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.     

Using plant microfossils from dental calculus to recover human diet: a case study from Tell al-Raqā'i,Syria

Dietary reconstructions based on plant microfossils, such as starch grains and phytoliths, have been useful in increasing our understanding of past human populations. Microfossils have been recovered from sediments, stone tools, and, more recently, dental calculus. Methods for recovering microfossils from dental calculus have yet to be firmly established and there is some question about potential damage to the teeth. Using a sample of teeth from the middle Holocene site of Tell al-Raqā'i, Syria, we tested using a dental pick to sample the calculus. ESEM images taken before and after sampling show no damage to the enamel surface, and examination of the recovered microfossils show that this method provides ample material for study, even when not all of the calculus is removed from the tooth. Preliminary identification of the plant microfossils suggests that these individuals were consuming a variety of plant foods, but that domesticated cereals such as wheat and barley made up a surprisingly small portion of their diet.     

Plant microfossils in human dental calculus from Nemrik 9, a Pre-Pottery Neolithic site in Northern Iraq

Samples of dental calculus were taken from 11 human individuals buried at Nemrik 9, a Pre-Pottery Neolithic site in Northern Iraq. All of them represented the time span of ca. 9100–8600 bp. In total, 95 microfossils were retrieved from these samples, including 70 phytoliths, 9 starch granules or clusters of starch, 3 pollens, and 1 xylem fragment. Most microfossils could be attributed to C₃ cool season cereals, most likely wheat and barley, which is consistent with previous knowledge about the composition of crops in early farming communities living in the Fertile Crescent. In addition, three phytoliths and one starch granule typical of C₄ warm season grasses were recovered including one subangular and faceted starch granule, which might derive from a native grass, but is not diagnostic of any genus. Prior to assigning diagnostic status to this starch, exhaustive reference work on native grass seeds is necessary. The presence of one Phragmites phytolith suggests non-alimentary processing of reeds using teeth or perhaps using the stem of this grass as a toothbrush or toothpick.     

Diet,Geography and Drinking Water in Polynesia: Microfossil Research from Archaeological Human Dental Calculus,Rapa Nui (Easter Island)

Microfossil analysis of human dental calculus provides consumption‐specific and archaeologically relevant data for evaluating diet and subsistence in past populations. Calculus was extracted from 114 teeth representing 104 unique individuals from a late 16^th to early 18^th century skeletal series on Rapa Nui (Easter Island) to address questions of human–environment interactions and possible dietary preference. Scanning electron microscopy was used in lieu of optical microscopy for its superior depth of field and resolution of surface detail. The calculus microfossil recovery produced 16,377 total biogenic silica microfossils: 4733 phytoliths and 11,644 diatoms. The majority of phytoliths correspond with the Arecaceae or palm family (n = 4,456) and the minority corresponds to the Poaceae or grass family (n = 277). Because of the relatively large sample size, we were able to test hypotheses related to age cohort, sex, dental element and geographic region. Results indicate no significant difference in phytolith or diatom recovery based on age cohort or sex. The high frequency and proportion of Arecaceae phytoliths found in calculus extracted from the anterior dentition suggests consumption of soft or cooked foods containing palm phytoliths and the high frequency of diatoms recovered from the southern part of the island argue for different sources of drinking water. Copyright © 2012 John Wiley & Sons, Ltd.     

The Ba/Sr ratio,carious lesions,and dental calculus among the population buried in the church La Concepción (Tenerife,Canary Islands)

Certain trace elements may accumulate in bone in relation to dietary habits, so some of them are of interest in paleodietary analysis. This is the case with strontium (Sr) and barium (Ba), whose potential value as paleodietary indicators is enhanced by their relatively inert metabolic behaviour. The presence of carious lesions may indicate consumption of sugar and vegetables, whereas the etiology of dental calculus deposition is multifactorial, although some authors consider this as an indicator of protein consumption. Based on these facts we analysed (1) Ba, Sr, and calcium (Ca) content of inner cortical bone obtained from the ramus mandibularis, by atomic absorption spectrophotometry, (2) presence of teeth with carious lesions, and (3) presence of teeth with calculus deposition in 62 mandibles. All samples were obtained from the church La Concepción, an 18th century burial place in Tenerife. Gender was assessed by analysing genetic expression of amelogenin in some cases (14), and by inspection of pelvic bones when available (41 cases). We found (1) Carious lesions in 32 cases, and dental calculus, in 39; no association was observed between sex and presence of dental caries or calculus deposition, nor between the sex and the proportion of carious teeth nor the proportion of teeth with calculus deposition; (2) people buried near the altar (priests and individuals of the highest social class) showed a significantly higher proportion of teeth with dental calculus deposition (χ² = 5.36, p = 0.021); (3) bone Sr and bone Ba were significantly higher than the values observed in a control group of 10 modern omnivorous individuals; the lowest Sr values were observed among people buried near the altar; and (4) the Ba/Sr ratio was directly related with the proportion of teeth with carious lesions. These data suggest that there were differences in dietary pattern among the individuals belonging to different social classes; overall, consumption of vegetables was widespread, as shown by the high proportion of carious lesions, in relation with raised Ba/Sr ratio, whereas consumption of marine products was scarce.     

