Measuring Linguistic Diversity


The Index of Linguistic Diversity is the first-ever quantitative measure of trends in the world’s linguistic diversity. It tells us that, since 1970, global linguistic diversity has diminished by 20%. Indigenous linguistic diversity has decreased even more markedly in most regions of the world. The 16 largest world languages have increased their share of the world’s population from 45 to 55%. These trends should concern us all. Why?

Linguistic diversity is part and parcel of the diversity of life in nature and culture. Any loss in linguistic diversity is a loss in the vitality and resilience of the whole web of life. Every time a language disappears, along with the cultural traditions and cultural knowledge it conveys, it’s a piece of the planet’s living fabric that gets torn off, leaving all of the living world more fragile, more vulnerable, and with fewer options for the future.

linguistic diversity
Credit: David Harmon and Jonathan Loh / Terralingua

There are about 7,000 languages spoken in the world today. However, the numbers of speakers of these languages are vastly uneven. To put it simply, there are a few languages each with a lot of speakers, and a lot of other languages each with a small number of speakers. In fact, the distribution is so skewed, that half of the world’s population speaks one or other of only 25 “big” languages, while the other half of the world’s population speaks one or other of the remaining 6,975 or so languages. And these smaller languages are increasingly losing ground to the “big” languages.

Concern about the loss of diversity and vitality of the world’s languages has been building since at least the early 1990s. Yet, this concern was mostly based on anecdotal evidence which suggested that many languages might become extinct by the end of the 21st century. Between 2005 and 2010, Terralingua co-founder David Harmon and colleague Jonathan Loh took on the challenge of providing sold scientific evidence on the state and trends of the world’s languages. As a part of a Terralingua-funded project, they gathered systematic quantitative data and developed the first-ever Index of Linguistic Diversity (ILD). The results of the ILD research were published in 2010 in a peer-reviewed article:.

Harmon, D., & Loh, J. (2010). The Index of Linguistic Diversity: A New Quantitative Measure of Trends in the Status of the World’s Languages. Language Documentation & Conservation, 4, 97-151.
linguistic diversity
Credit: David Harmon and Jonathan Loh/Terralingua
biocultural diversity
Credit: David Harmon and Jonathan Loh / Terralingua

The ILD reveals an alarming rate of decline in global linguistic diversity, showing that the world’s languages – not just their number, but also the linguistic and cultural diversity they represent – are being severely diminished. In just 35 years, between 1970 and 2005, global linguistic diversity has declined by 20%.
The dramatic decline in linguistic diversity is due to ever-growing social and economic pressures that are inducing or even forcing people to switch from generally smaller, more geographically restricted languages to larger languages, especially global languages like Mandarin Chinese, Hindi, English, or Spanish, or regionally dominant languages like Swahili. The top 16 languages spoken worldwide increased their share of the global population from 45% in 1970 to 55% in 2005.

The changes in the number of mother-tongue speakers are associated with shifts in the use of a given language in adult speakers, as well as with a decline in the transmission of that language to new generations.

The ILD data provide strong support to the claim that there is a global crisis of linguistic diversity loss. The ILD captures the magnitude of the problem in a way that is easy to understand and informative for researchers, educators, policy makers, and the general public.

world languages
Credit: David Harmon and Jonathan Loh / Terralingua
Credit: David Harmon and Jonathan Loh / Terralingua
Credit: David Harmon and Jonathan Loh / Terralingua

The ILD was developed not only to document these trends, but also to call attention to the importance of maintaining linguistic diversity for the conservation of biological diversity. Earlier work that Harmon and Loh carried out for Terralingua (2001-2005) had led to the development of an initial Index of Biocultural Diversity (IBCD), which suggested parallels and connections between the state of the world’s linguistic diversity and the state of the world’s biological diversity. (See downloads at the end of this page.)

The ILD has been chosen as one of the indicators relevant to Target 18 of the Convention of Biological Diversity (CBD) “Aichi Biodiversity Targets 2010-2020″, an international initiative aiming to counter the global loss of biodiversity. Aichi Target 18 recognizes the relevance of traditional knowledge (and of the languages in which traditional knowledge is encoded) for the conservation and sustainable use of biodiversity. The ILD is featured on the site of the Biodiversity Indicators Partnership (BIP), which promotes and coordinates the development and delivery of biodiversity indicators in support of the CBD.

For further information about the ILD and the IBCD, you can download the materials below. Or you may contact David Harmon and Jonathan Loh.



Index of Linguistic Diversity (ILD) 2006-2010

Harmon and Loh ILD peer-reviewed article, in Language Documentation & Conservation, Volume 4, 2010

ILD Supplementary Data Tables, 2010.

Abridged version of 2010 article  

Langscape Magazine, Volume 2, Issue 8, “The Case for Linguistic Diversity,” 2011

Biocultural Diversity Toolkit, Volume 4, “Documenting and Revitalizing Oral Traditions”

National Geographic News Watch interview on ILD, 2011 “Language Diversity Index Tracks Global Loss of Mother Tongues

Luisa Maffi’s video presentation on ILD at Trace Foundation, 2010

Article on ILD from Terraviva, 2008

This Plant Medicine Teacher is Reclaiming Anishinaabe Names for Species. Why That Could be Good for the Planet, CBC Radio — “The Current”


Index of Biocultural Diversity (IBCD) 2001-2005.

IBCD report: “A Global Index of Biocultural Diversity” Discussion Paper for the International Congress on Ethnobiology, University of Kent, UK, June 2004

Loh and Harmon peer-reviewed article, in Ecological Indicators, Vol. 5, 2005