Introduction to the project and excavation of Diepkloof Rock Shelter (Western Cape,South Africa): a view on the Middle Stone Age

This introduction presents the background to the present research project at Diepkloof Rock Shelter, initiated in 1998. It is followed by a series of original papers that were presented in November 2010 at the join 13th PAA Congress (Panafrican Association of Prehistory and Associated Disciplines) and 20th conference of SAfA (Society of Africanist Archaeologists) at the University Cheikh Anta Diop in Dakar (Senegal). These papers were presented in a “Symposium on the MSA sequence of Diepkloof Rock Shelter: a view on the cultural evolution of southern African modern humans” organized by Pierre-Jean Texier, Guillaume Porraz, John Parkington and Jean-Philippe Rigaud. This series of papers is a first attempt at a multidisciplinary reconstruction of the way Middle Stone Age people inhabited the site of Diepkloof and the way they interacted with their environment. The resultant narrative outlines artifactual change through the sequence and discusses the factors that might underlie it.     

Ochre resources from the Middle Stone Age sequence of Diepkloof Rock Shelter,Western Cape,South Africa

Although no paintings are associated with archaeological contexts before the end of the Middle Stone Age, hundreds of ochre pieces were discovered on numerous southern African sites suggesting a lasting tradition of ochre use. The variability and the significance of ochre exploitation remain however poorly documented. The MSA site of Diepkloof Rock Shelter (Western Cape Province, South Africa) offers an ideal opportunity to discuss questions of ochre procurement, processing, and use over a long sequence. This study develops an original methodology based on observations on one hand, and SEM-EDS, XRD and Raman spectrometry analyses on the other hand. By comparing raw materials with our geological database, we show that some iron-rich raw materials were collected more than 20 km from the site. Such long-distance procurement combined with other elements of the overall context suggests a planning of procurement. One main chaîne opératoire based on grinding was identified at Diepkloof. In comparison with other South African sites, we observed no evidence for use as loading agent in adhesives. We conclude that ochre use may follow regional cultural patterns.     

Functional insights into the innovative Early Howiesons Poort technology at Diepkloof Rock Shelter (Western Cape,South Africa)

The Howiesons Poort (‘HP’) is characterized by a set of technological innovations that mark a rupture in the Southern African Middle Stone Age. However perspectives regarding its origin and emergence remain speculative. The recent identification of an Early HP phase at Diepkloof Rock Shelter provides the opportunity to characterize the initial stage of this technology and to discuss various mechanisms behind its innovative characteristics.     

The Middle and Later Stone Age faunal remains from Diepkloof Rock Shelter,Western Cape,South Africa

The faunal sample from the Middle Stone Age (MSA) and overlying Later Stone Age (LSA) deposits of Diepkloof Rock Shelter (Western Cape Province, South Africa) includes at least 40 taxa, mostly mammals, but also tortoises, snakes, birds (especially ostrich represented by eggshell), and intertidal mollusks. The LSA sample contains only species that occurred nearby historically, including domestic sheep, which LSA people introduced to the region by 1800 years ago. In contrast, like other Western Cape MSA faunas, the Diepkloof MSA sample has more species and it is especially notable for five large extralimital grazing species. These imply a greater-than-historic role for grasses in the local vegetation, particularly in the post-Howiesons Poort (latest MSA) interval where the grazers appear most abundant. Extreme fragmentation and dark-staining impedes analysis of the MSA bones, but cut-marks, abundant burning, and numerous associated artifacts suggest that people were the main accumulators. Rare coprolites imply that carnivores could have contributed some bones, and concentrations of small mammal bones, particularly near the bottom of the MSA sequence, suggest a role for raptors. Tortoise bones are common throughout the sequence, and the MSA specimens tend to be especially large, as in other MSA assemblages. The LSA specimens are smaller, probably because LSA human populations were denser and preyed on tortoises more intensively. The most surprising aspect of the Diepkloof assemblage is its marine component. The coast is currently 14 km away and it would have been even more distant during much of the MSA when sea levels were often lower. Intertidal mollusks, particularly black mussels and granite limpets, are concentrated in the LSA and in the Late and Post-Howiesons Poort layers. Only LSA shells are complete enough for measurement, and the limpets are small as at other LSA sites. The implication is again for more intense LSA collection by relatively dense human populations. Both the LSA and MSA deposits also contain bones of shorebirds and Cape fur seals. Whale barnacles and occasional dolphin bones indicate that MSA people scavenged beached cetaceans.     

