Evidence of Diet Using Dental Pathology and Stable Isotope Analysis in Greek Populations

by Holland Butsch, Anthropology

Abstract: Within the field of bioarchaeology, teeth have often been described as the most important bone to uncover at an archaeological site. Our ability to analyze teeth through dental pathology and stable isotope analysis has given us the opportunity to uncover accurate information about past populations that could only ever be inferred. Teeth can give us insight into age, diet, infections, times of stress in adolescence, and non-dietary trends of use of teeth. Every culture throughout history can be defined by their food trends and dietary patterns. The foods that we eat during adolescence and through adulthood is permanently retained in our teeth because of the stable Carbon and Nitrogen isotopes that are associated with different food groups. Dental pathologies such as carious lesions, calculus, and tooth wear can also give insight into the texture and types of foods that we consistently eat throughout our lives. The purpose of this paper is to analyze five different case studies that focus on using dental pathological data and stable isotopic analysis to determine dietary trends in Ancient Greek populations. These trends are indicative of the societal standings between different sexes and different age groups within these populations in antiquity. While there is much literature defending the institution of gender roles in the past, it is evident, in some cases, that those gender roles became less prevalent as time went on.

dental pathology, diet, stable isotopes, ancient Greece, gender roles

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Understanding and utilizing the analysis of dental pathology and stable carbon and nitrogen isotopes can tell us a lot about the diets and culture of ancient Greek populations. The ancient literary sources highlight dietary differences between sexes as well as between age groups. Greece and North Macedonia make up the southern-most portion of the Balkan Peninsula and are bordered by both the Aegean and Ionian Seas. Although skeletal analysis centuries later could never be as accurate as historical accounts of cultural practices, anthropologists are duty bound to learn as much as possible to fill in the gaps. Diet patterns in Greek populations have become less bound by gender roles as time has progressed and there has been an overall improvement in dental health since the time of hunter-gatherer populations. This paper will discuss aspects of the bioarchaeological record throughout the Mediterranean and how such evidence of dental pathologies can give insight into the social structure of Greek society in antiquity.

Background

Dental pathology is studied in archaeological contexts by examining common macroscopic maladies such as carious lesions, calculus, antemortem tooth loss (AMTL), tooth wear, alveolar abscesses, and enamel hypoplasia. Analysis of these dental markers can give us evidence of diet and thus how it can change over time as well as “age-, sex-, and status-based differences in diet” (Keenleyside, 2008). Dental caries are formed when acid production leads to the demineralization of dental hard tissues and results in lesions that could lead to cavities (Bertilsson et al., 2021). Diet is commonly identified as the biggest factor leading to caries, generally due to the “bacterial fermentation of dietary carbohydrates, especially sugars,” (Keenleyside, 2008). Elements such as fluoride and strontium impede the formation of caries and are commonly found in marine foods (Keenleyside, 2008; Michael and Manolis, 2014) and water sources. Along with caries, dental calculus is one of the most common pathologies found in both modern and ancient times. Calculus is “mineralized plaque which adheres to tooth surfaces,” (Lieverse, 1999) and is caused by diets high in alkalinity and is most prominent in teeth nearer to salivary glands. There are two types of calculus: supragingival and subgingival. Supragingival calculus is above the gingival margin and can be associated with periodontally diseased or healthy teeth, while subgingival calculus is located within the gingival pocket and is always associated with periodontally diseased teeth (Lieverse, 1999).

Antemortem tooth loss (AMTL) is a possible consequence of dental caries and is “indicated by the resorption of alveolar bone in the tooth socket” (Keenleyside, 2008). Periodontal disease, an infection of the gums, is another main factor that leads to AMTL. Tooth wear is irreversible, progresses with age, and is generally associated with the texture of foods consumed and non-dietary uses of teeth. Enamel hypoplasia is a condition that suggests elevated levels of stress during development that led to the pause in growth of the enamel caps, resulting in linear pits that can tell us both the time of when a stress event occurred as well as how long it lasted (Vergidou et al., 2021).

Stable isotope analysis of carbon and nitrogen is used to determine the food groups that were consumed by archaeologically significant populations, and can, by extension, tell us dietary patterns in populations that are currently unknown. Isotopes are variants of atoms of the same element that have the same number of protons, but a different number of neutrons in their nuclei (Reitsema et al., 2020). The isotopic signals of food are absorbed into the tissue and reflected back in later analysis. The process of extracting and preparing samples for analysis begins with taking the bone sample and crushing it into small pieces with a mortar and pestle. The sample is then demineralized in 0.5 M HCl, rinsed with distilled water, soaked in a NaOH solution, rinsed again, and the collagen is then isolated. The process of collagen isolation requires the sample to be drawn through a filter, freeze-dried, and homogenized. The collagen is then run through a mass spectrometer for analysis (Petroutsa and Manolis, 2010; Dotsika and Michael, 2018; Reitsema et al., 2020). For well-preserved stable isotope samples, the carbon-nitrogen ratios (C:N) must fall between 2.9-3.6.

