Stem cells have the ability to renew and to differentiate into progenitor cells that ultimately form all of the tissues in an organism. The current interest in stem cells C both adult and embryonic C is through the promise that they hold for regenerative medicine.
That promise, however, relies on the assumption that stem cells will respond to our modifications of them in ways that we desire. However, experience with interventions in other natural systems C from fishing to antibiotics C shows that acting without thinking about evolutionary consequences is fraught with danger. The time for an evolutionary ecology of stem cells is now. I will show how this can be done, using the hematopoeitic system as an example. To begin, we model the system of stem, progenitor, and fully differentiated cells using a combination of stochastic simulation and associated ordinary differential equations. These models must capture the feedback controls C both positive and negatve C on the stem cell system. Once this framework is organized, it is possible to ask a variety of questions. In this talk, I will focus on two. First, I will use evolutionary invasion analysis to ask if modifications of stem cell parameters will have the effects that we desire. Second, I will use state dependent life history theory, implemented through stochastic dynamic programming, to understand why stem cells are mainly quiesencent and compare this result with the classic experiment of Till and colleagues. This work reminds us that nothing in biology makes sense except in the light of evolution.