Influence of grinding on the preservation of starch grains from rice

China is a major centre for rice domestication, where starch grain analysis has been widely applied to archaeological grinding tools to gain information about plant use by ancient Chinese societies. However, few rice starch grains have been identified to date. To understand this apparent scarcity of starch grains from rice, dry- and wet-grinding experiments with stone tools were carried out on four types of cereals: rice (Oryza sativa L.), foxtail millet (Setaria italica), Job's tears (Coix lacryma-jobi L.) and barley (Hordeum vulgare L.). The results reveal that dry-grinding produces significant damage to starches to the point where they may be undetected in archaeological samples, while wet-grinding causes only slight morphological changes to the starch grains. Moreover, rice starch grains have the most substantial alterations from dry-grinding, possibly impeding their identification. These findings provide a possible means to explain the relative scarcity of rice starch grains recovered from archaeological grinding tools, which it is suggested was caused by the use of the dry-grinding technique. Therefore, it is suggested that rice starch grains have been likely underrepresented in the archaeological record, and previous interpretations of starch analyses need to be reconsidered.     

Starch grain characterization of Prosopis chilensis (Mol.) Stuntz and P. flexuosa DC,and the analysis of their archaeological remains in Andean South America

The fruit (pods) of Prosopis (Fabaceae) are frequently recovered from pre-Hispanic Argentinian archaeological sites, suggesting that this genus was of importance in ancient economies in this region. Yet it is only recently that archaeobotanists have begun to carry out systematic research into this genus. Therefore many questions remain to be addressed concerning the food value of Prosopis fruit, and its potential contribution. This paper examines starch from the pods of two species, Prosopis flexuosa and Prosopis chilensis, for the purposes of describing and classifying their morphological features and biometrical parameters. Pods of both species were gathered from two extremes (northern and southern) of the Hualfín Valley, Catamarca, Argentina. Starch abundance is estimated and compared with that of Zea mays, an economically important plant with high concentrations of starch. This paper reveals that Prosopis pods contain very low amounts of starch compared to starch-rich edible species. Despite this, the recovery of Prosopis starch grains can be successfully used to assess archaeological tool uses. Prosopis starch grains were found to be highly variable in shape. Grain size ranged between 10 and 20 μm. Granule irregularity and the high birefringence under polarized light are two of the most important diagnostic features. No significant statistical differences were found in the structure (morphology, size and hilum) of the starch of the same species from both localities. Finally, the implications for the role of this plant in past societies are discussed.     

Potential misidentification of in situ archaeological tool-residues: starch and conidia

Microscopic identification of organic residues in situ on the surface of archaeological artefacts is an established procedure. Where soil components morphologically similar to use-residue types exist within the soil, however, there remains the possibility that these components may be misidentified as authentic residues. The present study investigates common soil components known as conidia, fungal spores which may be mistaken for starch grains. Conidia may exhibit the rotating extinction cross under cross-polarised light commonly diagnostic of starch, and may be morphologically indistinguishable from small starch grains, particularly at the limits of microscope resolution. Conidia were observed on stone and ceramic archaeological artefacts from Honduras, Palau and New Caledonia, as well as experimental artefacts from Papua New Guinea. The findings act as a caution that in situ analysis of residues, and especially of those less than 5 μm in size, may be subject to misidentification.     

Late Holocene Neotropical agricultural landscapes: phytolith and stable carbon isotope analysis of raised fields from French Guianan coastal savannahs

This paper summarizes phytolith analyses from four pre-Columbian agricultural raised-field sites of the coastal savannahs of French Guiana—Savane Grand Macoua, Piliwa, Bois Diable and K-VIII—and carbon isotope analyses from the first-named site. The combined phytolith and ¹³C isotope analyses evidence the transformation of the landscape from a relatively homogeneous wetland vegetation comprised of a mixture of C4 and C3 plants (the latter including Cyperaceae and other herbaceous monocots such as Marantaceae and Heliconia, Oryzoideae grasses, and other plants typical of frequently flooded areas) to the construction of raised fields that were dominated by C4 plants (maize and other Panicoideae grasses). Our analysis proves the utility of phytoliths for tracing the agricultural history of landscapes, showing that, as in other parts of the Central and South American lowlands, maize (Zea mays) was one important crop cultivated in raised fields. We also estimated the productivity of raised-field agriculture, showing that in combination with other subsistence activities, it certainly had the capacity to sustain sizeable populations.     

