Symposia of the Society for the Study of Human Biology, Volume V: Dental
Anthropology is a collection of papers that covers the application of dental pathology in the
context of anthropology. The book presents 15 studies that cover various human dental
variables and relates to different anthropological factors. The dental variables considered in
the articles include tooth morphology; occlusion and malocclusion of primate teeth;
morphogenesis of deciduous molar pattern in man; and double-rooted human lower canine
teeth. The text also covers topics about race specific dental traits such as radiographic study
of the Neanderthal teeth from Krapina; crown characters of the deciduous dentition of the
Japanese-American hybrids; and analysis of the American Indian dentition. The selection will
be of great interest to evolutionary scientists, such as anthropologists and paleontologists.
Dr. Heena Dixit Tiwari
Dr. Sneha Thakur
Dr. Asfar Zeya
Dr. Heena Dixit Tiwari, BDS, PGDHHM, MPH
Dr. Heena Dixit Tiwari is a Dental Surgeon & Scientific Writer with 7 years of
experience. She is from Raipur, Chhattisgarh where she completed her schooling. Further she
completed Bachelor of Dental Surgery from Rungta College of Dental Science & Research,
Bhilai, Chhattisgarh. Then Post Grdautae Diploma in Health Care and Hospital Management
from Disha Buisness School, Disha Institutes, Raipur, Chhattisgarh. She is also pursuing
Masters in Public Health from Parul Univeristy, Gujarat. She has work experiences in Dental
Clinics & Corporate Hospitals. She is a Scientific Writer for Writing Assistance with more
than 125 National & International Indexed Publications. She is also Reviewer for Indexed
Journals. She is author of 3 Professional Books published worldwide. She is a Life Member
of Indian Dental Association.
Dr Sneha Thakur, BDS, MDS
Dr Sneha Thakur Is a Dentist And Orthodontics Practicing In The State Of Jharkhand
For The Past 10 Years. She Was Born At Ranchi Jharkhand And Finished Schooling From
There. She Finished Her Under Graduation From Saveetha Dental College Chennai And
Persuaded Her Post Graduation At Hazaribagh College Of Dental Sciences Jharkhand. She
Was a Meritorious Student As An Undergraduate And Has a Distinctions To Her Name
Including a Gold Medal In Conservative Dentistry. Even As An Undergraduate She Had a
Keen Interest In Scientific Research And Has Paper Presentations At National And State
Level To Her Credit. She Has Won Best Paper For Four Of Them Apart From The World Of
Dentistry. She Is a Professional Photographer Voracious Reader And Avid Traveller.
Dr. Asfar Zeya, BDS, MDS
Dr. Asfar Zeya is a Dentist and an Oral and Maxillofacial Surgeon from Bathinda,
Punjab. He completed Bachelor of Dental Surgery from Kalinga Institute of Dental
Sciences, Bhubaneshwar, Odhisa. After graduation, he joined as a Junior resident in the
Dept. of Oral and Maxillofacial Surgery in Adesh Institute of Dental Sciences and Research
for a period of 14 months. Further he completed Masters of Dental Surgery in Oral and
Maxillofacial Surgery from Christian Dental College, Ludhiana, Punjab and achieved 3rd
rank in the college. After post graduation , he worked as an emergency medical officer
Covid -19 tertiary centers in Ludhiana and particularly in Christian Medical College and
Hospital, Ludhiana. He has a work experience in various Medical college, Dental college
and Corporate Hospitals. He is a life member of Association of Oral and Maxillofacial
Surgeons of India and Indian Dental Association .
1. DENTAL ANTHROPOLOGY — AN INTRODUCTION ......................................................... 2
2. THE HISTORY OF DENTAL ANTHROPOLOGY................................................................... 6
3. THE HUMAN DENTITION- TOOTH CLASSES ................................................................... 24
4. THE MASTICATORY SYSTEM AND ITS FUNCTION........................................................ 41
5. AN OVERVIEW OF DENTAL GENETICS............................................................................ 59
6. TOOTH CLASSES, FIELD CONCEPTS, AND SYMMETRY................................................ 75
7. DENTAL MORPHOMETRIC VARIATION IN POPULATIONS........................................... 97
8. ASSESSING DENTAL NONMETRIC VARIATION AMONG POPULATIONS ................. 122
9. FORENSIC ODONTOLOGY................................................................................................ 135
10. ESTIMATING AGE, SEX, AND INDIVIDUAL ID FROM TEETH ..................................... 153
11. THE FUTURE OF DENTAL ANTHROPOLOGY................................................................. 173
1. DENTAL ANTHROPOLOGY — AN INTRODUCTION
Dental Anthropology provides an excellent view into biological, ecological and cultural
aspects which help to detect and understand individuality, human behavior, living conditions,
and environments. Teeth are used to separate fossil hominids, demonstrate trends in hominid
dentition, reflect individual and group patterns of demography, biological relationships in the
context of affinity and kinship, aspects of diet and cultural adaptation, and supply information
on dental health, art, cult, and custom in fossil and archeological series. In forensic
odontology and anthropology, they permit the identification of unknown bodies in the context
of mass disasters, and the evaluation of bitemarks in corpse or objects.
Teeth and jawbones are used to address questions in numerous disciplines including
paleoanthropology, paleontology, prehistoric anthropology, archeology, dentistry,
comparative anatomy, genetics, embryology, and forensic medicine. Which are the main
advantages of dental remains to make them an object of study in so many disciplines? Jaws
and teeth are more durable compared to skeletal remains (less post-mortem decomposition,
best represented part of skeleton, record of fossil species, past and recent population), they
possess a high degree of morphological individuality representing personal, familial, and
population characteristics, and they can be directly observed and evaluated in both living and
past populations. Furthermore, because of their high heritability they are useful in assessing
evolutionary and population origins, developments and dynamics, they reflect dietary and
cultural behavior and environmental effects. And finally, the non-genetic characteristics of
teeth such as wear and disease make them well suited for research of dietary adaptations,
regional variation in disease manifestations, epidemiological status and others. Dental
anthropology makes ample use of this research potential. This discipline has a unique holistic
view of teeth, striving to place them in every possible context.
One objective of Dental Anthropology is the reconstruction of the phylo- genetics of humans
and primates. Our understanding of primate evolution is ultimately based on patterns of
phyletic relationships and morphological change in the fossil record. In this field, teeth are a
prime source of information (“key structures”) to reconstruct the form and life history of
early hominids, to understanding biological adaptation and patterns in human evolutionary
ecology. If, as is frequently the case, only teeth have survived, taxa are defined as dental
species. New analytical developments and conceptual advances — especially in dental
anthropology — have produced an enormous number of new answers to the main questions
of paleoanthropology, i.e. the relationships of the hominoids and the split of the hominid
lineage from those of other primates, the morphological changes in the hominid phylogeny,
the ecological niches of the fossil hominids, and finally the interrelationships of the various
fossil species. In this research sector, comparative anatomical, macroscopic, microscopic,
phylogenetic, bio- chemical, molecular, and ecological methods and results dominate.
Another objective of Dental Anthropology is the biological reconstruction of early
populations (prehistoric anthropology), using the ontogenetic and populational variability of
teeth. In this field, teeth are decisive for understanding biological developments and
dynamics as well as cultural and economic processes. The teeth of our ancestors are useful
for the reconstruction of life history by demographic parameters (estimation of age and sex),
morphological (anatomical) variants, individual features, nutritional patterns, origin and
population history, identification of familial relationships (for reconstructing social structures
in past populations), accidental and intentional cultural behaviour (artificial dental
modifications), and dental diseases. Apart from classical methods in this field, many
innovative techniques such as extraction of ancient DNA (aDNA), trace element and stable
isotope analyses are used in this context. Three applications of aDNA analysis are of interest:
access to genetic information at the individual, at the infrapopulation, and at the
interpopulation level. Trace element and stable isotope analysis is helpful in the detection of
subsistence strategies, endogamy versus exogamy, migration, social differentiation,
ontogenetic trends, toxic accumulation of elements such as Pb or As, and paleopathological
Finally there is the forensic objective of Dental Anthropology. In forensic medicine teeth play
an essential role in the personal identification of unknown bodies, of victims of crimes and
natural or civil mass disasters, and in cases of individuals in mass graves, victims of armed
conflict or of political terror. This objective, however, rather forms a discipline of its own,
forensic odontology. Apart from routine analyses, dental findings are used in investigations
concerning estimation of least number of individuals, population or ancestry of the
individuals, reconstruction of nutritional status and health history, occupational markers or
features caused by habitual activities, trauma, or other lifetime events. In case of isolated
parts of bodies or skeletons, death by fire etc., oral findings are often the only evidence for
the identity of the victim. In addition to the number and distribution of teeth, restorations,
dentures, congenital anomalies and other dental characteristics may aid the identification. In
forensic medicine, teeth, like (DNA) fingerprints, are individual, but as they resist the ravages
of time far better than other parts of the body, they represent an unsurpassed record of the
This spectrum of research objectives shows on the one hand that dental anthropology is
mainly rooted in the framework of biology, and on the other that Dental Anthropology forms
a strong bridge to paleontology, dentistry, genetics, ontogenetics, and to the humanities.
Generally the results of dental anthropology may be incorporated into the body of knowledge
of more than one science.
These considerations lead to the concept of this volume, which was initially formed some
years ago. Starting with aspects of Teeth in History, the book continues with chapters on
Dental Morpholog y, Structure, and Evolution, Dental Patholog y and Epidemiology, on teeth
in the context of Nutrition and Human Behaviour, Age and Sex Estimation by dental
parameters; and Geographical and Familial Tooth Variation. The 33 authors of the 26
contributions are specialists in many fields: dental anthropology, paleoanthropology,
prehistoric anthropology, molecular anthropology, paleopathology, forensic odontology,
forensic anthro- pology, archeology, anatomy, embryology, history of medicine, dentistry,
Consequently most aspects of the book are new, particularly the syntheses. This is now a
volume which provides an introduction to the field as well as a reference both for specialists
and students in anthropology, paleontology, ecology, dentistry, and the cultural sciences. The
basic literature and experience is of a broad international origin and not limited to English
language sources only. Moreover, the book can also contribute to further research on selected
topics of the field. Numerous illustrations and tables help to clarify the statements given in
2. THE HISTORY OF DENTAL ANTHROPOLOGY
Among the diverse tasks of the human dentition, the uptake and crushing of food is
doubtlessly the most characteristic. The English Victorian naturalist Richard Owen (1804-
1892) underscored the importance of this function in the introduction to his classic treatise
Odontography (1840—1845): “Teeth are firm substances attached to the parities of the
beginning of the alimentary canal, adapted for seizing, lacerating, dividing and triturating the
food, and are the chief agents in the mechanical part of digestive function”. This function,
however, did not emerge until a late phase of evolution. Before that time, primitive, tooth-like
structures or elements such as gill traps had facilitated food uptake (Gutmann 1997). Other
utilizations of the teeth are secondary, for instance the use of teeth as weapon or tool, as a
structure for the characterization of age and sex, or as ornamental objects (Kanner and Remy
1924; Alt et al. 1990; Kelley and Larsen 1991; Alt and Pichler, this volume). Additionally,
among humans teeth have great significance for vocal articulation (Schumacher et al. 1990)
and for the esthetics of the appearance (Alt 1994b).
