As discussed in a previous chapter, the evolutionary history of models has involved the speciation of fields of meaning–making. The practice here has been to take models that have evolved in specific fields and subject them to semiotic selection (testing) in other fields — analogous to the diffusion of biological species that have evolved in one ecosystem to other ecosystems in which they are subjected to biological selection. As could be expected, in some cases, this has resulted in modifications to the original field-specific model that reflect the process of adapting to fit the new context of use.