Jonathan Loh and David Harmon, in their new report, Biocultural Diversity: threatened species, endangered languages (PDF), develop analogies between biodiversity and linguistic diversity:
we have chosen two fundamental units or classifiers of nature and culture: species and languages. Species are the basic units of biodiversity; languages are a useful proxy to stand for the world’s diverse cultures. Other elements of biodiversity such as ecosystems or genes, and other aspects of culture such as religions, arts, or livelihood and subsistence strategies, are much harder to define and very much harder to measure. There are striking parallels between species and languages (p. 2).In a brief 60 pages, they take us through Biocultural Diversity; Evolution of Species and Language; Decline of Biocultural Diversity; and Status of Species and Languages. Among their conclusions are:
Two results are immediately apparent when comparing the status and trends in biodiversity and linguistic diversity. Firstly, at the global level, the trends are very similar, both the LPI (species) and ILD (languages) declined by about 30% since 1970, which suggests that biodiversity and linguistic diversity are being lost at similar rates. This supports the conclusion of the Red List analysis comparing the conservation status of languages and species: globally, linguistic diversity is at least as threatened as biodiversity.
The second result is that, while both biodiversity and linguistic diversity are threatened globally, they are declining at different rates in different regions of the world. By far the most rapid losses in linguistic diversity have occurred in the Americas where, according to the Red List analysis, 60% of languages are threatened or have gone extinct since 1970.
[...] Habitat loss and over-exploitation of species remain the greatest threats for most of the world’s biodiversity. [...]
The decline in linguistic diversity is normally a result of the process of language shift away from small indigenous languages toward larger, national or regional languages. Language shift is driven by a number of social, political and economic factors including migration, urbanization, national unification, colonization, and the globalization of trade and communications. Migrant communities often undergo a process of language shift, whether moving from one country to another, or from a rural to an urban area within the same country. Governments in many developed and developing countries actively promote a single national language at the expense of other, usually minority, languages for political reasons. (p. 44-45)In their "Epilogue" the authors sum up the vision underlying the vision as follows:
Maintaining diversity is not just a question of protecting endangered languages and species in remote hotspots of biocultural diversity such as the Amazon or New Guinea, vitally important though that is, conservation is also a matter of allowing diversity to thrive in those parts of the world where humans have already had a profound impact on the biological and cultural landscape, in the more densely populated parts of the planet. Recognizing and exploring the parallels between nature and culture, and understanding the processes that underlie their evolution, ecology and extinction, is a first step towards ensuring that we can continue to inhabit a world of incredible diversity. (p. 49)Loh, J. and D. Harmon. 2014. Biocultural Diversity: threatened species, endangered languages. WWF Netherlands, Zeist, The Netherlands. http://awsassets.panda.org/downloads/biocultural_report__june_2014.pdf