A Brief Review on the Application of Lanchester's Models of Combat in Nonhuman Animals

The Lanchester models of combat were originally created for human warfare. These models were inspired by advances in technology and automatic weaponry at the turn of the 20th century. They parameterize army group size and individual fighting ability to explain the mortality rate of soldiers in a group during battle. In the last few decades, they have been applied to conflicts involving interactions between groups of nonhuman animals of varying degrees of sociality. This review focuses on the predictions and applications of Lanchester laws to nonhuman animal contests. Behavioral researchers have used the Lanchester models to interpret a variety of life history strategies and behaviors, such as colony fission in army ants, size differences in native versus non-native ants, recruitment behavior in chimpanzees, and dominance hierarchies in birds. These researchers assumed that the Lanchester laws apply qualitatively, and sometimes quantitatively, to the specific circumstances studied. To increase their biological realism, mathematical modifications have been proposed. While applications suggest that these laws may explain a multitude of social behaviors, there are surprisingly few empirical tests. Thus, further empirical data are needed to fully assess the accuracy of the models in predicting outcomes in nonhuman animals and their usefulness to biological systems.