Middle Stone Age bone tools from the Howiesons Poort layers,Sibudu Cave,South Africa

Recently discovered bone implements from Middle Stone Age (MSA) deposits at Sibudu Cave, South Africa, confirm the existence of a bone tool industry for the Howiesons Poort (HP) technocomplex. Previously, an isolated bone point from Klasies River provided inconclusive evidence. This paper describes three bone tools: two points and the end of a polished spatula-shaped piece, from unequivocal HP layers at Sibudu Cave (with ages greater than ∼61 ka). Comparative microscopic and morphometric analysis of the Sibudu specimens together with bone tools from southern African Middle and Later Stone Age (LSA) deposits, an Iron Age occupation, nineteenth century Bushman hunter-gatherer toolkits, and bone tools used experimentally in a variety of tasks, reveals that the Sibudu polished piece has use-wear reminiscent of that on bones experimentally used to work animal hides. A slender point is consistent with a pin or needle-like implement, while a larger point, reminiscent of the single specimen from Peers Cave, parallels large un-poisoned bone arrow points from LSA, Iron Age and historical Bushman sites. Additional support for the Sibudu point having served as an arrow tip comes from backed lithics in the HP compatible with this use, and the recovery of older, larger bone and lithic points from Blombos Cave, interpreted as spear heads. If the bone point from the HP layers at Sibudu Cave is substantiated by future discoveries, this will push back the origin of bow and bone arrow technology by at least 20,000 years, and corroborate arguments in favour of the hypothesis that crucial technological innovations took place during the MSA in Africa.     

Assemblage variability and bifacial points in the lowermost Sibudan layers at Sibudu,South Africa

Building on the important work of Lyn Wadley at Sibudu, archeologists from the University of Tübingen have excavated the upper stratigraphic units of the Middle Stone Age (MSA) sequence down to the Howiesons Poort (HP). Here, we present the main results from lithic analyses of the lowest part of the Sibudan sequence to assess its overall variability and taxonomic status. Based on the new findings, we also discuss the implications for archeological systematics and the cultural evolution of modern humans in MIS 3 from a more general perspective. The Sibudan deposits encompass over 20 archeological horizons that span a 1.2-m-thick, well-stratified sequence whose base and top have been dated to ～58 ka (MIS 3). In contrast to the upper stratigraphic units, the lower Sibudan assemblages that we analyzed here show much higher use of local sandstone, quartz, and quartzite. These older units are characterized by frequent use of expedient core reduction methods, bipolar reduction of locally available quartz and quartzite, less retouch of blanks, and lower find densities. Tongati and Ndwedwe tools, which feature abundantly in the upper part of the Sibudan sequence, are entirely absent, as are unifacial points. Instead, notched and denticulated tools are common. Surprisingly, knappers manufactured small bifacial points, mainly made from quartz, by means of alternating shaping in the course of the oldest occupations. The results highlight the great diversity of human technological behavior over even short periods during the MSA, raising important questions about the mechanisms of behavioral change, cultural taxonomy, appropriate scales of lithic analyses, and the relationship between the HP and the Sibudan. Our findings further erode the old idea that bifacial technology in southern Africa is limited to the Still Bay. Research is increasingly showing that bifacial points come and go in different forms and contexts of African Late Pleistocene technology, impeding their use as chrono-cultural markers.     

Heat treatment in the South African Middle Stone Age: temperature induced transformations of silcrete and their technological implications

It was recently found that silcrete raw material was heat-treated during the South African Middle Stone Age (MSA) for altering its flaking properties. This finding led to hypotheses about the implications for the MSA hunter-gatherers such as the cost of thermal treatment in terms of investment and firewood. To date, these hypotheses lack a solid basis, for data on the thermal transformations of South African silcrete and, hence, the necessary heating procedure and heating environment, is missing. In order to produce such data, we conducted an experimental study within the framework of the Diepkloof project. This work is based on the petrographic, mineralogical and structural analysis of South African silcrete from the West Coast and its thermal transformations. Our results shed light on the nature of these transformations, the ideal heating temperatures and the tolerated heating speed. The processes occurring in silcrete are comparable to flint, i.e. the loss of chemically bound ‘water’ and the formation of new Si–O–Si bonds, but their intensity is less pronounced. Effective heating temperatures are significantly higher than for flint and the heating speed tolerated by South African silcrete is relatively fast. These findings imply that silcrete heat treatment cannot be directly compared with flint heat treatment. Unlike flint, heating silcrete does not require the setup of a dedicated heating environment and may have been performed in the same time as other fire related activities. This would represent only a minor supplementary investment in time and firewood. These results have broad implications for the discussion about technological evolution and the acquisition of specialised knowledge in the MSA.     

