Anthropology and oral health

Anthropology and oral health
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Contents
 Introduction
 Basic considerations
 Evolution of primate: primate phylogeny
 Steps in the evolution of man
 Recent human dental evolution:
 Traits in modern human dentition
 Anthropological basis for some dental diseases
affecting man
 Conclusion
 Bibliography

Introduction
 Man is the highest form of animal on this planet. Every one
of us must have at some point in our lives wondered as to
who and what we are and where we have come from?
 All the religions of the world have given their own
interpretation of the origin of the universe and the creation
of man. For e.g. The bible, stating that man had been
created in 6 days and in the creators own image. This view
was held by the western world for a long time.
Colonization and exposure to different races and discovery
of fossils which looked human and yet weren’t made many
scientists think of a different explanations for the origin of
man. The concept of evolution and natural selection
propounded by Darwin was responsible for giving rise to
new strains of thought.

What is anthropology
 Anthropology is the study of humans in all places
and at all times.
 Greek (anthropos=man, logos=the study of).

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History of the origins of anthropology:
 Anthropology is a recent discipline originating a
little more than a hundred years ago.
 The first course in the field was offered at the
University of Rochester (New York) in 1879.
 Modern anthropology has its roots in the European
expansion and colonization of the New World.

Various fields of anthropology:
A) PHYSICAL ANTHROPOLOGY.
 It is the study of people from a biological
perspective- focuses on the place of man in nature.
 It emerged as a search into the ancestry,
development, genetic, and other characteristics of
the human species.

physical anthropology
 Areas of interest:
 Evolution And Human Origins
 Human variation
 Primatology
 Dental anthropology
 Forensic anthropology

B) CULTURAL ANTHROPOLOGY
 Archaeology:
 Linguistics
 Ethnology

LIFE ON EARTH
The Concept of 'Deep Time'
 Assume the age of the universe is about 15 billion
years.
 If we imagine the time since the origin of the
universe as a calendar year,
 the imprint of life on earth Sept 25th.
 Dinosaurs would emerge  Dec 24th.
 Humans, latecomers upon the scene would at
last arrive on the final day, Dec31st.

Time line
Time line in years:
 Up to 25x106
Oligocene period
 25x106
– 5x106
Miocene
 5x106
– 2x106
Pliocene era
 2x106
– 12,000Pleistocene era
 12,000 onwards Recent

Linear time in three dioramas
 The first diorama 4.5 billion years, the
approximate age of the earth itself.
 The second diorama  4.5 million years of
hominin evolution. It is a story of bipedalism and
brains.
 The last diorama  45,000 years to include the
last of the great 'Ice Ages' of the Pleistocene, the
modern peoples of the Upper Paleolithic, the last of
the Neanderthals, and finally, the events of the
Holocene.

Evolution:
 Is defined as the origin and development of life
forms through time, of all species originating from
pre-existing species. It is an ongoing process being
the result of change produced by natural selection
and genetic change.'

The evolution process
The mechanisms of evolution are:
 Mutation
 Natural selection
 Recombination
 Gene flow

Types of evolution
Human evolution:
 Human evolution is the biological and cultural
development and change of our hominin ancestors
to modern humans.
Cultural evolution:
 Cultural evolution is the passing on of information
through teaching rather than just observation.

Terms: (2004 Science Week)
 Hominoids: are a primate super family
 Hominidae - the group consisting of all modern
and extinct Great Apes (that is, modern humans,
chimpanzees, gorillas and orang-utans plus all their
immediate ancestors). within the hominoid
superfamily

 Homininae: sub family consisting of tribes gorillini,
panini, hominini. I.e. it includes gorilla, chimpanzee
and the human species
 Hominini - a "tribe" within the hominids. The group
consisting of modern humans, extinct human species
and all our immediate ancestors characterized by a
number of features including bipedalism (including
members of the genera Homo, Australopithecus

HUMAN EVOLUTION: Primate
Phylogeny
 Modern humans  group of
mammals known as Primates.
The primates are:
 An ancient group of mammals
 Evolved in tropical forests and
all groups exhibit some
characters that reflect an
arboreal way of life

 Stereoscopic and color vision
 Opposable thumbs
 Prehensile tails
 All primates share a suite of physical features that
allows them to be classified into the taxonomic
order, Primatae.

 Today there are 153 different species of primates in
the world.
 Man; 1 genus, 1 species
 Lesser apes 4 genera, 11 species
 Greater Apes
 Old World monkeys: 14 genera, 72 species
 New World monkeys: 16 genera, 33 species
 Prosimians: 20 genera, 36 species

Evolution of primates:
 The primates evolved from insectivores at the
beginning of the Tertiary, about 65 Mya
Visual Predation Theory
 A hand with separate fingers and an opposable
thumb
 Good vision
 Occupy a new niche.
 Started eating different types,
 Developing different social systems.

