in a fixed locality.

Though still organised in small tribal units, they created a sufficient surplus of food to allow specialists such as potters and priests to earn a living. A small degree of personal wealth became possible, provided that one was prepared to fight to defend it. There was a political structure, burial of the dead in substantial tombs, and long-distance trade. At a slightly later stage metal-working in bronze and copper, then in iron, became common.

According to Professor J. M. Roberts, neolithic culture ‘is the matrix from which civilisation appears and provides the preconditions on which it rests’. [18]

Clearly, although we now speak of a single revolution, what we have in mind is a long drawn-out interaction between changes in the domestication of crops and animals, social structures and the environment, which went on over some thousands of years and at different times in different parts of the world. Some of the cultural factors, such as social stratification and use of a permanent home base, must have had long roots back into the ice age past.

Parallel to the settled village lifestyle of the local order, based on farming crops and raising livestock, we can place nomadic pastoral societies, based on livestock alone. Although the nomads were wanderers over the steppes and prairies, they still enjoyed enough of an economic surplus to support social differentiation into warrior and artisan classes.

The nomadic lifestyle also characterised many peoples of later times living in Central Asia, such as the Scythians, the Huns and the first Turks; there were similar communities of Mongols, Arabs and North Americans. By the first millennium BC they were specialists in the art of living on the move, following pasture with their flocks and herds. Although generally illiterate, they were skilled horsemen and archers, and carried out elaborate weaving, carving and decoration, but did not build permanent dwellings, for they lived in their tents.

The nomadic style of life reached its highest development in the 12th-century Mongol invasions, creating an empire which covered most of Asia as far west as Cracow and Damascus. But the nomadic pastoral culture itself was a blind alley. The Mongols and other warrior nomadic peoples could only consolidate their power by taking over the cities and economies of settled peoples, which had evolved directly from the farming villages of the local order.

The effects of agriculture, metalworking, house-building and long-distance trade were both to create a material surplus and to allow higher concentrations of population. Whereas in a hunter-gatherer society thousands of acres are needed to support a family, in a primitive agricultural society about 25 acres is enough, allowing a temporary burst of population growth.

A lifestyle on this pattern of subsistence farming survived into medieval Europe in the feudal system, into 19th-century Russia, and into modern times in many equatorial and southern regions of the world. But elsewhere, stagnation was challenged by progressive change.

Level 3: The imperial order

As local tribes grew stronger over time and extended their authority over a wider area, some of them experienced an urban revolution. This brought together a number of mutually reinforcing factors: city-building, authoritarian politics based on the supremacy of a monarch or dictator, institutionalised religion, a standing army, social acceptance of slavery, torture and capital punishment, a written language and libraries, a money economy with trade and taxation, monumental architecture with roads, palaces and temples, and a greater division of labour compared with village life.

Thus did the first known civilisations appear in Mesopotamia (around 3500 BC) and Egypt (3100 BC), a little later in the Indus Valley, Minoan Crete and China, and in the Americas, at the confluence of the Mississippi and Missouri, in Mexico and the Andes.

A society in transition to the third level shall be described as level 2-plus. While it is partway up the ladder taking it from second-level village life to third-level city life, it remains in an unstable state. If the transition is completed, it will settle onto the higher level; if for some reason it is not, it will fall back onto the lower one.

As an example of how early promise may remain unfulfilled, Roger Lewin describes the Anasazi of pre-Columbian New Mexico, whose level 2-plus society never fully blossomed onto level 3, and ultimately declined back onto a static level 2 several centuries before Europeans arrived there. And it was recently established that there was once a second-level farming culture in the New Guinea highlands which never began to embark on urbanisation at all. [19]

Obviously, when cities appear, villages do not vanish. Local-scale organisation continues, but is contained within the new system. Village life is modified by the wars, taxation, ideology and products of the city. Political and cultural power shifts to the city, and the prospects for further progress also gravitate to the centre.

This kind of regional-scale organisation, based on cities supplied by an agricultural hinterland, is the first which historians describe as ‘civilisation’. They are the earliest which we would recognise as a state rather than a tribe.

Whereas second-level societies are organised on a strictly local basis in which political power extends no more than perhaps a day’s walk from the centre, third-level civilisations are on the scale of kingdoms and empires. But on a planet as large as Earth, a globalised third-level society remains a practical impossibility.

(Stephen Gillett raises the amusing possibility of an intelligent species arising on an Earth-sized planet when all of its continents happen to be fused together in a single supercontinent, like Pangea, which contained all of Earth’s continents around 250–200 million years ago. The interior of the landmass would suffer extremes of temperature, being far from the moderating influence of the ocean, so the only usable territory for civilisation would consist of a large ring of coastal land. This could be dominated by a single civilisation at the level of the Roman Empire, though it would not have global reach. [20])

Third-level states were generally regulated by a written code of laws, and stratified into a wealthy ruling class, professionals of different kinds and a great mass of poor, illiterate working people. They were characterised by a governing bureaucracy, a capital city with private and public buildings and an agricultural hinterland, a state ideology or religion, and a permanent military establishment. Their key technologies were metalworking, masonry and writing. Their arts and literatures were highly sophisticated.

