Dos principios opuestos del despliegue concreto de los eventos sociales: La

Archaeology is widely used to study and infer the history of the human population. An advantage that archaeology has is that some of the material used in investigations are very robust and withstand deterioration through time very efficiently. Depending on the material used in investigation (i.e. wood, bone, stone, etc.) the time depth investigated could be very deep. Since early hominid species used stone tools, archaeology can investigate hominid associated culture and demographics up to millions of years before present.

It is generally assumed that the presence of flaked stone artifacts in the archeological record indicate the presence of true humans of the genus Homo. The time period in which members of the genus Homo had the ability to use and manipulate stone is known as the Stone Age. The Stone Age started ~2.5 million years BP and is divided into three stages, namely, the Earlier, Middle and Later Stone Age. Throughout all the stages of the Stone Age, humans were present in southern Africa. Their signature was left behind in the changes they caused in their environment and are studied by archaeologists.

By studying the archealogical record it is possible to identify certain demographic tendencies in the human populations involved. For example, it is possible through looking at the sizes and frequencies of archaeological sites to infer population densities and thereby identify population expansions and contractions. These expansions and contractions can then be linked to certain events in the paleoenvironment. Similarly, by studying the genetic variation present in extant populations one can also identify historical

population expansion and contraction patterns which can be dated to certain times in the past. It is therefore one of the aims of this thesis to identify these genetic signatures of population expansions and contractions and to try and correlate it with information available from the field of archaeology. The next section thus reviews the different stages in the archaeological record, their associated times, paleoenvironment and signatures of human occupation.

The Earlier Stone Age (ESA) occupied the time period from 2.5 million years BP to 250 000 years BP in southern Africa and is characterized by the use of large rudimentary flaked artifacts like handaxes. Throughout this stage there are evidence of the occupation of southern Africa by various hominans (humans and their extinct relatives) (Deacon and Deacon, 1999; Mitchell, 2002; Wadley, 2007).

The Middle Stone Age (MSA) saw the introduction of “cores” (pieces of rocks that are skillfully prepared to produce flakes of regular size and shape) into the archaeological record and stretched from 250 000 years BP to ~30 000 years BP in southern Africa. MSA tools were generally smaller than ESA tools and lack the large handaxes and cleavers.

There is no consensus on the definition of the MSA. Some archaeologists believe that it is a time related sequence while, others identify it as a package of technologies. For some archaeologists the MSA in southern Africa is associated with the appearance of anatomically modern people (Homo sapiens) (Wadley, 2007; Lombard, 2008). This was confirmed with the discovery of remains of early modern human fossils dated to 90 000 and 110 000 - 120 000 years BP at the Klasies River site in the eastern Cape. Further proof was the discovery of early modern human remains of a similar time period at a site named Border Cave on the KwaZulu-Natal, Swaziland border. Furthermore some form of symbolism can be dated as far back as 77 000 years BP. The shell beads from this period found at Blombos Cave imply individual or group identity and symbolism. While these cognizant and anatomically modern humans were roaming southern Africa, the European landscape was still dominated by Neanderthals (Deacon and Deacon, 1999; Henshilwood et al., 2002; Wadley, 2007; Lombard, 2008). The earliest known set of morphological characteristics associated with modern humans, however, appears in fossil remains from

2005). This finding does not exclude the probability that modern morphological traits existed in other regions of Africa (such as southern Africa) during this time. In other regions specimens may have been less well preserved or archaeological and paleontological investigations may not have been conducted as yet (Lahr and Foley, 1998; Reed and Tishkoff, 2006). Presently a multiregional origin model for modern humans within Africa is not as unlikely as it would be for global populations (Lahr and Foley, 1998; Campbell and Tishkoff, 2008).

Regarding the paleoenvironment of the MSA, it was previously believed that the period between 60 000 and 25 000 years BP was marked by very arid conditions in southern Africa, which led to a continuous population decline (Klein, 2000; Klein et al., 2004). This was partly inferred by an impoverished archaeological record for this period. Recently, however, a paper by Mitchell (Mitchell, 2008) summarised paleoenvironmental data that refute the presence of hyperarid conditions in southern Africa during this period.