Teeth and jaws usually abound among paleontological and archeological finds because of
their resistance to postmortal influences. As a consequence, many phylogenetic concepts are
based solely on the interpretation of tooth forms (Maier 1978). Since after completion of
amelogenesis tooth crowns do not undergo further changes (except pathological [e.g., caries],
and age-dependent processes [e.g., attrition]), teeth play an important role for comparative
anatomical investigations and for the reconstruction of phylogenetic mechanisms in the
evolution of mammals: “Tooth form varies with taxonomy and phylogeny and so can be used
to reconstruct evolutionary patterns” (Foley and Cruwys 1986, 1). Teeth have therefore
become “index fossils” in paleontology, paleozoology, and paleo anthropology (Hillson
1986; Thenius 1989; Henke and Rothe 1994; Alt and Turp 1997a). In addition, teeth provide
valuable information about environmental parameters and diet as well as answers to
biostratigraphic questions (Kay 1978; Maier 1984). ( Fig. 1.)
Fig. 1. Spectrum of scientific disciplines related to Dental Anthropology.
Teeth and dentition are today the focus of specific investigations in anthropology,
archeology, zoology, and other fields of the natural sciences and medicine (Fig. 1). In recent
decades, dental anthropology has had a great impact on phylogenetic research in
paleoanthropology and has contributed to advances in related disciplines such as primatology,
osteology, and population biology. Yet dental anthropology is not only useful for the
exploration of the past, but it also influences clinical basic research. For example, the
recognition of evolutionary trends, such as the size reduction of teeth and jaws, has important
implications for clinical dentistry.
Odontology, the precursor of dental anthropology, was the classical scientific discipline
dealing with fundamental questions about the development and structure of teeth (Peyer
1968; Wurtz 1985; Alt and Turp 1997a). During the 20th century, the interdisciplinary
significance of odontology increased as innovative methods were introduced. This process
was closely linked to concepts and developments in other scientific disciplines, such as
comparative anatomy, zoology, paleontology, embryology, and physiology, and it was
influenced by rapid advances in general and population genetics (cf. Vogel and Motulsky
199d). At the same time, methods derived from biomechanics, biochemistry, and statistics, as
well as technical procedures, such as the identification of microscopical structures, provided
valuable impulses for basic research in odontology.
In the 1960s, odontology became incorporated in the rapidly developing discipline of dental
anthropology. With few exceptions (e.g., in “forensic odontology”), the term “odontology”
has been completely replaced by “dental anthropology” (Brothwell 1963; Scott and Turner
1988). Today, dental anthropology is an important subdiscipline of physical anthropology. It
interdisciplinarily combines all those fields outside clinical dentistry which are concerned
with odontological questions. The historical development of dental anthropology, however,
has only recently become a subject of interest (Foley and Cruwys 1986; Scott and Turner
1988; Dahlberg 1991; Alt 1997 b, c).
Alt KW (1994a) Prothetics, periodontal therapy and conservative dentistry in the eighteenth
century. Bull Hist Dent 42: 67-70.
Alt KW (1994b) Die historische Entwicklung der zahniirztlichen Prothetik. In: Strub JR,
Ttirp JC, Witkowski SWJ, Htirzeler MB, Kern M (Hrsg) Curriculum Prothetik, Bd. 1.
Quintessenz, Berlin, p. 37-61.
Alt KW (1997a) Odontologische Verwandtschaftsanalyse. Individuelle Charakteristika der
Ziihne in ihrer Bedeutung flir Anthropologie, Archiiologie und Rechtsmedizin. Fischer,
Alt KW (1997b) Kategorien und Konzepte dentalanthropologischer Studien. In: Alt KW,
Ttirp JC (eds) Die Evolution der Ziihne. Phylogenie - Ontogenie - Variation. Quintessenz,
Berlin, p. 679-687.
Alt KW (l997c) Die historische Entwicklung der Odontologie und Dental-Anthropologie.
In: Alt KW, Ttirp JC (eds) Die Evolution der Ziihne. Phylogenie - Onto genie - Variation.
Quintessenz, Berlin, p. 47-76.
Alt KW, Ko~kapan C (1993) Artificial tooth-neck grooving in living and prehistoric
population. Homo 44: 5-29.
AIt KW, Parsche F, Pahl MW, Ziegelmayer G (1990) GebiBdeformation als Korperschmuck
- Verbreitung, Motive und Hintergrtinde. Zahniirztl Mitt 80: 2448-2456.
Alt KW, Ttirp JC (eds) (1997a) Die Evolution der Ziihne. Phylogenie - Ontogenie -
Variation. Quintessenz, Berlin.
Alt KW, Ttirp JC (1997b) Vergleichende Odontologie und Dental-Anthropologie. Bedeutung
- Positionen - Strategien. In: Alt KW, Ttirp JC (eds) Die Evolution der Ziihne.
Phylogenie - Ontogenie - Variation. Quintessenz, Berlin, p. 31-46.
AIt KW, Vach W (1991) The reconstruction of genetic kinship in prehistoric burial
- problems and statistics. In: Bock HH, Ihm P (eds) Classification, Data Analysis, and
Knowledge Organisation. Springer, Berlin Heidelberg New York, p. 299-310.
Alt KW, Vach W (1995) Odontologic kinship analysis in skeletal remains - Concepts,
methods, and results. Forensic Sci Int 74: 99-113.
Bailey SE (1996) Minutes from the 1996 Annual Meeting of the Dental Anthropology
Association (DAA), Raleigh-Durham, April 11, 1996. Report from the SecretaryTresurer.
Dent Anthrop Newsl 10 (3), 20-21.
Baume R (1882) Odontologische Forschungen I. Versuch einer Entwicklungsgeschichte des
Gebisses. Felix, Leipzig. .
Berkovitz BKB, Holland GR, Moxham BJ (1978) A Colour Atlas and Textbook of Oral
Anatomy. Wolfe, London.
Berkovitz BKB, Holland GR, Moxham BJ (1992) Color Atlas and Text of Oral Anatomy,
Histology, and Embryology. Mosby, St. Louis.
Bolk L (1913) Die Ontogenie der Primatenziihne. Fischer, J ena.
Bolk L (1914) Die Morphogenie der Primatenziihne. Fischer, Jena.
Bourdelle E, Bennejeant C, Wicart A (1937) Anatomie et physiologie bucco-dentaires.
Anatomie Dentaire Comparee. Bailliere, Paris.
Boyde A (1964) The Structure and Development of Mammalian Enamel. Phil Thesis,
Boyde A, Martin L (1984) The microstructure of primate dental enamel. In: Chivers DJ,
Wood BA, Bilsborough A (eds) Food Aquisition and Processing in Primates. Plenum
Press, New York, p. 341-368.
Brabant H (1965) Observations sur l' evolution de la denture temporaire humaine en Europe
occidentale. Bull Group Int Rech Sc Stomat 8: 235-302.
Brabant H (1967) Comparison on the characteristics and anomalies of the deciduous and
the permanent dentition. J Dent Res 46: Suppl 5, 897-902.
Brabant H, Klees L, Werelds RJ (1958) Anomalies, Mutilations et Tumeurs des Dents
Humaines. Prelat, Paris.
Brabant H, Twiesselmann F (1964) Observations sur l' evolution de la denture permanente
humaine en Europe occidentale. Bull Group Int Rech Sc Stomat 7: 11-84.
Brace CL (1979) Krapina, "classic" Neanderthals, and the evolution of the European face.
J Hum Evol8: 527-550.
Brace CL (1995) Trends in the evolution of human tooth size. In: Moggi-Cecchi J (ed)
Aspects of Dental Biology: Palaeontology, Anthropology and Evolution. Istituto di
Anthropologia, Florence, p. 437-446.
Brace CL, Rosenberg KR, Hunt KD (1987) Gradual change in human tooth size in the late
Pleistocene and post-Pleistocene. Evolution 41: 705-720.
Brace CL, Smith SL, Hunt KD (1991) What big teeth you had Grandma! Human tooth size,
past and present. In: Kelley MA, Larsen CS (eds) Advances in Dental Anthropology.
Wiley-Liss, New York, p. 33-57.
Broca P (1879) Instructions relatives a l'etude anthropologique du systeme dentaire. Bull
Soc Anthrop Paris 2: 128-163.
Brothwell DR (ed) (1963) Dental Anthropology. Pergamon Press, Oxford.
Brothwell DR (ed) (1990) Dental Anthropology. Macmillan, New York.
Brown T, Molnar S (eds) (1992) Craniofacial Variation in Pacific Populations. Univ Press,
Butler PM (1941) A theory of the evolution of mammalian molar teeth. Am J Sci 239:
Butler PM (1978) Molar cusp nomenclature and homology. In: Butler PM, Joysey KA(eds)
Development, Function and Evolution of Teeth. Academic Press, London.
Butler PM, Joysey KA (eds) (1978) Development, Function, and Evolution of Teeth.
Academic Press, London.
Campbell TD (1925) Dentition and Palate of the Australian Aborigines. Hassell Press,
Carlsen 0 (1987) Dental Morphology. Munksgaard, Copenhagen.
Cole S (1949) A History of Comparative Anatomy. From Aristotle to the Eighteenth Century.
Colyer JF, Sprawson E (1938) Dental Surgery and Pathology. Longmans-Green, London.
Cope ED (1874) On the homologies and origin of the types of molar teeth of mammalia
Educabilia. J Acad Nat Sci Philadelphia NS 8, Pt I: 71-89.
Cope ED (1883) Note on the trituberculate type of superior molar and the origin of the
quadrituberculate. Am Naturalist 17: 407-408.
Covert HH, Kay RF (1981) Dental microwear and diet: Implications for determining the
feeding behaviours of extinct primates, with a comment on the dietary pattern of
Sivapithecus. Am J Phys Anthrop 55: 331-336.
Crompton AW, Hiemae K (1970) Molar occlusion and mandibular movements during
occlusion in the American oppossum, Didelphis marsupialis L. Zool J Linn Soc 49:
Cruwys E, Foley R (eds) (1986) Teeth and Anthropology. BAR Int Ser 291, London.
Cuvier G (1835-1846) Lec;;ons d' Anatomie Comparee de Georges Cuvier. Crochard,
Daegling DJ, Ravosa MJ, Johnson KR, Hylander WL (1992) Influence of teeth, alveoli, and
periodontal ligaments on torsional rigidity in human mandibles. Am J Phys Anthrop 89:
Dahlberg AA (1945) The changing dentition of man. Am J Phys Anthrop 8: 15-25.
Dahlberg AA (1951) The dentition of the American Indian. In: Laughlin WS (ed) The
Physical Anthropology of the American Indian. Viking Fund, New York, p. 138-176.
Dahlberg AA (ed) (1967) Proceedings on the International Symposium on Dental
Morphology. J Dent Res 46: 769-992.
Dahlberg AA (ed) (1971) Dental Morphology and Evolution. Univ Press, Chicago.
Dahlberg AA (1991) Historical perspective of dental anthropology. In: Kelley MA, Larsen
CS (eds) Advances in Dental Anthropology. Wiley-Liss, New York.
Dahlberg AA, Graber TM (eds) (1977) Orofacial Growth and Development. Hague, Mouton.
Dempsey PJ, Townsend GC, Martin NG, Neale MC (1995) Genetic covariance structure of
incisor crown size in twins. J Dent Res 74: 1389-1398.
Dependorf T (1898) Zur Entwicklungsgeschichte des Zahnsystems der Marsupialia.
Denkschr Med Naturwiss Ges Jena, Bd. 6, Jena.
