Looking for another opportunity to integrate math and science? How two researchers applied game theory to explain the coevolution of microbes and humans and to predict some “pretty bad epidemics” in our biological future was the subject of a story in ScienceDaily, October 20, 2007. The original model by microbiologist Martin J. Blaser and mathematician Denise Kirschner appeared in the Oct.18, 2007, issue of Nature and was titled “The Equilibria that Allow Bacterial Persistence in Human Hosts.”

The most virulent human microbes cannot survive except in dense populations, lest they kill their host before finding a new one and thus expire themselves. On the other hand, well-adapted microbes such as Salmonella typhi have mechanisms that allow them to persist in human bodies without being fatal. They become active at a point in the host’s life cycle that favors the bacteria’s survival by transmission to another host before the current host dies. The researchers infer this strategy most likely evolved with the first small and isolated human populations, which provided limited opportunity for pathogen transmission, and consequently for pathogen survival. They use game theory to support their hypothesis.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The Life Science Content Standard C of the National Science Education Standards suggests middle school students “develop understanding of structure and function in living systems; regulation and behavior; populations and ecosystems; and diversity and adaptations of organisms.” All of these are touched upon when students investigate coevolution of pathogens and human disease patterns, or epidemiology.

Conflict Transformation, a detailed article from Beyond Intractability, is aimed at middle school mathematics teachers and describes what game theory is and how it’s useful. It also provides an example of game theory applied to and extending beyond the Prisoner’s Dilemma Game.

Once students understand basic assumptions of game theory as typically applied to human behavior, they can be coached in its application to evolution of successful pathogens. Keeping in mind natural selection is not a conscious process living things can choose to manipulate, one can observe which strategies a pathogen, in game theory terms, uses to avoid implicating (a term from the Prisoner’s Dilemma Game) itself and which increase its probability of survival.

Here are some additional resources that are part of the NSDL Middle School Portal collection to facilitate your instruction regarding coevolution, epidemiology, and pathogen virulence: Hot Zone: A WebQuest for 7th Graders, Mutations, Black Holes, and Antivirulence Genes and Epidemic! The World of Infectious Disease.

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Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.