 By around 30 Mya, a form of primate that shared
characteristics of both monkeys and later apes is
found in the fossil record. This is a fossil known as
Aegyptopithecus.

20Mya
10-20Mya
5-10Mya10-12Mya

 A tailless apelike creature evolved from
early monkeys about 15 to 20 Mya
 These were primitive forest-dwelling apes,
found in Africa (Kenyapithecus ) dry
woodland forests and
Europe( Dryopithecus)

 14 Mya A tailless
hominid, Sivapithecus –
fossil  shows marked
similarity to the present-
day Orangutan.
 the Ramipithecines,
lived in open woodlands
in India, Pakistan and
Turkey about 12 to 14
Mya ago.

 Proconsul, a small chimp-like
pongid that existed around 16
to 18 million years ago
 This fossil has been touted as
a potential common ancestor
for both chimpanzees and
man.

What led to the development of early
Climatic Changes
humans?

Mankind is the sum total of the
adaptive radiations of our ancestors

 Lemuroid radiation: primitive grasping
adaptation, with long digits and nails.
 Monkey radiation :complex of head, brain and
special senses emphasizing eyesight instead of
smell and hearing
 Australopithecines : upright walking which freed
the hands for tool use, and our unique foot.
 Early Homo species we inherit the use of tools,
fire and clothes. At sometime language also
emerged.

Hominins:
 By upright carriage and bipedal locomotion
 This freed hands for tool use and construction
 A large reorganized brain is another feature,
 A diminished face and teeth.

Steps in the evolution of man:

Early Human Phylogenetic tree:
 A phylogenetic tree is a graphical means to
depict the evolutionary relationships of a group
of organisms.

Humans have evolved form 2 species:
1) Australopithecine species
2) Homo species.

Graphic representation of human
phylogenetic tree

The Australopithecines
 The hominins split off from the apes about 5-7
mya.
 An older possible ancestor to Australopithecus sp.
has been found at dates ranging from 4.4 to 5.8
million years old and called Ardipithecus ramidus
(Australopithecus ramidus )

australopithecines
 They are found only in Africa, in the savannahs
 They walked upright,
 They had small brains (about a 1/4th
ours in size),
 Tool use was unlikely,
 And they had large protruding faces.
 They were highly dimorphic: males were about
twice the size of females.
 The Australopithecines had a three million year
career on Earth before dying out about a million
years ago.

AUSTRALOPITHECINES:
Are in general classified into two types:
 Gracile australopithecines
 Robustus species.

‘Gracile’ Australopithecines
Australopithecus Afarensis:
 Is Our most ancient ancestor
 Lived roughly 4 - 2.75 million years ago.
 Sexual dimorphism, varying from 1 - 1.7 m in
height and from 25 - 50 kg in weight.

A.afarensis
Features:
 Long curved fingers, long arms
relative to the length of their legs,
 Small brain capacity 450 cc.
 Had a large face relative to the
rest of the cranium. The forehead
is very small.
 The Zygomatic arches flair to the
side and produce the
characteristically broad face.

A.afarensis
Features…
 Sagittal ridge where strong
chewing muscles are attached.
 Marked prognathism of the face.
 The cranium attaches to the
backbone in a relatively
backward position when
compared with humans.

A.afaransis
Dentition status:
 Large pointed dimorphic
upper canines
 Angle and shape of the first
premolar
 Presence of primate spaces
 The molars are larger in size
than in modern humans

A.afarensis
Dentition status…
 The arcade is omega
shaped, intermediate
between the box row
in apes and the
parabolic curve in
humans

Australopithecus africanus:
 Inhabited the earth roughly 3 - 1.6 Mya
 The characteristic difference between
Australopithecus
africanus
Australopithecus
afarenis
Height 1.4 m 1.2 m
Brain
capacity
400 - 600 cc. 380 - 450 cc.
Other
features
Smaller incisor teeth
and a slightly flatter
face
Larger incisor teeth
and prognathic face

Australopithecus africanus…
 Smaller, more generalized
group.
 Direct descendent of A.
afarensis.
 The zygomatic arch is less
robust than other
australopithecines, and there is
no sagittal ridge or crest.

Dentition status:
 Specialized than the dentition of A. afarensis.
 The molar teeth are relatively larger in size than the
earlier form, for powerful chewing
 Wear on the teeth, viewed through an EM,
indicates that A. africanus ate comparitively soft
foods.
 This is in contrast to the grittier diet of the later
australopithecines, A. robustus and A.boisei

Compared to human dentition
 The size of A. africanus
teeth are larger
 The rows of teeth in A.
africanus are more parallel
rather than being parabolic
 The incisors are angled
forward instead of being
vertical in position,
Still, A. africanus dentition is closer to ours than any previous
hominid and more in line with that of early Homo that will follow.

