Complexity in Human Society and Cultural Regimes

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= this discussion continues the article: Complexity of Life and Biological Regimes


Fred Spier:

"It is no coincidence that animals which possessed the characteristics of both plant eaters and predators developed the biggest and most complex brains so far and came to dominate the world. For humans could exploit the matter and energy flows provided by both plants and animals. The secret of human success has been a brain that could facilitate communication, coordination and adaptation of their behaviour, including the use of tools, to an unprecedented extent. The specific development of the human brain may have been the result of many, perhaps unrelated, geological and biological changes, yet the evolutionary trend is clear – towards species with bigger and more complex brains which allowed them to better tap matter and energy flows.

In the animal kingdom, the human brain is the most complex of all, and it uses a great deal of energy. Magistretti et al. (2000) calculated that ‘although the brain represents only 2 % of the body weight, it receives 15 % of the cardiac output, 20 % of total body oxygen consumption, and 25 % of total body glucose utilization’. According to Eric Chaisson (2001: 139), while the average power density of human bodies is about 2 watt/kg, the power density of the human brain amounts to a whopping 15 watt/kg. This rather prodigious consumption must have had an upside. Natural selection would only have allowed the human brain to develop if it had made it easier for our ancestors to extract sufficient matter and energy to survive and, if possible, reproduce. And multiply they did, notwithstanding the fact that humans did not possess any other major biological weapons such as horns, hooves or venom. So far, the energy harnessed by using bigger and more complex brains has clearly outweighed the greater consumption of energy needed to keep the brains going.

Brains run complex software that can, at least in principle, be adapted according to the circumstances. This makes brainy animals far more adaptable, and therefore more effective, than living species which are not so well endowed. In the social sciences, this software is called culture. By using their cultural software, enhanced by ever more intricate forms of communication, humans have increasingly both adapted themselves to their environment and the environment to themselves. The sociologist Norbert Elias (1978) and the world historian William H. McNeill (1991; 1992: VII–XIII), among others, have made this point. More recently, David Christian characterized this process with the term collective learning. In Christian's view, collective learning operates for humans in ways similar to how natural selection works for the rest of nature (2003, 2004).

Culture and Energy

According to the view pursued here, cultural regimes are collective responses to the problems that people face. Yet one may wonder whether there is a bottom line to this problem-solving. Based on Leslie White's approach to culture as a way of capturing more energy, the Canadian ecologist Vaclav Smil summarized culture as follows:

From the perspective of natural science, both prehistoric human evolution and the course of history may be seen fundamentally as the quest for controlling greater energy stores and flows (Smil 1994: 1).

This approach may not be popular among social scientists. Surely, human behaviour is far more complex and varied than just harnessing energy. I would not deny that. But, following Leslie White, Marvin Harris, Jeremy Rifkin, Vaclav Smil and David Christian, among others, I argue that for most, if not all of human history, the quest for sufficient matter and energy to survive and, if possible, reproduce has been the overriding theme. And the reason that humans have been able to harness ever larger matter and energy flows is to be found in their culturally learned behaviour. The matter and energy flows that our species has sought to master had to be neither too large, because humans would have succumbed to their effects, nor too small, because they would not have supported human life sufficiently. As I have argued, this is not only true for human history but also for Big History as a whole.

All human efforts to capture matter and energy flows have inevitably generated entropy. While the low level radiation produced by human activities could comparatively easily be radiated out into the cosmic trash can, for matter flows this was not the case. As a result of the ongoing human activities, therefore, material entropy on the surface of the Earth has relentlessly increased.