Ebner V von (1890/91) Histologie der Zahne mit EinschluB der Histogenese. In: Scheff's
Handbuch fUr Zahnheilkunde. Bd. 1. HOlder, Wien, p. 209-262.
Eidmann H (1923) Die Entwicklungsgeschichte der Zahne des Menschen. Meusser, Berlin.
Euler H (1939) Die Anomalien, Fehlbildungen und Verstiimmelungen der menschlichen
Foley R, Cruwys E (1986) Dental anthropology: Problems and perspectives. In: Cruwys E,
Foley R (eds) Teeth and Anthropology. BAR Int Ser 291, London, p. 1-20.
Frankel M (1835) De penetori dentium humaniorum structure observationes (Beobachtungen
tiber die innere Struktur der Zahne). Nat Diss, PreBburg.
Frayer DW (1978) The Evolution of the Dentition in Upper Paleolithic and Mesolithic
Europe. Lawrence, Kansas.
Friant M (1933) Contribution a l'etude de la differenciation des dents jugale chez 1es
mammiferes. Publ Mus Natn Hist Nat Paris 1: 1-132.
Frisch JE (1965) Trends in the Evolution of the Hominoid Dentition. Bibliotheca
Primatologica, Fasc 3. Karger, Basel.
Gantt DG (1977) Enamel of Primate Teeth: Its Thickness and Structure with Reference to
Functional and Phyletic Implications. PhD Thesis, St Louis.
Gam SM (1977) Genetics of dental development. In: McNamara JA (ed) The Biology of
Occlusal Development. Center for Human Growth and Development, Ann Arbor, p.
Gidley J (1906) Evidence bearing on tooth-cusp development. Proc Wash Acad Sci 8:
Giebel CG (1855) Odontographie. Vergleichende Darstellung des Zahnsystems der lebenden
und fossilen Wirbeltiere. Abel, Leipzig.
Goose DH (1971) The inheritance of tooth size in British families. In: Dahlberg AA (ed)
Dental Morphology and Evolution. Univ Press, Chicago, p. 144-149.
Gregory WK (1916) Studies in the evolution of primates. Bull Am Mus Nat Hist 35:
Gregory WK (1922) The Origin and Evolution of the Human Dentition. Williams and
Guerini V (1909) History of Dentistry. Lea and Febinger, Philadelphia.
Gutmann W (1997) Chordaten-Konstruktionen und ihre Evolution. Von der Kiemenreuse
zum zahnbesetzten Kieferapparat. In: Alt KW, Ttirp JC (eds) Die Evolution der Zahne.
Phylogenie - Ontogenie - Variation. Quintessenz, Berlin, p. 363-390.
2.2 The History of Dental Anthropology 33
Haeussler A (1985) Dental Morphology of New World, Eastern Siberia, and Soviet Central
Asia Population. MA Thesis, Tempe AR.
Haeussler A, Turner CG (1992) The dentition of Central Asia and the quest for New World
ancestors. In: Lukacs JR (ed) Culture, Ecology, and Dental Anthropology. J Hum Evol
Special Issue 2: 273-297.
Hellman M (1928) Racial characters in human dentitions. Proc Am Philos Soc 67: 157-174.
Helmcke HJ (1953) Atlas des menschlichen Zahnes im eiektronenmikroskopischen Bild.
Henke W, Rothe H (1994) Palaanthropologie. Springer, Berlin Heidelberg New York.
Hertwig 0 (1874) Uber Bau und Entwicklung der Placoidschuppen und der Zahne der
Selachier. Z Naturwiss (Jena) 8: 331-404.
Heymer A (1986) Oko-physiologische Zahnabrasion bei den Bayaka-Pygmaen in
Zentralafrika. Curare 9: 51-58.
Hillson S (1986) Teeth. Cambridge Univ Press, Cambridge.
Hillson S (1996) Dental Anthropology. Cambridge Univ Press, Cambridge.
Hoffmann-Axthelm W (1985) The History of Dentistry. Quintessence, Chicago.
Hollander GA (1992) Dental anthropology: A view into biological and cultural factors. PhD
Hrdlicka A (1911) Human dentition and teeth from evolutionary and racial standpoint.
Dominion Dent J 23: 403-421.
Hrdlicka A (1920) Shovel-shaped teeth. Am J Phys Anthrop 3: 429-465
Hrdlicka A (1921) Further studies of tooth morphology. Am J Phys Anthrop 4: 141-176.
Hunter J (1771) The Natural History of Teeth. London.
Huxley TH (1853) On the development of the teeth and on the nature and importance of
Nasmyths "persistent capsule". Quart J Micr Sci 1: 149-164.
Hylander WI, Johnson KR (1994) Jaw muscle function and wishboning of the mandible
during mastication in macaques and baboons. Am J Phys Anthrop 94: 523-547.
Hylander WL, Mayhall JT (1996) In memoriam AlbertA. Dahlberg (1908-1993). Am J Phys
Anthrop 99: 627-633.
Irish JD (1993) Biological Affinities of Late Pleistocene Through Modem African
Aboriginal Population. The Dental Evidence. PhD Diss, Tempe AR.
Is~an MY (1989) The emergence of Dental Anthropology. Am J Phys Anthrop 78: 1.
Is~an MY (ed) (1989) Current directions in Dental Anthropology Symposium. Am J Phys
Anthrop. 78: 1-122.
Janis CM (1979) Aspects of the Evolution of Herbivory in Ungulate Mammals. PhD Thesis,
Janis CM (1988) An estimation of tooth volume and hypsodonty indices in ungulate
mammals and the correlation of these factors with dietary preference. In: Russell DE,
Santoro JP, Sigogneua-Russell D (eds) Teeth revisited. Mem Mus Natn Hist Nat C 53,
de Jonge T (1917) Die Kronenstruktur der unteren Pramolaren und Molaren. Ein Beitrag
zur Morphologie des menschlichen Gebisses. Med Diss, Zurich.
de Jonge TE (1926) Die Dimerie der Frontziihne. Z Ges Anat Z Anat Entwickl Gesch 78:
Kanner L (1928) Folklore of the Teeth. MacMillan, New York.
Kanner L, Remy CE (1924) Die Verwendung der Zahne auBerhalb des Mundes bei den
verschiedenen VOikern. Dtsch Mschr Zahnheilk 42: 573-578.
Kay RF (1973) Mastication, Molar Tooth Structure and Diet in Primates. Phil Diss, Yale
Kay RF (1978) Molar structure and diet in extant Cercopithecidae. In: Butler PM, Joysey
KA (eds) Development, Function, and Evolution of Teeth. Academic Press, London, p.
Keeler CE (1935) Heredity in dentistry. Dent Cosmos 77: 1147-1163.
Keil A (1966) Grundztige der Odontologie. Borntraeger, Berlin.
K. W. Alt et al.
Kelley MA, Larsen CS (eds) (1991) Advances in Dental Anthropology. Wiley-Liss, New
Kieser JA (1990) Human Adult Odontometrics. Univ Press, Cambridge.
King R (1994) John Hunter and the natural history of the human teeth: dentistry, digestion,
and the living principle. J Hist Med Allied Sci 49: 504-520.
Klatsky M, Fisher RL (1953) The Human Masticatory Apparatus: An Introduction to Dental
Anthropology. Dental Items of Interest Publ, Brooklyn.
Koenigswald W von, Martin T, Pfretzschner HU (1993) Phylogenetic interpretation of
enamal structures in mammal teeth: possibilities and problems. In: Szalay S, Novacek
MJ, McKenna MC (eds) Mammal Phylogeny. Springer, Berlin Heidelberg New York,
Kolliker A von (1863) Die Entwicklung der Zahnsackchen der Wiederkauer. Z Wiss Zool
Korkhaus G (1930) Die Vererbung der Kronenform und -groBe menschlicher Zahne. Z Anat
Kovacs I (1964) Contribution a I'etude des rapports entre Ie development et la morphologie
des racines des dents humaines. Bull Group Int Rech Sc Stomat 7: 85-120.
Kraus BS, Jordan RE (1965) The Human Dentition Before Birth. Lea and Febiger,
Krogman WM (1927) Anthropological aspects of the human teeth and dentition. J Dent Res
Ktikenthal W (1892) Dber den Ursprung und die Entwicklung der Saugetierzahne. Jenaische
Z Naturwiss 26: 469-489.
Kurten B (1982) Teeth: Form, Function, and Evolution. Columbia Univ Press, New
Lambert E (1877) Morphologie du systeme dentaire des races humaines. Bull Acad Roy Sci
Belg 43: 559-603.
Larsen CS, Kelley MA (1991) Introduction. In: Kelley MA, Larsen CS (eds) Advances in
Dental Anthropology. Wiley-Liss, New York, p. 1-5.
Lasker GW (1950) Genetic analysis of racial traits of the teeth. Cold Spring Harbor Symp
Qunat Bio115: 191-203.
Lavelle CLB, Shellis RP, Poole DFG (1977) Evolutionary Changes to the Primate Skull and
Dentition. Thomas, Springfield.
Leche W (1895) Zur Entwicklungsgeschichte des Zahnsystems der Saugetiere, Teil I,
Ontogenie. Bibliotheca Zoologic a, Heft 17.
Leche W (1902) Zur Entwicklungsgeschichte des Zahnsystems der Saugetiere, Teil II,
Phylogenie. Bibliotheca Zoologic a, Heft 37.
Lukacs JR (1983) Human dental remains from early Neolithic levels at Mehrgarh,
Baluchistan. CUff Anthrop 24: 390-392.
Lukacs JR (1993) Culture, Ecology and Dental Anthropology. Kamla-Raj, Delhi.
Maier W (1978) Zur Evolution des Saugetiergebisses - typologische und
konstruktionsmorphologische Erklarungen. Natur und Museum 108: 288-300.
Maier W (1980) Konstruktionsmorphologische Untersuchungen am GebiB der rezenten
Prosimiae (Primates). Abh Senckenb Naturf Ges 538: 1-158.
Maier W (1984) Tooth morphology and dietary specialization. In: Chivers DJ, Wood BA,
Bilsborough A (eds) Food Aquisition and Processing in Primates. Plenum Press, New
York, p. 303-330.
Mayhall JT (1992) Techniques for the study of dental morphology. In: Saunders SR,
Katzenberg MA (eds) Skeletal Biology: Research Methods. Wiley-Liss, New York, p.
2.2 The History of Dental Anthropology 35
Miles AEW (1972) Teeth and Their Origins. Oxford Biology Readers. Nr. 21. Oxford Univ
Miles AEW (ed) (1967) Structural and Chemical Organisation of Teeth, Vol I. Academic
Milner GR, Larsen CS (1991) Teeth as artifacts of human behavior: intentional mutilation
and accidental modification. In: Kelley MA, Larsen CS (eds) Advances in Dental
Anthropology. Wiley-Liss, New York, p. 357-378.
Moggi-Checchi JM (ed) (1995) Aspects of Dental Biology: Palaeontology, Anthropology,
and Evolution. Pontecorboli, Florenz.
Molnar S (1972) Tooth wear and culture: A survey of tooth functions among some prehistoric
populations. Current Anthrop 13: 511-526.
Molnar S, Richards L, McKee J, Molnar I (1989) Tooth wear in Australian aboriginal
populations from the Murray Valley. Am J Phys Anthrop 79: 185-196.
Moorrees CFA (1957) The Aleut Dentition. Harvard Univ Press, Cambridge MA.