Furthermore, he showed that a substantial archaeological record does exist for this period, albeit not as well studied as the periods that flank this stage (the earlier Stilbaai and Howiespoort cultures and the later LSA period). In addition many of the human foci, which exploited coastal recourses during this period, are today submerged since the sea-level was 30-60m below the present level (Mitchell, 2008).

The Later Stone Age (LSA) display technology to produce small specialized tools, such as microlithic tools and saw the introduction of bows and arrows, needles, bored stones, fishing equipment, etc. This period stretched from between 30 000 - 20 000 years BP to 2 000 years BP. The transition from the MSA to LSA is an uncertain concept, while some archaeologists believe the LSA began as early as 40 000 years BP, others insist that in certain regions MSA technology can only be found as recent as 20 000 years BP. It was suggested that the division of the MSA and LSA might be more of an archaeological construct than a real divide. The LSA do, however, have marked technological innovations and a regular occurrence of behaviour that were only rarely found in the MSA (Wadley, 2007). It is almost certain that the LSA sites were occupied by the descendants of the people who practiced MSA technology. Many sites have evidence for both complexes. San art, tools, burials and other remains of San hunter-gatherer lifestyle is associated with the

LSA and can be traced back with confidence as far as 22 000 years BP in the archaeological record. Also San social structure is very evident in archaeological remains for the past 10 000 years. Archaeological deposits from the MSA suggest that the social organization and rules of group behaviour did not change with the transition of the MSA into the LSA and were the same for the last 100 000 years or more. It is most likely that the MSA people that lived in southern Africa were the direct ancestors of the LSA people, Lesotho, southern Cape, Caledon valley, southern Namibia and the southern Kalahari. The LGM period (18 000 years BP) was associated by significantly colder conditions and intensified aridity before moister and milder conditions returned after 16 000 years BP. The LGM associated period (19 000 – 15 000 years BP) is marked by a major downturn in population size and distribution and may have caused localized extinctions. The rise in population numbers after the LGM was initially seen only at the few sites that existed though the LGM. The rise was slow until 13 500 years BP, thereafter population growth accelerated and deserted sites were reoccupied and new sites established. Distinct technological traditions for this period are reported for sites from South Africa (Robberg industry) compared to Namibian, northern Botswana and Mashonaland sites. It was suggested that this distinction could reach back to the distinct Tuu and Ju linguistic traditions and possibly also genetic distinctness (Mitchell, 2002).

Relative cool conditions remained throughout the Pleistocene to Holocene conversion (10 000 years BP) and maximum temperatures were only reached 8 000 years BP. The rise in sea level was effectively completed around 9 000 years BP and submerged large areas of previously exposed grassland. Groups became more concentrated and social exchange between groups increased. The later Holocene sites (~4 000 years BP) documents rising populations, expansions into new habitats and elaboration of material culture, especially in the Cape Fold Belt and Thukela basin. Technologies, which were characterized by delayed

farming” technology developed and practiced in the southern and eastern Cape, which regulates flowering and production times of geophytes, increased food production capabilities of populations dramatically (Mitchell, 2002).

The archaeological record from 2 000 years BP changed radically with the introduction of pastoralism to southern Africa. This transition is marked by the introduction of pottery and sheep remains in the archaeological record followed by the introduction of cattle and domesticated dogs. The herder way of life is associated with the people who spoke the Khoe languages. The general feeling among current researchers is that a sheep herding economy and ceramics were adopted by aboriginal Khoe-speaking hunter-gatherers from Bantu-speaking agro-pastoralists. These agro-pastoralists were spreading south from east Africa and arrived in Zambia/Zimbabwe ~ 2 100 years BP. Current theories suggests that the transfer took place in southeastern Angola, southwestern Zambia or northern Botswana. From the core area of northern Botswana the sheep together with the Khoe-speaking herders migrated southwards and gradually settled in between the hunter-gatherers from South Africa (Smith, 1983; Smith, 1992; Sadr, 1998).

