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in a long line of speculations about the primitive origin of click consonants, which have been largely motivated by the outdated idea that primitive people speak primitive languages, which has no empirical support.