The Emergence of Early Humans

Around three to four million years ago, the first early humans emerged in a landscape in which the energy levels were characterized by a rather narrow bandwidth. The East African savannas have a rather mild climate. All year round temperatures would have ranged between twenty and thirty degrees Celsius. This does not differ a great deal from the average human body temperature. As a result, the early humans did not need extensive protection against high or low temperatures. Also, the air pressure on the East African savannas is rather mild, on average about 0.9 atmospheres. In this situation, the early humans would have been able to keep a power density of about 2 watt/kg going (Cook 1971: 136).[6]

The oldest utensils made by human hands that can be clearly recognized as such date back to around 2.5 million years ago. Apparently, by that time early humans had found ways to increase their matter and energy flows with the possibilities their hands offered, including the development of an opposable thumb, which allowed far greater dexterity than before. Subsequently, natural selection for traits stepping up the harvesting of matter and energy (including defence and offence) may have led to the emergence of all-round hands suited for performing a great many different tasks, including the making and use of tools.

According to the late Dutch astronomer Anton Pannekoek (1953), tool-making and tool-use may well have led to the simultaneous development of language and thought. This would have favoured selection for bigger and more complex brains, which, in their turn, would have facilitated better tool-making and tool-use. Over the course of time, this feedback process would have allowed the early humans to harness increasing amounts of matter and energy. It may, therefore, not be coincidental that about only 500,000 years after the earliest known tools were made, two new human species with far bigger, and presumably also more complex, brains emerged in Africa, first Homo habilis (handy man), and a little later also Homo erectus (upright man).

Fire Control

While both these new human species used tools, Homo erectus also began to use fire. Homo erectus was also the first human species to leave Africa and spread to many places on the Eurasian continent. They learned to adapt to many different climatic zones, with temperatures ranging from minus 20 degrees Celsius to plus 50 degrees Celsius. In all these circumstances they managed to extract sufficient matter and energy flows to survive and reproduce for at least 1.5 million years. Early fire control allowed humans to intentionally burn the landscape in order to favour certain plant species and diminish the survival chances of others. Predators could be kept at greater distances. Fire control also facilitated big game hunting and the clearing of woods in order to provide pasture for game animals. Thus, through fire control humans may have changed the face of the Earth for a long time. In doing so, they may have influenced the biological and inanimate planetary regimes for an unknown period and to an unfathomable extent. Slowly but surely, as the hunted became hunters, a growing power difference between the early humans and other higher animals developed to the advantage of the ancient folk (Gamble 1995: 66–70; Goudsblom 1992; Pyne 2001). Instead of being mostly scavengers, humans became hunters. Through cooking, roasting and other comparable types of food preparation, humans gained access to a greater range of foodstuffs, and thus to new sources of matter and energy.

Just as life forms and Gaia had done before, the early humans began to create their own micro-climates that were favourable to the protection of their own complexity (and, unintentionally, also the complexity of some unwanted other species) more so than any other species before. All this signalled the beginning of a long process in which humans began to adapt the planetary environment according to their own desires and designs. In particular, modern humans, Homo sapiens, who may have emerged around 200,000 years ago, began to migrate to virtually all parts of the globe (the poles excepted). This was an unprecedented achievement, if one thinks of humans as animals, partly because of the range of environments in which humans learned to live, and partly in terms of the speed of the process. It meant that humans began to harness matter and energy in almost the entire inhabitable world, including the high mountains, where the air pressure was no greater than only 0.6 atmospheres. According to recalculated data from Cook (1971: 136), more recent gatherer-hunters would have handled power densities of about 5 watt/kg. This would have been mainly due to fire control. And as a result of human population growth, the total human use of matter and energy flows went up accordingly.

It is not clear to what extent this increase in power density would have led to any more food intake. It may well be that most of it was used for creating, or destroying, complexity beyond the human body. This was the beginning of a new trend, namely humans using ever larger energy flows to create or destroy external complexity. Ever since that time, this trend has continued to exist. This makes the use of power densities for human history more problematic, since Φm only refers to human bodily weight and not to the external mass that underwent the energy flows handled by humans. Obviously, humans have never managed to live for a long time with daily energy intakes greater than 4000 to 5000 kcal, which corresponds to about 4 to 5 watt/kg. Any substantially greater levels of energy consumed by humans could not possibly have flown through their bodies without destroying them. As a result, all the further increases in energy flows handled by humans must have flowed through external matter. Since I do not have estimates at my disposal of how large such external masses would have been, reliable corrections are not yet feasible. All the power densities for human history presented below must, therefore, be viewed with due caution. I view them first of all as indicating major trends and not as the last word on energy flows.