Experimental assessment of maize phytolith and starch taphonomy in carbonized cooking residues

Many taphonomic studies of plant microfossils, specifically phytoliths and starch, are concerned with post-depositional movement, contamination, and morphological changes due to environmental fluctuations or plant processing. Additionally, the identification of phytoliths and starches archaeologically are based on their presence or absence. This paper examines whether it is possible to identify maize (Zea mays ssp. mays) phytolith and starch abundance associated with different processing behaviors as replicated through experimentally produced cooking residues. If successful, identification of likely associated processing and taphonomy of these microfossils will allow for a more refined interpretation of plant use as it relates to timing and plant form and processing.     

Sweet potato (Ipomoea batatas) and banana (Musa sp.) microfossils in deposits from the Kona Field System,Island of Hawaii

Analysis of plant microfossils (pollen, phytoliths, starch grains and xylem cells) was carried out on 12 soil samples from a variety of pre-contact archaeological features in South Kona within a portion of what has been termed the Kona Field System, on the Island of Hawaii. The oldest radiocarbon ages of the sampled deposits are 1300–1625 AD and 1310–1470 AD. The pollen and phytolith evidence suggests a change from more to less trees and shrubs in the area as a result of human activity. We found phytoliths of banana (Musa sp.) leaves in most and starch grains and xylem cells of tuberous roots of c.f. sweet potato (Ipomoea batatas) in all of the samples, suggesting that the sampled features were associated with these crops and that both crops were cultivated intensively within the study area. Higher concentrations (volumetric) of starch and xylem in samples from older deposits suggest that cultivation was more intensive then. The apparent absence of starch and xylem remains of other tuberous crops archaeologically identified elsewhere in Polynesia suggests that tuberous cropping within the study area was mono-specific.     

Dirty teeth and ancient trade: Evidence of cotton fibres in human dental calculus from Late Woodland,Ohio

Analysis of ancient human dental calculus for the presence of inclusions related to diet and dental health has been overlooked in anthropological literature. Small particles of archaeobotanical debris, which would otherwise not be preserved in the archaeological record, can become incorporated into unmineralised plaque on teeth during mastication and oral manipulation. When plaque mineralises into calculus, debris is preserved in situ. Samples of dental calculus (n = 18) were collected from the Danbury site (33OT16) in Ottawa County, Ohio and viewed under a scanning electron microscope for inclusions. Analysis yielded a variety of noticeable inclusions, including mineralised bacteria, calcium‐phosphate crystalline structures and numerous phytoliths. Here we report the first evidence of fibres consistent with cotton (Gossypium spp.) embedded in the dental calculus from the Late Woodland component (900–1100 AD ) of the Danbury site. Prehistoric cotton has not been previously documented in Ohio. The distinct morphology of the Danbury cotton and its presence in the Late Woodland component at Danbury suggests long‐distance interaction at a time in Ohio when movement of exotic goods appeared to have diminished. These microscopic remains provide insight into paleoethnobotanical history of ancient Ohioans and attest to how analysis of dental calculus could be used to supplement other paleodietary and archaeological analyses. Copyright © 2010 John Wiley & Sons, Ltd.     

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.     