The Howiesons Poort and MSA III at Klasies River main site,Cave 1A

We present the results of a technological analysis of the Howiesons Poort and MSA III lithic artifacts from Cave 1A at Klasies River. We studied most of the debitage and retouched pieces from Deacon's excavations (about 3000 pieces) and all the cores and retouched pieces from three layers of Singer and Wymer excavations (640 pieces). Our analysis shows: (1) that HP blade production was based on the use of marginal percussion by soft stone hammer, as at Rose Cottage; (2) that impact scars at Klasies, Rose Cottage and Sibudu indicate that the backed pieces were hafted in two different ways; and (3) that the HP backed pieces were an innovative way of hafting spear tips but are not clear evidence of the invention of bows and arrows.We document the gradual evolution of debitage techniques within the HP sequence with progressive abandonment of the HP technological style. Very similar trends occur in the upper part of the HP sequence at Rose Cottage. The similarity in temporal trends between sites separated by more than 600 km has significant implications for the disappearance of the HP industry. We suggest that the disappearance of the HP was not due to a phenomenon of population contraction and isolation that caused the collapse of social networks. The internal evolution and parallel process of change documented at Klasies and Rose Cottage speak against a collapse of social systems and are associated with evidence of environmental and subsistence changes at the transition MIS 4/3.     

The context,form and significance of the MSA engraved ostrich eggshell collection from Diepkloof Rock Shelter,Western Cape,South Africa

Broken ostrich eggshells are commonly found in Middle Stone Age sites of southern Africa, presumably collected for food consumption, and later used as artefacts. At Diepkloof Rock Shelter, Middle Stone Age inhabitants used ostrich eggshells as a medium to convey abstract depictions. Since 1998, excavations at Diepkloof have recovered 408 engraved pieces of ostrich eggshells. The study of these shows that Diepkloof inhabitants applied a restricted set of geometric engraving patterns, with the dominance of 2 main motifs, one using a hatched band and the other sub-parallel to converging lines. These motifs coexisted, but shifted in frequency toward the latter through time. Together with evidence that ostrich eggshells were used as containers, these patterns support the hypothesis that engravings were made with respect to clear but flexible social conventions and were part of a complex system of visual and symbolic communication. Since our last report (Texier et al., 2010), a few engraved pieces have been found in lower stratigraphic units, expanding substantially the time-range of the engraving practice on ostrich eggshells at Diepkloof. The earliest engravings appear at the end of the Early Howiesons Poort phase, but become numerous only during the Intermediate and Late phases of the Howiesons Poort. The collection from Diepkloof is presently unique and likely underlines the existence of regional traditions within the Howiesons Poort. Interestingly, and significantly in our view, the engraving disappears at the same time as the Howiesons Poort technology. We argue that this disappearance may reflect a modification in the way late Middle Stone Age inhabitants interacted with one another.     

The MSA sequence of Diepkloof and the history of southern African Late Pleistocene populations

This paper presents the first multidisciplinary synthesis of the Middle Stone Age sequence of Diepkloof Rock Shelter (South Africa). We explore the main cultural changes that characterized southern African hunter–gatherer societies from OIS 5 to the beginning of OIS 3. We discuss the tempo of these changes, test the current interpretative hypotheses and explore an empirical model to explain the early appearance of symbolic marking within the Pleistocene hunter–gather societies of southern Africa.     