It is not very clear to what extent the matter and energy flows harnessed by early humans were sometimes too big or too small. It may well have happened that early humans occasionally started fires that went out of control and killed them. They may also have settled in places where, as a result of human exploitation or because of climate change or natural disasters, the extractable resources became too scarce for the early folk to survive. This may be very hard, if not impossible, to glean from the fossil record, which is very limited anyway.

The rise of modern humans may have led to the decrease in ecological complexity. First of all, the sustained burning of savannas and forests must have changed their biological composition. As a result, some species may have become extinct, while other species profited. It is unknown to me whether human fire control led to the emergence of any new species. Modern humans may well have exterminated a number of large animals, especially in those areas that had never been visited before, such as Australia and the Americas. Right now, it is not very clear whether climate change and/or diseases were also among the root causes of such extinctions. Yet it remains striking that only a few thousand years after humans moved into such new territories, most of these big beasts disappeared from the surface of the Earth. If true, this would represent an example of the decline of ecological complexity as a result of human action.

Up until 10,000 years ago, it does not seem as if humans brought about any great increase of material entropy. They were operating within the ecological web of the biosphere, and they did not accumulate any significant long-lasting material culture nor produce a great deal of long-lasting waste.

The Domestication of Plants and Animals

Curiously, the growing dexterity of human, as well as their capacity for communication, learning and remembering things, did not immediately produce any major changes in the ways Homo sapiens harvested its matter and energy flows. To be sure, between 200,000 BP and 10,000 BP, modern humans intensified production, yet they did not revolutionize it. Apparently, the capacity for culture, or collective learning, was a most important precondition for the domestication of plants and animals, but it was not its direct root cause. Around 10,000 years ago, however, our ancestors discovered new ways of extracting matter and energy from the environment. Slowly but surely, they began to gain control over the reproduction of plants and animals considered useful. As a result, humans could increasingly harness and manipulate the energy and matter flowing through the biological food chains. This signalled the beginning of the second great ecological regime transformation: agrarianization.

As we saw earlier, according to recalculated data from Cook (1971: 136) gatherer-hunters mobilized power densities of around 5 watt/kg. Early agriculturists, by contrast, would handle around 16 watt/kg. More advanced farmers and herders would do even better. They employed more than 26 watt/kg. This was a fivefold increase. This does not mean that agriculturists ate more, or better, than gatherers and hunters. Over the course of time, quite often the opposite appears to have happened. The increasing power densities of agriculturists point to the fact that these people handled larger energy flows in order to produce sufficient food and other material means they needed.

The circumstances in which agriculture could thrive were more circumscribed than those in which gatherers and hunters operated. Although the pressure and temperature ranges were probably rather similar, a sufficient water supply was far more critical. As a result, even today agriculture has not spread across the globe's landmass as far and wide as gathering and hunting had done before. Also, the cultivation of fish in the seas and oceans has been taking off only very recently. This is mostly due to the problem of how to control fish stocks, while, until recently, catches were often bountiful.

There has been an extensive academic discussion over where and how the agrarian revolution took place.[7] Yet even today, the causes behind this great transition are not well understood. Both climate change – the end of the last ice age – and growing population pressure appear to have contributed to the emergence of the agrarian way of life. But, whatever the precise causes may have been, the effects are clear. The more efficient food production allowed increasing numbers of people to survive and, if possible, reproduce. And so they did, in all places where the agrarian regime took root. In other words, most new matter and energy were converted into growing numbers of people. As a result, a self-generated dynamics evolved, which led to a steady expansion of the agrarian regime to all suitable places (White 1959: 45–57).