Plants exist in three different categories, each with a different stable carbon isotopic range: C₃ plants have the lowest δ¹³C values and include fruits, vegetables, and some grains; C₄ foods have the highest δ¹³C values and are made up of maize and sugarcane; CAM foods have intermediate values and include pineapple and cactus. The protein from freshwater fish, marine fish, and terrestrial animals also exhibit similar δ¹³C ranges as the plant groups, respectively (Reitsema, 2015). Nitrogen isotopes are used primarily to understand the consumption of animals and animal products. In general, δ¹⁵N values increase with more protein consumption, so plants will have the lowest δ¹⁵N values and carnivores will have the highest (Schoeninger, 2014; Reitsema, 2015).

Metanalysis

Anthropology is an expansive discipline with humanity being analyzed from every lens possible through multiple sub-disciplines. Within archaeology, dental pathology and stable isotopes are common tools used for analysis of age, diet, and geographic origins of skeletal remains. Because of its prevalence, and the frequent study of Greek sites and populations, it can be beneficial to understand how the topic of this paper fits within the grand scheme of all archaeological research, and to gain an understanding as to why certain trends may exist.

Figure 1. A representation of the search results containing “Dental path*” and “Greek” or “Greece.” There is an exponential increase in the number of published papers containing these terms from the mid-1970s to the present. All of the data was provided through a Web of Science search.

Figure 2. A representation of the search results containing “Diet” and  “Greek” or “Greece.” There is an exponential increase in the number of published papers containing these terms from the mid-1970s to the present. All of the data was provided through a Web of Science search.

By doing two different searches relating to dental pathology and diet in Greece on Web of Science, I have been able to compile all related articles for an analysis of trends over time. When searching “Dental path*” and “Greek” or “Greece,” a total of 2,857 publications were found once limited to only papers about Archaeology and the range of years was limited to be between 1923 to 2023 (Figure 1). When searching “Diet” and “Greek” or “Greece,” a total of 2,961 publications were found within the same time frame (Figure 2). The data sets have near identical trends, as there is an exponential increase in the number of publications as the years progress, with a major boom happening in the mid-2000s. Stable isotope analysis as a process was first used to analyze diet in the 1970s, and the more efficient and modern methodology of this practice was established in the mid-2000s, which would explain the dramatic rise in papers being published around that time. The slight decrease in the number of publications after 2020 would be due to the COVID-19 pandemic and the inability for research to be conducted in the field.  

When choosing the case studies for this paper, I was looking for scholarship that used large enough data sets to come to reasonable and accurate conclusions that could be used to describe the dietary trends of the entire population at those sites. It was important for the subject of this paper to make sure that they all used both dental pathology and stable isotope analysis to reach those conclusions.

Table 1. Summary of Sites with Conclusions of Diet and Social Relations
Site Locations	Ages Examined	# of Individuals		Diet Implications	Social Implications
Edessa (Dotsika and Michael, 2018)	20-35	4 Males	8 Females	Mixed diet; mostly terrestrial animals/animal products	No statistically significant differences between sexes or age groups on diet; opposes ancient literature on dietary differences between sexes
	36-50	2 Males	8 Females
Apollonia (Keenleyside, 2008)	18-35	22 Males	40 Females	Relatively soft, high carb diet; terrestrial animals/animal products	No statistically significant differences between sexes or age groups on diet; age progressive dental conditions present; higher level of tooth wear in males hints at non-dietary use of teeth
	36-50	37 Males	23 Females
	50+	14 Males	20 Females
Almyros (Michael and Manolis, 2014)	20-35	18 Males Total *	14 Females Total *	Mixed diet of protein and carbs	Females eat more carbs- aligns with gender roles; women stayed home and had more flexibility to eat while men worked and had defined mealtimes
	36-50
	51+
Apollonia Pontika (Schmidt et al., 2016)	0-1.9	21 Subadults **		Mostly dairy products and cereals; Soft weaning diet high in carbs	Most children weaned by 3 years old; weaning practices changed little over time
	2-3.9	32 Subadults
	4-5.9	13 Subadults
	6-7.9	17 Subadults
	8-9.9	10 Subadults
	10-11.9	5 Subadults
Pontokomi (Vergidou et al., 2021)	20-34	7 Males	13 Females	Small scale agriculture and livestock for meat and cereals	No statistically significant differences between sexes or age groups on diet based on dental pathology; likely a mixed economy with low socioeconomic status; shared lifestyle
	35-49	9 Males	8 Females
	50+	7 Males	6 Females
	18+	4 Males	4 Females