Ochre Provenance and Procurement Strategies During The Middle Stone Age at Diepkloof Rock Shelter,South Africa

Usually referred to in archaeological contexts simply as ‘ochre’, ferruginous rocks were commonly used during the Middle Stone Age (MSA) in South Africa. While ochre use by early modern humans has often been interpreted as reflecting complex behaviours, related procurement strategies and selection criteria remain poorly documented. Eight ochre sources from the surroundings of Diepkloof rock shelter in South Africa and 28 ochre pieces from the site's MSA levels were studied by XRD, ICP–OES and ICP–MS. Mineralogical and geochemical data demonstrate that ochre was both locally procured and transported to the site from more distant sources. Here, we investigate the reasons underlying the choice of particular local and non‐local ochre sources exploited at Diepkloof, emphasizing differences in their physico‐chemical properties. Regardless of the motivations behind ochre selection, our data shed new light on the behavioural complexity of MSA societies and suggest that ochre procurement strategies may be independent of subsistence concerns.     

Blade technology and tool forms in the Middle Stone Age of South Africa: the Howiesons Poort and post-Howiesons Poort at Rose Cottage Cave

It has been suggested that between 80 and 35 ka the Middle Stone Age record of South Africa reveals episodes of inventiveness and innovation, punctuated by apparent returns to more conventional technologies. One such episode is the Howiesons Poort (HP). The appearance of a range of small geometric forms, apparently used as insets in multi-component tools, has been considered as evidence of improved hunting weapons, with possible social and symbolic connotations. On the basis of evidence such as backed tool production, small blade technology, the occurrence of typical end-scrapers and burins similar to those encountered in the European Upper Paleolithic, long-distance transport of fine-grained raw materials, and non-lithic novelties, the HP is associated with increased levels of technological efficiency and with behavioral innovations that could have allowed the expansion of African populations to other regions. Yet our knowledge of HP technology and tool production is limited to the analysis of Klasies River Main site by Singer and Wymer and Sarah Wurz, and a few preliminary reports from other sites. This is why we present here a detailed technological and typological analysis of several HP and post-HP assemblages from the well-excavated, well-dated and well-stratified site of Rose Cottage. Our analysis shows: (a) that the HP blade production was a real technical innovation, but was not based on indirect percussion, as often suggested; (b) that blade production was based on the use of marginal percussion which does not occur in the blade production of the Eurasian Middle Paleolithic; (c) that the tool kit was dominated by backed pieces, but not all can be considered as hunting weapons; (d) that neither end-scrapers nor burins are typical of this industry and are no more an antecedent to the European Upper Paleolithic than the end-scrapers and burins of the Middle Paleolithic; (e) that patterns of raw material procurement do not conform to models based on evidence from Klasies; (f) that diachronic changes within the Rose Cottage sequence indicate slow, gradual abandonment of the technological style of the HP; (g) that the post-HP assemblages are of MSA character and are typologically and technologically quite similar to the European Middle Paleolithic; (h) that the lack of persistence of the HP innovations is in need of an explanation. The HP is not a monolithic entity. Implications for the symbolic interpretations of the HP phenomenon are discussed.     

The Middle Stone Age human remains from Diepkloof Rock Shelter (Western Cape,South Africa)

In the course of recent excavations at Diepkloof Rock Shelter (South Africa), three human remains were found in the Middle Stone Age layers. These human remains are two pedal phalanges (intermediate and distal) from a fifth ray, which belong to the same individual, and a deciduous first lower molar. The layers in which they were found represent the end of the Howiesons Poort and the beginning of post-Howiesons Poort occupation, and are radiometrically dated to MIS 3, between 45 and 65 kyr ago. They are thus very close in time to the assumed period of anatomically modern humans (AMH) dispersal out of Africa into Eurasia, a period for which very few remains are available in the African fossil record. Here, we describe these new remains and compare their morphology and dimensions to samples of African and Eurasian Pleistocene and Holocene humans. Our results show that the human remains from Diepkloof Rock Shelter fall well within the range of variation of AMH. The phalanges are of very small size and indistinguishable from those of recent humans. In addition, our analysis of the dm₁ underlines a large size variation at the end of the MIS 4/beginning of the MIS 3 in the Western Cape. The discovery of human remains at Diepkloof Rock Shelter, albeit limited to three small bones, enriches a poorly represented chronological period of the African hominin fossil record.     

