This is final post of a four-part post. See also parts 1, 2 and 3.

Finally, there is one other concept that needs introducing: Evolution. While evolution is not a causal variable, it is nevertheless important to understanding how human societies change. It seems to be a fundamental core of human psychology to attribute change to a human, god, organization or group of humans. We so easily assume that something happened because somebody knowingly and purposively caused it to happen.

But if one examines that list of trends and constants that I listed above, it is clear that no person, organization or god consciously decided to make them happen; few people are even aware that these changes have happened at all. These long-term changes were and are the outcome of millions of small-scale decisions made by individuals who were trying to solve short-term local problems. Few of them were even thinking about society as a whole. Even the leaders of a society typically focus on solving short-term problems without thinking through their long-term consequence (if it is even possible for them to do so).

Evolution is also critical to linking the theory to biological theories of evolution by natural selection. In biological evolution, plants and animals evolution because:

1. Nature starts with a finite amount of resources. Most of those resources ultimately come from solar energy.
2. Different individuals possess varying mix of heritable characteristics in their genes.
3. Some of those characteristics increase their probability of survival and reproduction.
4. Those individuals that survive to reproduce pass on a portion of their genes to the next generation. Assuming the environment does not undergo radical change, this increases the chances that their offspring survive and reproduce.
5. Over many generations, this process creates more complex and specialized life forms.
6. Most importantly, no one person, organization or god is in charge. Simplicity, given enough energy, transforms over time into complexity.

Just as evolution via natural selection transforms solar energy into complex forms of life, I believe that this process continues and even accelerates with the advent of modern humans. Humans have unintentionally tapped into this evolutionary process by transforming solar energy into technologically complex societies. Each society follows a different pathway due to differences in their geography, technology, skills, social organizations and values, but they all follow at least a portion of the following process:

1. The Sun creates solar energy by fusing hydrogen into helium. Sunlight injects energy into planet Earth, initiating the following process.
2. Plants transform solar energy into sugar (via photosynthesis).
3. Herbivores eat plants and transform it back into energy (via metabolism).
4. (In Hunter-Gather and Fishing Societies) Humans innovate technologies, skills and organizations that enable them to acquire food from their local environment by:
   • Hunting wild animals
   • Gathering wild plants
   • Fishing
5. (In Agricultural Societies) Humans innovate technologies, skills and organizations that enable them to acquire far greater amounts of food from their local environment by:
   • Farming domesticated plants, particularly grains.
   • Herding domesticated herbivores.
6. Increased food production creates a surplus for each farming family.
7. This food surplus enables farmers to trade with persons who possess skills related to non-agricultural technologies (for example bakers, blacksmiths, millers or butchers).
8. When trade reaches a certain level, trade-based cities with a wide variety of skills evolve.
9. These trade-based cities create a virtuous cycle of technological innovation and social cooperation. This virtuous cycle includes:
   • Increased population sizes for the entire nation.
   • Increased urbanization rates
   • Greater number of market transactions
   • Acquisition of new skills to conceive of, design build, test, use and repair new technologies
   • Greater specialization of skills
   • Greater cooperation between people within the same group
   • Expansion of the sphere of cooperation beyond just the family to create larger and larger social organizations
   • Higher levels of trust within the group
   • Lower levels of violence within the group
   • Increased positive-sum perspective (i.e. we can both get ahead by cooperating together, rather than trying to sabotage each other by lying, stealing or killing)
   • Greater valuation of achievement over status and military glory.
10. This virtuous cycle within trade-based cities also has a powerful effect on institutions:
    • Deepening complexity of existing institutions as they put to use new technologies and skills.
    • Emergence of new institutions based upon new technologies and skills.
    • Decline of institutions who are unable to make effective use of new technologies.
11. All of the above feed back into the technology base, enabling a faster rate of technological innovation. Each new piece of technology can be used in as a component in another more complex piece of technology.
12. Finally, the widespread usage of fossil fuels broadens the geographic scope of this cycle so that it encompasses more than just a few trade-based cities. The feedback loop could now affect entire regions, nations and eventually continents. If these trends continue, the entire planet will eventually be engaged.

The above process conceives of technological innovations as a fundamentally progressive force in human history, but one that it is seriously constrained by biology, geography and food production. This process explains why humans have been able to ratchet themselves up from naked apes, fundamentally constrained by biology and geography, into modern humans with sophisticated technology and complex social organizations with greater levels of cooperation and lower levels of violence.

All of the above may strike some readers as an extraordinarily optimistic, even dangerously naïve, view of the human history. What about all the wars, violence, poverty, racism, imperialism, extremist ideologies, exploitation, disease, famine and human suffering? Unfortunately, the factors on this terrible list have also played a key role in human history, so clearly there is far more to history than an endless parade of human progress.

