Select Page

Four phases of human history

This article summarizes the key ideas of human Big History. It discusses how the full sweep of human history can be divided into four periods of decreasing length – Natura, Agraria, Industria, and Informatia –. It describes the historical criteria used to classify human history in this way, and how this relates to the special interests of this PlantsPeoplePlanet web site – the relationship that exists between plants, people, and our planet.

The division of history into discrete periods for the purposes of analysis and study (periodization) is often controversial. After all, where do historical periods begin and end, and how convincing are the criteria of demarcation? The kind of periodization that is chosen will likely depend on the special interests of the study, and the choice of periodization itself can imply a particular interpretation of history. And if history is interpreted from many viewpoints and scales of time and place, then how may one periodization be compared to another?

Historical explanation inevitably entails the reduction of complexity. This need not be problematic, but there must be a clear statement of the question being posed along with an understanding of the scale of time and place – because the factors of critical historical significance will vary with these parameters. Explanations must use levels of abstraction appropriate to these conditional parameters. And the answer given must satisfy a critical and intelligent reader.

The question being asked is:

What are the major historical factors that have influenced the course of human history over the long term?

Answering this question is, of course, a tall order. But a historical analysis must begin somewhere, and an analysis that is not explicit in its goals will bring with it the mystery and confusion of implicit goals.

Social organization and energy

The four phases of human Big History described in PlantsPeoplePlanet are grounded in two interdependent historical factors: modes of social organization that are determined by energy availability, capture, and use.

These are the key selection criteria used for a long-term historical classification. They are treated as ‘ultimate’ criteria because, though both have important dependencies, neither can be reduced to simpler concepts.

Social organization

Social organization is defined by historian Ian Morris as:

‘. . . the bundle of technological, subsistence, organizational, and cultural accomplishments through which people feed, clothe, house, and reproduce themselves, explain the world around them, resolve disputes within their communities, extend their power at the expense of other communities, and defend themselves against others’ attempts to extend power’.[2]

This is probably as near as we can get to a crude generalized definition of history and the way that the structures of social organization are coordinated and directed towards the attainment of social goals.


The second long-term historical selection criterion is energy. Energy is an ultimate limiting historical criterion for social organization and social activity because it is a limiting factor for all activity. Social activity expends both the energy that powers human bodies and muscles (biological energy) and the additional energy used to attain social goals (social energy) essentially the energy provided by animal muscles and fossil fuels as facilitated by technology. Just as an adequate supply of biological food energy facilitates biological growth – of both individuals and populations – so a plentiful supply of social energy creates social growth – in the differentiation and complexity of social organization, technologies, economic activity etc.

Social organization depends on energy in three critical ways. Firstly, in terms of its availability. But availability is only potential. What happened historically depended on its ‘capture’. Of the various energy categories we use today (e.g. solar, wind, atomic, tidal, mechanical, heat, chemical, etc.) it is chemical food energy that is fundamental to us all, but critical to the survival of our ancestors. This factor is apparent historically in the transition from hunter-gatherer to farmer and the use of the concentrated and storable energy of cereal grains that supported both individual bodies and general population growth (Agraria). It is also evident in the launching of the Industrial Revolution in England where there was an abundant supply of the fossil fuel coal (Industria). But new forms of social organization create new meanings for ‘availability’, ‘capture’, and ‘use’ – mostly in terms of the technology available at different times in history. Industrial society had the machinery that could replace human and animal muscle many times over.


In the 19th century increasing social organization was regarded as an unquestioned good[1] no matter what it was directed towards ‘ . . . whether God, affluence, or a peoples’ paradise’ (Ian Morris). Today, faced with existential threats like climate change, environmental degradation, pandemics, the possibility of nuclear conflict, and increasing global inequality, we are not so sure. Civilized lifestyles have generated costs as well as benefits and given the choice perhaps we would, collectively, have chosen to forge a different historical path.

Social organization is not a measure of moral worth, intellectual capacity, or happiness – it is an objective measure of social differentiation and complexity. Social goals can be attained by simple societies using simple means.

Our tendency to value increases in social organization no doubt relate to some real-life synergistic benefits of scale. In many spheres of life more can be achieved in a shorter time by people in large organized groups. We are impressed by efficiency – getting things done – achieving social goals, in a way that we believe is making life easier for all. We feel fully justified in speaking of ‘advances’ in technology. This is why long-term history has tended towards an increase in the differentiation and complexity of material and symbolic culture: it is also the reason why increasing social organization (growth) is often regarded as ‘progress’.