Miihlreiter E (1870) Anatomie des menschlichen Gebisses. Felix, Leipzig.
Nichol CR (1989) Complex segregation analysis of dental morphological variants. Am J
Phys Anthrop 78: 37-59.
Osborn HF (1888) The evolution of mammalian molars to and from the tritubercular type.
Amer Nat 21: 1067.
Osborn HF (1892) The history and homologies of the human molar cusps. Anat Anz 7:
Osborn HF (1895) The history of the cusps of the human molar teeth. Int Dent J 7: 55-65.
Osborn HF (1907) Evolution of mammalian molar teeth to and from the triangular type.
Macmillan, New York.
Osborn JW (1973) Variations in structure and development of enamel. Oral Sci Rev 3:
Osborn JW (1995) A mechanical model stimulates the folding of the internal dental
epithelium during cusp formation. In: Radlanksi RJ, Renz H (eds) Proc 10th Int Symp
Dental Morphology. Briinne, Berlin, p. 22-26.
Osborn JW, Ten Cate AR (1983) Advanced Dental Histology. Wright, Bristol.
Owen R (1840-45) Odontography; Or, a Treatise on the Comparative Anatomy of the Teeth;
Their Physiological Relations, Mode of Development, and Microscopic Structure, in
the Vertebrate Animals. Bailliere, London.
Pedersen PO (1949) The East Greenland Eskimo Dentition: Numerical variations and
anatomy. Medd Gr!/lnI142: 1-256.
Peyer B (1968) Comparative Odontology. Univ Press, Chicago.
Pfretzschner HU (1992) Enamel microstructure and hypsodonty in large mammals. In:
Smith P, Tchernov E (eds) Structure, Function and Evolution. Freund, London, p.
Pfretzschner HU (1993) Enamel microstructure in the phylogeny of the Equidae. J Vertebrate
Paleont 13: 342-349.
Pindborg JJ (1970) Pathology of the Dental Hard Tissue. Musgaard, Kopenhagen.
Poole DFG (1976) Evolution of mastication. In: Anderson DJ, Matthews B (eds)
Mastication. Wright, Bristol.
Potter RHY, Corruccini RS, Green LJ (1981) Variance of occlusion traits in twins. J
Craniofac Genet 1: 217-227.
Radlanski RJ (1993) Contributions to the Development of Human Deciduous Tooth
Primordia. Quintessence, Chicago.
Radlanski RJ, Renz H (eds) (1995) Proceedings of the 10th International Symposium on
Dental Morphology. Briinne, Berlin.
Raschkow 1(1835) Meletemata circa mammalium dentium evolutionem (Untersuchungen
tiber die Entwicklung der Sliugetierzalme). Med Diss, PreBburg.
36 K. W. Alt et al.
Reddy VR (ed) (1985) Dental Anthropology: Application and Methods. Inter-India Publ.,
Regnault F (1894) Variations dans la forme des dents suivant les races humaines. Bull Soc
Anthrop Paris 4: Ser 5,14-18.
Remane A (1960) Zahne und Gebiss. In: Hofer H, Schultz AH, Starck D (Hrsg) Primatologia.
Bd. HII2, Karger, Basel, p. 637-846.
Rensberger JM (1973) An occlusion model for mastication and dental wear in herbivorous
mammals. J Paleont 47: 515-528.
Rensberger JM (1978) Scanning electron microscopy of wear and occlusal events in some
small Herbivores. In: Butler PM, Joysey KA (eds) Development, Function, and
Evolution of Teeth. Academic Press, London, p. 415--438.
Retzius A (1837) Bemerkungen tiber den inneren Bau der Zahne mit besonderer
Beriicksichtigung auf den im Zahnknochen vorkommenden Rohrenbau. Arch Anat Phys,
Berlin, AnatAbt 486-566.
Richards LC, Townsend GC, Brown T, Burgess VB (1990) Dental arch morphology in south
Australian twins. Arch Oral BioI 35: 983-989.
Rieger S (1993) Untersuchungen zur Geschlechtsbestimmung der Individuen einer
merowingerzeitlichen Skelettserie aus Baden-Wtirttemberg anhand der ZahnmaBe. Med
Riethe P (1955) Zur Phylogenie des Primatengebisses. Verlag Kunst und Wissenschaft,
Ritter R (1937) Uber die Frage der Vererbung von Anomalien der Kiefer und Zahne.
Rose C (1892) Uber die Entstehung und Formabanderungen der menschlichen Molaren.
AnatAnz 7: 392--421.
Russell DE, Santoro JP, Sigogneua-Russell D (1988) Teeth revisited. Mem Mus Natn Hist
Nat C 53, Paris.
Sakai T (1982) Morphogenesis of molar cusps and tubercles in certain primates. In: Kurten
B (ed) Teeth: Form, Function, and Evolution. Columbia Univ Press, New York, p.
Schindewolf OH (1948) Wesen und Geschichte der Palaontologie. Springer, Berlin
Heidelberg New York.
Schlosser M (1890/91) Die Differenzierung des Saugetiergebisses. BioI Centralbl 10:
Schnutenhaus S (1993) Weltverteilung der ZahngroBen. Uberprtifung der Eignung von
ZahnmaBen flir eine Taxonomie des Menschen. Med Diss, Ulm.
Schreger BG (1800) Beitrag zur Geschichte der Zahne. Beitr Zergliederungskunst 1: 1-7.
Schroder H (1906) Die ktinstliche Deformation des Gebisses. Abel, Greifswald.
Schroeder HE (1991) Pathobiologie oraler Strukturen. Karger, Basel.
Schulze C (1987) Anomalien und MiBbildungen der mensch lichen Zahne. Quintessenz,
Schumacher GH, Schmidt H, Bornig H, Richter W (1990) Anatomie und Biochemie der
Zahne. Fischer, Stuttgart.
Schwalbe G (1894) Uber Theorien der Dentition. Anat Anz Jena, Erg. Heft 9: 5--45.
Schwann T (1839) Mikroskopische Untersuchungen tiber die Obereinstimmung in der
Struktur und dem Wachsthum der Thiere und Pflanzen. Sander, Berlin.
Schwidetzky I (1988) Geschichte der Anthropologie. In: Knussmann R (Hrsg)
Anthropologie, Bd I, 1: Wesen und Methoden der Anthropologie. Fischer, Stuttgart, p.
Scott GR (1991) Dental anthropology. In: Dulbecco R (ed) Encyclopedia of Human Biology,
Vol 2, Academic Press, San Diego, p. 789-804.
Scott GR, Turner CG (1988) Dental anthropology. Ann Rev Anthropol 17: 99-126.
2.2 The History of Dental Anthropology 37
Scott GR, Turner CG (1997) The Anthropology of Modern Human Teeth. Dental
Morphology and Its Variation in Recent Human Populations. Cambridge Univ Press,
Shobusowa M (1952) Vergleichende Untersuchungen tiber die Form der Schmelzprismen
der Siiugetiere. Okajimas Folia Anat Jap 24: 371-392.
Simpson GG (1936) Studies of the earliest mammalian dentitions. Dent Cosmos 78:
Smith BH (1984) Patterns of molar wear in hunter-gatherers and agriculturalists. Am J Phys
Anthrop 63: 39-56.
Smith BH (1989) Growth and development and its significance for early hominid behavior.
Ossa 14: 63-96.
Smith BH (1991a) Dental development and the evolution of life history in the hominidae.
AmJPhysAnthrop 86: 157-174.
Smith BH (1991b) Standards of human tooth formation and dental age assessment. In:
Kelley MA, Larsen CS (eds) Advances in Dental Anthropology. Wiley-Liss, New York,
Smith BH (1994a) Patterns of dental development in Homo, Australopithecus, Pan, and
Gorilla. Am J Phys Anthrop 94: 307-325.
Smith BH (1994b) Sequence of emergence of the permanent teeth in Macaca, Pan, Homo,
and Australopithecus: Its evolutionary significance. Amer J Hum BioI 6: 61-76.
Smith BH, Crummett TL, Brandt K (1994) Ages of eruption of primate teeth: A compendium
for aging individuals and comparing life histories. Yearbook of Phys Anthrop 37:
Smith P and Zilberman U (1994) Thin enamel and other tooth components in Neanderthals
and other hominids. Am J Phys Anthrop 95: 85-87.
Smith P, Tchernov E (1992) Structure, Function, and Evolution of Teeth. Freund, London.
Spears J, Crompton R (1995) Mechanics of food reduction in hominoid molars. In: Radlanksi
RJ, Renz H (eds) Proc 10th Int Symp Dental Morphology. Briinne, Berlin, p. 387-390.
Spencer MA, Demes B (1993) Biomechanical analysis of masticatory system configuration
in Neandertals and Inuits. Am J Phys Anthrop 91: 1-20.
Starck D (1982) Vergleichende Anatomie der Wirbeltiere auf evolutionsbiologischer
Grundlage, Bd 3. Springer, Berlin Heidelberg New York.
Stewart RE, Prescott GH (1976) Oral Facial Genetics. Mosby, St. Louis.
Swindler DR (1976) Dentition of Living Primates. Academic Press, London.
Taylor RMS (1978) Variation in Morphology of Teeth. Thomas, Springfield.
Teaford MF, Runestad JA (1992) Dental microwear and diet in Venezuelan primates. Am J
Phys Anthrop 88: 347-364.
Teaford MF, Walker A (1984) Qualitative differences in dental microwear between primate
species with different diet and a comment on the presumed diet of Sivapithecus. Am J
PhysAnthrop 64: 191-200.
Thenius E (1989) Ziihne und GebiB der Siiugetiere. Hb Zoologie Bd 8, Mammalia. De
Thompson A (1903) Ethnographic Odontology: The Inca Peruvians. [so i. ;s. 1. ].
Tomes C (1872) On the nature of the cuticula dentis (Nasmyth's membrane). Quart J Micr
Sci 12: 321-326.
Tomes J (1887) A System of Dental Surgery. Lindsay and Blakiston, Philadelphia.
Topinard P (1892) De l' evolution des molaires et premolaires chez les primates.
Anthropologie Paris 3: 641-710.
Townsend GC, Brown T (1978 a) Inheritance of tooth size in Australian aboriginals. Am J
Phys Anthrop 48: 305-314.
Townsend GC, Brown T (1978 b) Heritabilities of permanent tooth size. Am J Phys Anthrop
Townsend GC, Yamada H, Smith P (1990) Expression of the entoconulid (sixth cusp) on
mandibular molar teeth of an Australian aboriginal population. Am J Phys Anthrop 82:
Townsend GC, Brown T, Richards LC, Rogers JR, Pinkerton SK, Travan GR, Burgess VB
(1986) Metric analyses of the teeth and faces of South Australian twins. Acta Genet
Med Gemellol 35: 179-192.
Townsend GC, Dempsey P, Brown T, Kaidonis J, Richards L (1994) Teeth, genes and the
environment. Perspect Hum BioI 4: 35-46.
Turner A, Wood B (1993) Comparative palaeontological context for the evolution of the
early hominid masticatory system. J Hum Evo124: 301-308.
Turner CG (1986) Dental evidence for the peopling of the Americas. Nat Geo Soc Res Rep
Turner CG (1990) Major features of Sundadonty and Sinodonty, including suggestions
about East Asian microevolution, population history, and late Pleistocene relationships
with Australian aboriginals. Am J Phys Anthrop 82: 295-317.