Late Pleistocene Technology at Rose Cottage Cave: A Search for Modern Behavior in an MSA Context

Recent excavations at Rose Cottage Cave, located in the Free State, South Africa, have revealed both a transitional assemblage, dated to ca. 20,000 bp, and a final Middle Stone Age (MSA) assemblage, dated to ca. 28,000 bp. Preliminary analysis of these assemblages was undertaken to determine if the current European model of a cultural revolution for the emergence of the Upper Palaeolithic can be applied to the southern African evidence. Examination of these assemblages revealed that differences occurred between the transition in Europe and that in southern Africa in both the chronology of the transition and the degree to which this complete cultural package is linked to the emergence of Late Stone Age (LSA) technology. The methods of lithic production, the chronology of the MSA/LSA transition, and the associated behavioral characteristics were examined and results indicated that the technological change which occurred during the MSA/LSA transition was not a dramatic innovation in technology but, rather, a shift in the emphasis of production from a level of technology already in place and demonstrate a level of continuity between the MSA and the LSA. As a gradual occurrence, the MSA/LSA transition does not seem to fit the time frame for the European Upper Palaeolithic; it both occurs at a later period and takes longer to transpire. In addition, the origins of symbolic use of lithics appear to lie within the MSA, indicating that a more complex set of behavioral adaptation was occurring in the late Pleistocene in southern Africa, and that the MSA/LSA transition in this region does not adequately conform to the model of a revolutionary shift in behavior and technology that is proposed for the Middle/Upper Palaeolithic transition in Europe     

Lithostratigraphy of Border Cave, KwaZulu, South Africa: a Middle Stone Age sequence beginning c. 195,000 b.p.

Border Cave is well-known for its Middle Stone Age (MSA) sequence and associated hominids, as well as for the earliest demonstrable Later Stone Age (LSA) (c. 38,000 b.p.) strata in southern Africa. Detailed lithostratigraphic and sedimentological study permits identification of 8 Pleistocene sedimentary cycles, including 6 major cold phases and 2 intervening weathering horizons. The 2 youngest cold phases are associated with the LSA and have 8 ¹⁴C dates 38,600-13,300 b.p. By gauging sedimentation rates in finer and coarser sediments, duration of sedimentary breaks, and allowing for differential compaction, the excellent radiocarbon framework provided by 28 available ¹⁴C dates can be extrapolated to the 6 cold intervals and 2 palaeosols that are older than 50,000 b.p. These clearly span oxygenisotope stages 4, 5 and 6, placing the base of the MSA deposits at c. 195,000 b.p., Homo sapiens sapiens at c. 90,000–115,000 b.p. and the sophisticated, microlithic “Howieson's Poort” industry at 95,000 b.p. These results require radical reassessment of the age and nature of the MSA complex and of the earliest evolution of anatomically-modern people.     

Increasing Behavioral Flexibility? An Integrative Macro-Scale Approach to Understanding the Middle Stone Age of Southern Africa

The Middle Stone Age (MSA) of southern Africa represents a period during which anatomically modern humans adopted a series of diverse cultural innovations. Researchers generally attribute these behavioral changes to environmental, neurological, or demographic causes, but none of these alone offers a satisfactory explanation. Even as patterns at site level come into focus, large-scale trends in cultural expansions remain poorly understood. This paper presents different ways to view diachronic datasets from localities in southern Africa and specifically tests hypotheses of environmental and cultural causality. We employ an array of analyses in an attempt to understand large-scale variability observed during the MSA. We evaluated the diversity of stone tool assemblages to model site use, examined transport distances of lithic raw materials to understand patterns of movement, assessed the cultural capacities required to manufacture and use different sets of tools, applied stochastic models to examine the geographic distribution of sites, and reconstructed biome classes and climatic constraints. Our large-scale analysis allowed the research team to integrate different types of information and examine diachronic trends during the MSA. Based on our results, the range of cultural capacity expanded during the MSA. We define cultural capacity as the behavioral potential of a group expressed through the problem-solution distance required to manufacture and use tools. Our dataset also indicates that the actual behavior exhibited by MSA people, their cultural performance as expressed in the archaeological record, is not equivalent to their cultural capacity. Instead we observe that the main signature of the southern African MSA is its overall variability, as demonstrated by changing sets of cultural performances. Finally, at the scale of resolution considered here, our results suggest that climate is not the most significant factor driving human activities during the MSA. Instead, we postulate that behavioral flexibility itself became the key adaptation.     