Social organization is not a ‘good’ in itself: it has disadvantages as well as benefits.  But in the social organization package comes competition, which is why history is often depicted in a narrow way as the exertion of power by one group over another. Biology seems to support this philosophy in its evolutionary maxim of ‘survival of the fittest’ extended into a vision of ‘nature red in tooth and claw’.

In today’s global society more and more people are coming to realize that the only necessity about social organization is the ultimate and necessary biological need to survive, reproduce, and flourish (biological axiom) – not the need for either violence or the capacity to dominate and subdue.

Historical factors

The article on classification concluded that the structure (key selection criteria) of any classification depend on the purpose (reason, intention, goal) for which it was created. It is only after the purpose of a classification has been clearly identified and stated that it is possible to establish the most meaningful analytical categories that can be used to assist understanding and explanation.

From studies of Big History – as seen from the perspectives of both long-term conventional history and of long term history on a cosmic scale – we have found that, when considering history over the long term, energy is necessarily an ultimate historical determinant. Though not a conventional element of historical research, it is energy that is the source of all activity: it is energy that ‘gets things done‘.

This study therefore begins with the understanding that major insights into human history derive from considerations of energy availability, capture, and use.

In any historical investigation, those factors that have the greatest historical significance relate to the scale of time, place, and circumstances that is under investigation. So, when we look, in more conventional historical terms at the fabric of long-term human history, it is built around degrees of social complexity. That is, much of history can be understood, explained, and interpreted as a view through the window of social organization (as constrained by the method of energy capture and use). Social organization is therefore a productive long term historical analytical category (see glossary) round which to build historical investigation; it is a foundational historical principle.

In simple historical terms: social complexity increased as new and more concentrated forms of energy were discovered, and existing energy sources were used more efficiently. To be successful (to persist) each phase required the effective governance of larger, and more interconnected social groups with increasingly complex (and sometimes competing) social, economic, and environmental demands.

The effectiveness of social organization has depended on the efficiency of its technologies (here defined as the mental and physical tools that facilitate mental and material existence), that is, the degree of development of material and symbolic culture.

This outline of the key factors at work in long-term human history also discerns those selection criteria most appropriate for assessing the long-term course of human history. These are the key selection criteria used to determine the four phases of human history that are outlined in the illustration below.


Energy is the ultimate source of all work and activity in the universe and it exists in many forms. 

For humans the most important questions about energy relate to its availability, capture, and use. Its ready availability relates to growth (of all kinds but notably that of living bodies, populations and economies). It is also a requirement for the building of complexity (notably the complexity of elaborate social organization) and its acceleration since the various elements of social systems can operate synergistically (see Media Gallery below) to increase the momentum of change.

For historical purposes there are two kinds of energy that have constrained the possible forms of social organization, biological energy and social energy:

Biological energy

Biological energy (food energy) is the energy that drives our biological metabolism, most notably the muscles that allow us to do social work – mostly the hunting and gathering that sustained humans during the long term phase of Big History referred to on PlantsPeoplePlanet as Natura.

Biological energy is derived ultimately from the Sun but only after it has been stored in plant chemicals during photosynthesis and then eaten as food. It is then ‘burned’ during muscle activity. Although meat is often a large part of the human diet this meat comes ultimately from plants.

Thus, it is ultimately plant energy that powers the organic growth and productivity we associate with biological agency (the propensity to survive, reproduce, and flourish) that distinguishes life from the inanimate and the dead.

Plant energy is the ultimate engine of biological evolution: but evolution occurs in a social and environmental context. 

Social energy

But in biological communities that thrive, some of the energy of each individual is devoted, not just to that individual life, but to the collective life of the group. Humans expend muscle energy (derived from plant energy) in gathering and hunting of food that sustains everyone. That part of biological energy directed to social ends can, for convenience, be referred to as social energy.

Just as increasing the supply of biological energy facilitates the growth, proliferation, and development of bodies, so increasing the supply of social energy promotes social growth and development.

For much of human history it was essentially the energy of human muscles that was used to achieve social goals, although there was also some use of fire, wind, and simple tools to increase efficiency.

A major transition in social organization occurred when, during the Agricultural Revolution (Agraria), humans learned to harness the energy of animal muscles (especially those of oxen and horses) – to pull ploughs and carts, and carry humans rapidly over large distances. This discovery revolutionized transport and food production.