Turner CG (1992) Microevolution of East Asian and European populations: A dental
perspective. In: Akazawa T, Aoki K, Kimura T (eds) The Evolution and Dispersal of
Modern Humans in Asia. Hokusen-Sha, Tokyo, p. 415-438.
Turner CG, Nichol CR, Scott GR (1991) Scoring procedures for key morphological traits
for the permanent dentition: The Arizona State University dental anthropology system.
In: Kelley MA, Larsen CS (eds) Advances in Dental Anthropology. Wiley-Liss, New
York, p. 13-31.
Ttirp JC, Brace CL, Alt KW (1997) Richard Owen and the comparative anatomy of teeth.
J Hist Dent 45: 11-16.
Vach W, Alt KW (1993) Detection of kinship structures in prehistoric burial sites based on
odontological traits. In: Andresen J, Madsen T, Scollar I (eds) Computer Applications
and Quantitative Methods in Archaeology. Univ Press, Aarhus, p. 287-292.
Van Reenen JF, Reid C (1995) The configuration of maxillary molars. In: Radlanksi RJ,
Renz H (eds) Proc 10th Int Symp Dental Morphology. Brtinne, Berlin, p. 167-171.
Verger-Pratoucy JC (1970) Recherches sur les mutilations maxillo-dentaires prehistoriques.
Bull Group Int Rech Sc Stomat 13: 133-310.
Visser JB (1948) Beitrag zur Kenntnis der menschlichen Zahnwurzelformen. Med Diss,
Vogel F, Motulsky AG (1996) Human Genetics: Problems and Approaches. Springer, Berlin
Heidelberg New York.
Waldeyer W (1864) Untersuchungen tiber die Entwicklung der Zlihne. Konigsberger Med
Jb, 1 Abt 4: 236-299.
Walker A (1981) Dietary hypotheses and human evolution. Philos Trans Roy Soc London
B 292: 57-64.
Walker PL (1996) Presidential address. Dent Anthrop NewsllO (3): 1.
Walkhoff 0 (1894) Mikrophotographischer Atlas der normalen Histologie men schlicher
Zlihne. Risel, Hagen.
Weidenreich F (1937) The dentition of Sinanthropus Pekinensis: A comparative
odontography of the hominids. Paleont Sinica, NS D 1: 1-132.
White TD, Suwa G, Asfaw B (1994) Australopithecus ramidus, a new species of early
hominid from Aramis, Ethiopia. Nature 371: 306-312.
White TD, Suwa G, Asfaw B (1994) Corrigendum. Nature 375: 88.
Whittaker DK, Hargreaves AS (1991) Dental restorations and artificial teeth in a Georgian
population. Br Dent J 171: 371-376.
Witkop CJ (ed) (1962) Genetics and Dental Health. McGraw-Hill, New York.
Wolpoff MH (1971) Metric Trends in Hominid Dental Evolution. Studies in Anthropology
2. Case Western Reserve University Studies Anthrop, Cleveland.
2.2 The History of Dental Anthropology 39
Wortman JL (1886) The comparative anatomy of the teeth of vertebrates.
Wortman JL (1902) Studies of Eocene Mammalia in the marsh collection, Peabody Museum.
Am J Sci 13: 39-46.
Wurtz G (1985) Zahnentwicklung: Kenntnisstand im Ablauf der Geschichte. Ferber,
Zittel KA von (1899) Geschichte der Geologie und Palaontologie. Oldenbourg, Munchen.
3. THE HUMAN DENTITION- TOOTH CLASSES
In archaeological contexts, the dentition is often the only part of a human skeleton that
remains, due primarily to the mostly inorganic nature of dental enamel. In osteological
analyses, loose teeth are common. For this reason, researchers should be able to distin-
guish between deciduous and permanent teeth, maxillary and mandibular teeth, tooth
numbers for the same class, and teeth on the left or right side of a jaw (antimeres).
Anatomy of the Crown
The crown is the visible aspect of a tooth within the oral cavity. It is composed of enamel,
dentine, cementum, and pulp. The crowns of the anterior teeth have a single incisal edge
(incisors) or cusp (canines). Posterior teeth have two or more cusps separated by grooves and
Enamel is the hardest tissue of the human body, its strength has
been compared to that of mild steel. It comprises 96% mineral and 4% organic content and
water (Eisenmann 1994). Due to its high mineral content, enamel can withstand the
mechanical forces of function (e.g., mastication) and food acids (Nanci 2013),
and a variety of post-mortem forces (e.g., soil pressure, water movement). The crown of a
tooth is the most likely element of a skeleton to survive post-depositional factors and
The hardness of enamel gives a tooth a brittle layer, which is countered by the softer
underlying dentine. Dentine is around 70% mineral, 20% organic tissue, and 10% water
(Torneck 1994). The bulk of a tooth is composed of this tissue. The pulp cavity is completely
enclosed by dentine except at the apex of the root. The crown and root meet at the dento-
enamel junction, or DEJ. Dentine is not exposed in the oral
cavity unless there has been rapid wear of the tooth crown or trauma that caused the
enamel to fracture. When dentine is exposed, it is generally yellowish in color (although
often brown in archaeological specimens). The dentine of the root is exposed when
there is resorption of alveolar bone.
Anatomy of the Root
Root dentine is covered by cementum. The cementum attaches to the periodontal
ligament, which holds the tooth in the socket. Cementum has two components: acel-
lular cementum extends from the cemento-enamel junction (CEJ) to the root apex;
and cellular cementum is found on the apical third of the root (Nanci 2013).
Anatomy of the Pulp Cavity
The pulp cavity is within the crown down to the apex of the root(s). Within the pulp
cavity is soft tissue that supports the dentine, along with major vessels, nerves, and var-
ious cells, including odontoblasts, fibroblasts, and undifferentiated ectomesenchymal
cells (Nanci 2013).
Identification of Teeth
Following is a brief discussion of tooth classes and the teeth present in each class.
The oral cavity has two dental arches: maxillary and mandibular. Each arch is
divided into left and right quadrants along the median plane. Within each quadrant
are three or four classes of teeth. The deciduous dentition contains three classes:
incisors, canines, and molars. Ontologically, the “deciduous molars” are the precursors
of the permanent premolars. Permanent molars have no precursors in the deciduous
dentition. Deciduous molars should properly be called premolars, but the present
chapter follows the historical usage of the term molar when referring to these
teeth. The permanent dentition includes four classes: incisors, canines, premolars,
and molars. Six sets of traits are used to distinguish one tooth from
Set traits: deciduous, permanent.
Class traits: incisor, canine, premolar, and molar. Arch traits: maxillary, mandibular.
Type or side: central, lateral; anterior, posterior; 1st, 2nd, or 3rd molars.
Population level: some populations have dental traits (or a suite of traits) at higher
frequencies than others
Identification of specific teeth and designating them as right or left is dependent on various
morphological details of the crowns and roots.
Cingulum: a shelf found about halfway up the lingual surface of the maxillary teeth and the
buccal surface of the mandibular teeth; it is the last part of the crown to grow actively before
calcification and is the source of several nonmetric crown traits.
Lingual marginal ridges: part of the marginal ridge complex on the lingual sur-
faces of the maxillary and mandibular anterior teeth; these ridges of enamel are on the mesial
and/or distal edges, and vary from faint to pronounced.
Lingual fossa: a small cavity in the center of the lingual surface of maxillary anterior teeth,
formed by a combination of raised cingula and marginal ridges.
Tuberculum dentale: this cingular trait of the maxillary anterior teeth (rarely man-
dibular) is expressed in the forms of pit(s), ridge(s), and/or tubercle(s).
Molar cusps are identified by name.
Cusps ending in -cone are maxillary and those ending in -conid are mandibular.
The primary or deciduous teeth begin development in utero and erupt between six
months and two years after birth. Only the deciduous dentition is present
in the oral cavity from approximately 2 to 6 years of age. Between 7 and 12 years, the
dentition has a combination of deciduous and permanent teeth (i.e., mixed dentition).
Each quadrant (i.e., right or left sides [antimeres]) of the upper and lower arcades, as
demarcated by the median plane, has two incisors (i1 and i2), one canine (c), and two molars
(m1 and m2); all four quadrants yield a total of 20 deciduous teeth (Figure 8.1a and b). While
the deciduous dentition is in functional occlusion, permanent teeth are forming within the
Set characteristics used to distinguish deciduous teeth from permanent teeth include the
following (see Figures 3.1c and d):
Figure 3.1 (a) Deciduous maxillary dentition denoting two incisors, one canine, and two
molars in left quadrant. (b) Deciduous mandibular dentition denoting two incisors, one
canine, and two molars in right quadrant. (c) Radiograph of maxillary dentition in A, showing
root structure of teeth and developing permanent tooth buds in alveolus. (d) Radiograph of
mandibular dentition in B, showing root structure of teeth and developing permanent tooth
buds (e.g., LM1) in alveolus. See text for details. Dental remains of a medieval child from the
Poulton Site, Cheshire, UK. Photos by Joel D. Irish. Radiographs of Poulton remains by
Carla Burrell, Eleanor Dove, and Carole Turner.
Deciduous enamel is thinner and may be more yellowish in color. Enamel “bulges”
out around the neck of the crown.
Crowns are shorter and more bulbous.
There is a severe cervical (neck) constriction.
Roots are narrow and thin, but long in comparison to crown height.
Root trunks (i.e., distance between the CEJ and bifurcation of the molar roots) of the
deciduous molars are shorter.
Molar roots are more widely spread or splayed - to fit over developing permanent
tooth germs within the alveolar bone.
In general, the crowns are free of defects and there are spaces between the teeth when in the
The crown of all incisors can be described as flat, “square-ish,” and spatulate. Of these,
the ui1 is the largest of the deciduous incisors (Figure 3.1a). The labial side is smooth
and somewhat convex, while the lingual side is concave. Along the CEJ of the lingual
side, there may be some development of a cingulum and marginal ridges. The medial
edge of the central incisors is straight and the mesio-occusal angle approximates a right
angle. The distal edge is slightly rounded, so the disto-occlusal corner is rounded off
slightly. The occlusal surface is straight. The root is large and conical with a labial
groove; the root tips can tip labially.
Set traits (to distinguish from permanent tooth): crown is smaller, roots are smaller
with a labial groove, and the mesiodistal width is the greatest dimension; for
permanent teeth, crown height is the greatest dimension.
Arch traits (to distinguish from other arch): larger crown and root.
Type traits (to distinguish from others within class): the ui1 is larger and the crown is
To side: with the crown facing down and the lingual side facing you, the straight
mesial edge is on the side the tooth is from.
The profile of the lateral maxillary incisor (ui2) looks elongated compared to ui1.
The crown has a longer mesial edge than the slightly curved distal edge. The occlusal
surface is straight with a rounded distal-occlusal angle. The crown has a slight
“fan” shape (Figure 3.1a). The labial surface is smooth and the lingual surface can
exhibit some development of the cingulum and marginal ridges. The root is conical
Set traits (to distinguish from permanent tooth): crown and root are smaller. Arch
traits (to distinguish from other arch): crown is larger.
To differentiate from the i1: the crown is narrow and more elongated.
To side: With crown down and the lingual side facing you, the straight mesial edge is
on the side the tooth is from.
The central mandibular incisor (li1) is the smallest of the deciduous incisors
(Figure 3.1b). Both the li1 and the li2 have a small crown with straight distal, mesial, and
occlusal surfaces. The crown is very even and square in shape. The lingual and labial surfaces
are smooth. Roots are short and flattened mesiodistally.