Paleoethnobotany in the Neotropics from Microfossils: New Insights into Ancient Plant Use and Agricultural Origins in the Tropical Forest

Analysis of plant microfossils (phytoliths, pollen, and starch grains) from archaeological and paleoecological sediments in the humid Neotropical forest can provide information on some formerly intractable problems in American paleoethnobotany and archaeology. Each technique has strengths that redress the other's shortcomings, and all three microfossils can be recovered from early sites, securely identified, and dated. Agricultural origins, Pleistocene/ Holocene environmental changes, and the evolution of slash-and-burn agriculture are three important issues that yield substantial results to phytolith, pollen, and starch grain study. Microfossils of a number of domesticates, including maize, manioc, squash, bottle gourd, arrowroot, and leren, have been identified in contexts dating from 9000 to 7000 radiocarbon years B.P. The scope and methodology of traditional paleoethnobotany should be expanded to routinely include microfossil study.     

The decomposition of starch grains in soils: implications for archaeological residue analyses

Recent research involving starch grains recovered from archaeological contexts has highlighted the need for a review of the mechanisms and consequences of starch degradation specifically relevant to archaeology. This paper presents a review of the plant physiological and soil biochemical literature pertinent to the archaeological investigation of starch grains found as residues on artefacts and in archaeological sediments. Preservative and destructive factors affecting starch survival, including enzymes, clays, metals and soil properties, as well as differential degradation of starches of varying sizes and amylose content, were considered. The synthesis and character of chloroplast-formed ‘transitory’ starch grains, and the differentiation of these from ‘storage’ starches formed in tubers and seeds were also addressed. Findings of the review include the higher susceptibility of small starch grains to biotic degradation, and that protective mechanisms are provided to starch by both soil aggregates and artefact surfaces. These findings suggest that current reasoning which equates higher numbers of starch grains on an artefact than in associated sediments with the use of the artefact for processing starchy plants needs to be reconsidered. It is argued that an increased understanding of starch decomposition processes is necessary to accurately reconstruct both archaeological activities involving starchy plants and environmental change investigated through starch analysis.     

Assessing the feasibility of identifying maize through the analysis of cross-shaped size and three-dimensional morphology of phytoliths in the grasslands of southeastern South America

This paper tests the feasibility of applying a technique developed by Piperno and Pearsall (Am. Antiquity 49 (1984) 361; Phytolith Analysis: An Archaelolgical and Geological Perspective, 1988, Academic Press: San Diego; Paleoethnobotany, 2000, Academic Press: San Diego) based on size and three-dimensional morphology criteria of cross-shaped phytoliths to identify maize in a previously unexplored region outside of the Neotropics; the grasslands of southeastern Uruguay. Because the area is dominated by subtropical Panicoid grasses that produce abundant cross-shaped phytoliths, intensive studies of the regional Panicoid grasses are needed to ensure that no wild taxa have phytoliths that are potentially confusable with maize. With this in mind, I carried out analysis of cross-shaped phytoliths in 35 Panicoid, 5 Oryzoid and 1 Bambusoid grasses, as well as on nine modern soil samples that belong to the most representative vegetation formations of the area. This study demonstrates that an application of multivariate (linear discriminant function) analysis together with qualitative and other assessments of cross-shaped phytolith assemblages as originally described by Piperno and Pearsall can be successfully used to distinguish the presence of maize in the grasslands of southeastern Uruguay. The technique provides a useful tool to trace the dispersal of maize into the southern cone of South America.     

Starch grains analysis of stone knives from Changning site,Qinghai Province,Northwest China

Plant residues recovered from prehistoric stone artifacts can be used to help explain tool function and plant use. At the Changning site in Qinghai Province, Northwest China, dating from 4000 yr BP, we examined starch granules extracted from three slate stone knives. A total of 153 starch grains were retrieved from three stone knives, from which we identified starches from legumes, the Triticeae tribe, foxtail millet (Setaria italica), broomcorn millet (Panicum miliaceum), roots and tubers. These results indicate that the stone knives may have been used for a variety of activities that included reaping grasses and food processing. The species of starch grains retrieved from the study sample reveal that diverse crops were cultivated at the Changning site 4000 years ago.     

Starch grain analysis for groundstone tools from Neolithic Baiyinchanghan site: implications for their function in Northeast China

Large numbers of groundstone tools have been uncovered from archaeological sites in the Early Neolithic period in China. Traditionally they are often regarded as agricultural tools for processing cereals. In this paper we report preliminary starch grain analysis of groundstone tools from Baiyinchanghan site to gain a better understanding of use of these tools in the Northeast China. We found that starch grains on these groundstone tools are most likely from Quercus sp. The result of this study indicates that many groundstone tools for the Early Neolithic period were used to process wild and domesticated plants alike.     

