Research

Background

We are now certain that modern humans – our species, Homo sapiens – evolved in Africa roughly 200,000 years ago. But we are much less sure about whether at this time we also developed our unique capacity for ‘complex culture’ (including highly sophisticated language and symbolic material culture – in short, modern ways of behaving) or whether we evolved this much later. However, in the last decade or so the archaeological record of the Middle Stone Age (MSA), especially in southern Africa, has come to the global forefront of this debate due to a series of spectacular finds of symbolic material culture (beads, engraved ochre, incised ostrich eggshell water flask fragments etc.) dated to roughly 100-60,000 years ago. This pre-dates the earliest occurrences of similar artifacts in Eurasia by 40,000 years, effectively shattering the long-held notion that modern humans experienced a ‘behavioral revolution’ soon after entering Europe. What certainly did occur when humans entered the cold, challenging northern latitudes was an explosion of symbolic expression, as evident in the extremely rich Eurasian Upper Paleolithic record of cave (e.g. Lascaux, Chauvet etc.) and portable art (e.g. Venus Figurines etc.) and other ritual indicators; this was almost certainly a response to environmental and paleodemographic stressors that selected for social cohesion, cooperation, communication (hence increase ritual behavior and exchange objects) and/or social competition for scarce, widely distributed resources (hence increase in social signaling through symbolic material culture). After all, the world at 40,000 years ago was in the midst of an Ice Age, and much of Europe would have been a tough place to live, giving rise to description of the ‘highly symbolic’ archaeological record there as reflecting ‘arctic hysteria’.

However, the African MSA evidence shows very clearly that the capacity for behaviors every bit as sophisticated an complex as those exhibited by Upper Paleolithic Eurasians were possessed by modern humans in Africa at least 80,000 – and perhaps even as long as 200,000 – years ago (or even longer, but this is the subject of a major debate). There are several main reasons why we have only recently discovered this. One is that Paleolithic archaeology has been dominated by European researchers with European research biases within an implicitly (and sometimes explicitly!) unilinear social evolutionary framework (i.e. innovations must have originated in Europe, and were later “received” in Africa and other less “culturally advanced” areas of the world). Second, Paleolithic research has been conducted on a much more intensive basis in Europe than Africa, which is vast, less academically well developed and less wealthy. Third, as noted above, Africa is fundamentally different continent to Europe ecologically and climatically, and thus presented our ancestors with very different sets of adaptive challenges that often did not entail the expression of full symbolic behavior, at least not in forms that we can recognize (i.e. how can we be sure that only beads, pendants, art etc. are imbued with symbolism? What about perishable material like body paint etc.? Might we be biased at the outset with assumptions of what symbolic material culture we expect to find?).

Therefore, instead of a ‘symbolic explosion’, the African MSA archaeological record shows long periods of what seem like cultural stasis, with rapid bursts of innovation. The two most famous such bursts of innovation are southern African archaeological industries called the ‘Still Bay’ and the ‘Howiesons Poort’. Both were relatively short-lived archaeological industries, the Still Bay dating to between ~75-70,000 years ago and the Howiesons Poort between 65-60,000 years ago. Both are characterized by sophisticated stone and bone tools, evidence of complex hunting techniques, broad dietary resource exploitation including marine foods like fish, shellfish and seals, and, critically, material culture with clear symbolic intent including the world’s oldest art – engraved ochre pieces from Still Bay levels of the now famous site of Blombos Cave on South Africa’s southern Cape coast.

Adaptations to Marginal Environments in the Middle Stone Age

Despite these incredible findings that southern Africa has produced in the last 10-15 years, the debate over modern human behavioral origins has again stagnated. There are probably many reasons for this, but two major ones are as follows. First, as mentioned above, artifacts with clear, unambiguous symbolic intent like beads and artwork are incredibly rare in the archaeological record. Sometimes they do not occur in the archaeological records of very recent peoples, whom we know for certain were no different from ourselves. This is because these objects represent one of many forms of cultural response to specific and usually inter-related stimuli, whether environmental (e.g. rapid climatic change), social (e.g. population packing) or economic (e.g. resource stress). For example, cultural evolution may suddenly select for bead manufacture in a given society if the climate shifts drastically and certain resources in some of that society’s geographical range become scarce – beads will be exchanged between groups, creating alliances and bonds which can be called upon by the hard-put-upon group when they need to move into another group’s patch to whom nature has been kinder. The point is that these sorts of symbolic materials are not always needed, and in any case people may have made similar things that either (a) did not preserve in the archaeological record or (b) did preserve we do not recognize as symbolic.

