Genetics research of the Hadzabe of Tanzania and the KhoeSan of Southern Africa has helped a group of American and Russian researchers answer an old question: Where do click languages come from?
Languages can be related to other languages by the similarity. When languages share common features (like words or grammar), they are more related than languages that don’t share these features.
For example German and English are related langauges because they share very similar ways of making a sentence which is different from another language like Hindi.
In the 1960’s Joseph Greenberg grouped all languages that have a collection of clicks consonants and their accompanying sounds together in the Khoisan-language phylum.
This a video of a KhoeSan speaking a click language.
This phylum included the Southern African Khwe and San languages but also the Tanzanian language isolates, Hadzane (spoken by the Hadzabe of the Lake Eyasi in north-central Tanzania) and the Sandawe. Their language is dissimilar to every other known language.
For both the hadzane and the Kwe and San, clicks are essential for the language. Click languages are very rare and the repertoires shared by Hadzane and the KhoeSan languages are very complex. Because of these two facts, it is unlikely that the clicks were invented independently by the two groups instead the two groups must have shared the same ancestral click language and thus at some point they must have had a common ancestor. The similarity between these two groups, the age of separation from other humans and the use of clicks suggest that they could have once shared an ancestor that lived across East Africa.
The hadzabe are primarily still hunter-gatherers and some people believe they may have been living in that area of Africa since the the arrival of the earliest modern humans to the region.
The ju/’hoansi (or !kung) are hunter-gathers from Northern Namibia and Botswana who speak a KhoeSan language.
The idea of a continuous population (and therefore their language too) is not a new idea for genetics or archaeology (see the recent work on ancient African DNA ).
Early suggestions as to why the populations became isolated were that the Bantu-expansion interrupted the ancestor’s distribution. This doesn’t work out in the end. The separation between the Hadzabe and the KhoeSan is much older than the Bantu Expansion.
The Ju/’hoansi have a long-term separation from other humans based on the genetic results from Non-Recombining Y chromosome markers. This study suggests based on microsatellites that the divergences could be ~ 70K-163 Kya.
The Hyper-Variable region 1 of mitochondrial sequence shows that the Ju/’hoansi, Mbuti, Biaka and Hadzabe were the most genetically distant from other African populations and the San-Hadza genetic distance was the greatest, meaning they have the oldest separation of all present-day populations. The hadzabe had mtDNA haplogroups L1a, L2 and L3 while ju/’hoansi had haplogroups L1d and L1k. They shared no haplotypes showing that they are a set of isolated and divergent African lineages.
The same was seen in the Y chromosome data where the M112 (B2b haplogroup) was highest in Ju/’hoansi and the microsatellite alleles asssociated with the M112 were not shared between Hadzabe and Ju/’hoansi, and they differed by a large number of repeats.
The Hadzabe, however, share more with the rest of the humans than the Ju/’hoansi did, showing that the Hadzabe are more related to the rest of the human population.
This result is important because it means that all other human languages have lost their clicking sounds. The relationship between southern African KhoeSan languages has been controversial because of their divergence from each other and other languages but now there is an answer that seems to make sense.
Knight, A., Underhill, P. A., Mortensen, H. M., Zhivotovsky, L. A., Lin, A. A., Henn, B. M., … Mountain, J. L. (2003). African Y Chromosome and mtDNA Divergence Provides Insight into the History of Click Languages, 13, 464–473. https://www.sciencedirect.com/science/article/pii/S0960982203001301
Mzansi Mix 
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