Another major social transformation in social organization occurred when it was discovered that the energy of fossil fuels could be used to drive machines built for social purposes. Machines fed with fossil fuels were vastly more efficient than animals, and they eliminated the need for either animal or human toil.

The combination of fossil fuels and machinery produced an explosion in productivity, population numbers, and economic growth. Social organization gathered complexity with new and more efficient methods of engineering and construction, communication, and transport systems (Industria). Over time, the per capita proportion of human energy consumption dedicated to social, rather than biological ends, has increased at least 40-fold as shared collective learning has accumulated, and the world has become more complex, interconnected, and interdependent.

All human activity is ultimately driven by the plant food energy that sustains human biological metabolism. However, economic productivity and growth – the social metabolism we now associate with a global economy – has depended on the supplementary social energy of fossil fuels.

We are now living at the start of a new human energy transition (Informatia) confronting yet again the problem of energy availability, capture and use as the social energy of fossil fuels is replaced by the social energy of non-plant renewable sources like solar, wind, and nuclear. We are just has depended historically on the supply of biological and social energy provided by plants.

Biological & cultural evolution

The lives and lifestyles of humans, when viewed over the long term, can be seen as being the product of two major processes: biological evolution, and social evolution. Just as, in historical terms, social energy was superimposed on biological energy, so social evolution was superimposed on biological evolution.

Biological evolution

Biological evolution was described above in a narrow way as the gradual change in physical characteristics of organisms as new species emerge and millennia pass by.

Since all biological agency demonstrates a ‘value’ – as the tendency to survive, reproduce and flourish – those organisms that have survived evolution are regarded by biologists as ‘successful’, and have achieved this success by adapting to their environments.

Socio-cultural evolution

Is it appropriate to transpose a notion like that of biological evolution into the social sphere? Isn’t this some kind of category mistake creating irremediable confusion about units of selection and what constitutes ‘adaptation’.  Surely, the application of the idea of ‘evolution’ to society as the ‘survival of the fittest’ can be used to support everything from eugenics to fascism.

Historically, social goals have usually been achieved by developing ever more effective ways of ‘getting things done’, that is, by building ever more efficient modes of social organization. The most successful societies – those that have been able to persist by dominating or absorbing other societies, cultures, and civilizations – have taken advantage of the benefits of complexity and scale.

But how have societies built up increasingly complex and powerful forms of social organization?

Cast into the wild, and wanting to survive, it is convenient to think of our options as being of two kinds that must work together. First, we have our muscles and our hands to ‘get things done’. But we also need our brains to think through possibilities and options.

Both our bodies and brains can build on their potential by a process of learning. It is as though our ‘bare hands and bare brains’ can accumulate physical and mental tools (technologies) that build social organization by making it more efficient and effective.

The physical and mental tools that we use to manage social organization are forms of technology. We speak of physical tools as material culture. These material tools can be as simple as fashioned stones, or as complicated as computers – as directly associated with survival as a spade or tractor, or as distantly related to survival as a painting or piece of architecture. The mental tools of symbolic culture can be as simple as one person’s idea, or as complicated as shared mental systems passed down the generations – like language, mathematics, religion, attitudes, beliefs, systems of government etc.

What is especially important is the fact that both material and mental culture can evolve: it is cumulative in the sense that it can develop what has already been learned in an accelerating synergistic process of collective learning.

We can think of biological systems, during biological evolution, as slowly building up genetic changes as adaptations to environments (improvements). Biological evolution thus becomes the accumulation of historical biological information stored in genes.

But we can also think of the adaptation (improvement) of material and symbolic culture by the accumulation of newly discovered material and symbolic facts. Just as biological evolution has adapted to environments by gene modification, so communities have adapted to circumstance by meme modification. That is, cultural evolution tends to use collective learning as its tool of adaptation, thus becomes the accumulation of material and symbolic historical cultural information stored in memes.

It is now clear that the history of humanity reflects biological evolution, supplemented by the cultural evolution of technology (tools) of material and symbolic culture that contribute to the social organization that ‘gets things done’. These factors are all ultimately dependent on the availability, capture, and use of energy.

Technology can be progressive and cumulative, achieving ends in more efficient ways as it builds on the technology of the past but it can also be used for ends that do not ultimately serve the future of humanity.

Clearly the actual path of cultural evolution is neither linear nor necessarily ‘for the better’. What is theoretically possible, and what actually occurs in societies, are two very different things . . . so it is important to understand the factors that are critical in the emergence of social organization.

