Student Research: Dental Hypoplasias in the Cornwall Collection

Bianca Brenes conducted research with the DBP from Fall 2009-Spring 2010. A McNair Scholar at Sonoma State University, she presented the following poster at the McNair Symposium this past April.

Introduction:

Dental defects have long been studied as indicators for socioeconomic stress and physical stress from the surrounding environment (Goodman and Rose 1980; Sarnat and Schour 1941). This great amount of research, done in various parts of the world, helps to demonstrate how dental defects are indicators of environmental trends. One example of a stress indicator is linear enamel hypoplasias (LEH), where the thickness of the enamel is affected during development (Sarnat and Schour, 1941). They can appear as bands that surround almost the entire tooth or as lines or grooves occurring on the tooth itself (Goodman and Rose, 1991: 281). Occasionally, linear enamel hypoplasias are an effect of the nutritional status , but they  can also be caused by hereditary or local traumas, thought these are rare amongst most study findings. (Goodman and Rose, 1991:279-281).

Nutritional status could easily be defined as a function of which nutrients are consumed, but Goodman (1991) explains how other outside sources affect the enamel development, such as disease and lifestyle. Hypoplasias are useful  because they indicate stress that occurred during a child’s developmental stages, when tooth crown formation is affected (Lanphear, 1990: 35). Stress is most common in childhood due to the weaning process, which is defined as the introduction of more substantial food with the termination of  breast-feeding (Sillen and Smith, 1984).

My responsibilities on the Dilmun Bioarchaeological Project (DBP) include recording the presence and absence of teeth, antemortem tooth loss, and dental defects such as caries, calculus, and linear enamel hypoplasias (LEH). For the purpose of this poster, I will focus on the linear enamel hypoplasias that present within the skeletal material, excavated by Peter Cornwall in the 1940s from the island of Bahrain (ancient Dilmun) in the Persian Gulf. The collection is currently housed at the Phoebe Hearst Museum, at the University of California, Berkeley, with material dating as far back as the Dilmun and Tylos periods, which range from ca. 3500 – 1500 BCE to ca. 300 BCE – 300 CE (Farahani 2007).  During these time periods, consumption of dates was very common, due to the fact that they grew in abundance along the peninsula (Hojgaard 1980). This has lead to assumptions of nutrition and lifestyle that may have caused dental defects within the population (Hojgaard 1980; Littleton and Frohlich 1989; Nelson 1999).

Methods:

Linear enamel hypoplasias were measured using Mitutoyo Absolute Digimatic digital calipers (150 mm). Measurements were taken of the height of the entire tooth crown, along with the distance from the cementoenamel junction to the defect. The numbers were then worked into the equation established by Goodman and Rose (1991), which is shown here:

Age at formation = age at crown completion – [(years of formation/crown height) x defect height (from CEJ)]

The preceding equation can be used to determine the age at which the stress event occurred.  Half year intervals are used to determine the age range for the stress event: this takes better account of their eruption rate and provides an age range of the hypoplasia-affected tooth type (Goodman and Aremelagos 1985ab, Goodman and Rose 1991). Finally, all measurements were taken more the once to assess intra-observer error, which was used to supply an average age for the teeth.

Results:

Out of the nine individuals in the collection with teeth, all together 112 teeth were either missing or present. 30% of those teeth were fully resorbed, which indicates tooth loss antemortem. The other 70% were present, either still attached to the mandible or maxilla, or present but not attached to the alveolar bone. LEH were observed on 4 individuals out of the 9, with 12/112 (10%) of the teeth recorded. 

Figure 1 demonstrates the frequency of hypoplasias on the incisors, canines and molars. The peak frequency for the defects on the canines was between 4-4.5 years of age, while the peak frequency for the incisors was between 1-1.5 years of age and the peak frequency for the molars was between the ages of 3-3.5 years of age.