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。     

Reassessing the northern limit of maize consumption in North America: stable isotope,plant microfossil,and trace element content of carbonized food residue

In combination, the analysis of carbonized food residue for stable C and N isotopes, elemental composition, and plant microfossils (phytoliths and starch granules) offers a powerful tool for understanding patterns of prehistoric maize (Zea mays) consumption in small-scale societies. Using this approach, we conclude that maize was more widely consumed in North America than previously suspected. Between ∼AD 700 and 1600, despite little or no archaeological evidence of gardening, corn was a widespread component of diet on the eastern Canadian prairies. This pattern, furthermore, extended into the adjacent boreal forest at about the same time. However, carbon (δ¹³C) and nitrogen (δ¹⁵N) values on food residue samples vary widely, suggesting significant overall dietary differences from one region to the next. Analysis of a subset of residue samples for elemental composition (using ICP-OES [inductively coupled plasma–optical emission spectrometry]) may help identify broad trends in the provenience of foods consumed at these sites.     

Calculus,periodontal disease and tooth decay among the prehispanic population from Gran Canaria

In the prehispanic Gran Canaria there are some anthropological differences between the coastal inhabitants who buried their dead mainly in tumuli, and those from the central mountains, mainly buried in caves. Some data, as the prevalence of auricular exostoses, and a different bone Ba/Sr ratio support the view that there were differences in economy and diet between both groups of islanders. Moreover, the proportion of carious teeth was significantly higher among the population buried in caves. In the present study we analysed the prevalence of dental calculus, periodontal disease and antemortem tooth loss in remains of 791 individuals belonging to the anthropological collection of the Museo Canario (Las Palmas). Calculus deposition was very frequent (88.51%), no differences existing between men and women or between those interred in tumuli or in caves. Age at death was the only parameter independently related to calculus deposition by stepwise multivariate analysis. Periodontal disease was observed in 66.78% of the population, significantly more in men (χ² = 4.88, P = 0.027). No differences existed between individuals buried in tumuli and in caves. Antemortem teeth loss was observed in 64.73% of individuals, no differences existing between men and women or between those interred in tumuli or in caves. There was a significant association between calculus and periodontal disease (χ² = 18.07, P < 0.0001). Both caries (χ² = 8.40, P = 0.004) and periodontal disease (χ² = 44.96, P < 0.0001) were associated with tooth decay. However, the proportion of teeth with calculus deposition (in relation to observed teeth) was significantly higher among the population buried in tumuli (Z = 3.18, P = 0.001), although no differences were observed when the proportion of antemortem lost teeth and alveoli with periodontal disease were compared among people buried in tumuli and in caves, but women showed significantly lower proportions of alveoli with periodontal disease and antemortem tooth decay. These data suggest that the population buried in caves had a different dietary pattern to that of those buried in tumuli, since calculus deposition -more frequent in the latter-may be related to the consumption of proteins. The results also point to the existence of differences in diet between men and women.     

Do silica phytoliths really wear mammalian teeth?

There is considerable literature suggesting that silica (opal) phytoliths cause dental enamel microwear in mammals. Much of this literature cites a single study from 1959 as evidence that silica phytoliths are harder than mammalian tooth enamel and so have the potential to cause dental microwear. No other studies using similar methodology have actually confirmed whether phytoliths are harder than dental enamel.     

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.     

Stable carbon and nitrogen isotopes of human dental calculus: a potentially new non-destructive proxy for paleodietary analysis

Fifty-eight dental calculus samples from medieval and post-medieval skeletons from Vitoria, Spain, and a single sample from an Alaskan Inuit were tested for stable carbon and nitrogen isotope compositions. There was sufficient carbon and nitrogen concentrations to obtain δ¹³C and δ¹⁵N values, and the samples from Spain produced results that were replicable and comparable to European isotope values based on bone collagen collected from literature sources. The Alaskan Inuit calculus sample yielded a δ¹⁵N value of +17.5‰, well beyond the range of the Spanish samples, but consistent with literature data for modern Greenlandic Inuit consuming a diet rich in marine food. There are several potential sources for carbon and nitrogen in calculus. The results of this study yield stable isotope values consistent with those obtained from other biomaterials used as isotope proxies for paleodietary research, including bone collagen, hair, and fingernails, although further work is necessary to verify the fidelity of calculus as an isotope proxy. Many studies in bioarchaeology are precluded by curatorial concerns regarding the destructive analysis of primary biomaterials. However, calculus is an “add-on”, or secondary biomaterial, that is not an integral part of the dental or skeletal system. Hence, its consumption during analysis is technically not destructive. Therefore, isotope analysis of dental calculus may provide a potential new avenue for paleodietary analysis where the use of other primary biomaterials is precluded.     

