The authors of Vanishing Voices assert that this trend is far more than simply disturbing. Making explicit the link between language survival and environmental issues, they argue that the extinction of languages is part of the larger picture of near-total collapse of the worldwide ecosystem. Indeed, the authors contend that the struggle to preserve precious environmental resources, such as the rainforest, cannot be separated from the struggle to maintain diverse cultures, and that the causes of language death, like that of ecological destruction, lie at the intersection of ecology and politics.

And while Nettle and Romaine defend the world's endangered languages, they also pay homage to the last speakers of dying tongues, such as Red Thundercloud, a Native American in South Carolina, Ned Mandrell, with whom the Manx language passed away in 1974, and Arthur Bennett, an Australian, the last person to know more than a few words of Mbabaram.

In our languages lie the accumulated knowledge of humanity. Indeed, each language is a unique window on experience. Vanishing Voices is a call to preserve this resource, before it is too late.