Editing Click consonant (section)

==Click genesis and click loss==
One genetic study concluded that clicks, which occur in the languages of the genetically divergent populations Hadza and !Kung, may be an ancient element of human language.<ref>{{cite journal |last1=Tishkoff |first1=S. A. |last2=Gonder |first2=M. K. |last3=Henn |first3=B. M. |last4=Mortensen |first4=H. |last5=Knight |first5=A. |last6=Gignoux |first6=C. |last7=Fernandopulle |first7=N. |display-authors=3 |year=2007 |title=History of click-speaking populations of Africa inferred from mtDNA and Y chromosome genetic variation |journal=Molecular Biology and Evolution |volume=24 |issue=10 |pages=2180–95 |doi=10.1093/molbev/msm155 |pmid=17656633 |doi-access=free }}</ref> However, this conclusion relies on several dubious assumptions (see [[Hadza language]]), and most linguists{{citation needed|date=June 2019}} assume that clicks, being quite complex consonants, arose relatively late in human history. How they arose is not known, but it is generally assumed that they developed from sequences of non-click consonants, as they are found allophonically for [[doubly articulated consonant]]s in West Africa,{{sfn|Ladefoged|1968}} for {{IPA|/tk/}} sequences that overlap at word boundaries in German,<ref name=germ /> and for the sequence {{IPA|/mw/}} in [[Ndau language|Ndau]] and [[Tonga language (Zambia)|Tonga]].<ref group=note>Here the labial {{IPA|[m]}} may have assimilated to the velar place of the {{IPA|[w]}}, as {{IPA|[m͡ŋw]}}, with the release of the labial before the velar later generating a click {{IPA|[ᵐʘw]}}</ref> Such developments have also been posited in historical reconstruction. For example, the [[Sandawe language|Sandawe]] word for 'horn', {{IPA|/tɬana/}}, with a lateral affricate, may be a cognate with the root {{IPA|/ᵑǁaː/}} found throughout the [[Khoe languages|Khoe family]], which has a lateral click. This and other words suggests that at least some Khoe clicks may have formed from consonant clusters when the first vowel of a word was lost; in this instance *{{IPA|[tɬana]}} > *{{IPA|[tɬna]}} > {{IPA|[ǁŋa] ~ [ᵑǁa]}}.

On the other side of the equation, several non-endangered languages in vigorous use demonstrate click loss. For example, the [[Khoe languages|East Kalahari languages]] have lost clicks from a large percentage of their vocabulary, presumably due to [[Bantu languages|Bantu]] influence. As a rule, a click is replaced by a consonant with close to the [[manner of articulation]] of the click and the [[place of articulation]] of the forward release: alveolar click releases (the {{IPA|[ǃ]}} family) tend to mutate into a velar stop or affricate, such as {{IPA|[k], [ɡ], [ŋ], [k͡x]}}; palatal clicks (the {{IPA|[ǂ]}} family) tend to mutate into a palatal stop such as {{IPA|[c], [{{thin space}}ɟ], [{{thin space}}ɲ], [cʼ]}}, or a post-alveolar affricate {{IPA|[tʃ], [dʒ]}}; and dental clicks (the {{IPA|[ǀ]}} family) tend to mutate into an alveolar affricate {{IPA|[ts]}}.{{Citation needed|date=April 2011}}