At this stage we find human muscle power extensively supplemented by external power sources, usually introduced as early as the second level. Horses, oxen, camels, llamas or elephants may be used as beasts of burden or for personal transport; wind or running water may be employed to drive ships or mills.

But third-level societies had definite limits. Although they may have burned fossil fuel, they had no way of converting its energy into mechanical work. They knew nothing of current electricity, the periodic table of the elements or telescopic astronomy. Their knowledge of geography faded into ignorance after a few thousand kilometres in any given direction.

All empires and substantial kingdoms down to the European Middle Ages belong to this same basic form: through the Persian, Greek, Roman and Inca empires, China, the Islamic caliphate, down to the monarchies of medieval Europe.

Successful impositions of imperial order achieved something close to territorial security – whether through political unification of an island such as Britain and Japan, or by absorbing all its competitors for the time being, as did ancient Egypt and China, and the Roman, Mongol and Inca empires. At this point, societies were once again faced with the choice between stagnation and expansion. But however desirable geographical expansion may sometimes have seemed to their rulers, at this stage it became dependent upon material progress, particularly in technology. And to the people of 500 and more years ago, brought up within a deeply conservative view of the world, it must have been hard indeed to stumble across the formula that would bring progress to life in such an unexpected direction.

So most imperial societies stagnated. Ancient Egypt and China demonstrate thousands of years of intermittent political stability at a modest living standard before the intervention of invaders. Rome grew decadent and fell to Germanic tribes; Constantinople was conquered by the Turks under Mehmet II; the great Islamic Arab empire of the Abbasids was brought down by the Persians and the Mongols; the Mongol empire fragmented and faded away, absorbed into the identities of the nations it had conquered; in America the Mayan civilisation decayed from within even before the arrival of the Aztecs and subsequently the Spanish. Always the central authority grew corrupt, the regions got restless and either went their own way or were detached from the empire by a resurgence of external threats, and the grand vision of conquering the whole world was forgotten.

And yet the whole world has in the end indeed been conquered. (‘The change which came about in world history after 1500 is quite without precedent. Never before had one culture spread over the whole globe.’ – Professor Roberts.) Over the past 500 years Western European culture and civilisation have expanded to the point where their products – science and technology, the ideals of human rights and duties, national identity, modern concepts of finance, air travel, sport, music, the mass media and so on – are accepted the world over. How did this come about?

It could only happen because late medieval Europe embarked on the second option, that of making material progress, particularly technological progress, and putting that advantage to good practical use – in short, Europe embarked on the industrial revolution.

Level 4: The global order

An early key development was the building of improved sailing ships which could steer closer to the wind. Prince Henry ‘the Navigator’ of Portugal sponsored voyages along the coast of Africa which resulted in the rounding of the Cape of Good Hope and sea access to the Indian Ocean by the late 1490s, outflanking the stranglehold on trade imposed by the Islamic Middle East. Meanwhile the Spanish crown supported Columbus’s crossings of the Atlantic and Magellan’s expedition, which resulted in the first European circumnavigation of the globe by 1522. Half a century after Magellan the English repeated his feat: with the backing of Queen Elizabeth and the lure of Spanish treasure ships ripe for plundering, Sir Francis Drake completed the second circumnavigation in 1580.

Other key technologies included the improvement of gunpowder weapons, the solution to long-distance navigation with the Harrison chronometer, and ultimately the exploiting of fossil fuels to drive steam and internal combustion engines, which opened up the possibilities of mechanised mass production and of fast and regular transport across both land and sea. Electricity consolidated the process by making possible the telegraph and subsequently the wireless. In the hands of people such as Galileo and Herschel, the telescope allowed scientists for the first time to begin to appreciate the true situation of mankind in the wider universe. Systematic chemistry, codified by Lavoisier, started a long process of scientific understanding and manipulation of matter.

Obviously, the significance of the voyages of Vasco da Gama and Columbus is not that they were the first. Columbus was certainly not the first European to discover America, since Leif Eriksson had arrived in Newfoundland half a millennium before him. The Chinese had also discovered America, not to mention that continent’s original ice age colonists, and it is not impossible that there were trading links between South America and Africa in prehistoric times. [21]

But the 15th-century Europeans were (unknown to them) at the vanguard of a wave of future exploration, commerce, colonisation and development which did not peter out but grew steadily into a new kind of civilisation, one with intercontinental, ultimately global reach. America was not discovered – in a sense capable of making a lasting difference to subsequent history – by Columbus and his men alone, but rather by a whole armada of explorers, soldiers, missionaries, merchants, adventurers, slavers, planters and botanists whose overseas explorations were tolerated, even encouraged, by Western European civilisation as a whole.

