Diversity is the natural state of the world (Harmon 2001). It is the quintessence of the evolutionary process as found in the natural world in its multiplicity of flora and fauna called biological diversity and in the constructed world in its multiplicity of cultures called cultural diversity. Language diversity is part of the co-evolution of humans with ecological diversity and it is comparable with the evolution of diversification of species. Languages are the core component of the ecologically evolved cultural diversity, which enable representation and transmission of the core aspects of cultures for acquisition by succeeding generations of the community and for interaction with other contemporary communities. It is natural for cultural diversity to emerge and sustain itself through language diversity. It is established empirically (Harmon 2002) that the diversity in nature and culture are integrally related and they are connected with the development of ecosystems and with their sustainability. This has given rise to the concept of biocultural diversity as a unified phenomenon. Most of the specialists in the respective fields of study of nature and of culture and the common people seem not to be aware of the connection between diversity in nature and culture. The awareness of the common people about the connection between culture and language is more socio-political and psychological and less philosophical in nature. One piece of evidence is that an increasing number of minority linguistic communities transplanted in the midst of a dominant linguistic community ask seriously the question whether they can maintain their culture without their language.
The awareness of, and scientific enquiry into, biological diversity transformed into concern and activism for the preservation of that diversity, renamed in the 1980s as biodiversity (Wilson1988), when the people saw the loss of diversity to be coupled with environmental degradation instigated by human behavior. It is not that extinction of biological species did not occur before in paleo-historical times. It has occurred five times in a massive scale, each separated by millions of years, extinguishing together more than ninety per cent of species that ever lived (Heywood 1995). But the earth regenerates itself every time with new species. The impending sixth extinction feared by specialists will be the first one after modern humans (Homo sapiens) came into existence 250-200 thousand years ago and the human language emerged sometime after this evolutionary happening and before the modern humans migrated out of Africa 100-70 thousand years ago. The sixth extinction, if it happens, will be the one caused by humans and it may include the human species (Pimm and Brooks 2000). It will then be the one that includes extinction of languages. Even if there is no total extinction as feared, there is increasing loss of language diversity now directly attributable to human action.