A language is not just a body of vocabulary or a set of grammatical rules. … Every language is an old-growth forest of the mind.

Wade Davis, an ethnobotanist and National Geographic Explorer-in-Residence, has often argued that cultural and linguistic diversity are as vital to humanity as biological diversity is to ecosystems. This line is associated with his public talks and writings on endangered languages and what he calls the “ethnosphere,” especially in the early 2000s when he was widely lecturing on globalization’s impact on Indigenous knowledge systems. In that setting, Davis uses ecological metaphors to make vivid that a language encodes generations of experience, memory, and worldview—so its loss is not merely technical (words and grammar) but a diminishment of human possibility.

Davis contrasts a reductive view of language—as a toolkit of vocabulary and rules—with a richer understanding of language as a living cognitive habitat. Calling each language an “old-growth forest of the mind” suggests depth, complexity, and irreplaceability: like an ancient forest, a language is built over long time spans, contains intricate interdependencies, and cannot be quickly recreated once destroyed. The metaphor also implies that languages shape perception and values, storing ecological knowledge, social ethics, and spiritual imagination. The quote functions as an argument for linguistic preservation: protecting languages protects distinct ways of thinking and being human.