基于人牙结石的淀粉粒证据探讨裴李岗遗址先民植物性食物来源

人牙结石淀粉粒分析是开展古代居民食物来源研究的有效途径之一。用此方法对河南新郑裴李岗遗址仅存的两具裴李岗文化人骨牙齿上的结石开展了淀粉粒分析,成功提取出38颗淀粉粒,其中可鉴定种属的淀粉粒主要来自于栎属、豆科和块茎类等非农作物,少量有可能来自于粟黍类作物。虽然分析样品较少,提取出的淀粉粒数量不多,但这一结果或许表明采集植物有可能构成了裴李岗遗址居民植物性食物的主体。结合贾湖、莪沟、石固和寨根等裴李岗文化遗址的植物考古学研究,裴李岗文化居民的食物结构具有广谱性特征。本研究为全面认识中原地区裴李岗文化居民食物构成和聚落生业经济,深入探讨中原地区早期农业形成过程等提供了新思路和新证据。     

Changes in starch grain morphologies from cooking

One of the three main plant microfossils, starch grains are increasingly used as markers of diet, plant domestication, tool use and site organization, because their morphology and features provide a means to identify the plant that produced them. However, starch grains are susceptible to damage when they are exposed to heat in the presence of water, as in cooking. We documented the changes that occur in the starch grains of 10 domesticated plant species due to exposure to different cooking methods, in order to better understand how cooking alters the appearance of the grains, and if these cooking methods might be identifiable in the archaeological record. Our results show that some cooking methods produce unique, identifiable damage on some types of plant starches, but generally each plant species reacts uniquely to cooking. In order to record the changes for each plant species, we have created a database, available at (http://www.osresearch.net/∼hollyf/starchdb/index.cgi), to which registered users can add their own images of cooked starch grains.     

Morphometric Analysis of Camelid Remains from the Alero Deodoro Roca (ADR) Site (Córdoba,Argentina). An Attempt to Characterise Body‐Size Variability in Sierras Pampeanas Australes Region

This paper focuses in the morphometric analyses of Lama guanicoe remains recovered from the hunter–gatherer archaeological site Alero Deodoro Roca, located at Sierras Pampeanas Australes region (Córdoba Argentina), an area that has little information on the body‐size variability of these artiodactyls. Because of the sparse osteometric data in the region, we focused on determining inter‐intraspecific differentiation of wild camelids through corroborated osteometric techniques and multivariate statistical analyses of proximal phalanges. Our results showed a clear interspecific differentiation between modern vicuñas and archaeological specimens. We could also distinguish at least three guanaco size groups (small, medium and large) with the archaeological remains from the late Holocene (3000–3600 bp ) of the site, presenting medium‐size characteristics. Finally this paper aims at establishing a first approach in the characterisation of guanaco body size in the mountainous region of Córdoba. Copyright © 2016 John Wiley & Sons, Ltd.     

The differential survival of native starch during cooking and implications for archaeological analyses: a review

Cooking makes foods more palatable and digestible, less toxic and suitable for longer-term storage. Starch granules usually undergo gelatinisation during cooking, resulting in the loss of native structure and morphology. Once fully gelatinised, starch is very difficult to recognise microscopically and to classify taxonomically, impeding identification of cooked starch in archaeological food residues. Gelatinisation involves a complex interplay between temperature, moisture content and the presence of solutes, lipids and proteins, as well as species-specific starch physicochemical properties. Understanding the influence of these factors, particularly moisture, on the degree and extent of starch conversion during heat treatment enables predictive models of native starch survival in archaeological samples based on cooking method and food type. The findings of this review indicate that differential native starch survival may significantly influence archaeobotanical reconstructions and interpretations of artefact function.     

Stone-boiling maize with limestone: experimental results and implications for nutrition among SE Utah preceramic groups

Groups living on Cedar Mesa, SE Utah in the late Basketmaker II period (Grand Gulch phase, AD 200–400) were heavily maize-dependent, but lacked beans as a supplemental plant protein, and pottery vessels for cooking. Common occurrence of limestone fragments in their household middens suggests 1) limestone may have been used as the heating element for stone-boiling maize and 2) this practice might have made some maize proteins more available for human nutrition. Experiments examined these possibilities; results indicate that stone-boiling with Cedar Mesa limestone creates an alkaline cooking environment suitable for nixtamalization of maize kernels, and that maize cooked in this fashion shows significant increases in availability of lysine, tryptophan, and methionine. Archaeological limestone fragments from a Grand Gulch phase site show amounts of fragmentation and changes in density consistent with repeated heating. While not conclusive, these data indicate that further research (e.g., examination of archaeological limestone fragments for maize starch grains or phytoliths) is warranted. It is suggested that greater attention be paid to archaeological indications of stone-boiling with limestone among maize-dependent but pre-pottery societies.     