Set traits (to distinguish from permanent tooth): crown and root are smaller. Arch
traits (to distinguish from other arch): smaller crown than the ui2 and almost perfectly
Type traits (to distinguish from others within class): smaller crown than the li2 and
almost perfectly square.
To side: the li1 is difficult to side; with the crown facing up, the CEJ points slightly
distally off midline on the lingual side. Often there is little or no asymmetry that can
be used to determine side.
The li2 has a rectangular crown with a longer mesial edge and a slightly shorter distal
edge. The occlusal surface slopes mesiodistally. The labial surface is flat, while the
lingual surface has little or no cingulum and marginal ridge development. The roots
are conical in shape with a distal tilt to the root tip. Both the mesial and distal root
surfaces can exhibit grooves.
Set traits (to distinguish from permanent tooth): crown and root are smaller. Arch
traits (to distinguish from other arch): the ui2 is larger.
Type traits (to distinguish from others within class): the li1 is almost perfectly square.
To side: With the crown up and the lingual surface facing you, the occlusal surface
slopes mesiodistally on the side it is from.
Primary canines are characterized by a single, large, cone-shaped cusp with a large, robust
root. There is only one member of the class within each quadrant of the dental arch (Figure
The two uc teeth have short, squat, cone-shaped crowns. The mesial border “bulges” out, and
the distal margin curves down to the CEJ. The root is long, robust, and conical. Root
morphology varies, sometimes exhibiting a lingual groove.
Set traits (to distinguish from permanent tooth): smaller.
Arch traits (to distinguish from other arch): uc crowns are squat and rounder. To side:
With the tooth in proper orientation and with the lingual surface facing you, the
mesial side bulges out. The root may have a lingual groove and labial deflection of the
The canines have taller, more rounded crowns than their maxillary counterparts. The mesial
edge “bulges” outward, while the distal edge has a relatively straight slope to the CEJ. The
root is large and conical.
Set traits (to distinguish from permanent tooth): smaller in size.
Arch traits (to distinguish from other arch): lc teeth are taller and rounder and have
less lingual surface variation in relation to a cingulum or mesial and distal marginal
To side: with the tooth in proper orientation and the lingual side facing you, the
mesial side shows a bulge.
The deciduous maxillary molars have three roots: two buccal (mesial and distal) and one
lingual. Unlike the permanent dentition there is no root trunk. The roots start at the cervical
neck and spread wide for development of the underlying permanent premolar crown (Figure
The um1 looks superficially like a permanent premolar. The crown commonly has
two cusps, with a large central groove running mesiodistally between the two
(Figure 3.1a). On the crown are the buccal cusp (paracone) and the slightly smaller
lingual cusp (protocone). Sometimes there are two other cusps present: a distobuccal
(metacone) and a distolingual (hypocone). There can be a sheath between the lingual
root and distobuccal root or between the lingual and mesiobuccal root.
Set traits (to distinguish from permanent tooth): generally has two cusps as opposed to
three or more in the permanent tooth, lacks a root trunk, and has widely spread roots.
Arch traits (to distinguish from other arch): the lm1 is unique and cannot be confused
with the um1.
Type traits (to distinguish from others within class): the um2 looks like the permanent
To side: With the crown facing down and the two buccal roots facing away from you,
the tuberculum molare at the CEJ bulges “up” the mesiobuccal root.
The um2 looks like the permanent maxillary first molar in that it has two buccal roots
and one lingual root and a square-ish crown, often with four cusps. It differs from the
permanent first molar in that it lacks a root trunk, often has a root sheath, and is smaller
in size. The um2 is square and usually has four cusps: two buccal cusps (paracone and
metacone), a larger mesiolingual cusp (protocone), and a smaller distolingual cusp
(hypocone; Figure 3.1a). If the crown has only three cusps, the small distolingual cusp
Set traits (to distinguish from permanent tooth): smaller and lacks a root trunk.
Arch traits (to distinguish from other arch): the lm2 has two roots and five
Type traits (to distinguish from others within class): the um2 usually has four cusps
opposed to the two cusps of the um1.
To side: With the crown facing down and the two buccal roots facing away from you,
the small distolingual cusp is on the side the tooth is from. There is no tuber-
The mandibular molars have two roots: one mesial and one distal. As with the maxillary
isomeres, the roots are spread wide and lack a root trunk. The lm1 is unlike any other
tooth in the deciduous or permanent dentition. It is elongated along the mesiodistal
axis and narrower buccolingually, giving the crown a rectangular shape (Figure 3.1b).
There are two cusps: a larger, “pointy” mesiobuccal cusp and a smaller mesiolingual
cusp. The distal talonid can have several smaller cusps within a basin.
Set traits (to distinguish from permanent tooth): unique tooth. Arch traits (to
distinguish from other arch): unique tooth.
Type traits (to distinguish from others within class): unique tooth. To side: the
tuberculum molare is present on the mesiobuccal corner of the tooth; it bulges
“down” the mesiobuccal aspect of the mesial root.
Except for its smaller size, the lm2 looks almost exactly like the first permanent molar
(i.e., LM1) that forms within the alveolar bone behind it (see Figure 3.1d). It has a
rectangular crown with five cusps and mesial and distal roots. When viewing the crown
from the buccal surface, three cusps and two grooves are evident (Figure 3.1b). The
largest of the buccal cusps is the mesiobuccal cusp (protoconid). The mesiobuccal cusp
is separated from the distobuccal cusp (hypoconid) by the buccal groove, which
sometimes terminates in a buccal pit. A fainter groove separates the hypoconid from
the smallest and most distobuccal cusp; that is, the hypoconulid.
When viewed from the lingual surface, two cusps are evident: a mesiolingual cusp
(metaconid) and a mesiodistal cusp (entoconid). These cusps are separated by the lingual
groove. On the occlusal surface, there is a deep central groove that separates the buccal and
lingual planes. There is a mesial pit, central pit, and distal pit. The pattern of the grooves
determines which cusps are “touching”; this is the primary determinant of Y-, X-, and +-
Set traits (to distinguish from permanent tooth): it is smaller and the enamel may be
more yellowish than the permanent molar and does not generally have a root trunk.
Arch traits (to distinguish from other arch): two roots instead of three and usually five
cusps instead of the four found on the second maxillary molar.
Type traits (to distinguish from others within class): unique tooth.
To side: With occlusal surface up and larger mesial cusps away from you, three
cusps will be present on the side the molar is from. There is no tuberculum molare.
The secondary human dentition (also called permanent or succedaneous) begins to erupt at
approximately 6 years of age and completes eruption by 18-21 years. There are usually 32
teeth, classified into four classes (Figure 3.2a and b). Two incisors (I1 and I2), one canine
(C), two premolars (P1 and P2), and three molars (M1, M2, and M3) are present within each
quadrant (note use of uppercase letters to differentiate these designations from those for
Figure 3.2 (a) Permanent maxillary dentition denoting two incisors, one canine, two
premolars, and three molars in left quadrant. (b) Permanent mandibular dentition denoting
two incisors, one canine, two premolars, and three molars in right quadrant. (c) UP1 showing
common two-root variant. (d) UM2 showing three roots common in maxillary molars. (e) P1
showing single root with Tomes’ variant (i.e., groove). (f) LM2 showing two roots common
in mandibular molars. See text for details. All photos of C-Group Nubian remain from
Hierakonpolis (a and b) and Christian Nubian remains from Semna South (c-f) by Joel D.
The central incisor—that is, UI1—replaces the deciduous central incisor; they are
designed for cutting or slicing during mastication. A secondary function relates to facial
expressions and speech. The UI1 looks like its deciduous counterpart but is signifi-
For UI1s there can be two developmental grooves on the labial surface that corre-
spond to three or more projections on the incisal edge, called mamelons (Hillson 1996).
Mamelons tend to wear off in individuals over the age of 7 or 8, depending on diet. Lingual
marginal ridges i.e., shoveling; may be present.The root is cone shaped and large. The apex
may have a mesial or distal tilt, so the root is not diagnostic for siding.
Arch traits (to distinguish from other arch): the mandibular roots are flat and crowns
Type traits (to distinguish from others within class): the UI2 is smaller and narrower.
To side: With the crown facing down and the lingual surface facing you, the mesial
edge is straight and the distal edge is curved. In addition, the mesial CEJ displays a
deep curve. It may be confused with canines if the crowns are worn.
The lateral incisor, or UI2, is smaller and the crown is shorter and narrower than that of the
UI1. The crown may exhibit mamelons, but they are fainter in expression. The crown is
slightly asymmetric, with the mesiobuccal corner projecting down more than the distal
corner. There is more variation in the form of the tuberculum dentale compared to the UI1.
The root is conical in shape.
Arch traits (to distinguish from other arch): conical roots and larger crown. Type traits
(to distinguish from others within class): smaller than UI1.
To side: The mesial edge is straight and the distal edge is curved; the CEJ on the
mesial surface has a deep curve.
The permanent mandibular central incisors (LI1) are the smallest teeth and also the most
difficult to side (Figure 3.2b). The crowns are symmetric and square in shape. The CEJ is
curved on both the mesial and distal surfaces. The lingual surface rarely shows any variation
with regard to tubercles, but there are sometimes faint marginal ridges. The root is fairly short
and flattened mesiodistally.
Arch traits (to distinguish from other arch): much smaller than the UI1.
Type traits (to distinguish from others within class): the LI2 has an asymmetric
To side: Sometimes the CEJ on the lingual side is useful; the deepest curve of the CEJ
is slightly off midline to the mesial.
The lateral incisors (LI2) have an asymmetric crown with the mesial occlusal corner
higher than the distal occlusal corner. The occlusal surface of the crown slopes distally.
The crown is broader mesiodistally compared to the central incisor. The occlusal
surface may have mamelons. The lingual surface does not have strongly expressed
dental traits. The CEJ on the lingual surface is most concave distally. The root is
Arch traits (to distinguish from other arch): the maxillary incisor has a conical root;
the mandibular incisor has a flattened root.
Type traits (to distinguish from others within class): the LI1s have symmetric crowns.
To side: With the crown facing up and the lingual surface facing you, the
asymmetry of the crown and lingual CEJ indicates the side the tooth is from.
Anterior teeth wear mesiodistally; this may remove the asymmetric aspect of
The maxillary canine crown (UC) is a single large cusp that is rounded in cross-section. The
distal occlusal edge is longer and more deeply curved compared to the mesial edge. The
mesial and distal marginal ridges are not as distinct and the lingual fossa is not as deep (if
present), as shown by the incisors. On the lingual surface, there is a ridge running from the
CEJ to the cusp tip, creating mesial and distal lingual fossae.
Arch traits (to distinguish from other arch): the UCs are rounder and squatter in
To side: With the crown pointing down and the lingual surface facing you, the
curved distal surface indicates the direction the tooth is from. The CEJ on the
mesial surface is deeply curved compared to the distal surface. Often the root tilts
The mandibular canine (LC) is more rectangular in outline and the root and crown are not as
disproportional in ratio as the UC. The crown is “twisted” distally, so when holding the
crown from the distal plane, most of the lingual surface is exposed. The lingual surface has
minimal morphology. The mesial occlusal edge of the crown is shorter, while the distal edge
is longer and curved.
Arch traits (to distinguish from other arch): LC is more incisiform than UC; the crown
is more rectangular and twisted distally.