In the same way, a number of innovations, including gunpowder, printing with movable type, the sternpost, the magnetic compass and paper money, were originally invented, not in Europe, but by Sung China. The Chinese had a head start over Europe of 1,500 years in casting iron; their naval expeditions reached from Indonesia to East Africa in the 15th century, discovered the Americas and almost certainly circumnavigated the globe a century before European sailors.

But the traditional mandarin culture of China valued stability above all else, and had little interest in what it regarded as peripheral regions of the world. Revolutionary change was anathema; so, therefore, was economic growth.

The Ming emperor’s grand ambitions – a new northern capital at Beijing, the rebuilding and extending of the Great Wall and the Grand Canal – hit problems, there was a crisis, and when he died fighting the Mongols the traditional culture reasserted itself. Further maritime exploration was abandoned, and finally prohibited by law. [22] Europe, on the other hand, evolved an outward-looking enterprise culture. Therefore it was Europe which evolved a sustained intercontinental reach, not China.

As Professor Roberts points out: ‘What he called “a sort of black stone” was burnt in China when Marco Polo was there; it was coal, but there was to be no Chinese steam engine’.

So historic events such as Columbus’s rediscovery of America, or Gutenberg’s reinvention of printing with movable type, only acquire their iconic status in retrospect, in the light of follow-up events. What told in the long run was not who was first, but who consistently followed through.

When a third-level civilisation embarks on material growth, it can be described as level 3-plus: it is climbing a ladder towards a new state, even though most of its population do not realise what they are creating. It is of necessity a globalising society, since the same spirit of discovery and utilisation which enlivens science, technology and economic growth also spurs on explorers and colonists.

From our modern perspective we may regret the explosion of violent conquest which Britain and the continental European nations unleashed on the rest of the world from 1492 onwards. But we cannot avoid the fact that the morality of human rights we today would like to extend to indigenous peoples, and similar rights for endangered animal species, and the powers to legally recognise and enforce their claims, are the inventions of the conquering globalising civilisation, not the earlier-level societies it first subdued and expropriated.

The globalising process is equally dependent upon mass literacy, printing, telegraphy, free-market capitalism and the Protestant work ethic. Its intellectual foundation is science, which, as well as unlocking the wealth of natural resources, inaugurates a materialist conception of the world, in sharp competition with the authoritarian traditional religions which characterise the imperial order.

The explosive combination of a rational view of man, the economic need for expanding markets leading to mass consumerism, and mass education and mass literacy, have an internal logic which leads to increasing resistance against traditional power structures, and hence to political revolutions, declarations of the rights of man, the abolition of slavery, the introduction of racial and gender equality, and the overthrow of arbitrary religious and sexual taboos. In this way material progress reinforces and is reinforced by moral progress, despite the fog of war, revolution, tradition and conflicting visions of the future through which this progressive tendency must grope its way.

The nations of Europe were far indeed from being ruled by the same emperor, but even as they competed for colonies and markets they were at the same time cooperating to unify the world under a network of transport and communications links, a handful of major languages and a common system of trade in goods and currencies. Even when they went to war with each other, horrific as the wars were they did not throw the West into decline; quite the opposite, as the inventions spurred on in the war years opened up new avenues of civil expansion afterwards, including air travel, electronics and nuclear power, not to mention the new political institutions of the League of Nations and the United Nations which attempted, for the first time, to place the relations between competing powers on a more rational basis.

The fourth level, the global order, therefore resembles the state of society which we have today: a world society increasingly unified, not so much politically, as by trade, global finance, the mass media and mass migrations. The key technologies today are the jet engine, satellite communications and Earth observation, both military and civil, although these characteristics of a global order (level 4) merely consolidate the trend that was set in motion by the invention of the steamship during the expansionist imperial order (level 3-plus) less than two centuries earlier.

One difference between the global and imperial orders is that in the imperial order political power was of first importance while trade was merely an instrument of it; in the global order, on the contrary, the importance of political power is waning and that of commerce and the mass media is growing to the point of replacing it.

A modern politician’s options are severely circumscribed by the economy and the mass media compared with those of his predecessors a few generations ago. It is as if we are no longer ruled by a king or a president, but by global capital and public opinion. It may still be possible for a political leader in the developed world to march his armies and his nuclear warheads into battle, but it has become increasingly irrational for him to do so, unless his enemy is very much weaker. Armed conflict in the West is becoming limited to terrorism, on the one hand, and post-colonial policing, merging into United Nations peace-keeping operations, on the other. Major wars between equally developed states are increasingly regional in scope and limited to relatively backward countries.