From the modern to the archaeological: starch grains from millets and their wild relatives in China

Starch grains from 31 modern samples of millets derived from the seeds of 7 species within the genus Setaria and 2 species within the genus Panicum were analyzed to determine diagnostic morphological characteristics. Ancient starch grains recovered from a sample of broomcorn millet (Panicum miliaceum) excavated from the Cishan site (10.0-7.6 cal yr BP) in the North China Plain were then subjected to the same analyses to determine the differences in morphologies, if any, between modern and ancient samples. The data indicate that morphological features, and particularly surface and fissure features, will allow for solid identifications of ancient millet starches, while size classes will be helpful, but will not be dependable taxonomic indicators.     

Plant exploitation and ethnopalynological evidence from the Wadi Teshuinat area (Tadrart Acacus,Libyan Sahara)

Pollen analyses of 13 archaeological sites in the Wadi Teshuinat area, in southwestern Fezzan, Libya, were synthesised to explore the potential contribution of palynological investigation to archaeological research in this area. During the Holocene, the sites were occupied by pre-Pastoral (hunter–gatherers) and Pastoral (pastoralists) cultures. Different pollen stratigraphies and floras characterised the diverse sites and the relevant cultural phases. Pollen data were reported by discussing the sites separately, and by combining them to interpret the regional data set. Emphasis was made on the anthropogenic pollen indicators and grasses, including large grass pollen grains (>40 μm), which were considered evidence of plant transport into the site. These were ethnobotanical markers, human-made evidence of plant harvesting by hunter–gatherers, or of animal breeding by pastoralists. The disappearance of some wild cereals was also observed, consistent with increasing climate dryness and land exploitation. Macroremains were used as a parallel tool to better understand plant exploitation in the region.     

Ancient DNA confirms a local origin of domesticated chenopod in eastern North America

Domesticated chenopod was an important starchy seed crop in eastern North America before the rise of maize agriculture. Domesticated chenopod first appeared in North America during the fourth millennium B.P., however its wild progenitor and site of domestication remain unresolved. Archaeological evidence suggests a local domestication in the Eastern Woodlands, while morphological similarities with modern Mexican cultivars indicate a possible introduction from Mesoamerica. To distinguish between these two scenarios, we isolate chloroplast DNA (cpDNA) from modern and archaeological North American chenopods sampled from across their geographic range. Our results demonstrate that the chenopod grown in the Eastern Woodlands was locally-derived, indicating that independent domestication events gave rise to the ancient eastern North American and modern Mexican cultivars. These results strengthen the argument for an entirely native pre-maize crop complex with chenopod as a major component.     

Millet microremains—an alternative approach to understand cultivation and use of critical crops in Prehistory

The term “millets” is used to identify several genera of grasses (Poaceae), most of which belong to the subfamily Panicoideae. Millets are one of the major food sources in arid and semi-arid areas of the world and they have been important crops in the prehistory of Africa and Eurasia. In this paper, we discuss phytoliths and starch grains from two of the less studied major millets (Pennisetum glaucum and Sorghum bicolor) as well as from some small millet species that are not normally considered of much importance (so-called forgotten millets: Digitaria ciliaris, Echinochloa colona, Echinochloa frumentacea, Brachiaria ramosa, Setaria pumila and Setaria verticillata). The preliminary results of this study on phytolith morphology, both at single and joined (silica skeletons) morphotypes, and starch grains show great potentials for the identification of different genus or species on the basis of microremains.     

Dental wash: a problematic method for extracting microfossils from teeth

A variety of microfossils, originating from plant foods, become trapped in the dental calculus matrix. Processing of dental calculus allows extraction of these microfossils. The resulting data can be used to reconstruct diet at the individual and population levels as the identification of microfossils like starch grains and phytoliths to the generic level, and sometimes to the species level, is possible. However, in some archaeological sites, dental calculus deposits do not preserve well enough to be processed. To prevent the loss of information in such cases, we present a technique, called “dental wash”. It permits extracting microfossils from cryptic dental calculus deposits. In the two experimental archaeological cases presented herein we identified phytoliths, starch grains as well as a diatom fragment with this method, whereas in a control sample no microfossils were found. Moderate damage to the teeth was detected when they were already friable due to poor preservation. Minor damage to the surface of well-preserved teeth was observed. This indicates that the proposed method is efficient in recovering microfossils, but unacceptable because of damage to teeth. If the method can be refined, it will expand the potential of dental calculus analysis to a greater range of archeological sites.     

A short note on starch and xylem of Colocasia esculenta (taro) in archaeological deposits from Pitcairn Island,southeast Polynesia

We present results of starch analysis of archaeological deposits from Pitcairn Island. High concentrations of starch grains preserved in cell membranes, and xylem tracheary elements, consistent with introduced Colocasia esculenta (taro) were found. Because of limited age control, we are uncertain if the microfossils are prehistoric. Problems associated with identifying taxa with small starch grains in extractions from weathered deposits are highlighted.