To side: With the crown up and viewed from the distal plane, most of the lingual
surface should be evident. When viewed from the mesial plane, little of the lingual
surface can be observed.
Maxillary premolars have one or two (buccal and lingual) roots (see Figure 3.2c).
Both premolars (UP1 and UP2) have two cusps: the buccal paracone and the lingual
protocone (Figure 3.2a). The first maxillary premolars have buccal cusps that are
larger and higher than the lingual cusps. The distal border of the buccal cusp is
rotated away from the alveolus, so the axis of the two cusps is not parallel. The roots
are relatively conical and may or may not be completely separated. If not separated, a
strong groove is likely to be present, running from the CEJ to a notch with two
apices present. The roots almost always tilt distally, a condition that can be used as a
diagnostic tool for siding.
Arch traits (to distinguish from other arch): mandibular premolars typically have a
Type traits (to distinguish from others within class): the UP2 has cusps of almost
equal height; the axis of the buccal and lingual cusps is close to parallel.
To side: Holding the crown by the roots with the crown facing down, the larger cusp
is buccal and the smaller is lingual. The lingual cusp is often offset mesially. The
mesial root surface can have a root concavity and the root tips tilt distally. When
worn, the two maxillary premolars can be confused.
The paracone and protocone of the UP2 are of almost equal height, but the paracone
is “pointier” and bulging compared to the protocone. The mesial concavity is not as
marked as that of the first premolar. The UP2 is generally, but not always, smaller than
the first (Figure 3.2a). Unlike the UP1, the UP2 usually has a single fused root with
Arch traits (to distinguish from other arch): the mandibular counterparts usually have
a single root.
Type traits (to distinguish from others within class): UP2 cusps are of equal
height, their axes are close to parallel, the crown is smaller, and the roots are usually
To side: Holding the tooth by the roots with the crown facing down, the pointier
cusp is buccal. The lingual cusp is slightly offset mesially. The root(s) tilts distally.
Mandibular premolars (LP1 and LP2) generally have two cusps, the buccal protoconid and
the lingual metaconid, and ordinarily a single root. The LP1 has a large protoconid and a
much smaller metaconid; the occlusal surface is at a 45-degree angle and is diagnostic for
identification. The protocristid (crest) connects the protoconid and metaconid; it is usually
continuous but sometimes interrupted by the central groove (see Figure 3.2b). The distal
basin is larger than the mesial basin on the occlusal surface. The mesial ridge is long and
straight, while the distal ridge is short and curved. The presence of mesial and distal grooves
Arch traits (to distinguish from other arch): the LP1 has a single root and a very small
lingual cusp compared to the lingual cusp of the maxillary premolars. A deep mesial
groove (Tomes’ root variant) may be present on the LP1 (see Figure 3.2e). Type traits
(to distinguish from others within class): the LP1 is the only premolar to have a 45-
degree angle to the occlusal surface.
To side: With the lingual surface facing you, the metaconid is offset from the mid-
line toward the mesial aspect; the mesial ridge is long and straight, while the distal
ridge is short and curved. The root can tilt distally.
The LP2 has a larger and higher metaconid (lingual cusp) compared to the LP1. Usually the
protocristid does not connect the two cusps, and the central groove runs between them
(Figure 3.2b). A third cusp, the hypoconid, is not uncommon on the lingual surface. The
single root has a distal tilt.
Arch traits (to distinguish from other arch): a single root and the lingual cusps are
Type traits (to distinguish from others within class): the LP2 lingual cusp is much
larger than that of the LP1. The LP2 is also more likely to have a second lingual cusp.
To side: The metaconid is offset mesially and the distal basin is larger than the mesial
basin on the occlusal surface. The root has a distal tilt.
The anatomy of the three maxillary molars is similar. The UM1s have three roots (two
buccal, one lingual) and large root trunks. There are usually four cusps on maxillary
molars: the paracone, metacone, protocone, and hypocone. The hypocone is the
smallest of the four (and can be absent on the UM2 and UM3). On the buccal surface,
between the paracone and metacone, is a buccal groove. Between the protocone and
hypocone is a lingual groove. A morphological feature often present on the mesiolin-
gual side of the protocone is Carabelli’s cusp.
Arch traits (to distinguish from other arch): the maxillary molars generally have three
roots (Figure 3.2d) and four main cusps. The lingual surface is gently rounded, while
the buccal surface is vertical in orientation.
Type traits (to distinguish from others within class): The first maxillary molar is
the largest, with crown size decreasing distally (i.e., UM1>UM2>UM3). The roots
are well separated in the first molar; the likelihood of root fusion increases for the
UM2 and especially the UM3. The hypocone is most often present on the first
molar and decreases in size and frequency on the UM2 and UM3. Inter-proximal
wear facets form on the surfaces between molars. The UM1 and UM2 usually have
two inter-proximal wear facets, one mesial and one distal. The UM3, if erupted, has
just a mesial facet. If the latter tooth has not erupted, UM2 has only a single mesial
To side: With two roots toward the buccal plane and a single lingual root facing you,
a distolingual hypocone helps determine side.
Mandibular first molars (LM1) typically have two roots, one mesial and one distal, and
a crown with five cusps. These molars exhibit extensive morphological variation in the
form of accessory cusps, grooves, pits, and root number. The LM1 is similar to the second
deciduous molar in morphology. When the crown is viewed from the buccal surface, three
cusps and two grooves are evident. The largest of the buccal cusps is the protoconid. The
latter is separated from the hypoconid by a buccal groove that can terminate in a buccal pit. A
fainter groove separates the hypoconid from the smallest and most distobuccal cusp, the
hypoconulid. Two cusps can be observed when viewed from the lingual surface; the
metaconid and entoconid are separated by a lingual groove.
Arch traits (to distinguish from other arch): mandibular molars generally have two
roots (Figure 8.2f) and five cusps. The lingual surface is vertically oriented and the
buccal surface is gently rounded (the opposite of maxillary teeth).Type traits (to
distinguish from others within class): the LM1 is the largest of the three molars, with
splayed roots and five distinct cusps. The more distal molars
are smaller, the roots are more likely to be fused, a fifth cusp (hypoconulid) is com-
monly absent, and the more fused the roots are, the greater the root tilt. As with
maxillary molars, inter-proximal wear facets can be used to help determine molar
To side: The distally placed hypoconulid is toward the buccal surface; the buccal
surface is gently rounded.
4. THE MASTICATORY SYSTEM AND ITS FUNCTION
Why does the oral function of humans and other mammals not play a more central role in the
life sciences? It is difficult for someone who is obsessed with the subject to understand this,
but here are some clues to traditional attitudes in this regard. Dentists have long held the
view that mechanical tooth-food contacts do not really matter. Their training courses often
effectively equate “dental function” with “occlusion,” that is, with tooth-tooth contact. So the
need for alignment of the upper and lower teeth to achieve efficient food breakdown without
damaging themselves in the process seems either to have been misunderstood or deemed
irrelevant. Food intervening between the teeth appears to be regarded as little more than a
cushion that can lie there during waking hours. In contrast to medical education, where the
normal function of each body part is taught in detail, dentists focus more on “dysfunction,”
which refers usually to pain in various areas (most often located around the jaw joint), and
“parafunction” (rubbing the teeth together at night, a condition called “bruxism”). These
issues are researched much more thoroughly than normal physiological processes like
ingestion and mastication because the latter do not form foci for treatment. In contrast,
swallowing does get attention as a normal process, because difficulty in swallowing (called
dysphagia) is a medical specialty. Biologists with an interest in digestive physiology seem to
be biased against a detailed study of normal oral function, but for a different reason. They
allot a rather slim role to the function of the mouth because they do not believe that it
contributes much to digestion. Most texts on the digestive system start with the receipt of
food into the stomach (Lucas et al. 2009), with the mouth seen mainly as a reception area for
the digestive tract—and not much more than that. Models of the digestive process that are
either virtual (Penry and Jumars 1987; Alexander 1991) or based on physical imitation
(Minekus et al. 1995, 1999) do likewise. What is most important in these models is that oral
clearance of particles manages to keep pace with the rest of the gut since, in any sequential
process, the limiting factor is the slowest link in the chain.
Ecologists think more positively about the importance of oral treatment, at least
concerning ingestion. One of the classic studies of evolutionary adaptation is that of the
diversity of the shape and size of the beaks of finches in the Galapagos in response to
the occupation of different dietary niches (Grant and Grant 2006). However, the
mechanical reasons for the morphological change in the beaks, other than size param-
eters that influence gape, has not been explained. There are now parallel studies of
ingestion in primates, with an important case study on bark gouging by marmosets
where the mechanics of the process are being studied (Vinyard et al. 2003, 2009;
Thompson et al. 2014).
It is mastication, however, that is the major distinguishing characteristic of mammals.
Unfortunately, this function is difficult to study in the wild, because the muscular cheeks
effectively mask what is going on. The most intense biological interest in tooth form and how
it relates to diet and normal function concerns mastication; nevertheless, this focus has come
from paleontologists, because teeth are the most commonly pre-
served body parts of fossils. The catch, though, is that function must be inferred in fossils,
because there is usually no direct evidence for diet.
Food scientists have always known that the flavor of foods, as sensed in the mouth,
is important to acceptability by consumers, but until recently they did little or no
“in-mouth” research to ascertain how flavor is perceived. As far as food texture—the
physical “mouthfeel” of foods—is concerned, they have concentrated on
psychophysical methods. Quantified perceptions of the physical characteristics of
foods are made by trained sensory panelists based on definitions of the oral behaviors
they have learned and are assumed to be applying. The test foods are then deformed
in mechanical testing machines to specified degrees to provide a force. Several proce-
dures are current in the food industry. Sometimes correlations between perceptions
and mechanical test results hold up; however, in some circumstances they fail to reach
significance (particularly when discrimination becomes very fine), and it has been
difficult to explain why.
Much is now changing, as will be indicated at the end of this chapter, but one of the
shared opinions that seems to have emerged from all these approaches to oral function
is that the human mouth seems to be overengineered. The range of forces and move-
ments that the jaws can achieve, and the robusticity of the mandible in particular,
would appear excessive and rarely reached. Recent research is starting to address this
from several directions. Extra-oral food particle size breakdown techniques and exten-
sive use of heat treatment of food prior to ingestion (Wrangham 2009) have undoubt-
edly reduced the need for modern humans to do much more in the mouth for digestive
purposes than to pass food particles down to the esophagus. Food particle size reduction
may still be necessary with the teeth, but foods softened by cooking can be swallowed
at larger sizes than hard foods (Lucas and Luke 1986). This is in many ways a reversion
to a reptilian or avian type of mouth, where the critical emphasis is on little other than
gape. It seems likely that such techniques date back a long way: several million years to
early tool use in the case of food processing, and potentially more than a million
years for cooking (Wrangham et al. 1999; Wrangham and Conklin-Brittain 2003; Wrangham
2007; Carmody and Wrangham 2009). These techniques are not specific to
Homo sapiens: Neanderthals were heat-treating food too (Henry et al. 2011).
Once explained in this way, the masticatory experience of modern humans should
not bias comparative work in mammals. Natural food is difficult to acquire. The reason
is that no plant or animal wants its structural framework to be eaten. Those parts at
greatest risk of predation are defended, often mechanically. So feeding is a struggle that
inevitably leads at times to limits being reached—and those limits need to be designed
adequately for survival. Given this background, the purpose of this chapter is to suggest
how a dental anthropologist could approach oral and dental function. The chapter
starts by outlining the limits to force production and to movement; it then considers
ingestion, mastication, and swallowing in sequence. Finally, an assessment is offered as
to how new approaches to oral function in non-anthropological subjects may assist
interpretations of anthropological material.