This is a complicated question but, to keep matters simple, the question may be loosely reframed as follows:

– What should be done – values

– What can be done – scale

– The rate at which it is done – technology

How it is actually donesocial organization

World Population

Human population growth over the long term

The graph extends from 10,000 BCE around the end of Natura and beginning of Agraria. It is projected through to 2100 CE and is a stark representation of the population explosion that accompanied the use of fossil fuels during Industria from around 1800 to 1950, to be followed by the Great Acceleration in economic and population growth after World War II as humanity moved into Informatia.

Courtesy the American Museum of Natural History

Social organization

It has already been asserted that a long-term view of history can be obtained by studying social organization as the ‘capacity for getting things done’ (both material and intellectual things). In a loose general sense history shows that those peoples that have subjugated or dominated other peoples have been those that have taken advantage of the synergies of scale by using the most efficient and effective technologies – treated here as the collective learning associated with material and symbolic culture.

Social organization is more than good governance and administration; it tends to follow the direction of the synergistic advantages of scale and the integration of all activities into ever larger systems operating at increasing speed.  There have been times when simplicity won out: but, in general, it seems that a good big’un beats a good little’un. The human world, once consisting of small nomadic bands of 20-40 people, is now integrated into a single vast globalized whole with more than half the world’s population living in cities.

Viewed over the long term we can see how the broad sweep of human history has been constrained by not only energy availability, but the human desire and capacity to capture and use it. At first it was geography that determined energy availability, but as technology became more sophisticated, the meaning of geography changed.

Long-term human history, then, can be clearly divided into four phases based on energy availability, capture and use.

The mobility of the nomadic lifestyle of hunter-gatherers and pastoralists placed limits on the numbers of children that could be managed, putting a cap on family and group numbers as an optimum form of social organization under such an energy regime.

A major energy threshold was crossed with the advent of a settled agrarian existence when energy could be concentrated and stored in cereal grains, thus providing the conditions needed for the further development of material culture.

Another energy threshold was crossed when the highly concentrated energy of fossil fuels was combined with the technology of heavy machinery of Industria.

Finally, the environmental impact of fossil fuels prompted a transition to renewable energy sources.

So, four phases of social organization may be distinguished in human history as defined by energy source and use:


  • Natura – the food energy of wild plants is used to power human muscles to obtain food, build physical structures, and provide movement and transport.

  • Agraria – settled communities eating cultivated plants provided the concentrated storable energy, as grain, needed to support a rapid increase in population numbers. Hierarchical societies with a division of labour were also able to quickly develop material and symbolic culture aided by the records of written language, coinage etc.  The energy efficiency of harnessing the muscle-power of domesticated animals, combined with the material technology like the wheel, improved the synergies of scale by improving the efficiency of food production, transport, and trade, all backed by formidable armies and navies

  • Industria – food energy obtained mostly from cultivated cereals and used to power the muscles of man and beast is supplemented by fossil fuel energy used to drive machinery that can greatly enhance food production, building construction, and transport systems

  • Informatia – cultivated plants continue to provide biological energy but the social energy of fossil fuels is progressively replaced by that of renewable energies. Per capita energy use in developed countries begins to plateau and developing countries adopt more energy-efficient methods of attaining material wellbeing.


In Natura it was mostly human muscle that was needed to build dwellings, hunt, and search for food. But in the course of history better ways of ‘getting things done’ were discovered or, in other words, more efficient ways of using energy for social ends.

In Agraria, as social groups became larger, it became possible for one group to persuade others to do the hard physical toil needed to obtain food and construct buildings so that they could devote their time to other activities. Slavery was one such division of labour. But it was also found possible to use the muscle-power of domesticated animals: oxen to pull ploughs and carts, and horses for transport.

A major change in social organisation occurred in Industria when it was found that concentrated plant energy in the form of fossil fuels could be used to drive heavy machinery. This use of plant energy totally transformed transport and communication systems and trade as factories and mills provided more household goods. As populations and cities grew, sailing ships became steamships and roads and railways expanded across the world.

In Informatia, our current era, the facility to now access materials and expertise from around the world facilitated the production of complex equipment like computers, while the climate change resulting from the atmospheric carbon dioxide produced by the use of fossil fuels, has resulted in the increased use of renewable and other energies needed to maintain vast and complex internationally-connected cities.

