Stanford University that the original human language may have had clicks. The purported evidence for this is genetic: speakers of Juǀ'hoan and Hadza have the most divergent known mitochondrial DNA of any human populations, suggesting that they were the first, or at least among the first, surviving peoples to have split off the family tree. In other words, the three primary genetic divisions of humanity are the Hadza, the Juǀʼhoan and relatives, and everyone else. Because two of the three groups speak languages with clicks, perhaps their common ancestral language, which by implication is the ancestral language for all humankind, had clicks as well. However, besides the genetic interpretation, this conclusion rests on several unsupported assumptions: Both groups have kept their languages, without language shift, since they branched off from the rest of humanity; Sound change, a very common phenomenon, affected neither language to the point that its primeval phonology became unrecognizable; Neither group borrowed clicks as part of a sprachbund, as the Bantu Nguni languages (Zulu, Xhosa etc.) and Yeyi did; and Neither the ancestors of the Juǀʼhoan nor those of the Hadza developed clicks independently, as the creators of Damin did. There is no evidence that any of these assumptions are correct, or even likely. Linguistic opinion is that click consonants may well be a relatively late development in human language, that they are no more resistant to change or any more likely to be linguistic relics than other speech sounds, and that they are easily borrowed: at least one Khoisan language, ǁXegwi, is believed to have reborrowed clicks from Bantu languages, which had earlier borrowed them from Khoisan languages, for example. The Knight and Mountain article is the latest in a long line of speculations about the primitive origin of click consonants, which have been largely motivated by the outdated idea that primitive people speak primitive languages, which has no empirical support. In popular culture In Peter Watts's science-fiction novel Blindsight, Hadza is presented as the human language most closely related to the ancestral language of vampires, citing the debunked hypothesis that clicks are good for hunting. References Bibliography Edward Elderkin (1978) 'Loans in Hadza: internal evidence from consonants'. Occasional Papers 3, Dar es Salaam. Kirk Miller (2008) Hadza Grammar Notes. 3rd International Symposium on Khoisan Languages and Linguistics, Riezlern. ———— (2009) Highlights of Hadza fieldwork. LSA, San Francisco. Kirk Miller, ed., with Mariamu Anyawire, G.G. Bala,