System Dynamics Computer Model - Pleistocene Extinctions

Read the Paper:
    Combining Overkill, Climate Change and Second Order Predation: Counter Intuitive Results (view in PDF)

by Elin Whitney-Smith

This paper reports on an expansion of the dissertation model (PEM 1.0). In this version of the Pleistocene Extinction Model (PEM 2.0) a simplified version of climate change is introduced. This allows tests of combination hypotheses:
  • Climate change alone made servere enough to cause extinction
  • Climate change of this severity plus Overkill
  • Climate change of this severity plus Second Order Predation (2op)

Have a preview of the surprising results by running the flash slide shows
Single Hypothesis runs
  • Overkill
  • Second Order Predation (2op)
  • Simplified version of Environmental degredation
Combination Hypothesis runs
  • Overkill combined with Environmental degredation
  • 2op combined with Environmental degredation

Run the Full Model (PEM 2.0):

  1. Click on the PEM2005.zip file. This will download the zip file with the model.
  2. You will have to download a Run Time Version of the software; from Ventana Systems
  3. Once you have installed the software, open the zip file and click on the model PEM2005.mdl.

Read the Dissertation:
    Second Order Predation and Pleistocene Extinctions: A System Dynamics Model (view in PDF)

Run the Dissertation Model (PEM 1.0):

  1. Click on the PEM2001.zip file. This will download the zip file with the model.
  2. You will have to download a Run Time Version of the software; from I See Systems (Formerly High Performance Systems)
  3. Once you have installed the software, open the zip file and click on the model Xtinct.stm. A screen will appear telling you to click to continue.
  4. If the screen doesn't disappear automatically close it using the 'X' button in the upper right hand corner of the window.
  5. The extinction model will open.
Because it is a Run Time Version of the software; you will not be able to save models or changes to models.

When the model opens you will see a graph showing second-order predation. If this fills your screen press Control H to toggle back and forth between the graph and the interface. You can also resize the graph screen to see the chart pad and the interface which may be under it.

Pressing 'Control R' will start the model running. Click on the triangle at the bottom left of the graph pad to see other pages. (You can do this while the model is running).

The chart pad will appear and disappear with the graph pad. Clicking on the triangle at the bottom left of the chart will show other pages of the chart. If you cannot see the chart pad it may be covered by the graph pad. Move the graph pad by clicking and dragging on the upper edge or resize by clicking and dragging the border.

Getting Started with PEM 1.0

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