All of the major powers in the Second World War have been at peace with one another ever since 1945. Whenever they have been involved in military conflicts, they have been concerned with the projection of their power into distant parts of the world, on the imperial model, rather than with a threat to their own home territory; such wars included the Korean and Vietnam wars, the Soviet invasion of Afghanistan, the British recovery of the Falklands, and the 1991–2003 Gulf War.

The only serious threat to the great powers’ actual existence came with the Cold War, which was fought not on the battlefield but through economic, technological and psychological means. The disruption to most people’s lives was minimal compared with what it would have been in a shooting war, the casualties were insignificant, and the lasting legacies were the enormous technological surge of the space race and the break-up of the old tsarist empire. The first of these was of incalculable value in preparing the ground for the next great phase of expansion of mankind, while the latter’s dangers were defused by the desire of the successor states of the Soviet Union to integrate into the global economy.

The Cold War was won not so much by the West as by the impersonal forces of economics, public opinion and technology: the destructive power of nuclear weapons being so great and the structure of a modern economy so delicate, it was in nobody’s interest to actually start a Third World War. This is peace, imposed not by the superior force of a particular emperor but by the superior force of economics, the media and technology: not Pax Americana so much as Pax Technologica. Frankenstein’s monster turned out to be so terrible that no one political power could tame it and turn it to its purposes.

Yet while humanity endures, history never comes to an end, and a future nuclear war remains likely. Even in the most developed countries, power can still fall into the hands of a group capable of reckless, even self-destructive violence in the service of a nationalist or religionist ideology (the Nazis were one such party). At the same time, nuclear weapons already exist in the hands of some poorer countries, and they could very plausibly be driven by their internal problems to launch a hopeless attack on the West.

The global order suggests a sense of global rather than sectarian identity. But it remains vulnerable to disruption while imperial-level ideologies still possess political clout.

Of course, the fact that the countries of north-western Europe embarked on globalisation around 1500 can never be taken as evidence that they were from that moment on inevitably predestined to become a fourth-level global civilisation. Another invasion by the Golden Horde or a spot of freezing weather (perhaps induced by cometary or volcanic dust or orbital fluctuations) could easily have nipped modernity in the bud, perhaps forever.

The same warning applies to us now. For our present-day society is poised uncertainly between levelling off and settling onto a static level 4, or continuing its expansion as a growth-oriented level 4-plus.

Level 5: The interplanetary order

With the achievement of a global society, it might well appear that our options for renewed expansion are as restricted as were those of 15th-century Europe. Then, however, there was a new avenue of growth which nobody had seriously exploited before: maritime exploration in sailing ships. And today, also, a new route beckons: expansion into outer space using space ships.

It does not take a great prophet to foresee this movement into space. Just as the history of the past 500 years was dominated by the expansion of European civilisation out of Europe to achieve global unification, so the history of the next 500 years has the strong potential to be dominated by the renewed growth of our originally fragmented, now global civilisation out of the terrestrial globe altogether on a quest for possession of the entire Solar System.

Professor Roberts is clear on this point: the Apollo Moon landings were ‘a sign of the latest and greatest extension by Homo sapiens of his environment, the beginning of a new phase of his history, that to be lived on other celestial bodies’. In his epilogue he adds: ‘It cannot be said that landing on the moon is more or less of a landmark [...] than, say, the mastery of fire, the invention of agriculture or the discovery of nuclear power. But it is emphatically an event of that order.’

But what specific economic or ideological factors might operate to drive forward the humanisation of the Moon and Mars and points beyond? What might be the 21st-century analogues of the rivalry between imperial powers, the lust for spices and gold, the glory of the monarch and converts for the church, that propelled Renaissance galleons across perilous oceans and round the Horn?

They are not difficult to guess at. The first private visitors to space have paid large sums for the privilege (around $20 million for a week on the International Space Station). Other prospective space tourists have signed up for sub-orbital hops above the atmosphere; it cannot be long before an economical spaceplane opens up near-Earth space for orbiting hotels in which large numbers of tourists can frolic in weightlessness and admire the full splendour of their home planet. (When our australopithecine ancestors went for a swim, they cannot have guessed that they were physically preparing us for life in space.)

Again, locating a UN conference centre in high orbit (Apollo 11 astronaut Michael Collins suggested an altitude of at least 100,000 miles) or on the Moon, for thrashing out the world’s problems from a vantage point where those problems are seen for the first time in something like their true perspective, is an intriguing possibility. (No politician of the future will be regarded as competent until he or she has personally witnessed the view of Earth from lunar distance.)

As orbital activity increases, so does the economic attractiveness of mining asteroidal water for rocket propellant, and then of mining construction materials such as aluminium, iron, titanium and basalt fibreglass from the Moon and near-Earth asteroids. Large-scale solar power harvested in space and beamed down to Earth by microwave is another likely economic motivator of space development, especially as oil becomes scarce and fears of its polluting effects increase.

