Carrying capacity is best known today as a means of expressing the finitude of Earth's resources relative to the human population. However, the concept has been used in a remarkably wide range of fields beyond demography and geography, including anthropology, ecology, population biology, range and wildlife management, engineering, medicine, and law. Considered across all these uses, carrying capacity may be defined as the maximum or optimal amount of some X that can be conveyed or supported by some encompassing entity or place Y. The cogency and utility of this definition depend on the X and Y in question, however, and an understanding of its complex history is necessary to evaluate carrying capacity as a concept.

In the 1840s, when the term originated, carrying capacity referred to ...