Case Study 1: Edessa, Greek Macedonia – 2^nd-4^th Centuries CE

In their 2018 study, Dotsika and Michael examine the diet of a population in Edessa, a town in Greek Macedonia. The 22 individuals studied from this site were excavated from the Western cemetery of the Acropolis site, dating back between the 2^nd and 4^th centuries CE. The individuals were separated into two age groups, young adults which were 20-35 years old, and middle aged adults which were 36-50 years old (Table 1). Nineteen femoral fragments and sixteen teeth were isotopically analyzed to determine what types of diets were consumed by the population at the time and if any differences were noticeable between age groups and sexes.

Based on the mean isotopic values for δ¹³C and δ¹⁵N, it is suggested that the Edessan population ate a mixed diet from both C₃ and C₄ foods. The nitrogen values also suggest significant terrestrial animal and animal product consumption. Despite access to the Edessaios River, there is little evidence of freshwater or marine animals being consumed as a primary source of protein. There are three individuals who were more likely to have consumed more aquatic life in their diet, and which stresses the importance of “identifying individuality within generic isotope patterns” (Dotsika and Michael, 2018). There were no statistically significant differences between the male and female carbon and nitrogen isotopic values, indicating that both groups ate similar foods. However, females presented a wider carbon isotopic range, which could suggest a more diverse diet. This suggestion should be taken lightly, however, due to the unequal sample size of six males and sixteen females. There were also no statistically significant differences between the young adult and middle aged adult groups, but there are indications from the enamel tests that there could have been a change in diet over time since adolescence.

This population acquired the largest portion of their protein diet from C₃ sources, such as wheat, barley, and some terrestrial animals and animal products (Dotsika and Michael, 2018). When compared to other studies, the results of Edessa’s δ¹³C_coll were most similar to populations that consumed millet and millet-fed animals as a primary source of C₄ foods. Analysis of the teeth found on site suggest a low carbohydrate intake since there is a low caries rate, as well as the possibility of high quantities of fluoride in the water or food to offset the rate of growth.

Case Study 2: Apollonia, Bulgaria – 5^th-2^nd Centuries BCE

Keenleyside’s 2008 study assesses a skeletal sample for variations in dental disease with respect to age and sex using dental pathology and confirming with stable isotope analysis. Apollonia was founded in 610 B.C. and very quickly became a prosperous city with a strong trading relationship with the nearby Thracian population. From 1946 to 1949, a large-scale excavation uncovered 801 graves from the Kalfata necropolis, located on the shore of the Black Sea. A later excavation uncovered another 400 burials, all of which date between the 5^th to 2^nd centuries BCE. This study focuses on samples from the most recent excavation (Table 1).

Faunal remains, food remains, and ritual fireplaces also found at the site indicated that “the population subsisted on a varied diet of grains, nuts, fish, meat, and shellfish” (Keenleyside, 2008). The dentitions of 162 adult skeletons were analyzed and separated into three age groups: 18-35 years, 36-50 years, and 50+ years of age (Table 1). When recording different dental pathologies, the rates often differed tremendously when comparing between individuals versus among all teeth. As such, 53.8% of individuals were afflicted with carious lesions but only 7.7% of overall teeth had caries. There were no statistically significant differences between sexes or age groups for caries, but caries rates do increase with age. AMTL was common in the sample, affecting 45.7% of individuals and 10.3% of teeth, with no statistically significant differences between sex or age found. Abscesses were the least common pathology found, but they were observed significantly more in males than in females, and rates always increased with age. Dental calculus was the most common pathology observed, affecting 79.1% of individuals and 44.5% of teeth in the sample. No significant differences between sex or age groups were found for calculus rates, as well as for tooth wear and enamel hypoplasia.