Geoarchaeological investigations at Diepkloof Rock Shelter,Western Cape,South Africa

The sedimentary sequence at Diepkloof Rock Shelter formed through a complex interaction of depositional and post-depositional processes and was variously influenced by biogenic, geogenic, and anthropogenic agents. Here, we present the results of a micromorphological study of the sediments at Diepkloof, focusing in particular on the numerous anthropogenic inputs and modifications recorded within the sequence. By applying the microfacies concept, we were able to identify hearth burning and maintenance, bedding construction and burning, and surface modification by trampling as major processes that contributed to the formation of the site. The human activities recorded within the sediments show a marked change throughout the sequence, implying a shift in the use of the site over time. The present study also provides a context for evaluating other classes of artifacts and data collected from the site.     

New ages for the post-Howiesons Poort,late and final Middle Stone Age at Sibudu,South Africa

Optically stimulated luminescence (OSL) measurements are reported for single grains of quartz from deposits within Sibudu rock shelter. Such measurements enable rejection of unrepresentative grains and application of the finite mixture and central age models to obtain the most reliable age estimates. Three types of single-grain equivalent dose (D_e) distributions were observed: one sample represented a single dose population, three samples indicated mixing between Iron Age (IA) and Middle Stone Age (MSA) deposits, and 10 samples (in addition to the three mixed samples) showed scattered distributions. The latter type resulted from differences in the beta dose received by individual grains. For these samples, the beta doses were modelled and adjusted accordingly. Ages for the 14 samples collected from MSA deposits post-dating the Howiesons Poort (HP) resulted in three age clusters, which are stratigraphically consistent with the three informally named cultural phases at Sibudu: namely, the post-HP, late MSA and final MSA. Weighted mean ages of 58.5 ± 1.4 ka, 47.7 ± 1.4 ka and 38.6 ± 1.9 ka were calculated for these phases, respectively. The three phases were separated by two occupational hiatuses with durations of 10.8 ± 1.3 ka and 9.1 ± 3.6 ka. We hypothesise that the punctuated presence of humans at Sibudu was determined by large-scale fluctuations in climate during oxygen isotope stage (OIS) 3, which resulted in alternating wet and dry periods. Phases of occupation correspond to wet periods when fresh water was available in the Tongati River, whereas intervals of site abandonment correspond to dry periods when people were forced to migrate in search of a reliable source of fresh water. Where people migrated to, remains unresolved.     

Shellfish Exploitation Strategies at the Pinnacle Point Shell Midden Complex,South Africa,During the Later Stone Age

Pinnacle Point, Mossel Bay, is best known for the preservation of the earliest evidence for systematic shellfish exploitation by humans during the African Middle Stone Age (MSA). Comparatively little is known about the shellfish gathering strategies of the Later Stone Age (LSA) inhabitants of this region. This article reports on five LSA sites at the Pinnacle Point Shell Midden Complex excavated by the Centre for Heritage and Archaeological Resource Management in 2006 and 2007. These sites represent 2,000 years of hunter-gather and herder settlement and subsistence in the region. Shellfish remains from the five middens were analyzed in order to understand the exploitation patterns of their LSA inhabitants. Information on the relative abundance of different mollusk species in these assemblages and, where possible, the average size of collected specimens, is then compared with published accounts of shellfish material from other sites along the southern Cape coast. These include roughly contemporary assemblages from Noetzie, Hoffman's/Robberg Cave and sites in the Garcia State Forest, and MSA assemblages from Pinnacle Point, Blombos Cave, and Klasies River Mouth. Regional continuities in gathering strategies focused on a range of bivalves and gastropods, and chronological shifts in the exploitation of rocky shores and sandy beaches, and different littoral zones, are apparent.     

Discriminating between the end products of the earlier Middle Stone Age sub-stages at Klasies River using biplot methodology

The difference between the culture-stratigraphic entities, the MSA I and MSA II, in the Klasies River sequence is explored by statistical analysis of the end products. Technological analysis of the cores, end products and waste products suggested that the MSA I and MSA II represent distinct technological traditions aimed at producing different end products. To quantify the difference between the end products, points and blades, extensive univariate and multivariate statistical analyses of continuous variables have been undertaken. Biplot methodology is adopted for enhancing the statistical analysis. Canonical variate analysis biplots are constructed and alpha-bags added for visual displays of the overlap and separation among the different groups. It is demonstrated that the platform thickness relative to length is useful in discriminating between the end products of the MSA I and MSA II. Statistical analyses support a clear distinction between the MSA I and MSA II.