Diversity linguistics is the scientific study of human language in its full diversity, going beyond the study of major official languages, focusing in depth on particular lesser known languages or in breadth on comparison, whether structural-typological or historical.
Diversity linguistics has existed since the 18th century in a variety of ways, but until recently it has not been conceptualized as a coherent field of study with a community of scholars that are in constant dialogue with each other. In-depth study of small languages was done mostly by missionaries until a few decades ago; historical-comparative linguistics was seen as a way to supplement the historical study of the major languages (and the corresponding nations); and structural-typological comparison was long confined to a few linguists with philosophical interests.
This has been changing fast over the last few decades. With Joseph Greenberg’s empirical approach to universals and Noam Chomsky’s speculations about universal grammar, interest in general properties of human language structures has increased dramatically since the 1960s. The descriptive linguistics of underdescribed languages has realized that it can profit enormously from typological insights, so that the dependence becomes mutually – descriptivists and comparativists need each other’s works and insights. More and more descriptivists have ventured into typology, while armchair typologists have felt the need to go out and describe languages. And historical-comparative linguistics has changed quite radically, too: Historical linguists working on non-Indo-European languages are increasingly connected with each other across the language families, they are of course well-connected with fieldworkers (often fieldworkers become historical linguists or vice versa), and with the increasing importance of areal typology, they have become more and more interested in typology as well.
Thus, it is possible to speak of a field of “diversity linguistics”, even though this term is not widely used (yet). By adopting this term, linguists working within this field would signal that they feel responsible for, and competent in, a larger domain of study than is signaled by narrower terms like”typology”, “descriptive linguistics” or “historical linguistics”. Moreover, “diversity linguistics” sounds cool – contrast that with “descriptive linguistics”, which had a positive ring in the 1950s (cf. Gleason 1955) but is increasingly being replaced by “documentary linguistics” anyway. “Historical linguistics” sounds as if the practitioners spend most of their time in archives instead of using software from bioinformatics to unravel the human past. And “typology” is a term that no nonlinguist even begins to understand (which is why I prefer to replace it by “comparative linguistics”, or “structural-comparative linguistics” if a contrast with “historical-comparative linguistics” needs to be made).