While it is expected to see sex differences in caries rates to give evidence to traditional gender roles in Greek society, the results suggest that both groups were consuming foods with similar cariogenic properties (Keenleyside, 2008). When compared with other archaeological studies, the 7.7% caries rate in teeth is at the lower end of the ranges reported for other Greek skeletal samples and for populations with mixed economies. The high prevalence of dental calculus and patterns of dental wear suggest a diet high in carbohydrates and a relatively soft diet. Stable isotope analysis confirms a heavy reliance on carbohydrates and little difference between sexes in diet patterns, which is contrary to the ancient literature. However, apatite-collagen spacing does hint at a slightly higher carb consumption by females and a slightly higher protein consumption by males.

Case Study 3: Almyros, Corfu – 7^th Century BCE-2^nd Century CE

In 2014, Michael and Manolis published a study in order to explore potential dietary differences between sexes in an ancient Greek population. This study examines 32 skeletons from the Almyros cemetery in Corfu, which is located on the north end of the island and dates back to between the 7^th century BCE and the 2^nd century CE. The individuals were split into three age categories: young adults (20-35), middle adults (36-50), and older adults (51+; Table 1). Out of the 1024 possible teeth available, 381 are present and 35 were lost ante-mortem.

Females presented a statistically significant higher rate of dental caries in teeth than males at 13.6% versus 4.3%, respectively. When broken down between locations of where the carious lesions were found between sexes, it is also statistically significant that the female rates are much higher than the male rates among all possible locations: occlusal, buccal, mesial, and distal. There were not carious lesions found on the lingual surfaces for males or females. In addition to having a higher quantity of caries in females, those carious lesions also tended to rate at a much higher degree than the males. Females were the only individuals examined that showed caries reaching down into the roots of the teeth. Differences between sexes and age groups in caries rates were not statistically significant.

The total percentage of caries in the population was calculated to be 7.9%, which falls within the ranges of both a mixed diet (0.44-10.3%) and an agricultural diet (2.2-26.9%), but it is suggested that the population at Almyros had a mixed, balanced diet of both protein and carbohydrates (Michael and Manolis, 2014). The higher caries rate in females suggests that they ate more carbohydrates than the males, as well as aligning more with the traditional gender roles outlined in the ancient literature. The differences between males and females in AMTL was not found to be statistically significant, and there was little dental wear present in the sample.

Case Study 4: Apollonia Pontica, Bulgaria – 5^th-3^rd Centuries BCE

The Schmidt et al. study from 2016 analyzes deciduous dental pathology and carbon and nitrogen isotopes to investigate feeding and weaning practices of infants and determine the prevalence and variation of dental pathology in subadults of an Apollonian sample. The sample consists of 98 subadults ranging from three months to eleven years old, found between seven different locations in the Kalfata-Budjaka necropolis dating between the 5^th and 3^rd centuries BCE (Table 1).

An analysis of the δ¹⁵N values of subadults revealed a trend of the youngest individuals (0-1.9 years) having the highest values and the values decreasing with age until age 4, where the values are lower than the adult female mean. Out of 942 deciduous teeth, there was only one abscess found and 57 carious lesions on 49 teeth. The youngest individual with caries was 2 years old, and there was a statistically significant increase in carious lesions with age. Dental calculus and tooth wear were noted, and both increased with age. With the exception of four individuals, nitrogen analysis indicates that weaning went from the ages of 6 months to 3 years, and the diet was primarily dairy products and cereals. Those other four individuals continued weaning until four, four and a half, and six years old. Due to previous studies, it is known that breast milk has a low cariogenicity and does not promote enamel decalcification. The weaning diet, however, was high in carbohydrates and very quickly allowed the development of caries and calculus. The soft diet is the likely reason for low tooth wear, although that could also be attributed to the short period of use prior to death.       

Case Study 5: Pontokomi, Western Macedonia, Greece – 1^st-4^th Centuries CE

In their 2021 study, Vergidou et al. investigate the dietary profiles between various “social identities” using dental pathology. One hundred and one burials were excavated from the Vrysi site in Pontokomi, Western Macedonia, Greece, which resulted in a total of 61 adult skeletons and 1052 teeth to be examined split into three age groups: young adults, middle adults, and older adults, dating between the 1^st and 4^th centuries CE (Table 1).

Periodontitis was present in 90.1% of individuals, and rates were nearly equal between the sexes. Periapical cavities were present in 55.7% of individuals and 4.8% of teeth, and although they were more common in females individually and males per alveoli, neither of the rates were statistically significant. Fifty-nine percent of the individuals experienced AMTL, with the progression of age exhibiting a higher frequency of the condition. Dental calculus was found in 82% of individuals and was found to not progress with age, but the mandibular teeth did have significantly more calculus. Dental caries affected 67.2% of the assemblage, and females showed significantly more lesions in the middle and older adult groups than the males. Males also showed a significantly higher rate of tooth wear than the women. Overall, there were more statistically significant differences at the tooth level than the individual level.

