What Is the Nature of Theories and Models in Biology?

Biologists try to understand the living world at large by zooming in on tractable portions of it and by constructing and studying models. If you want to study long-term evolution in real time, you can follow finch populations in their natural habitats in the Galápagos (Grant & Grant 1993) or you can evolve microbial models in flasks in a laboratory (Lenski et al. 1991). If you want to understand how multicellularity first emerged in eukaryotes, you cannot go back in time to examine that event directly. Instead, you can construct and study a variety of models: for example, agent-based computer simulations, model organisms such as yeast or volvox, or model-based phylogenetic reconstructions (Bonner et al. 2016).