In lieu of an abstract, here is a brief excerpt of the content:

Chapter 11 POPULATION MODELS AND COUNTERINSURGENCY STRATEGIES DOMINIC D. P. JOHNSON AND JOSHUA S. MADIN All guerilla units start from nothing and grow. mao tse-tung Efforts to contain terrorist or insurgent populations share many characteristics that would be familiar to any modern ecologist studying the dynamics of natural populations. The quantitative tools of ecology may therefore be useful in understanding these types of conflicts. We use data on two insurgencies , one that was defeated (Malaya 1948–1960) and one ongoing (Iraq 2003– ), to examine whether a population model can offer useful insights about insurgency growth, and what counterinsurgency strategies are most likely to be effective. Population models focus on parameters critical to the success or failure of counterinsurgency campaigns: insurgent population size, mortality rates, recruitment rates, and population carrying capacity caused by resource constraints. After fitting a simple population growth model with external mortality to the two data sets, we demonstrate the relative impact of seeking changes in mortality, recruitment, or carrying capacity on the future insurgent population size, and the importance of extinguishing threats early on, before they become established. Our models are, like all models, simplifications of complex events, focusing on a handful of parameters that we deem important and ignoring many others. For this reason, the results must be interpreted with caution. However , this is also precisely why models are useful: (1) the aim is to distill key factors from a confusing array of information; (2) some of our results succeed in describing actual events in the historical Malayan insurgency, suggesting that the models can account for real patterns with only basic variables; and (3) in fast-moving conflicts there is often little time or opportunity to obtain or verify comprehensive data, so the most useful analytical tools are ones that offer straightforward predictions with the limited data available. If we can extract fundamental patterns from the fog of war, we can identify practical goals for action. 159 Model results for Iraq suggest that: (1) if conditions had stayed the same as they were in January 2006 (i.e., low levels of sectarian violence), the Iraqi insurgency would have collapsed in 4.5 years, but only if the United States continued its trend of improving military performance; and (2) moderate changes to recruitment, carrying capacity, or mortality could, in combination , have defeated the insurgency in 6 to 12 months. The rise of sectarian violence in Iraq may therefore have foreclosed an opportunity to defeat the insurgency in a relatively short time. Natural Systems as Ecological Models of Conflict Natural systems are a hugely intricate web of interacting species, processes, environmental factors, and human-induced change. In order to distill these highly complex systems into manageable, understandable units, biologists have learned that populations are often best understood by focusing simply on fundamental data and models relevant to population change. The same may be true of apparently confusing human conflicts, but the rationale for doing so may occur only to biologists. Like populations of any species, human groups unified by an agenda or ideology are born, grow, and eventually die. Although the actual factors that regulate such human groups and nonhuman biological populations may be different, their underlying effects on population size are the same. For example, the growth of human groups is driven by immigration and recruitment; similarly, the growth of animal and plant populations is driven by immigration and biological reproduction (in ecological parlance, “recruitment” of surviving offspring into the breeding population). Quantitative models of human conflict have a long history, beginning with Lewis Fry Richardson’s and Quincy Wright’s studies of arms races and the causes of war (Richardson 1960, 1978; Wright 1983). Since then, rapidly increasing computational capabilities and techniques have allowed the development of a broad range of models that may be used to study human social dynamics (Cederman 1997; Epstein 1997; Ehrlich and Levin 2005; Epstein 2006). Models derived specifically from ecology have, for example, been used in studying the dynamics of public protest and coercion (Francisco 1996, 2004), and the life cycles of empires (Turchin 2005). Ecological models could, in principle, be generalized to any type of con- flict from gang warfare to conventional interstate wars. Here, however, we focus on insurgency, exploiting the techniques and tools of a simple population model to explore the dynamics of insurgent populations. Models offer two main opportunities: (1) by understanding and manipulating population parameters such as mortality, recruitment, and carrying capacity, populations can be either sustained...

Share