New insights into the consumption of maize and other food plants in the pre-Columbian Caribbean from starch grains trapped in human dental calculus

In a first region wide study, starch grains from human dental calculus from the pre-Columbian insular Caribbean (dating to ca. 350 B.C.–A.D. 1600) are used to identify important plant foods in the diet and to assess potential dietary differences related to age or sex. Results give important insights into pre-Columbian maize (Zea mays) consumption throughout the region, confirming recent studies that indicate that maize was more commonly consumed in the insular Caribbean than originally thought. No age or sex based differences in maize consumption were found. Furthermore, based on the results of new experiments regarding grinding and pressure damage to starch grains, it is clear that maize in the Caribbean was ground, baked and consumed as bread as was the case in large parts of the mainland. Based on our results we tentatively suggest maize consumption in the Caribbean was at least in some cases associated with feasting and ceremonial activities. The variety in other plant foods identified (mostly tuberous root crops) shows that the pre-Columbian inhabitants of the region consumed a broad spectrum, but locally variable diet in which a variety of root crops functioned as staple crops, including marunguey (Zamia sp.) and sweet potato (Ipomoea batatas). We found no indications for the traditionally assumed heavy reliance on manioc (Manihot esculenta) cultivation in the region.     

Efficient but destructive: a test of the dental wash technique using secondary electron microscopy

The Boyadjian et al dental wash technique provides, in certain contexts, the only chance to analyze and quantify the use of plants by past populations and is therefore an important milestone for the reconstruction of paleodiet. With this paper we present recent investigations and results upon the influence of this method on teeth. A series of six teeth from a three thousand years old Brazilian shellmound (Jabuticabeira II) was examined before and after dental wash. The main focus was documenting the alteration of the surfaces and microstructures. The status of all teeth were documented using macrophotography, optical light microscopy, and atmospheric Secondary Electron Microscopy (aSEM) prior and after applying the dental wash technique. The comparison of pictures taken before and after dental wash showed the different degrees of variation and damage done to the teeth but, also, provided additional information about microstructures, which have not been visible before. Consequently we suggest that dental wash should only be carried out, if absolutely necessary, after dental pathology, dental morphology and microwear studies have been accomplished.     

Pervasiveness of phytoliths in prehistoric southwestern diet and implications for regional and temporal trends for dental microwear

Our previous analysis of phytolith content of coprolites showed that calcium oxalate phytoliths from desert food plants caused dental microwear among prehistoric Texas hunter-gatherers. We demonstrated that phytoliths from desert succulents were ubiquitous and abundant in hunter-gatherer coprolites. We found that calcium oxalate phytoliths were harder than human dental enamel. We concluded that phytoliths from desert succulent plants caused dental microwear and hypothesized that such dental microwear would be common in other desert hunter-gatherer and horticultural peoples. Presented here are further analyses of phytoliths from coprolites. Two additional hunter-gatherer sites and three Ancestral Pueblo (Anasazi) horticultural sites are included in this study. Calcium oxalate phytoliths are ubiquitous in coprolites from hunter-gatherer sites in the Mojave Desert and the Colorado Plateau. For the three Ancestral Pueblo sites, calcium oxalate phytoliths from desert succulents (agave family and cactus family) are the most common types of phytoliths encountered. However, silica phytoliths are also present in Ancestral Pueblo coprolites. The data demonstrate that phytoliths from non-cultivated desert plants were a source of dental microwear for the pre-maize Archaic hunter-gatherer bands and maize-reliant Ancestral Pueblo villages.     

Stress near the start of life? Localised enamel hypoplasia of the primary canine in late prehistoric mainland Southeast Asia

Localised hypoplasia of the primary canine (LHPC) is characterised by roughly circular defective areas of thinned or missing enamel on the labial surface. This defect is rarely reported in bioarchaeological research. Using samples from late prehistoric mainland Southeast Asia, this paper documents the prevalence of LHPC to produce baseline data for this defect. The samples are from seven archaeological sites in Thailand and collectively span from ca. 4000 to 1500 BP. In the combined samples, 32/79 (40.5%) of individuals and 47/199 (23.6%) of teeth had LHPC. The high occurrence of LHPC may suggest there was poor maternal and infant health. There is also a high occurrence of caries associated with LHPC, which has implications for the assessment of deciduous dental health. This paper stresses the importance of the collection of dental enamel defect data from deciduous teeth including LHPC in bioarchaeological research.