Over the course of time, this led to a decrease in the matter and energy the remaining wild plants and animals could harness. They were increasingly marginalized or even became extinct. And since agrarian societies harnessed more intensive matter and energy flows, they proved dominant over the ancient gatherer-hunter regime. Just like the undomesticated plants and animals, this earlier human regime was also pushed back to places where farmers and herders could not, or would not, go. Today, all true gatherer-hunter regimes have completely disappeared.

Although agrarian societies became far more efficient in harvesting matter and energy flows than gatherers and hunters, this did not necessarily mean that all members of the band were better off. As a result, it may well be that, over the course of time, the average peasant had access to fewer calories than his ancestors during the age of gathering and hunting. As part of agrarian regime, people began to make an increasing variety of things, including better houses, storage areas, ceramics, forms of art, and monumental graves, with shapes that had not existed before during the known history of the Universe. In other words, the age of the teacup had begun. Many, if not all of these new shapes had the same general aim: the preservation of forms of complexity humans deemed desirable. As a result, the early folk began to produce more entropy also.

There are some striking parallels between the rise of complex animals in biological evolution and this phase of human history. The increasing interdependence of the cells of which multi-cellular organisms are constructed, as well as their inter-cellular division of labour, was parallelled by the growing human interdependencies and human social division of labour. In both cases, the resulting increased harnessing of matter and energy flows made those involved both more constructive and more destructive. The other parallel is that, while the speed of both biological and human innovations increased, the life spans of both the living species and the human cultural regimes involved decreased.

Early State Formation

The transformation into an agrarian regime led to social change. Because people became more tied to the land they worked, they began to live closer together and in greater numbers than ever before. This led to an increasing social division of labour. Yet these societies, which were largely based on kinship, remained comparatively egalitarian. To be sure, over the course of time agrarian societies became more hierarchical. Yet as long as there was enough room to move, no powerful group could impose itself upon others for long.

After about five thousand years, however, the agrarian revolution led to a most important social regime transformation: the emergence of states. In its barest essence, states are social regimes the elite of which has succeeded in monopolizing the important means of violence, at least to the extent that they are able to dominate the state. In the final analysis, this meant harnessing important matter and energy flows and denying them to others. This inevitably involved taxation: the channelling of matter and energy flows produced by others. Early state formation meant that for the first time in history, humans began to systematically exploit other humans as matter and energy sources. In the centers of early states this led to increasing cultural complexity, while independent local forms of complexity declined.

Robert Carneiro (1970) pointed out that all early states emerged in ecologically circumscribed geographic situations: usually fertile river valleys surrounded by dry areas, mostly deserts. In other words, these were regions where the harvesting of matter and energy flows was comparatively easy, while they were flanked by areas with only very limited opportunities for doing so. This situation allowed the people who succeeded in manipulating larger matter and energy flows to dominate their weaker fellows. As a result of the growing inequality and the concomitant social division of labour, the matter and energy flows within and among societies became increasingly complex. This is not the place to go into any detail, but, in general terms, it seems clear that the new social regimes were first and foremost dealing with the questions of who would perform the tasks of matter and energy extraction; its elaboration and preservation; and, last but not least, who would have access to the results of all this labour. As was the case with biological evolution, there were a few basic strategies for doing this: using disinformation, stealing, and using force. In all likelihood, all these things would have happened during all stages of human history. Yet during the period of state formation this became more apparent and organized. Since that time, humanity has expended a great deal of energy on pursuing these strategies and on countering them.

All this required new ways of safeguarding information. Up until that time, most cultural information had been stored in individual brains. With the rise of the early states, however, humans invented systematic regimes for recording information by material means, ranging from clay tablets to woollen cords. This allowed them to increasingly harness matter and energy flows. The art of writing allowed, in fact, a more efficient use of both information and disinformation. Since, for the powerful strata, control over the information flows became increasingly important, huge efforts were expended to make sure that they were used in their own interests, while access was denied to others. This included limiting such information flows to privileged and often tightly controlled professional groups, the use of secret codes, and public displays of propaganda. Although it took a long time, the dissemination of the art of writing worldwide was inevitable. In our time, mostly as a result of the rise of worldwide electronic communication, we have witnessed a new explosion in the importance of externalized information and its associated uses for both information and disinformation.