But human achievements are not propelled by economics alone. Apollo 11 astronaut Buzz Aldrin compared the lunar adventure to the ancient pyramids and medieval cathedrals, and certainly the vision of mankind as the bringer of life to formerly dead worlds is an immensely motivating one.

The 20th century has seen man the consumer (of goods, entertainment, rights) and man the destroyer (of nature through pollution, of himself through nuclear weapons and economic injustice). The 21st century is ripe for a more optimistic vision of what it means to be human, and the conception of man the agent of creation, at one with an endlessly creative nature, seems tailor-made to fill that need.

The prospects for a new millennium of dynamic growth are good, provided that the conflicts of the 21st century do not inflict a fatal injury on global culture.

We may project a future economy based on a mixture of solar and fusion power, whose industrial processes have been revolutionised by increasing efficiency. We can foresee the replacement of the present uneasy stand-off of amoral materialism and religious dogma by a conception of reality based on nature’s spontaneous creativity, man’s place at the cutting edge of that creativity, and the common cause of all life as redeemer of the barren wastelands of the pre-biotic cosmos. A growing rejection of racist ideologies will be locked in place as ever more people see Earth from space with their own eyes, and return home with a sense of planetary rather than narrowly national identity.

For these reasons, we must add a level 5 to our snakes and ladders model: the interplanetary order. It is the logical extension into the future of the levels leading up to it. But we cannot be confident that our own civilisation will necessarily achieve an interplanetary level of organisation.

As the 21st century opens, we stand on the threshold that takes us from a mature global civilisation to one expanding into its interplanetary environment. The first humans have walked, driven, explored and cracked jokes on the surface of the Moon. The major planets have been photographed from close up; the first robot probes to free themselves completely from the Sun’s gravity have begun their eternal voyaging through the Galaxy (Pioneers 10 and 11, Voyagers 1 and 2, soon to be followed by the first probe to Pluto and the Kuiper Belt, launched in January 2006).

Will these early explorers, like Leif Eriksson or the 15th-century Chinese navy, be denigrated, ignored and forgotten? Or will they, like Christopher Columbus, be followed by an ever-increasing stream of explorers, scientists, entrepreneurs, tourists and colonists?

The study of human history so far strongly suggests that of all intelligent species in the universe, some can be expected to expand their civilisations into their local planetary system. It also hints that many others will not do so. The success rate, given our current lack of knowledge, is unknown.

The main stages of development defined so far on the snakes and ladders model merge one into the next as new technologies and new ideas are taken up, hesitatingly at first, only later displaying their full potential for change. For example, the early gunpowder weapons of the 15th century were clumsy and slow. It was only in the 18th and 19th centuries that firearms became efficient enough that the breech-loader and the water-cooled, self-loading Maxim gun could enforce Western power around the world, thus helping to inaugurate a global pattern of economic interests which has led to our modern view that all nations share one world together.

Although the world is now dominated by the economic and military power of the global order, there remain governments which, while happy to use the communications, power, transport and weaponry which industrialisation has placed in their hands, favour the parochial outlook of an earlier stage. For them, the characteristic imperial-order outlook of a national or religious identity defended by only a portion of humankind may be more satisfying than earning their way in the cosmopolitan economy, and making their contribution to the global funds of international law, arts and sciences.

Again, millions of Third-World poor have no choice but to live lifestyles more appropriate to the lower levels. Despite their presence, we characterise the system as a whole as fourth-level because political and cultural power is concentrated in institutions – governments, corporations, voluntary groups – which have global reach, and change is driven by them.

One further aspect of the model is that, when we consider population sizes, we find that the different levels have very different carrying capacities.

The number of people who can be supported by a nomadic hunter-gatherer lifestyle on Earth is the smallest, and presumably very similar to that of their pre-human ancestors (Professor Roberts puts the world population of the Upper Paleolithic age 20,000 years ago at ten million). The progressive developments of agriculture and industry hugely increase this number to the six thousand million of the present day. The interplanetary order increases the allowable population again, as it implies that all the material and energy resources of the Solar System are available for constructive application, with technologies increasingly more advanced than those of today.

A further surge of population growth over the next thousand years or so will therefore be essential to fully realise the immense opportunities that lie before us. One problem is the falling birth rate in wealthy societies. On the other hand, a breakthrough in human longevity would create a population surge. What is certain is that the energy and material resources of the Solar System are perfectly capable of comfortably carrying a human population of many millions of billions of people.

Level 6: The interstellar order

How far might a growth-oriented interplanetary civilisation go? The logical extension of the pattern so far requires us to add a further level to represent expansion on an interstellar scale. Any energetic level 5-plus society would have the potential to spread widely throughout the Milky Way, re-engineering the worlds it found in extrasolar planetary systems to provide acceptable living space. Such a level 6 would have a carrying capacity for a population millions or billions of times greater than before.