Forces and Displacements
As a preliminary to discussion of how the mouth acts, a brief description of forces and
movements is offered. However, no details of the movement of the jaw (temporo-
mandibular) joint itself are given for reasons of space. Four large muscles can be
recruited to provide the bite force against food (Figure 4.1). The temporalis muscle
is thin and fan shaped, attached to the side of the skull over the temporal fossa down
to the coronoid process of the mandible. It is covered by a fibrous sheet from which
some of its fibers derive, and is thus barely palpable. The masseter muscle provides
much of the power of a bite. It runs down from an attachment to the whole length of
the zygomatic arch to the ramus (the vertical part) of the mandible. The electrical
activity of both the temporalis and masseter are easily accessed by surface electromy-
ography because they lie close to the skin, so we know a great deal about how they
act. In contrast, the medial and lateral pterygoid muscles lie deeper, beneath the
ramus of the mandible and the zygomatic arch, and are thus inaccessible to standard
surface electrode placement. The medial pterygoid is less powerful than the masseter,
but assists it with a similar direction of pull during jaw closing. The lateral pterygoid
is more enigmatic. Its superior head is active in closing, where it appears to help to
adjust the direction of the bite force away from the jaw joint as food is contacted
Forces are also generated by the tongue, which is actually a large bag of muscle
lying inside the dental arcade in the floor of the mouth; it is capable of extensive
movement. The largest tongue muscle, important in manipulating food within
the mouth, in speech, and in swallowing, is the genioglossus (shown attached to the
inside of the fused mandibular symphysis in Figure 4.1). The tongue would appear
to be positioned to push the teeth outward. It is opposed by the buccinator muscle
of the cheek. If you look at the buccinator fibers in the diagram, they run antero--
posteriorly. Yet the action of the buccinator is to press food against the cheek. The
muscle acts by fixing its ends. The anterior end of the muscle is fixed at a point
marked by a fibrous knot called the “modiolus,” just beyond the corner of the
mouth. Contraction of many facial muscles keeps this point stable. The modiolus is
the functional anterior end of the cheek. The posterior end of the muscle is an inter-
digitation of fibers (called the pterygomandibular raphé) with the superior constrictor of the
pharynx (Figure 4.1). With these two ends fixed, muscular contraction brings the cheek
toward the teeth. The range of movements that the mandible can make (Figure 4.2) is a
reflection both of what the muscles can manage and the range of the jaw joint. The extremes,
called border movements, can be mapped quite easily. The available field of movement is
called the envelope of motion and is the shaded area inside the border movements depicted in
Figure 4.1. Tongue movements, as far as they are known, are described briefly in the
Figure 4.1 Force generation by some of the most important muscles. The mandible has been
separated anteriorly at the fused mandibular symphysis to view attachment areas (shaded) to
its internal surfaces. (a) Anatomical arrangement of the muscles of mastication: temporalis,
masseter, and medial and lateral pterygoids. Other muscles important in jaw opening
(digastric) or control of food particles in the mouth (anterior to posterior: orbicularis oris,
buccinators, and the superior constrictor of the pharynx) are also shown. (b) Approximate
direction of action, depending on what fibers are activated, of the muscles of mastication
shown. Relative magnitude of the maximum force they can exert are indicated by the size of
arrows. The temporalis is divided arbitrarily into anterior and posterior fibers. The two heads
of the lateral pterygoid are also separated, but this has greater importance. The superior head
probably has a completely different role to that of the larger inferior head (which is active in
jaw opening), being active in jaw closing. Also indicated is the attachment site of the
mylohyoid to the mandible, a muscle acting strongly during swallowing, and the
genioglossus, the largest tongue muscle.
Figure 4.2 Pattern of jaw displacement. The border movements (maximum movement in
each direction) of the jaw are illustrated by sketching the movement of the lower central
incisors in both side (a) and frontal (b) views. The main muscles that produce these
movements are indicated. The box (bottom) shows a stereotyped chewing cycle shown as a
solid black line. Cycles are highly variable, but rarely reach the borders (shown in gray).
Ingestion is the word given to the entry of food into the mouth. The jaw opens vertically (in
the midline) to allow the (often large) food particles into the mouth. The
incisors, or sometimes the cheek teeth if food is very hard, control bite size.
Simultaneously, the tongue leaps forward to collect these particles. The mechanics of
the process are complicated and were first investigated only in the 1980s (Osborn,
Baragar, and Grey 1987). However, there are now many more papers on this subject,
some of which at least attempt to link food properties to the process (Agrawal and
Lucas 2003; Sui et al. 2006; Ang, Lucas, and Tan 2006; Agrawal et al. 2008; Thompson
et al. 2014). The most common assumption is that incisors can be modeled as wedges
(Vincent et al. 1991; Ang, Lucas, and Tan 2006) at a variable angle to the direction of
the force (Paphangkorakit and Osborn 1997) and with a variable proclination
(Paphangkorakit and Osborn 2008) and crown curvature (Deane 2009).
Chewing (or mastication) is the process of first reducing the size of solid food particles by
breaking them with the teeth (so that digestive enzymes have lots of surface
area to act on); and then mixing them with saliva so that they generally stick together
as a ball (a food bolus). Getting the food particles to cling together allows clearance
of the mouth of particles, making it efficient, leaving it clean (well, cleanish), and
allowing safe swallowing. In plant-eating mammals (and humans are plant eaters),
chewing generally reduces average food particle sizes by an order of magnitude, scal-
ing down food dimensions from the centimeter range to those in the low-millimeter
range by the time of swallowing (Fritz et al. 2009). So there is a tenfold reduction in
particle size. An order of magnitude of size reduction like this must increase the rate
of digestion later on in the gut, simply because the reaction rates of liquid enzymes
are proportional to the surface areas of the solid food particles on which they act.
Since particle size is usually measured as a linear dimension in studies of food commi-
nution in the mouth, surface area would be expected to increase as the square
of particle size. We can conclude that food surfaces are often expanded something
like ~100-fold. Accordingly, the digestive effects of the physical side of mastication
cannot be dismissed.
The following is a brief account of what happens in a chew (inset in Figure 4.2).
Since each chew is rather like a rotary up-down movement, we talk of each chew being
a chewing cycle. Mastication is based on the up-down, open-close movements of the
jaw. Opening provides a clear space for food particles to be thrown from the tongue
onto the occlusal surface of the teeth, while closing the jaw brings the teeth into contact
with food particles so as to break them. The exact jaw movement varies from cycle to
cycle, depending on whether food is on one side of the mouth, which it usually is, or is
distributed bilaterally. The following is a stereotype. During jaw opening, movement is
generally vertical. The lower heads of both right and left lateral pterygoids are active
during jaw opening, when they pull the mandible downward in collaboration with the
digastric muscle. Early opening is slow while late opening is fast. At the start of closing,
the jaw deviates quite rapidly toward one side of the mouth, the side where food is
going to be chewed. The jaw then closes more slowly, moving back to the midline at
occlusion. This deviation of the mandible tends to force broken food particles to fall toward
the tongue rather than toward the cheeks.
Why the speed differences here? Well, in early jaw opening, a large amount of sensory
information is being collected. Food particles that have just been broken by the teeth
have fallen toward the lingual side of the teeth. The tongue leaps forward to collect these
and pushes them against the hard palate. As it leaps forward, it dips its tip into the pool
of submandibular saliva and mixes this with the food particles. As these particles are
pressed against the hard palate, the tongue can assess the size of the group of particles
and, therefore, how wide to open the jaw. If the jaw does not open wide enough, then
the particles will not fit between the upper and lower teeth. The jaw always opens much
wider than necessary to accommodate the particles on the occlusal surface. As the tongue
moves back, it assesses how well the food particles stick together. We can sum up and say
that it is the surface properties of food particles that are being assessed during this early
opening period of a chewing cycle, that is, food particle shape and size, the total volume
of food particles, and the stickiness of the food. Sensing all this and responding to it
takes time, so early opening is slow. By late opening, all the decisions—such as “swallow
now or carry on chewing instead?”—have been made. So, late opening is faster.
Early closing is relatively stereotyped too, but in later closing, when the teeth are about
to hit the food particles again, the jaw slows. Make a mistake with jaw speed and you could
break your teeth. During late closing, the fracture properties of the food are being assessed:
how resistant the food is to being broken. Different food properties can be adapted to by
changing the angle at which the jaw (and thus the teeth) moves into the food. So the slow
phases of jaw movement reflect periods of sensory assessment of the food, the faster
periods more stereotyped movement. Note, however, that the overall speed of jaw
movement is not very flexible. It seems to be controlled by a central pattern-generating
mechanism in the brain stem. You can chew very slowly, but it is difficult to chew very fast.
Mastication is simply a succession of such chews. Since each chew is rather like a
rotary up-down movement, we talk of each chew being a chewing cycle. The exact jaw
movement varies from cycle to cycle, but we can stereotype it. During jaw opening,
movement is generally vertical. Early opening is slow, while late opening is fast. At the
start of closing, the jaw deviates quite rapidly toward one side of the mouth, the side
where food is going to be chewed. The jaw then closes much more slowly, moving back
to the midline at occlusion. This deviation of the mandible tends to force broken food
particles to fall toward the tongue rather than toward the cheeks.
Swallowing will be dealt with very briefly, but it raises important issues to do with food
particle stickiness that are relevant to processes like plaque formation around the teeth
and caries. Swallowing is a clearing process that is initiated voluntarily, but
later becomes reflex once food particles have been cleared from the tongue. For optimal
efficiency, the process should move chewed food particles as a set from the mouth down
to the stomach in one batch. Food clearance lower down the gut is not a problem,
because there is surplus fluid resulting from glandular secretions, and this flushes food
particles along from one step to the next. In addition, processing in the stomach turns
food into slurry, which in itself facilitates transport: peristaltic movements of the gut
shift pliant material much more easily than stiffer stuff (experiences with diarrhea versus
constipation are informative in this regard).
Although food particles are generally reduced to a low-millimeter size range by the
time swallowing occurs, experiments and surveys show that the decision to swallow is
not directly triggered by particle size (Lucas 2004). In particular, evidence shows that
there is often an inverse correlation in humans between the particle size reduction rate
and the size of particles at swallowing. Humans with full dentures, who have very slow
particle size reduction rates, often swallow extremely large particles. In experiments on
subjects with natural dentitions, changing the mouthful not only changes the number
of chews to swallow, it also changes the particle sizes that are swallowed. A very small
mouthful is always swallowed at smaller particle sizes than larger ones. It appears that
the rate of food particle size reduction is probably not being sensed. It does not have
any obvious end-point anyway and could continue indefinitely.
An important conceptual advance in the 1980s postulated that swallowing might
depend on a combination of two thresholds: particle size and particle lubrication
(Hutchings and Lillford 1988). Both of these involve sensory criteria that have to
be satisfied for swallowing to take place. So, for example, an ingested raw oyster
satisfies both size and lubrication thresholds on entry to the mouth and can be swal-
lowed immediately. In contrast, a slice of a mandarin orange, which is not reduced
in size by chewing, needs sufficient juice expressed from it for it to be swallowed; in
other words, it needs lubrication. Nuts have to be chewed both to reduce their size