Since states were getting bigger and more complex, their inhabitants did not know all the others face to face any longer. In order to keep the state together, the rulers had to expend a great deal of energy on forging overarching identities, first with the aid of the emerging state religions, and later by using state bureaucracies including schools. Benedict Anderson calls the results of such efforts ‘imagined communities’ (1991). In most early states, such overarching identities were usually expressed in terms of symbolic kinship, with gods, kings and queens often portrayed as the ‘fathers and mothers’ of their people.

Some new matter and energy flows were used for constructing the first large buildings, essentially huge artificial hills, most notably pyramids. In order to build them, human and perhaps animal muscle power was used to defy gravity and produce the first architecture of power. Since that time, humans have continued to make such things. While the more recent constructions have perhaps become more intricate, for a long time they did not become much taller. Only during the industrial period did it become possible to construct buildings that grew in height once again. Yet the biggest gains were made during early state formation and not in recent times. This was the result of the limits gravity poses for such human endeavours. The shapes of smaller artificial objects (such as teacups) were, of course, less constrained by gravity. As a result, they could exhibit a far greater variation.

State formation was not an ecological regime transformation. No new techniques were pioneered that would revolutionize the extraction of matter and energy from the surrounding environment. Certainly, inventions were made, some more important than others, most notably the increasing exploitation of energy flows from wind and water – both derived from solar energy. In some areas, people began mining coal and other combustible substances. Yet up until the Industrial Revolution, the ways in which people extracted matter and energy from the environment and used it for productive purposes in fact changed little.

The techniques that facilitated the extraction of matter and energy from other people, by contrast, most notably arms and armies, underwent revolutionary change. A new dynamics of growing social competition had begun, which led to the growth and expansion of states at the expense of independent farmers, herders and gatherer-hunters. It took about five thousand years before the process would be (almost) completed, yet this was the way states began to spread all across the world. To be sure, for a long time, tribal societies with sufficient destructive power – the Mongols offer probably the clearest example – could still overpower some states. But, in order to stay in power, the invaders could not maintain both their tribal status and their dominance over state societies for long. If the conquerors wished to consolidate their power, they had to adopt the lifestyles of the complex societies they had conquered.


In my view, globalization is the emergence of a worldwide division of labour. Globalization is therefore a social regime transformation. This global division of labour was created by people who could be described as belonging to the middle classes. In contrast to traditional elites and peasants, these emerging middle classes were not tied to the land. As a result, they could only increase their matter and energy flows through trade, production and conquest. About five hundred years ago, some emerging middle classes succeeded in escaping from the control of their traditional rulers. Over the course of time, they were able to take over state control, first in the Seven United Provinces, next in parts of the British North American colonies, and subsequently elsewhere in the Americas and Europe. Especially since the beginning of the nineteenth century, because of the Industrial Revolution and the resulting emergence of middle classes worldwide, this process has gained momentum all around the globe.

The first wave of globalization began after Europeans had learned to exploit the energy stored in winds and ocean currents to transport themselves and their cargo all around the world. For the first time in human history, people began circling the globe within their own lifetime. Europeans began to sail the Seven Seas on ships armed with heavy guns looking for profit wherever it could be found. Soon, this led to a struggle for dominance between Spain, Portugal, Great Britain and the Seven United Provinces in the Americas, Asia and the Pacific area. As a consequence, these three great world zones merged into one single global entity increasingly dominated by Western Europe.

Especially after large portions of the Americas had been forcibly integrated into the growing world economy and direct trade links all over the world had been established by both peaceful and military means, a global social division of labour began to take shape. This led to a further intensification of the matter and energy flows. As a result, global cultural complexity began to rise. Local forms of complexity, by contrast, were often overwhelmed by these new matter and energy flows and succumbed or became marginalized.