Australopithecus robustus:
o From around 2 -1.2 Mya, southern Africa was
inhabited by a robust species of early human.
o Adaptations of the cranium were associated with a
"heavy-chewing complex." which enabled these
early humans to eat large amounts of tough, fibrous
foods.

australopithecus robustus
 The zygomatic arches -
cheek bones - are large
and positioned forward
on face, creating a
characteristic dish-
shaped face.
 They flare very wide,
creating a large space
between the arch and the
skull, and opening
known as the temporal
fossa.

A.robustus
 The foreward migration of
the cheekbones creates more
space for temporalis muscles to
pass under the zygomatic arch,
and to accommodate a larger
masseter muscle.
 In males, a prominent sagittal
crest, provides an anchoring
point for the large temporalis
muscles.

Australopithecus boisei.
 2.3 - 1.2 Mya, eastern Africa  early human
species Australopethecus boisei.
 Most extreme version of the ‘robust’ early
humans in eastern Africa.

A.boisei
 A, boisei had a skull highly
specialized for heavy chewing.
 Major change in Earth's climate,
which involved larger, irregular
fluctuation,
 The highly specialized A.boisei
might not have been able to effect
such adaptability in the face of
change.

Dental condition A. robustus and boisei
 Both had large, massive molars
larger than earlier hominid
molars.
 The incisors also were relatively
small.
 The jaw was relatively boxy in
appearance.
 EM examination of the wear on
the teeth indicates that the diet
was composed of hard plant
fibers and grit.

Dental condition A. robustus and boisei…
 Human jaws  400 pounds of
bite force but robust
australopithecines  exceeded
1,700 pounds.
 It was a specialized diet of high
fiber that led to this dramatically
well developed jaw along with
the massive molars.

HOMO SPECIES:
The authors B. Wood and M. Collard (Science 1999
284:65): present a revised definition for the genus
Homo. They suggest that a fossil species should be
included in Homo only if the following can be
demonstrated:
 More closely related to H. sapiens
 Estimated body mass more similar to that of H.
Sapiens

 Reconstructed body proportions that match those
of H. Sapiens
 Postcranial skeleton whose functional morphology
is consistent with modern human-like obligate
bipedalism and limited facility for climbing;

 Teeth and jaws that are more similar in terms of
relative size to those of modern humans
 Evidence for a modern human-like extended period
of childhood growth and development

Homo habilis
 First definite hominine in the fossil record
 Found only in Africa
 First hominid tool-user existing 2.5 million years
ago (“handy man”)
 Probably coexisted with australopithecines that
lived at the same time (around 2.0 mya)
 Bipedal, larger cranial capacity (700 cc) than
australopithecines (500 cc)

H.habilis
 Generally globular shape to crania.
 Also had some australopithecine
characters (dentition, humerus/femur
ratios, etc.)
 An “apelike” (long arms and a small
body) body structure was
characteristic of the Homo habilis.

H.habilis
Dentition status:
 The flat face and large molars resemble the
Australopithecus lineage.
 Molar teeth present a more squared outline and are
more identifiably modern
 The teeth as a whole, but particularly the posterior
teeth & canines have undergone a reduction in H.
habilis when compared to A. africanus.
 The third premolar ( ie of the primitive mammalian
type), which in Australopithecines tends to be as large
as or larger than the fourth premolar has now become
smaller, anticipating the modern condition.

H.habilis
 The grinding teeth, have generally lost their complex
enamel wrinkling (crenulations)
 The increase in the size of the brain and the diminution
of the teeth is reflected in the reorganization of the
skull.
 The cranial vault is now higher. The maxilla and
mandible are decreased in size and bone thickness
because the teeth are decreased in size.

H.habilis
 Because the dentition is not as large, the muscles of
mastication which move the teeth are not as
heavily developed.
 Thus, in Homo habilis the bony face protrudes less
(is less prognathous and more orthognathous), the
area medial to the cheek bone (zygomatic arch) is
smaller, the mandible is lighter in construction and
the temporal lines reveal a smaller temporalis
muscle.

Homo erectus:
 Homo erectus was a wide ranging species who
lived on earth for over a million years.
 It originated in Africa and was the first to move
out of Africa. The following are the established
'firsts' for erectus:

H.erectus
1. First hominids out of
Africa, going into
Europe and Asia during
the Pleistocene glacial
period maybe 300 000
years ago.

H.erectus
2. First to use systematic hunting
3. First 'home base' camps
4. First systematic tool-making
5. First use of fire
6. First extended childhood; sexual dimorphism now
only 20-30%

H.erectus
7. The evolutionary trends toward relatively greater
cranial capacity, orthognathy, dental reduction,
and greater body size which had begun in H.
habilis, continued in its descendants.

