Dental Anthropology

Measuring and testing the teeth of living primates could provide a window into the behavior of the earliest human ancestors, based on their fossilized remains. Research funded by the National Science Foundation and led by University of Arkansas anthropologist Michael Plavcan takes us one step closer to understanding the relationship between canine teeth, body size and the lives of primates.

In an article published in American Journal of Physical Anthropology, Plavcan and colleague Christopher B. Ruff of Johns Hopkins School of Medicine report on an initial examination of the function of the shape of canine teeth in primates. This is the first published comparative analysis of canine strength for primates.

Understanding more about the function of canine teeth can lead to new models for understanding human evolution. Plavcan has been studying primate teeth and skulls for 24 years and spent four years collecting dental data for this analysis.

The researchers compared the size, shape and strength of canine teeth from 144 primates with similar measurements taken from 45 carnivores. They examined the relationship of the size of primates’ canines to body size and the relative strength of the teeth. This comparison could help answer the speculation about the function of male primates’ canine teeth in the competition for females. Are the canines used as weapons or simply for display?

“The reason we wanted to use the carnivores is that we know carnivores use their canines for killing,” Plavcan said. “If primates’ canines are too weak to function as weapons, then they’re all just for show.”

Among anthropoid primates, it is well known that the canine teeth of males are up to four times as long as those of females. The researchers compared the canine teeth of male and female primates.

“If the male’s canines are stronger than the female’s canines that would imply there is sexual selection for strength and that the tooth is actually used as a weapon,” Plavcan said. “Female’s canines are short, and shorter, stubbier objects are harder to break. So, if the long, thin male canines are as strong or stronger than those of the female, that would also suggest they are capable of being used for fighting.”

The results were mixed in an interesting way.

“We found that the primate canines are generally as strong as or stronger than carnivore canines,” Plavcan said. “But they are not associated with any sort of estimate of sexual selection.”

Generally the canines of males and females were equally strong. Given that primates have such strong teeth in general, the researchers suggested a couple of possible explanations. It could be that all primate males have strong teeth because of a significant risk to reproductive success for any male who breaks a canine tooth. Or it could be that the strong teeth are due to basic inherited design.

Hominids – the primate family that produced humans – retain body mass sexual dimorphism; that is, males typically have a greater body mass size than females. At the same time, the difference in size in canine teeth between males and females is lost.

“This goes back to the earliest hominids,” Plavcan said. “In fact, one of the few diagnostic characteristics of hominid evolution is reduction in canine size dimorphism while maintaining strong body mass dimorphism.”

For example, gorillas have chunky teeth set in massive bodies. To have canines proportionately as long as other primates, a male gorilla’s canines would have to be 25 centimeters long, and the teeth at the base would then be too wide for his jaw.

“This suggests that there may be an upper limit on canine size in primates simply due to spatial constraints on fitting such teeth in the jaws,” the researchers wrote.

The difference in body size between male and female hominids has been the subject of study because it is an obvious and important trait. Yet there are drawbacks to using body size to understand sexual selection. A change in body size can impact many other aspects of life, including metabolism, feeding patterns and vulnerability to predators. Canine teeth, on the other hand, are a far simpler system.

“With canines, we can go in and effectively construct an experiment that allows us to control for all these other variables and look at only one thing,” Plavcan said. “The same phenomenon that works on the canines, we can translate into the body mass and then into behavioral models for the fossil record.”

Plavcan is an associate professor of anthropology in the J. William Fulbright College of Arts and Sciences at the University of Arkansas. He and Ruff are authors of “Canine Size, Shape, and Bending Strength in Primates and Carnivores” in the May issue of American Journal of Physical Anthropology.

No crystal skulls, no alien corpses were found. But the archaeological excavations in Boljoon town, south of Cebu, offer just as interesting—and more realistic—finds on Cebuano culture and tradition.

New discoveries have led to more questions, that need expert study, said Jose Eleazar “Jobers” Bersales, chairman of the Department of Sociology and Anthropology of the University of San Carlos.

Bersales reported the group’s findings in last Thursday’s lecture held at the Cebu Cathedral Museum that was also attended by Cebu Archbishop Ricardo Cardinal Vidal.

Bersales, an archeologist, said among those unearthed a few meters from the Patrocino de Maria Parish in Boljoon town south of Cebu province were 26 burials, antique ceramic dishes and jars, a necklace of precious stones and one large gold earring.