Interpretations:

 Research done by Karen Hojgaard (1980) on the prehistoric population of Bahrainshows that childrenwere exhibiting a great amount of stress between the ages of 2-3 years. Like in the DBP collection, the teeth that she studied were limited in number and had sustained lots of damage, making observation of the hypoplasias difficult. From my survey of the literature on LEH studied in Bahrain, Hojgaard’s article was the only one mentioning the defect, and only in a small paragraph. Most research on dentition done for this population  focused mainly on caries, calculus and antemortem tooth loss, thus making ours one of the few sets of LEH recorded for Bahrain.

Thus, we can infer from these data that children were experiencing high developmental or nutritional stress between the ages of 1-4.5 years of age. Also, by looking at Fig 1 we can also see that they were experiencing stress at other times of their developmental growth as well. This can help demonstrate around which time the child was possibly being weaned off of breastfeeding and onto more substantial foods. In other words, it is possible that the children were being introduced to more fish, meats, dates and various other vegetables (Littleton and Frohlich 1989;1993). Another possibility is that it could also mean that food may have been hard to come by while their mother was trying to wean them off of breastfeeding. To conclude, dental defects can help paint a clear picture of any given population. Hopefully with more studies of LEH in the ancient populations of Bahrain, better conclusions can be drawn about their diet and lifestyle.

Literature Cited

Goodman A.H., Armelagos, GJ and Rose CJ 1980 Enamel hypoplasias as indicators of stress in three prehistoric populations from Illinois. Human biology. 52:515-528.

Goodman, Alan H., Rose, Jerome C. 1991. Dental Enamel Hypoplasias as Indicators of Nutritional Status. In: Wiley-Liss, Inc. p. 279-293.

Farahani A. 2007. A Preliminary Analysis of Ceramic Artifacts from the Hearst Cornwall Bahrain Collection. Unpublished, project use.

Hojgaard K. 1980. Dentition on Bahrain, 2000 B.C. Scandinavian Journal of Dental Research 88:467-475

Littleton J, and Frohlich B. 1989. An Analysis of Dental Pathology and Diet on Historic Bahrain. Paleorient 15:59-75

Littleton J, and Frohlich B. 1993. Fish-Easters and Farmers: Dental Pathology in the Arabian Gulf. American Journal of Physical Anthropology 92:427-477

Nelson GC, Lukacs JR, and Yule P. 1999. Dates, Caries, and Early Tooth Loss During the Iron Age of Oman. American Journal of Physical Anthropology 108:333-343

Sarnat B.G., Schour I. (1941) Enamel hypoplasias in relation to systemic disease: A chronological, morphological and etiological classification. Journal of American Dental Association 28:1989-2000

Acknowledgements:

The research presented here would not have been accomplished without the help of Professor Alexis Boutin (Assistant Professor of Anthropology, Sonoma State University) and Benjamin Porter (Assistant Professor of Middle Eastern Studies, University of California, Berkeley). I would also like to thank the Phoebe Hearst Museum for all their help and support with the Dilmun Bioarchaeological Project. Lastly, I would like to thank the McNair Program at Sonoma State University for pushing me to gain experience in my field and to learn from the stress and happiness this journey endures.

Filed under: Bahrain, Skeletal, Student research

Student Participation in the DBP: Spring 2010

We were fortunate to have three undergraduates from Sonoma State assisting with analysis of the skeletal and dental remains this Spring. Each has written a summary of her responsibilities and reflected on what the experience has meant to her professionally and personally.

Bianca Brenes (B.A. Anthropology, 2010)

It has been an exciting year being a part of the DBP team, located at the Phoebe Hearst Museum at University of California, Berkeley. As part of my research for the McNair Scholars Program, I focused on linear enamel hypoplasias present in the collection. My duties within the project included but were not limited to: inventory of all dental material present in the collection, scoring and coding of wear on the teeth, measurements of linear enamel hypoplasias, as well as taking inventory of select skeletal material. For the purposes of my research, I focused entirely on the dental material present and worked on measuring and re-measuring the enamel hypoplasias to determine at what age the people experienced nutritional defects.

