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Cosmic Evolution

Another cosmic evolution project—in conjunction with Peter Richerson, University of California, Davis—has just been completed. It is a hands-on introduction to Dynamic Models of Human Systems which consists of eight fully developed, online, easy to use and understand visual flow diagram dynamic system models of scenarios drawn from across the social sciences. These models, using linked differential equations, explore exponential population growth, basic and technically advanced hunter-gatherer and farming communities, boom and bust civilizations, recent economic growth, and our current environmentally challenged limits to growth.


The descriptive text and models can be accessed (free to all) at:

Each model features:

• A contextual social-science introduction to the model.
• A visual flow diagram of colored-coded icons for stocks and adjustable flow valves, and connecting lines (with arrows) that show the flows of stocks and information between the icons.

• A free online simulator with color-coded controls that allow users to exercise the model by setting their own initial stock values and model parameters within allowable ranges.

• A color-coded table that lists all the model parameters, their units, and associated equations (which are not required to understand the model or explore its behavior).
• Example model simulations that illuminate key features of the model.
• Ideas for additional model simulations are provided, along with suggested settings for initial stock and parameter values.
•  A link to the Stella computer model block diagram and high-level code is provided so those with appropriate Stella software can download and modify the model.


The eight models:

1. Population Growth

This first simple Malthus population model introduces Stella Graphic flow model symbology and terminology. It also demonstrates the inherent dynamic tendency of populations to explode toward infinity, a tendency Malthus suggested would always be limited by unpleasant checks like starvation, pestilence, and sexual abstinence. Each of the remaining seven models covers a phase in the growing importance of cultural evolution dynamics from a planetary perspective. Malthus' model remains an element in all of them.

2. Basic Hunter-Gatherer

For about two million years, hominid technology improved very slowly. Hominids were rare, and the primary dynamic was changed in the hunter/prey populations, including the constantly repeating classic "rabbit and fox" boom and bust oscillation modeled by Lotka-Volterra linked differential equations.

3. Hunter-Gatherers with Evolving Technology

More recently, our species' hunting technology—thanks to cultural evolution—evolved faster than prey genetic evolution could counter it. The explosive growth of our once rare species led to the mass extinctions of the large game animals that human hunters preferred in many areas of the globe.

4. Basic Farming

As megafauna sources of food dwindled or went extinct, and the global weather improved, a shift to farming provided more efficient utilization of land, allowing the human population to gradually grow in a brief era of relative stability.

5. Farming with Dynamic Technology

However, as the pace of farming technology improvements quickened, farming became dynamically unstable. The positive feedbacks inherent in technological progress supercharged farming mutualisms, causing human populations, locally, to explode toward infinity until they crashed into the ceilings of starvation and pestilence noted by Malthus.

6. Dynamics of Civilizations

Civilizations, which introduced non-farming elites (kings, priests, soldiers, and artisans), added yet another dynamic as the farmers and elites competed for limited resources. This competition often resulted in civilizations having dynamic "rabbit and fox" boom and bust cycles, an oscillation demonstrated by Peter Turchin's Selfish Elites model.

7. Exogenous Economic Growth

However, with the recent advent of the industrial and agricultural revolutions, production—thanks to accelerating technological advances as modeled by Nobel Laureate economist Robert Solow—increased even faster than the rapidly ballooning human populations, thus avoiding the nasty Malthusian checks (at least temporarily).

8. World Dynamics

In the long run, however, Solow's rapid technological advances could not stop the dynamic cultural evolution of humanity from heading toward Infinity. On the way, necessarily, we will run head-on into firm, unyielding planetary ceilings as famously modeled by Jay Forrester and Donella Meadows in their Limits to Growth. The hunt for a way to evade Malthusian checks goes on.

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