Even after three phases of excavations that began in February last year, they failed to find the original foundation of the centuries-old church. If found, it would help determine the actual date of the parish’s founding that had been debated by historians.

“Boljoon figures large in the defense against Islamic marauders,” he said on the significance of the parish in Cebuano history. The church was built in 1783 and was renovated during the time of paroko kapitan Julian Bermejo, one of only two priests given the title, Bersales said.

Archaeological finds

“We think this is a Christian burial site,” Bersales said. “Cebu was never Islamized.”

In a separate lecture on the skeletal remains, physical anthropologist and osteologist Bonn Vito Aure said the bones recovered on site were individually identified and sorted.

They determined the gender from the cranial (head) and pelvic forms. Age was determined through dental analysis of the wear and tear of the teeth.

Aure said there were two children—one aged three–three adolescents, seven young adults, seven middle adults and six old adults.

“Eighty percent of the individuals have caries (tooth decay), which indicates that they consumed a starch-rich diet. This means the people were already involved in agriculture,” he said.

Aure also noted the early use of toothpicks and the practice of tooth filing possibly for aesthetic purposes. But this needs further study since teeth filing in other Asian countries like Indonesia is functional to enable people to eat sago, a type of powdery starch.

Pre-Spanish Cebuanos in the town had osteomyelitis or bone infection which usually results from bacterial contamination, abscess or injury, based on the remains found.

Items 500 to 600 years old were dug up.

“This is the first time that gold was excavated,” the archeology professor noted. He cited one large tubular earring worn on the right ear of a male.

A similar sample, dated between the 14th and 16th century, is found in the Bangko Sentral ng Pilipinas Gold Collection.

There was also a necklace made from six carnelian gemstones, four red glass beads, six gold spacers and three gold pendants with carvings.

Other unearthed objects:

- Three ceramic dishes made during the time of Chinese Emperor Wan Li, the Zhangzhou period between 1573 and 1620

- two bowls from Anxi kiln in Fujian province in China produced between the 1590s and 1620s.

•A jar of the late Ming Dynasty (1590 and 1620)

Bersales said a similar artifact was recovered from the Dutch East Indies ship, Witte Leeuw, that sank in 1613 while on its way back to Holland.

•Five daggers and spears , some with fiber marks which could be abaca weave or sinamay.

In other excavation sites near the convent, experts unearthed bones of wild pigs and cows, piles of stones, small shells, broken pieces of ceramics and bronze Christian medallions.

Notable archeological facts

Males were also found buried with their hands clasped across their chests. The females were buried with their hands covering their genital area, said Bersales in a separate e-mail.

Two distinct burial positions were noted. Some skeletons showed the head facing the south or oriented north-south. Another group was buried with the head oriented east-west.

The bones did not indicate that those buried were fisherfolk. They were likely traders.

“We have not found net sinkers or shells lining the grave that would be normally expected from burials found near the shore or beach,” Bersales said.

“This is the first time in the history of archeology in the Philippines where the head is covered with two ceramic wares since recorded excavations began in the 1920s,” he added.

Carbon dating of four bone samples sent to to the University of Arizona revealed that the skeletal remains are between 340 and 500 years old.

PUBLIC INTEREST

In a message to lecture participants, Cardinal Vidal said the interest in treasures unearthed in Boljoon is “not only the concern of the academe and the Church. It is everybody’s concern.”

Some of the archaeological finds are on display at the Cebu Cathedral Museum.

“Museums are a source of national pride and national consciousness and it is important for the children to see what it is like to be part of their country,” said Vidal, who opened the exhibit.

Vidal said experts had managed to discover “details of ordinary life” of the Cebuanos’ ancestors.

Other questions have to be resolved, said Bersales, who admitted it would take more than a decade of research at a cost of more than P1 million for archaeologists to fully assess the items discovered in Boljoon.

“Is the area a settlement or a burial site? It could be both, but we found one unit was topsy turvy,” he said.

Bersales also said they have to determine whether the items were from the colonial or pre-colonial period or both.

“When did Boljoon enter the orbit of permanent Augustinian work?” he asked.

“Excavations on the entire are of the church complex are needed, the publication of this book and video production to support the documentation of the findings,” he said.

Source: CEBU Daiily News

(Reconstructing diets in human ancestors)

Dental microwear is the study of the microscopic scratches and pits that form on a tooth’s surface as the result of its use.