After Europeans had become firmly established along the Atlantic seaboard of North America and were no longer dependent on matter or energy flows from Europe, a considerable number of them succeeded in getting rid of their colonial masters. They declared themselves independent from Britain and formed the United States of America. This new state was controlled by the wealthier members of society, both landlords and people belonging to the middle classes. The French revolution, in its turn, found great inspiration in this liberation movement on the other side of the Atlantic Ocean. This set the tone for societal shifts all over Europe. Yet arguably, the greatest shift took place in the Spanish and Portuguese Americas. The French occupation of the Iberian Peninsula had weakened Spanish and Portuguese control to such an extent that the emerging Central and South American middle classes could get rid of their colonial masters. Unfortunately for them, however, they soon found themselves in the grip of the local landholding elites. As a result, even today the Latin American middle classes are still struggling to get free from that grip.


The third great ecological transformation, industrialization, greatly reinforced these trends, owing to the fact that it was based on fundamentally new ways of tapping energy sources for productive uses. Until that time, all machines had been driven either by human and animal muscle power or by wind and water energy. These were all renewable energy sources. The harnessing of fossil fuels for productive purposes, however, first coal and later oil and gas, implied fundamentally new ways of handling matter and energy flows. Industrialization was, therefore, a major ecological regime transformation. As a result, huge power differences within and among societies developed. In industrializing societies, nationwide cultural complexity rose once again, while many forms of local complexity declined. In the rest of the world, cultural change as a result of industrialization proved inevitable also.

According to recalculated data from Cook (1971: 136), the early industrial societies would have handled on average a power density of about 77 watt/kg. Today, by contrast, more advanced technological societies may command about 200 watt/kg or more. Again, this means that, although such people may eat more than ever before, most of the increase is due to external energy flows. Industrial societies emerged in temperate zones with temperatures ranging between minus 20 to plus 30 degrees Celsius. The air pressure was close to one atmosphere, while there were always abundant water supplies. Although since that time many industrial production processes have moved to places where temperatures can be higher, interestingly the other conditions have not changed a great deal yet. Today, there are very few industries in high mountainous areas or in regions lacking sufficient water. In other words, the spread of industrial life across the globe has been even more limited than the spread of agriculture (which, in its turn, had been more limited than gathering and hunting). And, while risking to state the obvious, in contrast to gathering-hunting and domestication of plants and animals, industry has not yet taken off in seas or oceans.

Let us return to the early rise of industrialization. Control over the new production processes allowed the middle classes to become the most wealthy and powerful stratum of society. This was, in fact, Marx's observation of the bourgeoisie taking over the state. In order to gain state control, the middle classes began to campaign for voting rights for the wealthier portion of society. Later, the emerging working classes succeeded in organizing themselves to the extent that they could also gain access to democracy. These societal shifts led to the emergence of democracies we are now familiar with. This process is now spreading around the world for exactly the same reason, the rise of middle classes worldwide.

Since access to the new matter and energy flows was initially very unequally divided, huge worldwide power differences evolved. As part of this process, the industrializing nations began colonizing large parts of the world. After almost all the conquerable world had been subjugated, the newly industrialized nations battled it out among themselves. This led to two world wars. Yet over the course of time, all the areas which successfully industrialized became wealthy to an extent unparalleled in human history, first the elites and later also sizable portions of the general populace. Apparently, the elites found it impossible to keep the new matter and energy flows to themselves. This was partially the result of the fact that more and more people began to live in cities, where they could pose a direct threat to the elites. And after the industrialization of agriculture and of transport had made sure that urban populations could be fed, increasing numbers of people could move to the cities. As a result, the first huge (and rather complex) metropolitan areas emerged, housing many millions of people.

The spread of industry based on fossil fuels all around the world has led to unprecedented levels of the global social division of labour, and thus to a growing global complexity at the expense of local and regional forms of complexity. While the first industrialized nations have succeeded in remaining rather powerful, newcomers are increasingly challenging their positions. Especially since the 1960s, many energy- and labour-intensive industries have moved to areas where the production costs are lower.