Page Menu




short term   ->   long term
individual   ->   global




accelerating synergistic growth in collective learning, technology, material complexity, globalization

values & norms




food & agriculture
transport & communic'n
manufacture & trade
raw materials, mining, engineering



impact of population (urbanization) technology




Daily food needs - 1500-2000


   Natura       -     5000-10,000
   Agraria       -    10,000-30,000
   Industria    -    200-230,000
   Informatia  -   200,000 +

History unfolds

The simple societies of Natura were powered by human muscle fed a diet of wild plants and hunted animals.

The settled communities of Agraria that followed were powered by the muscles of both humans and domesticated animals with a diet consisting mostly of cereal grains and the meat of domesticated animals.

During Industria more people lived in towns and cities their biological muscle energy based on a similar diet to before but with social energy supplemented by that of the fossil fuels coal, oil and gas which, when combined with new technology like heavy machinery, greatly increased the efficiency of construction, transport, communication, manufacturing and therefore trade. During Industria there was a massive increase in the quantity and rate of social activity.

Our present phase, Informatia, has full global interconnection and is now resolving issues of global governance, one of these being the gradual replacement of fossil fuel energy with energy from renewable sources. Other concerns include the economic demand on natural resources by the growing human population, global pandemics, the problems surrounding human migration and the consequences of rapid advances in electronic technology.

Key points


  • All activity in the universe depends on the expenditure of energy.
  • A distinction may be made between biological energy – as the energy needed to maintain biological metabolism – and social energy as the energy used to achieve social objectives.
  • Biological energy is the energy that drives biological metabolism and it is derived ultimately from that of the Sun, converted to chemical energy by plant photosynthesis, and absorbed as food (this includes meat): it is a key limiting factor for the way living organisms survive, reproduce, and flourish.
  • Social energy is the engine of social growth in population numbers, economic throughput (trade, construction, transport systems, technology etc.) and, ultimately, knowledge. Some biological energy, such as muscle energy, can be directed towards the achievement of social goals and is therefore both biological and social energy.
  • Energy use has been enhanced by the use of physical and mental tools (technology) that are both progressive and cumulative when they build on technology of the past.

Social organization

Key points

  • For any historical period, those factors that have the greatest historical significance relate to the scales of time, place, and circumstance that are under investigation
  • Over the full span of human history, it is the degree of social complexity (social organization) as constrained by the method of energy capture and use that emerges as yielding the most productive insights
  • Energy is used to drive growth – of population numbers and material culture
  • Two forms of energy can be distinguished: biological energy that drives bodies, and social energy that drive social activity
  • During the four phases of human existence there has been a progressive increase in the propotion of energy dedicated to the social activity that increases the material culture
  • More energy is obtained by either finding new and more concentrated energy sources, or by using existing sources more efficiently
  • energy is used more efficiently by applying technology – the tools that supplement what can be achieved with our bare hands and bare brains. Material tools can be as simple as fashioned stones, or as complicated as computers. Mental tools can be as simple as one person’s idea, or as complicated as shared mental systems passed down the generations, like language and maths
  • Complexity of social organization is reflected in the degree of sophistication of the material culture
  • The four phases of human history are defined by their primary sources of energy: in the phase Natura this was the food energy of wild plants (on which hunted animals also depended); in Agraria it was the food energy of cultivated plants; in Industria it was the food energy of cultivated plants supplemented by the concentrated energy of fossil fuels; in Informatia it was the energy of cultivated plants and fossil fuels supplemented by an increasing proportion of energy from renewable sources
  • Historically there has been a trend from spirit-based and animistic religions to polytheistic, then monotheistic and secular societies. Human wellbeing was at first negotiated with personified nature, sometimes through inspired intermediaries like the shaman-medicine man. Later, with the advent of writing, there followed an academic and priestly class that established explanatory and legal systems that both moderated and officiated over supernatural powers.




10,000    –    0.002
8000    -    0.005
6000    –    0.011
4000    –    0.028
2000    –    0.072
1000    –    0.115

1      –    0.30
500     –    0.20   
1000      –    0.31      
1100      –    0.33      
1200      –    0.38      
1300      –    0.35      
1400    -
1500    -    0.43–0.50
1600    -    0.50–0.58
1700    -    0.60–0.68
1800    -    0.89–0.98
1900    -    1.56–1.71
2000    -    6.06–6.15
2100    -    c. 10–13   

Media Gallery


Systems Innovation – 2016 – 14:15

First published on the internet – 1 March 2019
. . . 24 October 2022 – reorganized and revised


Four phases of long-term human history – Image Courtesy Rob Cross – June 2019

Print Friendly, PDF & Email