No agreement on what constitutes a safe and reproducible anticontamination protocol exists for ancient starch research. Protocols applied to laboratory work may represent 'symptomatic treatment' only, as contamination of archaeological materials in the field may be more extensive than realized. This paper is the first systematic study on the impact that modern starches from surface and buried soils, windborne dispersal, human motion, excavation techniques and toolkits, and field attire has on archaeological sample quality. The study area is Olduvai Gorge, Tanzania. We identify seven starch types (discrete granules, n = 788) that embody the starch contamination landscape for the region. This study also demonstrates the various diagenetic changes that buried starch granules undergo in a short time, such as cavitation, fissuring, disruption and gelatinization. There are significant differences in morphotype class representation between the topsoil starches and those collected deeper below ground at excavated sites. Diagenetically transformed granules from underground storage organs dominate in soils, while native starches from cereal endosperm (Panicoideae and Triticeae) abound above ground in airborne samples. Furthermore, we illustrate how lithic samples excavated under standard field conditions can be contaminated, and that when a sample is compromised during excavation, it may be impossible to distinguish between target and introduced starches, especially when granules are identical or morphologically similar. The paper provides field recommendations to control false positives.
Ancient starch research illuminates aspects of human ecology and economic botany that drove human evolution and cultural complexity over time, with a special emphasis on past technology, diet, health, and adaptation to changing environments and socio-economic systems. However, lapses in prevailing starch research demonstrate the exaggerated expectations for the field that have been generated over the last few decades. This includes an absence of explanation for the millennial-scale survivability of a biochemically degradable polymer, and difficulties in establishing authenticity and taxonomic identification. This paper outlines new taphonomic and authenticity criteria to guide future work toward designing research programs that fully exploit the potential of ancient starch while considering growing demands from readers, editors, and reviewers that look for objective compositional identification of putatively ancient starch granules.
Rapid environmental change is a catalyst for human evolution, driving dietary innovations, habitat diversification, and dispersal. However, there is a dearth of information to assess hominin adaptions to changing physiography during key evolutionary stages such as the early Pleistocene. Here we report a multiproxy dataset from Ewass Oldupa, in the Western Plio-Pleistocene rift basin of Olduvai Gorge (now Oldupai), Tanzania, to address this lacuna and offer an ecological perspective on human adaptability two million years ago. Oldupai’s earliest hominins sequentially inhabited the floodplains of sinuous channels, then river-influenced contexts, which now comprises the oldest palaeolake setting documented regionally. Early Oldowan tools reveal a homogenous technology to utilise diverse, rapidly changing environments that ranged from fern meadows to woodland mosaics, naturally burned landscapes, to lakeside woodland/palm groves as well as hyper-xeric steppes. Hominins periodically used emerging landscapes and disturbance biomes multiple times over 235,000 years, thus predating by more than 180,000 years the earliest known hominins and Oldowan industries from the Eastern side of the basin.
The assumption that taxonomy can be ascertained by starch granule shape and size has persisted since the late nineteenth and early twentieth century biochemistry. More recent work has established that granule morphological affinity is scattered throughout phylogenetic branches, morphotype proportions vary within the genus, granules from closely related genera can differ dramatically in shape, and size variations do not reflect phylogenetic relationships. This situation is confounded by polymorphism at the species and tissue level, resulting in redundancy and multiplicity. This paper classifies morphological features of starch granules from 77 species, 31 families, and 22 orders across three African ecoregions. This is the largest starch reference collection published to date, rendering the dataset uniquely well-suited to explore (i) the diagnostic power of unique morphometric classifiers and their frequency, (ii) morphotypes that cut across taxonomic boundaries, and (iii) issues surrounding the minimum counts needed to accurately reflect granule polymorphism, variability, and identification. In a collection of 23,100 granules, taxonomic identification occurred very rarely. In the instances it did, it was at the species level, with no occurrences of a single morphotype or complement identifying all species within a family or genus. Some families cannot be uniquely identified, and morphometric types are shared despite taxonomic distance for three quarters of the taxa. However, this reference collection boasts 98 unique identifiers located in the Arecaceae,
Water, vegetation, and human habitats are tightly coupled, and Olduvai Gorge, Tanzania is an exceptional locality for examining evolutionary events that associate with water availability and environmental stability or change. This project investigates interactions between and among paleo-hydrology, habitat type, and the human response to changing environmental settings. The objective is to interpret the climate and environmental context of the oldest Acheulean stone tool industry at Olduvai Gorge using plant leaf wax lipid marker molecules, or biomarkers, as a source for carbon and hydrogen isotopes. The emphasis is on a roughly 200,000-year period (1.83 to 1.66 Ma), a timeframe that includes a key transition in stone tool technology from the Oldowan to the Acheulean, and the widespread distribution of the genus Homo.To investigate the human-environment interactions for Olduvai’s earliest Acheulean, terrestrial sediments from Beds I and II were systematically sampled and processed for normal (n-) alkanes and n-alkanoic acids. The focus is on the Frida Leakey Korongo North (FLK-N) and West (FLK-W) archaeological sites, which contain Oldowan and Acheulean tools, respectively, the geologic feature known as the Castle, and multiple landscape geological samples. From a methodological perspective, the innovation lies in the detailed environmental analyses using leaf wax biomarkers as a proxy record for paleo- hydrology and vegetation, and for the assessment of changes in precipitation, temperature, atmospheric CO2, aridity/humidity and plant type.The results indicate that both Oldowan and Acheulean assemblages were predominantly used within woodland settings with abundant freshwater nearby. The archaeological sites were situated within a mosaic environment of open grassland, closed riparian and groundwater-fed woodlands, lacustrine habitats, and ecotones. Both technological types were most likely used to process plant material such as hard-shelled nuts and fruits, but the Acheulean was also utilized for exploiting underground tubers as well as meat obtained in open settings.
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