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Image Courtesy Rob Cross – June 2019

Four phases of human history

From studies of Big History we have found that, when considering the full sweep of human history, it is the degree of social complexity, the form of social organization as constrained by the method of energy capture and use, that is the most productive long term historical analytical category (see glossary) round which to build further investigation; it is like a foundational historical principle.

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.

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 key distinguishing features of four phases of human history are outlined in the illustration above. Our interest is in the role played by plants in this unfolding of human history, and also to understand how these factors are related to sustainability.

Our study of Big history has revealed that the most productive lens through which to view human history is that of social organization which, of necessity, falls under the constraints of energy capture and use.


Energy is the ultimate source of all work and activity in the universe and it exists in many forms. For our purposes we can distinguish two kinds of energy that have limited 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. This 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.

Social energy

Increasing the supply of social energy facilitates social growth. This takes many forms. Usually described in simple terms as ‘economic growth’ it includes construction, trade, communication and transport systems (infrastructure), improved technology and so on. Historically the collective long-term consequences (though not necessary consequences) have included escalating population numbers with greater social complexity, interconnection, interdependence, and knowledge accumulation.

The rate of social metabolism has depended historically on the supply of biological and social energy provided by plants.

Leveraged energy

Social activity gathers momentum by supplementing what can be achieved with our bare hands and our bare brains by using tools (technology). Physical 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 or mathematics.

The history of technology is therefore closely linked to our ability to not only use the available energy more efficiently, but to access energy in new and more concentrated forms. When there is efficient communication, technology can be progressive and cumulative, achieving the same ends in more efficient ways as it builds on the technology of the past.

Social organization

Growth in population numbers and material culture are constrained by energy availability and use as determined by historical circumstance.

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 – cultivated plants provide the concentrated stored energy, as grain, needed for an increase in population numbers and division of labour, facilitated by harnessing of the muscle-power of domesticated animals to improve the efficiency of food production and transport.

  • 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 energy sources. 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.


Energy facilitates growth as an increase in complexity of social organization – in population number, material culture, and symbolic culture.

Material culture relates to the physical objects of human existence and their associated activities. Symbolic culture, or nonmaterial culture, relates to the abstract components of culture such as its language, attitudes, beliefs, and the information stored and transmitted in collective learning. The various elements of society operate synergistically (see Media Gallery below) to increase the momentum of change.

What is theoretically possible, and what actually occurs in societies, are two very different things . . . so what other factors are critical in the emergence of social organization?

This is a complicated question but, to keep matters relatively 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 donegovernance

Cultural evolution

Just as in biology, socio-cultural characteristics that offer some long term benefit or advantage will tend to persist: they are, in effect, ‘cultural adaptations’.

Inevitably two important question arise. Firstly, should we regard the process of social complexification as progressive – is this humanity adopting ever-improved and superior modes of existence? Secondly, how are we to compare the processes of biological and cultural evolution?

This needs further discussion.

Cultural progress

At the time of Australian settlement it was taken for granted that the move to agriculture was cultural and moral progress from a ‘lower’ state of tribal savagery to a ‘higher’ state of civilization.

In part this was a perception of a moral world like a Great Chain of Being) dating back to at least Aristotle, and adopted by Christianity, whereby all things existed in a natural hierarchy of being with some in a ‘higher’ (morally superior) state than others. So, for example, the prevailing view of the world in the 18th century at the time of Australian settlement was that Aboriginal people should adopt agriculture, not only as an ‘improvement’ on their existing living conditions, but also because it was morally uplifting. Europeans at that time regarded the social and technological sophistication and capacity to dominate other societies, as a demonstration of their ‘civilized’ mode of existence, in contrast to the animal-like savage living in a wild state of nature. On the Great Chain of Being white Europeans had fulfilled their destiny by being positioned in both a natural and God-given position at the top of the human ladder of life.

Social complexification has clearly resulted in what many would regard as progress – longer lives, medical services, secure food supply etc. This does not mean that cities and modern modes of civilization are the only possible or desireable ways to live.

Today we understand that possession of the tools of social domination does not justify their use for that purpose. Nor does it imply the moral superiority of those who possess them, or that their possession is always for the better.

Social evolution

In the late 19th century society began realigning the Great Chain of Being to Darwin’s theory of evolution. Just as life evolved, so too did societies. This was regarded as part of the natural law, a view that became known as social Darwinism. Humanity had progressed triumphantly from Stone Age to Bronze Age and Iron Age, advancing inexorably into the Industrial Revolution according to the laws of social evolution. Different kinds of social organization were simply progressive phases passing sequentially from savagery and barbarism towards civilization. Insofar as the idea of civilization entailed cities (civis – city-dweller, citizen) a hunter-gatherer could never be considered civilized.

Over time this view lost favour as its underlying moral, racial and ethnic arrogance became more apparent. It was also becoming apparent that the nomadic lifestyle had its advantages while urban living brought its own unique set of problems. Indeed, Darwin‘s theory of evolution indicated that a successful organism was one that was well-adapted to its environment. In the light of this principle how are we to view Europeans and Aboriginals, both then and now? Perhaps the nomadic lifestyle was longer-lasting and more resilient than European urban societies?

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.




short term -> long term



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



coll. learning - innovation



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



impact of population (urbanization)




Daily food needs - 1500-2000


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




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   

World Population

Human population growth

The graph extends from 10,000 BCE projected through to 2100 CE.
Courtesy the American Museum of Natural History

Media gallery


Systems Innovation – 2016 – 14:15

First published on the internet – 1 March 2019

Dragonfly metamorphosis. An example of emergence as the origin of new and unpredictable phases.
Clinton & Charles Robertson from Del Rio, Texas & College Station, TX, USA / CC BY 2.0 (
Courtesy Wikimedia Commons

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