While I believe the above process accounts for much of the change in history, it is clearly not the only factor in human social development. For virtually all of human history, change has been excruciatingly slow. So slow that most people notice very little change to their society or their technological toolkit within their lifetime.

Worse, there have been times when human development appears to have moved “backwards”, or, more commonly, the benefits of technological innovation are monopolized by a small elite. For much of human history, the common man has not benefitted much from technological progress.

This lack of progress was caused by counter-veiling factors that retard or undermine the progressive force of innovation.

• The rate of technological innovation is exponential; i.e. it is partly based upon the amount of technology that is already in existence. Because most people think of exponential growth as being synonymous with rapid growth, it is easy to see how this factor explains the rapid technological innovation of the current era. Today we have so much technology that the rate of innovation is high and keeps increasing.
  But the fact that the rate of innovation is exponential also explains why innovation was so slow for tens of thousands of years. Because humans evolved from apes, our initial toolkit was near zero, probably no more complex than a twig or leaf. Starting from such a small technology base meant that the initial rate of innovation was excruciatingly slow for millennia, until the total amount of technology reached a large enough size to make progress noticeable.
• The rate of innovation is also partly based upon population size. The larger the number of humans, the larger the number of opportunities to come up with new ideas for improved technologies. The vast majority of these ideas result in failure, but a few evolve into improvements over existing technology.
  Today the world’s population is over seven billion. This enables a huge number of innovative ideas to occur each year. The population of early humans, however, was tiny in comparison, probably on the order of a few thousand or tens of thousands. The small population size of early humans limited the number of new ideas that could possibly have occurred at any one time.
• As Thomas Malthus observed, increased food production leads to more babies and more babies must be fed. In this way, much of the increased food production of the past has been literally eaten up by a larger population. Rather than the standard-of-living increasing, the population increases. Technological innovation that is slower than the birth rate leads to few benefits for the masses.
• While a larger population increases the chances of technological innovation, some types of people are far more likely to innovate than others. To sustain rapid technological innovation, humans with specialized skills must concentrate geographically (usually into cities). But in order to produce enough food to survive within the carrying capacity of the land, humans must do the opposite: they must disperse. Because one must survive before one can innovate, the needs for survival dominate. It was only with the invention of highly productive agriculture within the last 3000 years that humanity has been able to overcome this conundrum by evolving large trade-based cities.
• Fundamental geographical barriers have completely stopped technological development in the vast majority of societies:
  • Most ecosystems cannot support Agriculture, meaning that societies in those biomes cannot advance beyond Hunter-Gatherer, Fishing or Herding societies (each of which will be covered later). These types of societies have too low a population density to support much innovation.
  • Even fewer ecosystems support Plow-based Agriculture, a critical technology for creating a surplus of food needed to support trade-based cities.
  • Some of the ecosystems that could potentially support Plow-based Agriculture lack domesticatable grains and herd mammals, making it extremely difficult for them to create a sizable surplus of food.
  • Most regions do not have navigable rivers or coastlines with natural ports, dramatically increasing the cost to import food surpluses into cities and export more complex technologies out of cities.
• As mentioned earlier, before the Industrial Revolution, the vast majority of man work hours has been devoted to producing food. This gives little opportunity for technological innovation in other sectors.
• Because technology-based progress is built upon face-to-face human interaction, it is highly localized. Even in societies with numerous trade-based cities, much of its geographical area and population are dispersed into rural hinterlands. A farmer might be only a few miles from an area that is rapidly progressing, but they will not notice much of a difference in their lives. Trade-based cities are often rapidly evolving islands of prosperity in an ocean of very slow rural growth.
• All of the above means that the conditions that promote rapid technological innovation have been extremely rare. Until the Industrial Revolution only a tiny portion of the world’s population possessed skills related to emerging technologies. Those people were generally restricted to cities with small populations or capital cities which were dominated by technophobic landed elites.
• Though Agricultural societies had the food output necessary to support cities full of specialized workers, titled elites usually dominated their political, religious, military and economic institutions. These elites focused on promoting their own social status, military glory, so they were suspicious of new technologies that did not directly benefit themselves. This attitude stifled most technological innovation, except for the domains of the military and luxury consumption.
• Many Agricultural societies were also dominated by highly centralized political and economic organizations. Monopoly in history has been more common than competition. These centralized institutions enabled landed elites to maintain their political control, social status and economic wealth, but it also stifled the diversity of ideas necessary to foster innovation.
• Societies with powerful militaries have often destroyed more technologically advanced societies. While technology plays an important role in military power, it is not the only factor. Also important is population size. Until the Industrial Revolution, technologically progressive societies had small populations, while many empires had huge populations. This created a great disparity in military power. Most technologically progressive cities were eventually absorbed into larger empires, killing the very foundation of their innovation.

Now that I have sketched out the conceptual framework on a high-level, we can move onto describing the details of each factor.