Much of the dental microwear research that has been conducted thus far has focused on humans and non-human primates. These can be used as models to reconstruct diets in human ancestors and other fossil primates. [Image: SEM micrograph for Gorilla gorilla wear facet.]

Source: Deptt of Anthropology - University of Arkansas, © Neogene Paleoecology Working Group

Some articles in the Dental Anthropology Journal

The Dental Anthropology Newsletter Volume 9, Number 2, 1995

* The Triform Variant: 1, Definition, Classification and Population Distribution- Shara E. Bailey
* The Matty Canyon Population: Dental Observations of Late Archaic Individuals from Southern Arizona- Lorrie Lincoln-Babb
* Milan Dokladá and a Tour of Brno in the Czech Republic- Charles Merbs
* Dental Anthropology (Book Review)- Korri Dee Turner
* On the Cope-Osborn Theory of Trituberculy (Poem)- Kathy Swindler

The Dental Anthropology Newsletter Volume 10, Number 2, 1996

* Presidential Address- Winter 1996 by John R. Lukacs
* Premolar Numbering and Agenesis in Primates by Gram P. Jones
* Stress Impact in Central Italy during the Iron Age: The Evidence of Linear Hypoplasia by Cucina, A. Coppa, and D. Mancinelli

The Dental Anthropology Newsletter Volume 10, Number 3, 1996

* Presidential Address- Phillip L. Walker
* Cro-Magnon and Qafzeh- Vive la Difference- C. Loring Brace
* An Unusual Etruscan Gold Dental Appliance from Poggio Gaiella, Italy: Fourth in a Series by Marshall Joseph Becker
* A New Look at Premolar Trait Variation: Maxillary Premolar Accessory Ridges (MxPar)- Scott E. Burnett

The Dental Anthropology Newsletter Volume 11, Number 1, 1996

* The Dental Anthropology Association World Wide Web Site- Phillip L. Walker
* Cervical Enamel Projections and Enamel Pearls in a Collection of Australian Extracted Molars- Dimitra Lekkas and Grant Townsend
* Abrasion of Teeth in Population Groups from Historical Periods in the Region of Former Yugoslavia- Dinka Mucic and Marija Duric-Srejic
* The Incidence of Torus Mandibularis in Malay Peoples
* An Unusual Maxillary Molar from Prehistoric New Mexico- Marsha D. Ogilvie

Dental Anthropology Volume 12, Number 1, 1997

* A Strategy for Comparing Odontometrics among Groups- Edward F. Harris
* Research World: Foreign Correspondent Occasional Reports 1 Russia- Christy G. Turner II
* Dental Analysis and Determination of Occupational Activities of a Peruvian Formative Population- Gretchen A. Nelson
* Dahlberg Scholarship Established at the University of Toronto- John Mayhall

Dental Anthropology Volume 12, Numbers 2-3, 1998

* An Odontometric Investigation of the Affinities of the Nazlet Khater Specimen to Prehistoric, Protohistoric and Modem African Origins. Ron Pinhasi
* Another Talon Cusp: What does it mean? Christy G. Turner II
* Dental Anthropology at the University of California, Santa Barbara-C.M. Kellner
* The Anthropology of Modern Human Teeth: Dental Morphology and its Variants in Recent Human Populations.-C. Loring Brace

Dental Anthropology Volume 13, Numher 1, 1998

* Loss Of Lingual Enamel in Lower Incisors of Papionini. David G. Gantt, Christopher P. Strickland, And John A. Rafter
* Dental Health and Diet of Two Prehistoric Populations from Chile’s Semi-Arid North. Maria Araya Rosado
* A Unilateral Connate Incisor from a Ca. 2,000 Year Old Mandible from the Middle Columbia River Plateau. Guy L. Tasa
* Premolar Double Teeth In A Group Of Irish Orthodontic Referrals. C.M. Mcnamara, O. Cooney, M, O’sullivan, And T.G. McNamara
* Analysis Of The Optical Properties Of Medieval Enamel. Ljiljana Tilhacek-Sojic and Marija Djuric-Srejic
* Dental Anthropology at the University Of Oregon. Guy L. Tasa And Debbie Guatelli-Steinberg
* Japanese, Dental Anthropology Association. John Mayhall

Dental Anthropology Volume 13, Number 2,1999

* Crown Diameters of Deciduous Teeth in Jordan. F. M. Hattab, A.S. Al-Momani, O. M. Yassin, M. A. O. Al-Omari, A.N. Hamasha, M.A. Rawashden, and A. Tavas.
* A Brief Comment on an Intentionally Modified Tooth from the Rio Talgua Region in Northeastern Honduras. Nicholas P. Herrmann, Derek C. Benedix, Ann M. Scott, and Vaileri Haskins
* Dental Anthropology at the Hebrew University - Jerusalem, Israel. Rebecca Haydenblit
* 11th International Symposium On Dental Morphology in Oulu, Finland. Edward F. Harris.

