Culturally they are divided into the hunter gatherer San (commonly known as Bushmen, although this can be interpreted as derogatory) and the pastoral Khoi (sometimes known as Hottentots, although this is generally considered obsolete and sometimes offensive). The Khoisan languages are noted for their click consonants.
Over the centuries the many branches of the Khoisan peoples were absorbed or displaced by Bantu speaking societies who were migrating south in search of new lands, most notably the Xhosa and Zulu, who both have adopted some Khoisan clicks and loan words into their respective languages. The Khoisan survived in the desert or in areas with winter rains which were not suitable for Bantu crops. During the colonial era they lived in South Africa, Namibia and Botswana. Today many of the San live in parts of the Kalahari Desert where they are better able to preserve much of their cherished culture.
According to Knight et al. (2003) Y-haplogroup A, the most diverse or oldest-diverging Y haplogroup transmitted purely by patrilineal descent, is today present in various Khoisan groups at frequencies of 12-44%, and the other Y-haplogroups present have been formed by recent admixture of Bantu male lineages E3a (18-54%), and in some groups, noticeable Pygmy traces are visible (B2b). The Khoisan also show the largest genetic diversity in matrilineally transmitted mtDNA of all human populations. Their original mtDNA haplogroups L1d and L1k are one of the oldest-diverging female lineages as well. However, analysis of neutral autosomal (inherited through either parent) genes finds that the Khoisan are similar to other sub-Saharan African populations.
The presence of Haplogroup A, especially the subclade A3b2, in East Africa have led some to speculate on an ancient connection between those populations and the Khoisan, although the negligibly small frequencies of the A haplogroup that were observed in some recent genetic studies on East Africans puts this theory in serious doubt.
One interpretation is that the Khoisan are the earliest-diverging human group, or even a group that has preserved the original human lifestyle along with genetics. More conservatively, it can be said that the patrilineal or matrilineal descent of most individuals in most other human groups have passed through common genetic bottlenecks that are later than the most recent common patrilineal ancestor or most recent common matrilineal ancestor shared by all humans, and that the ancestors of the Khoisan avoided these particular bottlenecks. Such bottlenecks might be associated simply with the chance reproductive success of particular males, or with the settlement and subsequent expansion of a small group (e.g. modern humans venturing out of Africa, or the Sahara Pump Theory, or recovery from disasters like the Toba catastrophe) or have even more complex causes.
This does not show that the Khoisan were particularly isolated through history and prehistory; in fact, the autosomal genes demonstrate interchange with other African populations.
Kimberley's Rough /Diamond Remembered; Thami Ka Plaatjie Pays Tribute to !Khoisan X, /a Friend, Brother, Teacher and Comrade
Oct 19, 2010; It has pleased God that !khoisan X should depart these troubled shores and enter the ethereal realm of eternity. Benny...