Second, and related to this, research in southern Africa on this critical period suffers from a geographic bias towards the Cape coasts (sites like Blombos, Klasies River, Pinnacle Point, Die Kelders etc.). A combination of ocean current upwelling and coastal geomorphology makes the Cape’s shorelines some of the most productive in the world, and there is abundant evidence that MSA populations made good use of them. The resource productivity and stability provided by Cape ecology almost certainly influenced the subsistence-settlement systems and perhaps social organisation of MSA forager groups who exploited them. Models of MSA life-ways derived from sites in the Cape are, therefore, unlikely to be appropriate for reconstructing human adaptations in other locales, especially more challenging environments. This is especially problematic since a very high level of adaptive flexibility is another uniquely human trait, and one that enabled us to rapidly leave Africa ~80-60,000 years ago to become the dominant species world-wide. In light of the central role that current evidence suggests Africa played in modern human cultural and cognitive origins, superimposing cultural signatures from one, highly specific biome onto others severely constricts our understanding of early behaviorally modern human adaptive potential. To address this, I created and co-direct (with Genevieve Dewar, University of Toronto) an international, multidisciplinary project entitled, Adaptations to Marginal Environments in the Middle Stone Age (AMEMSA; www.amemsa.com). AMEMSA aims to help understand where, when, how and under what environmental conditions in Africa our species developed the capacity for such remarkable adaptive plasticity. To accomplish this, the project investigates human responses to marginal landscapes in southern Africa. Marginal environments, or those with low ecological productivity and/or predictability, are important analytical settings because they pose resource stresses and logistical challenges that demand flexible, creative solutions. The timing, pace and modes of their colonization within Africa can thus help us understand the cultural evolutionary development of resilient behavioral systems typical of modern foragers, such as expansive social networks. AMEMSA targets two such settings: (1) the inland, high-altitude grasslands of eastern Lesotho and (2) the sub-arid coastal desert of Namaqualand, South Africa.

The project consists of two phases, the first of which is near completion and has laid the groundwork for the second. In the first phase, targeted excavations were conducted at significant rockshelters with deep later Pleistocene sequences: Melikane, Sehonghong (both in Lesotho) and Spitzkloof (a series of three adjacent rockshelters in Namaqualand). The Lesotho sites have highly significant, pulsed sequences spanning the last 85,000 years. The Spitzkloof rockshelters are still under excavation, but thus far 60,000 year-old levels have been encountered that overlie even older deposits. Having established robust, detailed archaeological and paleoenvironmental records for both regions based on these sedimentary sequences, the second phase will greatly expand the sphere of investigation to incorporate the rich archaeology and geomorphology of the surrounding mountain and desert landscapes. Unusually high densities of open-air MSA lithic scatters and (in Namaqualand) shell middens, along with rich paleoenvironmental repositories in the form of sediment exposures, have been identified in the vicinities of each of the rockshelters studied to-date. Relating the data from these open-air locales to the excavated rockshelter cultural and paleoenvironmental frameworks will provide a rare opportunity to enlarge the lens of MSA enquiry from its traditionally restricted window of the archaeological trench to the broader, shifting marginal landscapes in which our ancestors ‘cut their teeth’ before encountering the full range of global ecosystems beyond Africa. In the process, the second phase will provide us with fundamentally new insights into how that spread was made possible.

The project involves the tight integration of multiple archaeological and paleoenvironmental proxy data generated from both excavated and open-air situations in order to understand how early modern humans spatially organized themselves to optimally exploit high-altitude grasslands and semi-arid desert. We have assembled and coordinate a team of specialists from universities in the UK, USA, Canada, South Africa and Australia to analyze and integrate diverse datasets from these sedimentary sequences, incorporating: chronological (AMS 14C, single-grain OSL); geoarchaeological (sedimentology, micromorphology); paleoenvironmental (charcoals, phytoliths, pollen, isotopes of bone and sediments, site formation); subsistence (fauna, macrobotanicals); and lithic typo-technological and functional evidence. Beyond project direction, our specialist involvements entail the characterization of all recovered lithics on technological and typological grounds (Stewart), and faunal remains using well established zooarchaeological methods (Dewar). In the broadest sense, the rockshelter results suggest that, although occupations in these settings were strongly pulsed, in each region there is a marked change from sporadic to more intensive occupational episodes. As such, we are revealing something of the very processes by which later Pleistocene Africans were mastering the specific challenges of these habitats. The second phase of the project takes this work a crucial step further by widening our understanding about group mobility patterns and adaptive responses in the open landscape itself.

With this upcoming second phase, we shall conduct off-site archaeological surveys along with geomorphological surveys aimed at both reconstructing landscape evolution and developing continuous, high-resolution later Pleistocene paleoenvironmental sequences from sediment exposures. The positions and compositions of all MSA lithic scatters, quarry sites and (in Namaqualand) shell middens will be recorded with high precision Differential Global Positioning System (DGPS) units using fixed, ground-based reference stations, and spatial analyses will be performed using an integrated relational/GIS spatial database. Colluvial/paleosol and alluvial sediment exposures, which abound in both areas, will be sampled using vertical sediment columns and diverse paleoenvironmental analyses performed on pollen, spores, phytoliths, plant macrofossils, and sediment compositions and isotopic signatures. These open-air datasets will then be related to the dated rockshelter sequences using comparative typology for the lithic scatters, and radiometric dating for the shell middens (14C) and paleoenvironmental sediment exposures (bulk 14C and OSL). Research on this crucial period of human evolution can thus begin to move from the static, site-specific investigations that currently predominate towards more dynamic reconstructions of early modern human subsistence-settlement systems set against robust regional paleoenvironmental frameworks.