We already possess the ability to exchange radio signals with anybody who may wish to communicate from any star on this side of the Galaxy. While aliens are hard to find among the starfields, the position and radio frequency of a starship which we had launched ourselves would be precisely known. Navigation would be a doddle compared with the intricate manoeuvres performed routinely by modern space probes such as Voyager, Galileo and Cassini.

The major technical problems concern component reliability, life support in an artificial closed system, mining of resources in extrasolar planetary systems, and, over and above everything else, the question of mastering the immense power needed to drive a starship to its destination within a reasonable period of a few decades. No doubt subtle issues of human health when living permanently away from Earth will also arise. These would all have been thoroughly explored during the previous centuries of interplanetary growth.

It is inconceivable that Earth alone, let alone America or Europe alone, could ever build a starship. But as a project undertaken by a Solar System economy which is as far advanced beyond our present-day level of prosperity as ours is beyond the economy of Shakespeare’s England, it would be perfectly feasible.

Obviously, a starship project would also have to overcome economic and political hurdles. Some astronomers believe that these would pose such a barrier that level 5 civilisations would be eternally quarantined from direct contact with one another (though they would always be able to exchange radio or laser messages). We shall revisit these arguments in the next chapter.

The snakes and ladders model does not prejudge the issue, but merely indicates a possible line of development. Maybe our descendants will go to the stars, if the circumstances are favourable. Maybe some other species will. Maybe nobody will.

The fact remains that there exist many potential ecological niches for technobiotic life in the Galaxy which can only be reached by starship. It is impossible to be certain whether life will continue its course of colonising every possible niche as it comes to it, but we are still free to express an opinion about whether we would value an extension of creativity to those silent worlds.

We can only guess at how an interstellar society might look. It will presumably transport large amounts of power in the form of antimatter, the most concentrated form of energy conceivable by present-day physics, and the only one so far known to be capable of storing the enormous energy needed to reduce interstellar journey-times from centuries down to decades. We can also guess that there will be a fusion between man and machine as genetic, medical, information and manufacturing technologies converge into one, and the practical attainment of personal immortality.

Assuming that an interstellar civilisation can get started, its progress to galactic maturity will be assured if the rate at which new planetary systems are colonised is greater than the rate at which those colonised backslide into stagnation and relative barbarity, as we shall explore in more detail in chapter 7.

The expansion of human population (and of the species we take with us into space for ecological stability and companionship) could be staggering: millions of billions in each star system must be multiplied by the millions, perhaps billions, of colonisable planetary systems which will eventually come within reach of a sixth-level civilisation.

The snakes and ladders model illustrates how interdependent are the scale of organisation of society and its available technologies. It is only the technique of farming that propels a people from level 1 to level 2, when they find it possible to form more concentrated communities living in permanent settlements. Near the top end of the model, it is only the technologies allowing an economy based on the manipulation of raw matter and energy – as opposed to the pre-digested resources available to us on Earth: metals concentrated conveniently into ores, energy into coal and oil, oxygen and water free for the taking – that make a future spacefaring civilisation conceivable.

Equally interdependent are the scale of organisation and the prevailing weapons technologies which regulate the balance between the centralisation of political power and the ability of individuals and small groups to resist that power. For it is clear that no central authority can come into existence until it has found a way to create and maintain a practical monopoly of physical or moral coercive force over those it would rule.

So alongside improvements in food production we also find a progression from stone to bronze to iron weapons, then to gunpowder and modern high explosives, and finally (for the present) to nuclear explosives, electronic guidance systems and surveillance, whose use is conditioned by the parallel growth in public opinion, propaganda and resistance to propaganda, all mediated by the mass media.

Beyond the stars

We may now top off the snakes and ladders model by adding a seventh level: unnamed, of unknown population size, drawing on unknown sources of power, attained by unknown technologies, and motivated by unknown beliefs and perceptions. In this way we preserve a reminder of the open-endedness of the model, and of life’s potential for evolving new orders of existence which we cannot yet conceive.

Whether there exists any final state of development of human or rather post-human life beyond which it is impossible to progress is a question that cannot be answered until our knowledge of the universe is effectively complete. But proving that our knowledge was complete at any particular moment would be a logical impossibility (it could only be proved by starting from the assumption that it was true, for otherwise it would be impossible to decide whether any factors that were still unknown would invalidate it).

Gödel’s theorem suggests that in any case our knowledge never could be complete. There will always be more to discover, more leaps in understanding to make, more distant horizons to cross.

It will be obvious that Kardashev’s level I corresponds to a level 4 society on the snakes and ladders model – in human history, somewhere in the 21st century. In the same way, Kardashev’s level II matches our level 5, and his level III, our level 6.

But the snakes and ladders overview of history extends Kardashev’s scheme back into our own past, making an explicit overlap with the era of human history studied by students, academics and politicians who may until now have had no interest in space development. The implications for the future course of human history are now equally explicit, and grounded firmly in our past history.