The low caries rate and lack of statistically significant dental pathology in many areas suggests a “socially homogenous community where all individuals experienced the same lifestyle,” often being seen in communities with low socio-economic status (Vergidou et al., 2021). The Pontokomi community likely had a mixed economy with both small scale agriculture and livestock for meat. Cereals, vegetables, and meat from livestock were all likely basic elements to the diets of these individuals.

Discussion

Ancient Greek societies have been a significant area of study within bioarchaeology for centuries, meaning continued research in the country is usually extensions or confirmations of previous studies and what we already know about Greek culture throughout time. All of the case studies above date somewhere between the 7^th century BCE and the 4^th century CE, when traditional gender roles are still playing a prominent part in the home lives of Greek citizens. It was presumed prior to analysis that the inferior roles of women in ancient Greece would be reflected in their diet patterns, as women were often “third in the hierarchy behind their husbands and sons” (Michael and Manolis, 2014), and were not given access to as much protein for consumption, being forced to eat primarily carbohydrates for nutrition. This trend is confirmed in the Michael and Manolis (2014) study, in which dental pathological analysis indicated that females ate significantly less protein and more carbohydrates in the diet, which resulted in deeper carious lesions. Women in ancient Greek society “spent the majority of their lives – and meals – within the household” (Reitsema et al., 2020), whereas men would have eaten outside of the home and generally been prioritized over women. The men’s diets would be comprised of considerably more protein than women and different types of plants (Reitsema et al. 2020), according to stable isotopic analysis.

These gender roles are challenged, however, by Dotsika and Michael (2018), Keenleyside (2008), and Vergidou et al. (2021), as there is little to no difference in dietary patterns between sexes. These results could be due to the later time periods and could begin to reflect how societal standards were changing to look more like society today. These trends could also be attributed to lower and some middle class societies having to forego these gender roles in order to make sure they are provided for. Since one of the biggest reasons for sex-based dietary differences is due to women staying home and having more flexible mealtimes, in the lower socioeconomic classes more women would be working and spending time outside of the home, which would change their dietary habits.

Studies have previously shown that the switch from hunter-gatherer populations to sedentary, agriculturally based groups during the Neolithic era was a major contributing factor to the decrease in oral health. However, Angel (1944) suggests that urbanization has led to the overall improvement of dental health. While the introduction of mass produced sugar and processed foods has led to an increase in disease prevalence, preventative strategies and advances in dentistry have led to the improvement of dental health (Bertilsson et al., 2022).

Galen, a prominent Greek physician and philosopher, wrote extensively on Graeco-Roman diet and its impact on medicine, primarily inspired by Hippocrates and his work with the four humors. The humoral theory is based on the idea that good health relies on a balance of four fundamental fluids in the body, and diet is a notable player in maintaining that balance. Galen wrote “that a good diet ensured health was a fundamental concept of ancient medicine, since food could cause disease or restore health through its effect on the balance of the humors” (Grant, 2000). This concept is evident in the relationship between the types of foods that were consumed by the Greeks and the types of oral pathologies that were discovered on the skeletal samples. His works describe the staples of Greek diet to be cereals, legumes, olive oil, and wine (Keenleyside, 2008). Especially in cereals, the grit of the foods consumed were cited to be a major factor in the wear seen on teeth across all skeletal samples from each case study site.

Conclusion

Differences in diet between sexes and age groups have been shown to have less statistically significant differences as time has progressed, indicating, at least among the lower and middle classes, that traditionally prescribed social roles are also becoming less significant. Ancient Greek populations consume primarily cereals, wheat, and terrestrial animals and animal products in their diets, along with olive oil and wine. While protein consumption varies less with time, female samples continue to indicate a heavier reliance on carbohydrates than males, which tends to result in a higher prevalence of dental calculus and carious lesions. Further research can be conducted with a wider sample size and spanning over a more continuous time period to track how diet patterns have changed in Greek populations.

As with any study, there are limitations that affect this analysis. The most glaring ones would be the limited sample size and broad time range. Further analyses could focus within a more specific time period in antiquity and find more studies to cover a larger portion of Greece. Further analysis of stable isotopic elements could also provide insight into more niche topics within the bioarchaeology of diet such as weaning practices and migration patterns.

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Acknowledgements: Dr. Laurie Reitsema, Adam Kazmi

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