Two migration routes are proposed, the first hypothesizes that stock keepers came west through northern Botswana and Namibia, down the Atlantic coast to the Cape and then further along the south coast and inland Cape areas (Stow, 1905; Cooke, 1965). This theory is based on the occurrence of paintings of sheep and shepherds in Zimbabwe and the ecological improbability of moving through the central Kalahari. This theory is also supported by records of oral traditions (Stow, 1905; Cooke, 1965). The second theory proposed that Khoe groups from northern Botswana acquired livestock from their Bantu-speaking Iron Age neighbors to the north. Subsequently their population and herds grew and the population spread south along the Zimbabwe/Botswana border, east of the Kalahari, towards the confluence of the Orange and Vaal Rivers. From there some groups spread south to the coast following one of the river valleys such as the Seekoe River and from there east and west along the coast. Other groups followed the Orange River to the Atlantic from where they spread north into Namibia and south into Namaqualand (Elphick, 1977). At the moment various archaeological findings lends more support to the Atlantic coastal route through Namibia (Mitchell, 2002). The earliest dates for the arrival of sheep

and ceramics in the Cape is 2 100 years BP in the northern Cape and 1 900 years BP on the southern Cape coast (Sealy and Yates, 1994; Henshilwood, 1996). It is further suggested that some of the hunter-gatherers of the Cape area were recruited and incorporated into Khoe culture. Those who remained hunter-gatherers moved into areas unsuitable for domestic stock or settled into an established working and trading relationship with the herders (Smith, 1983; Smith, 1992; Deacon and Deacon, 1999).

Both theories support population movement from the northern Botswana Khoe groups together with the pastoralism culture to the southern parts of Africa. This is supported by the linguistic, glottochronology findings that the KhoeKhoe languages of the south, diverged from the Kalahari Khoe languages ~2 000 years BP (Ehret and Posnansky, 1982). The homogeneity of the KhoeKhoe dialects further indicates a rapid recent expansion. The KhoeKhoe expansion is, however, only one component of the spread on the Khoe language group. The explosion of sites across Botswana in the last 2 000 years coupled to the oral traditions of Khoe-speaking San groups that they formerly owned livestock might be an indication of the Kalahari Khoe expansion linked to pastoralist groups/culture (Walker, 1995; Mitchell, 2002).

Certain evidence in the archaeological record, however, indicates that a simple demic diffusion model might not be sufficient to explain the spread of pastoralism. The spread of ceramics is thought to be associated with the spread of pastoralism and the two technologies form a package. The rapidity of the spread of ceramics ahead of the pastoralist culture and their occurrence in sites where herders never penetrated raises questions. If ceramics and pastoralism was a package spread by the KhoeKhoe herders they would regularly co-occur, which is not always the case. There would also be a ceramic stylistic chain that link assemblages in the Cape and southern Namibia to those in Botswana from whence they came. The stylistic chain would thus mirror the migration routes of the people. Archaeological sites with sufficient material are not adequate to make definite conclusions. Thus far, however, evidence of radical differences between styles argues against a common origin (Sadr, 1998; Mitchell, 2002).