Most notably during the twentieth century, people began to create an ever expanding set of microclimates. Not only houses for people were heated during the cold seasons, but also houses for cultivating plants (greenhouses). The next step was to create cold microclimates during the hot seasons. This included refrigerators, specialized railroad cars, freight trucks and ships, which made possible the production and transportation of meat and other perishable foodstuffs on a large scale. Cooled or heated microclimates for comfort and pleasure were the next step. They include climate controlled houses and cars; artificial ice skating rinks and skiing slopes; tropical swimming pools (not very surprising, since we are still a tropical animal). The exploration of space and of the deep seas led to the development of microclimates in the form of space ships and suits, submarines and diving suits. Never before during the history of the Earth has a species created such a diversity of artificial microclimates.

Industrialization has made possible to feed entire populations with unprecedented amounts and varieties of foodstuffs. Especially in societies where the service sector has become dominant, most people perform less manual labour than ever before. As a result, on average they are becoming heavier than ever before in human history. It is not yet clear what the upper limits of the digestible matter and energy flows are, but in affluent societies at least some people appear to be making determined attempts to reach them. In other places, by contrast, great numbers of people still struggle with the opposite problem.

Industrialized societies have become more powerful yet also more vulnerable. Right now, all industrial societies are very dependent on the dwindling stocks of fossil energy. Seen from a long-term perspective, the exploitation of the limited supply of fossil fuels can only be temporary. But, whatever the future may bring, up until today the large scale use of fossil fuels has made possible levels of global cultural complexity that were hitherto unimaginable, although at the cost of the decline of older forms of local and regional complexity. Today, people, matter, energy and information circle the globe in way unprecedented during any period of the Earth's history.

All the matter and energy flows harnessed by humans have resulted in increasing material entropy on the surface of the Earth in the forms of waste products. Even allowing for a possible enhanced greenhouse effect, the generated heat can still be comparatively easily radiated out into the cosmic entropy trash can. But virtually all the material results of human action will remain on this planet. For most of its history, humans have relied on the existing biological waste disposal regime in order to get rid of their trash. Especially since the Industrial Revolution, however, more and more materials have been made that cannot not be easily recycled by terrestrial biology. In addition, more matter has been dispersed across the face of the Earth than ever before. One may wonder whether humans will be able to invent an efficient trash recycling regime and, if not, what the consequences will be.

In the 1940s, scientists in different parts of the world began to explore possible new forms of energy, because they suspected that new and hitherto unimaginably large energy flows could be tapped. The use of nuclear bombs and later the more peaceful uses of nuclear energy demonstrated that they were right. In terms of energy flows, the energy liberated by nuclear fission is part of a rather limited piggy bank of energy on the Earth which originated from supernova events. The energy from hydrogen fusion, by contrast, is stored in a similar piggy bank, but this time originating from the Big Bang. If people find ways of harnessing the energy flows resulting from nuclear fusion in constructive ways, there may be a great deal of energy available in the future. For the time being, however, most of the energy liberated by both nuclear fission and fusion has been used destructively.

The Increase in Energy Used by Humans

If the numbers presented earlier are correct, there has been a rise in power density from the 2 watt/kg handled by early humans to about 50 watt/kg for contemporary human society as a whole (Chaisson 2001: 139). If true, the power densities during human history would have multiplied by about sixty times. Yet the total energy flow handled by humans has risen considerably more, since the human population as a whole has risen from a few thousands to over six billion today. This represents an increase by a factor of one million. All the energy flows harvested by humans during their history combined must, therefore, have increased by a factor of about sixty million.

Although a reliable breakdown of these energy flows is difficult to achieve right now, a good portion of it is the result of the harvesting of domesticated plants and animals, while most of the rest can be attributed to the exploitation of fossil fuels and nuclear energy. In both cases, we may be reaching the upper limits of the available energy flows that can profitably be exploited. Moreover, it is not clear whether these limits will be sustainable in the long run."