Furthermore, on our scheme the levels representing stable civilisations are set off from one another by intermediate stages of progressive revolution or retrogressive decline. So for example level 3-plus represents the unstable period from, say, the voyages of Columbus and da Gama, Mehmet II’s cumbersome cannon at the siege of Constantinople, the Gutenberg Bible and Galileo’s telescope, through to the working out of their full implications in the jumbo jet and motor car, the atomic bomb, the computer and relativistic quantum mechanics.

A static level 4 would look very like our present-day situation, but with no space exploration beyond low Earth orbit, and with progress in genetics, nanotech, nuclear fusion, information and other technologies suffocated by red tape or public resistance.

Could this actually happen? Easily. There has been a noticeable slowdown in progress since the heady optimism of the 1960s. A pessimistic anti-growth culture has appeared, feeding on popular panics over depletion of natural resources, climate change supposedly caused by industrial carbon dioxide emissions, and the fantasy of nanomachines running amok and reducing the biosphere to grey goo, even though these are based on only the flimsiest of scientific speculations. So it is perfectly possible that within the next few decades our civilisation will abandon further growth and attempt to stabilise itself at the global level.

A static global civilisation would have to be based on a sustainable industrial power supply. If it tried to shut off all new technology development while it was still dependent upon coal, oil and gas, then obviously it would be heading for catastrophic decline within a century or so.

Such a disaster looks very unlikely, simply because there is so much energy available for the taking. There are basically two ways the energy economy could develop to meet future demand: through terrestrial power sources, or extraterrestrial ones.

On Earth we have relatively small-scale and intermittent wind and terrestrial solar power, and the large-scale sources of nuclear fission and, probably within a couple of decades, nuclear fusion. Some combination of these, together with increasing energy efficiency, could maintain our global civilisation for some thousands of years until it fell into decline for political, military, cultural or meteorological reasons.

Extraterrestrial power, in the form of solar energy harvested in space and transmitted to Earth by microwave, would stimulate space development and more or less guarantee that we develop into a level 4-plus, multiglobalising civilisation. A successful attempt to gather large-scale solar power would therefore remove the threat of decline altogether.

Although there are many examples in history of the decline and fall of individual nations and empires, the complete worldwide loss of a level on the snakes and ladders model has never yet been documented.

It is possible that we will some day discover traces of an early society which developed agriculture, and maybe even built the first cities, long before the end of the last ice age, but which subsequently fell back onto a stone age level of existence. Perhaps such remains are yet to be found underwater, on the ancient coastlines of the ice age regions of Beringia or Sundaland, which were flooded when the globe warmed (they are now the South China Sea and the Bering Sea).

If that has ever happened, it will only have affected a limited geographical region, and tribes elsewhere in the world will have been unaffected.

Global collapse would be different. A level 4-minus civilisation – one declining from level 4 to level 3 – would be like the Great Depression and the collapse of the Soviet Union rolled into one, and would be worldwide in extent. After being swallowed by this snake, climbing back up a ladder would be very difficult, and might even prove impossible.

Given that a level 4 global civilisation is more vulnerable to self-inflicted disaster (war, pollution) than those on lower or higher levels, and also critically dependent upon non-renewable reserves of fossil fuels and concentrated mineral ores, the transition from level 4 to level 5 seems to be more delicate than the others. If we fumble it this time, having exhausted too great a proportion of Earth’s natural resources, we may not get a second chance, and our descendants may subsequently be confined to the lower, pre-industrial, levels for the remaining lifespan of our species.

Would a non-human civilisation have to follow the pattern of the snakes and ladders model? Or would we be falling into the trap of assuming that because events happen to have turned out this way in our own case, this is the only way they could have happened?

It is often asserted that intelligent aliens would be so different from us as to be beyond our wildest imaginings. Actually, that is gratuitous mystification – and the purpose behind it is to attack the competence of the Enlightenment standard of reason.

No: if aliens inhabit the same universe as us, they must be subject to the same laws of physics and patterns of biological evolution. They will need to eat and procreate. They will need legs to walk, hands to grasp, eyes to see, lungs to breathe. They will have to have had more primitive ancestors, and conditions stimulating their growth over millions of years. Even gasbags floating in the clouds of a giant planet, or silicon-based rock-beings, would need these or similar means of interacting with their environment.

Knowledge cannot grow without experience, therefore rational intelligence is inseparable from physical technology – this is the lesson of the overthrow of Aristotle by experimental scientists from Galileo onwards. A creature without hands can be a poet and a lover, but its practical knowledge will never be able to advance beyond passive appreciation of what nature has placed in front of it. The snakes and ladders model describes something quite different: the course of a species which actively changes its environment. How many different ways of doing this are there?