The theories supporting a demic diffusion, argues that it would be very improbable of hunter-gatherers to adopt the pastoralist culture and therefore a population that spread the pastoralist culture is essential. Two hypotheses exist about the interaction between hunter-gatherers and herders. The first is that there is a great deal of overlap between these social and economic categories, and hunters who obtained stock could easily convert to herding, while herders who lost their stock easily fall back to hunting (Elphick, 1977). This theory thus support that at least some of the first livestock diffused southward from one to another group of hunter-gatherers (Deacon et al., 1978; Deacon, 1984; Klein, 1986; Kinahan, 1995). The other hypothesis supports separate social and economic groups that do not interchange easily (Parkington, 1984; Parkington et al., 1986). These separate groups can be identified archaeologically through different cultural signatures in deposits (Smith et al., 1991; Smith, 1992). Hunter-gatherers are seen as groups living on the fringe of herding society. They utilize wild resources, but occasionally interact as clients, through trading with herders. The hunters will also make forays against the herds of the herders leading to persecution and wars. Hunting and herding is thus quite discrete economic categories with hunter-gatherers occupying niches on the fringes of pastoralist society in a lower class or subservient status. These theories argues that the pastoralism culture requires a fundamental change in how hunter-gatherer social relations are organized and that the conversion of hunter-gatherer culture to pastoralism is very improbable (Parkington, 1984;

Parkington et al., 1986; Smith, 1986; Smith et al., 1991; Smith, 1992; Boonzaier et al., 1996).

Archaeology can, however, not conclusively prove whether the spread of pastoralism is associated with a demic diffusion of populations together with the pastoralist culture or a diffusion of the culture on its own. An intermediate model where only few individuals, perhaps only males, spread and transferred the pastoralist tradition and their language to resident hunter-gatherer groups further south is also possible. A genetic approach using male specific and female specific markers would be ideal in this case and would be addressed in one of the aims of this thesis.

The introduction and manipulation of iron and copper tools in southern Africa is known as the Iron Age and is associated with the arrival of the pre-colonial Bantu-speaking farmers

(Deacon and Deacon, 1999). The relationship and interaction between the hunter-gatherers and the in-moving Bantu-speakers is another hotly debated topic in the archaeological community. While some groups support hunter-gatherers as affluent independent communities (Marshall, 1976; Lee, 1979) others support the theory that in-moving Bantu-speakers marginalized, dispossessed and isolated San communities (Wilmsen, 1989; Wilmsen et al., 1990). There is also support for a theory that San-Bantu-speaker relations varied temporally and geographically. In some instances they may have retained their independent hunter-gatherer lifestyles and in some they may have been marginalized and subjected by Bantu-speakers (Campbell, 1990; Sadr, 1997).

Furthermore, some communities may in fact have had active and beneficial trade relations with Bantu-speakers and therefore benefiting indirectly from the cultivator/pastoralist culture (Nurse, 1983; Denbow and Wilmsen, 1986; Campbell, 1990; Sadr, 1997). Some resolution to this problem might be found in the analysis of population expansion and bottleneck/contraction signals found in genetic data. If in-moving pastoralists adversely affected San communities a signal of a recent population contraction would be evident.

Such a post-Neolithic population bottleneck was indeed proposed recently through analysis of hunter-gatherer genetic data (Excoffier and Schneider, 1999) (see further discussion in section 1.2.2.2). An investigation of genetic evidence for recent population bottlenecks associated with the in-moving herders will form the basis of one of the aims of the present thesis.

The major events evident in the archaeological record in the history of the LSA San hunter-gatherers and the Khoe herders can be summarised as follows. During the MSA to LSA transition (30 000 – 20 000 years BP) there was the introduction of the specialized LSA technology and certain sites showed increases in population sizes but only for truncated periods. The population density only increased noticeably from 13 500 years ago and especially in the last 4 000 years. The hunter-gatherers from northern Botswana adopted a herding economy (and perhaps the Khoe-language) 2 000 years BP and migrated southwards into South Africa. During the same time Bantu-speakers moved southwards from East Africa and settled in the eastern parts of South Africa (Deacon and Deacon, 1999; Mitchell, 2002). There was trade and interaction between San, Khoe and the

metal-colonization the eastern part of southern Africa had been populated by Iron Age Bantu-speakers for about 1 000 years. Hunter-gatherers had developed working relationships with the Bantu-speakers as well as the Khoe herders who had been settled in the southern and western parts of southern Africa for at least 1500 years. This situation was disrupted by the loss of control over land with the start of the European colonization (Deacon and Deacon, 1999).