This project helped me to focus on my research and learn more about the society we were studying. I previously had no knowledge of Bahrain or the Arabian peninsula and what it entailed. Through studying the teeth and researching on them, I was able to gather more information about the period I was focusing on and what type of nutritional conditions they were dealing with. Also, with the frequency of visits to the museum, I believe I was able to stay on top of my paperwork and materials as it stayed fresh in mind. This project helped me to focus on my responsibilities and duties. Due to time constraints for my research paper, I was able to work within a tight time frame and accomplish my goals. I later presented my research at the McNair Symposium, at Sonoma State University, and will soon be publishing the article in the McNair Scholars Journal. If it were not for this project I would not have been able to expand my knowledge of bioarchaeology, forensics, and the Arabian Peninsula. Also, I would not have been able to expand my curriculum vitae and gain experience to put forth towards grad school. Thanks to this program I have been able to mature intellectually and learn how to prioritize and focus on my work.

 

Mary Beth Glisson (Anthropology major)

I began navigating my way through a bachelor’s degree in Anthropology with the thought that my education was about the journey and not about a career change because, as an adult student approaching retirement, it seemed unlikely I would ever be able to work in the fields that have captured my interest and imagination – that of bioarchaeology and paleontology. However, as my education has progressed, I began to see that maybe a new career isn’t totally out of the question. This hopeful and exciting feeling was due largely to Dr. Alexis Boutin when she gave me the opportunity to participate in the Dilmun Bioarchaeology Project (DBP).

I worked with Dr. Boutin and two other students in the basement of the Phoebe A. Hearst Museum in Berkeley, California examining human remains that were excavated from Bahrain in the early 1940s. Although each student was limited to only five visits to the museum, the experience was invaluable academically and professionally as it helped me gain focus on my new career path.

As part of the research team, my responsibilities were to identify and catalog the human remains by recording the individual bones being examined, and then indicate which side of the body the bone came from, condition, quantity of each bone, and in the case of multiples of the same bone, the minimum number of human individuals included. I also watched for bone pathologies, performed some dentition analysis, and was always on the lookout for pieces of bone that could be fit with other pieces but had been broken in burial, excavation, or shipping. Although museum rules don’t allow for gluing these pieces together, being able to see the fit helped a great deal in identification. Sometimes I took measurements of the bone to help determine stature, age, and sex of the individuals contained in the collection, and at other times I reanalyzed previously cataloged remains in order to check for inter-observer error.

Perhaps the most interesting and fulfilling of the tasks I performed was the cataloging of the remains and watching for possible fits between bones. In doing so I was able to put into practice what I had spent so many lab hours doing in class, and I enjoyed feeling like I was part of a larger team – together we were determining who these people were who had been transported from graves in Bahrain to a museum basement in California. Even errors made during my analysis of the bones made for a richer learning opportunity.

The greatest impact working on this project had on me was that it confirmed what I already suspected – that bones are where my interests lie. Ultimately my goal is to work in Africa doing exactly what I was doing with the DBP – analyzing human remains – except in Africa I would be working with remains that are millions of years old! The DBP has helped me see that I’ve made the right choice in education and career, and has given me valuable experience to include on my resume when I’m finally ready to work, or even volunteer for another project.

 

Natalie Sadler (Anthropology major)

My journey at Sonoma State has been a rough one until Fall semester of 2009 when everything seemed to come together for me. I joined the Anthropology Club and made a lot of new friends and I took an osteology class with Dr. Alexis Boutin. I have always liked bones and forensics but I hadn’t realized until that class that I have a natural affinity for it and that showed in my exam scores and classroom lab work. I applied for this internship even though I believed I would not be accepted. Well, I was chosen and it means the world to me that Dr. B has recognized this potential in me and wants to help me develop it further. Working with the Dilmun Bioarchaeology Project has certainly given me the first opportunity to do so for which I am very grateful.

Some of my responsibilities at the Hearst were creating inventories of the skeletal remains, measuring bones with sliding calipers, recording and analyzing dentition, and forensic analysis of some pelvises. Much of my time was spent creating inventories of the bones present, checking mine against a 1^st inventory, looking for discrepancies, and then working together to correct them. The best part of my day was when I had mixed piles of metacarpals and metatarsals and had to determine which they were, what number in the sequence they are and which side they came from.