It is true that we can imagine an intelligent creature which progresses only so far up the sequence of levels before running into a barrier which it cannot cross. If it lived on a planet with little or no fossil fuels or metal ores, it might find it impossible to industrialise, though it could still develop agriculture. If it found the absence of gravity physically intolerable, it would probably never venture in person into space (though a genetically engineered version of it might, if it wanted badly enough to send its children into space).

If it was nocturnal and used echo location instead of sight, it would never know that the stars exist (unless it invented an instrument that converted visual images to something it could perceive), and the same might apply to an intelligent creature with compound eyes rather than our camera eyes. If it lived on a planet with abundant food, a steady climate and no predators, it might never experience the incentive to develop any level of civilisation, even while it might still have the physical capacity to do so.

In the wider context of non-human civilisations, these are all factors which might apply in addition to the questions of geography, climate, ideology and so on which have shaped human history.

The model highlights the importance of specific milestones: the mastery of fire, the agricultural revolution, urban organisation, the industrial revolution, the space race.

The physical facts of astronomy make it impossible for any multicellular species to travel beyond its world of origin without first undergoing an industrial revolution which substitutes chemical fuels for muscular strength; industry is impossible without the large-scale organisation of city life; cities are impossible without a food surplus. Any species on the road from biological evolution to technological civilisation must work its way through a snakes and ladders game similar to the one presented here.

The future sketched by the model is more speculative. It focuses on spatial expansion for the very good reason that Earth is only a tiny part of the Solar System, and the Solar System only a tiny part of the Galaxy. Meanwhile there exist in the Solar System and the Galaxy in general vast tonnages of materials and megawattages of power which are ripe for employment by rational life, as has already occurred on Earth’s surface.

One major parallel development is the molecular revolution whose beginnings we are living through, where genetic engineering, nanotech manufacturing, information and medical technologies all converge. As we saw in chapter 2, humanity is in the process of transforming itself into a new kind of species.

But this is not an alternative to a future in which we create a spacefaring civilisation. Just as steam power was not invented to drive ships, yet one of its world-changing applications turned out to be in oceanic navigation, so the molecular revolution is tuned to making possible the materials, ecosystems and extended lifespans that will one day make planetary and space colonies and ultimately starships a practical proposition.

Meanwhile the minuteness of planet Earth set against the endless starfields of the Milky Way is a dramatic visual expression of the choice facing mankind for the foreseeable future: physical expansion, or stagnation.

The levels on the snakes and ladders model show a consistent pattern, one which is echoed on ever-increasing scales. They represent successive stages in human capabilities to transcend our biological limitations and harness the power of the imagination to our desires. They are a shorthand for successive stages of the expansion of society in terms of geographical range, population size, power consumption, flows of information, ability to survive disasters, both natural and self-inflicted, and of successively more sophisticated definitions of what being ‘civilised’ means.

The first astronauts to walk on Mars will renew the adventures of the Polynesian explorers, Captain Cook and the Pilgrim Fathers in a manner suitable to their age. The first engineering team to tame antimatter will rediscover fire for their age. The pattern of development is consistent: we discovered America, therefore we now reach for the planets, and ultimately the stars – so long as we continue to be able to take advantage of each opportunity to create a new order of society as it presents itself.

We have reached a crucial stage in the game. Our global civilisation finds itself in an unstable state. It is therefore poised between two points of stability: one more advanced than we are at present, and one less so. To many people it feels like a precarious situation. But once we break out of the global eggshell by learning how to use the raw materials of space which have not been pre-digested for us by our Mother Earth, then our future growth will be secured on a much sounder footing.


14. Stephen Oppenheimer, Out of Eden: The Peopling of the World (Constable, 2003), prologue.

15. According to Alister Hardy, Elaine Morgan, Phillip Tobias and others. See Kate Douglas, ‘Taking the plunge’, New Scientist, 25 November 2000, p.28-33.

16. The experiment was conducted by Nicholas Toth and Sue Savage-Rumbaugh, in collaboration with the bonobo Kanzi. Reported in Roger Lewin, Human Evolution: An Illustrated Introduction (Blackwell Science, 4th edn 1999), p.133-34.

17. Alan Taylor, American Colonies: The Settlement of North America to 1800 (Penguin History of the United States, 2001), p.18-21.

18. J. M. Roberts, History of the World, 1993 edition, p.24. Further quotes taken from p.500, 363, 817, 920.

19. Roger Lewin, Complexity: Life at the Edge of Chaos (Dent, 1993), p.1-8, 192-96. Emma Young, ‘Farming pioneered in ancient New Guinea’, New Scientist, 28 June 2003, p.20.

20. Stephen Gillett, World-Building (Science Fiction Writing Series, ed. Ben Bova, Writer’s Digest Books, 1996), p.98-99.

21. John Blashford-Snell’s theory and expedition described in The Sunday Times, 15 March 1998, p.1.23.

22. Lucidly described in Gavin Menzies, 1421: The Year China Discovered the World (Bantam, 2002, 2003), part I on p.45-106.