Dental Anthropology Volume 13, Number 3, 1999

* Corono-Radicular Grooves in a Large Sample of Human Maxillary Incisors. Sarbim Ranjitkar, Janet Fuss, Dimitra Lekkas and Grant Townsend
* Dental Anthropology of the Neolithic Russian Far East: I Eurasian Russia. A. M. Haeussler
* Dental Anthropology at Arizona State University. Alma J. Adler.
*  Report from the Editor of Dental Anthropology. A. M. Haeussler

Dental Anthropology — by Simon Hillson;

Dental Anthropology : Fundamentals, Limits and Prospects — by Kurt W. Alt (Editor), et al;

Dental Anthropology: Application and Methods — by V. Rami Reddy (Editor)

Advances in Dental Anthropology by Marc A. Kelley, Clark Spencer Larsen (Editor)

The human masticatory apparatus: An introduction to dental anthropology by Meyer Klatsky

Dental anthropology of the Libben Site, Ottawa County, Ohio (Kent State University. Graduate School. Master’s Theses ; Department of Anthropology and Sociology) by Thomas R Przybeck

A guide to the literature on the dental anthropology of post Pleistocene man (Toledo Area Aboriginal Research Club bulletin : Supplementary monograph ; no. 1) by Seamus P Metress.

The Anthropology of Modern Human Teeth : Dental Morphology and its Variation in Recent Human Populations (Cambridge Studies in Biological and Evolutionary Anthropology) by G. Richard Scott, Christy G. Turner II.

Aspects of dental biology: Palaeontology, anthropology, and evolution (Leonardo series)

Butler, P. M. (1963) Tooth morphology and primate evolution,In: Dental Anthropology, Vol. V, Symposium of the Society for the Study of Human Biology, (ed. D. Brothwell),Macmillan Co., New York,

Carbonell, V. M. (1963): Variations in the frequency of shovel-shaped incisors in different populations. D. R. Brothwell(ed.), Dental Anthropology, pp. 211-234, Pergomon Press.

Apical—the surfaces of a tooth that face towards the apex of the roots

Buccal—the surface of canines, premolars and molars facing the cheeks

Cervix—the meeting point of the crown and root (the CEJ-cement-enamel junction)

Cingulum—broad bulge girdling the cervical one-third of the crown

Contact area—area of contact between two teeth where the mesial and distal surfaces of adjacent teeth abut

Crest—large ridges descending from the apices of cusps or connecting two cusps

Crown—the part of the tooth that projects into the mouth;  coated with enamel

Cusp—pyramidal or cone shaped elevation on the occlusal surface of a tooth with three to four ridges or crests descending from its apex

Cuspid—elevation smaller than a cusp

Cuspule—elevation smaller than a cuspule

Dentine—the tissue that forms the core of the whole tooth

Distal—the surface of all teeth that faces along the dental arcade away from the median sagittal plane

Enamel—the hard coating covering the crown of the tooth

Fissure—a fault resulting from the imperfect joining of two cusps or lobes

Fossa—round depression

Groove—linear, trough-like depression between cusps

Incisal—the cutting edge of incisors and canines (equivalent to occlusal in the teeth that overlap during normal occlusion

Labial—the surfaces of incisors facing the lips

Lingual—the surface of all teeth that faces the tongue

Lobe—large, rounded projections on occlusal surface

Mammelons—rounded prominence (on incisal margins when they first erupt)

Mesial—the surface of all teeth that faces along the dental arcade towards the median sagittal plane

Occlusal—the surface of all teeth that parallels the plane in which upper and lower dentitions meet.  In particular, it is used to describe the surface of premolars and molars that meets in normal occlusion

Pit—small circular, tightly defined depression on crown

Pulp—the living tissue of the tooth

Ridge—similar to crests, but smaller and less sharply defined

Root—the part of the tooth embedded in the jaws;  coated with cement

Tubercle—small, rounded prominence on surface of tooth

Wear facet—flat, polished surface created by habitual contact between teeth