The rate of change between neighboring Salishan languages often depends on their environments. If for some reason two communities diverge, their adaptation to a new environment can separate them linguistically from each other. The need to create names for tools, animals, and plants creates an array of new vocabulary that divides speech communities. However, these new names may come from borrowing from neighboring languages, in which case two languages or dialects can grow more alike rather than apart. Interactions with outside influences through trade and intermarriage often result in language change as well.