I also got to spend some time taking measurements of the bones like the maximum diameter of the femur head, humeral head and the calcaneus. I also measured the metacarpals and read a supplementary article by Jantz and Meadows about calculating stature from metacarpal lengths. Something I found surprising and that challenged some preconceptions I had were that the measurements of the Dilmun people are to be computed with the regression formulas for American Black populations which makes sense considering the close proximity of Bahrain to Africa. Because of the lighter skin tone of Middle Eastern people, I had just assumed that they would fall into the statistical category for the White population. It was enlightening to have those preconceived notions of race and skin color challenged.

It was important to get some hands on experience with dentition. Sonoma State doesn’t have a collection of real loose teeth so this experience augmented what I learned in my osteology class. Teeth are a great source of data about a population. Caries can reveal information about diet quality, patterns of wear can tell something of the life activities, and the presence of hypoplasias can indicate periods of stress and malnutrition.

Another task was obtaining age estimates from pubic symphyses using the Suchey-Brooks scoring system. As a person ages the billowy ridges on the symphyseal face wear down.I also looked for evidence of trauma and pathology on any of the remains and some of the things present were a Schmorl’s node and osteoarthritic lipping on the vertebrae.

One of the highlights of my time in Berkeley was meeting the visiting researcher from Tennessee who was taking cranial measurements of an Inca collection using this cool laser technology. What was most fascinating for me was to see the trepanation in most of the crania and Dr. Boutin pointed out some that showed definite signs of healing and another that likely caused the individual’s death. It just amazes me that people survived those surgeries without modern technology and sterile medical practices.

Being chosen to help on the Dilmun Bioarchaeology Project gave me a boost of confidence in my professional abilities working with human remains. It gave me the drive to seek out other opportunities using the connections I have made since starting in anthropology and now I’m analyzing some human remains in Sacramento that are thousands of years old. I have started by creating a basic inventory of what bones are present. I have been invited back to continue over the summer and some things I would like to accomplish are taking measurements, documenting dentition to firm up the age estimation, and document any pathologies or injuries and possible causes of death.

Filed under: Bahrain, Skeletal, Student research

Status Report on Skeletal Analysis

During the Spring 2009 semester, the skeletal analysis team focused on creating a preliminary inventory of skeletal remains, with the aim of evaluating the collection’s research potential. So far, we have been able to estimate the minimum number of individuals (MNI) represented in the Cornwall collection, obtain a sense of the sample’s demography, health, and behavior, and track burial patterns (e.g., single vs. multiple interments, burial taphonomy). Continuing research will include finalization of the inventory, as well as confirmation and further exploration of demographic characteristics already noted for each skeleton.

Approximately 24 burial features are represented: one jar burial, two features in a “small cemetery locality,” and 21 tumuli. Only one tumulus has individuals represented from multiple cists (Tumulus B2). The remains of at least 32 individuals are present in the Cornwall collection (MNI=32). The vast majority of burial features appear to have been single interments (n=20), with three double burials, and two multiple burials. At least 13 of the burial features included faunal remains.

Inventory data have been used to estimate the completeness of the 32 skeletons, which conveys the possibilities and limitations of the Cornwall sample, based on preservation issues. Overall, 34.4% of the skeletons were mostly complete, 12.5% were fairly complete, and 53.1% were fragmentary.  Although the proportion of mostly complete skeletons may seem low, we observed further that the majority of these were very well preserved, i.e., major bones and diagnostic features were extant and intact. Preliminary estimates of sex revealed ten possible or probable males and six possible or probable females.  An age assessment of twenty-eight individuals revealed a majority of adults (n=20; 71.4%) with some older adolescents (n=3; 10.7%), children (n=2; 7.1%), and infants (n=3; 10.7%). Several pathologies are exhibited at high frequencies, including antemortem tooth loss, degenerative joint disease, and Schmorl’s nodes. A handful of seemingly isolated pathological conditions also require further study and research, as well as confirmation of diagnosis. These include a healed depressed fracture of the cranium, a traumatic injury to the medial epicondyle of the humerus, and a congenital growth defect.

Filed under: Bahrain, Skeletal, archaeology, Bahrain, Skeletal