H.erectus
 Brain capacity of 800 - 1300 cc,
 The frontal and temporal lobes of the brain were
apparently less developed.
 The skull is lower and the face still protrudes more
than modern humans.

H.erectus
Dentition status:
 The jaws and teeth of H. erectus are still large
compared to those of modern humans but smaller than
those of earlier hominids.
 In particular, the sizes of the back teeth of H. erectus
are decreased compared to Australopithecines.
 The anterior teeth of erectus are larger than those of
modern humans.
 The upper central incisors are distinctively shovel-
shaped.
 Electron-scanning microscopic examination of erectus
teeth reveals a pattern of extensive meat eating.

Neanderthals: The Neandertal Man -
Homo neanderthalensis.
 The period between 100 000-40,000 years ago in
Europe and Asia, was characterised by the last Ice
Age
 Almost similar to H. erectus, but considered to be a
different species.
 27 differences between the human samples and that
of the Neandertals.
 The Neanderthals were of short build dominated by
enormous noses

H.neanderthalensis
 Their skeletons show that they had a very muscular
body.
 They had a barrel-shaped chest, slightly bent
thigh bones and stronger fingers and toes.
 They rarely lived past 45. Only 10% were aged
35 or over. That contrasts to a figure of about
50% for modern hunter/gatherers.
 Had severe arthritis, worn teeth, and fractures
like rodeo riders.

H.neanderthalensis
 Skilled stone tool technology
 They cared for their sick and elderly, had
intentional burials, and possibly practiced cave
bear cults.
 They suddenly disappeared about 35,000 years
ago, replaced by modern humans like us.

H.neanderthalensis
 The skull of the Neanderthals was dominated by
the large brain (average 1400 cm3, up to 1750 cc)
 Organization of the brain was different from that of
the modern humans.
 The Neanderthals had a smaller neocortex, which
gave the skull a relatively low forehead. At the
same time the skull was very long.

h.neanderthalensis
Dentition status:
 The jaw of the Neandertal
was massive and large,
and lacked a prominent
chin.
 The wisdom-tooth 
largest of the molars,
ample retromolar space
 This combined with
proximal wear and
physiological mesial drift
would mean no third
molar impaction
problems.

H.neanderthalensis
 Taurodontism
 Very large canines and incisors relative to their
molars and premolars.
 Exhibit very heavy wear on the front teeth, 
chewing hides or other materials.
 Mature relatively fast. Australopithecines
matured as nearly twice the rate of modern
humans. Neanderthals appear to have a similar
pattern. less time to learn a language.

Homo Sapiens
 200 000 - 300 000 years ago.
 The H.sapiens structure is similar to that of the
H.erectus, yet Homo sapiens skulls were slightly
rounder and larger.
 The forehead rises vertically above the eye orbits
and does not slope as in Neanderthal.
 The brow ridges are small.
 The face does not protrude very much (an
orthognathic face) and a strong chin is evident.

H.sapiens
 Their teeth and jaws were noticeably smaller,
which corresponds with, they're fragile face due to
the reduction of the masticatory apparatus.
 This implies reduced chewing and probably a
reduction in the use of teeth as tools
 Canines become less sexually dimorphic and they
no longer protrude past the occlusal plane.
 The Homo sapiens brain capacity averaged an
impressive 1 350 cc

Trends in human development
1) Bipedality

3)Dentition
 Are two basic directions in the
evolution of hominid dentition
 The first is for larger back teeth and
is associated with A. robustus and A.
boisei
 Specialized their diet towards
vegetation.
 Coupled with the large molars,
massive muscular structures to aid
chewing developed in these early
hominids.

 The other direction
 smaller teeth and a parabolic
shape to the palate.
 The decrease in the size of the
teeth is thought to be related of
a diet that included a wide
variety of foods.
 There was less emphasis on
plant foods that required heavy
chewing.

4) Specialization
 boisei represents a specialized
direction for hominids.
 The massive face, large
premolars and molars, and
sagittal crest each mark this
specialized form.
 Climatic changes

 First, did not possess the fire-bearing capabilities
of homo erectus.
 Second, they were dependent on a highly
specialized plant diet that may have undergone
modification in a cooler climate; H. erectus
enjoyed a much more varied and flexible diet. This
may have been a key to survival.

 There are obvious advantages to increased
brain capacity.
 Greater behavioral flexibility to adapt to
different environmental circumstances.
 Ability to manufacture more complex tools,
 Construct sturdier shelters,
 And use fire for warmth, protection and
cooking.
 It also was easier to transmit innovative
behaviors from one generation to the next.

 Large brains also have costs.
 A longer gestation period and extension of the
period of care for the infant following birth is
required as Much of the development of the
human brain occurs after the birth.
 The growth of the brain requires a high level of
energy intake for the mother not only during
the longer gestation (pregnancy) but for a
relatively extended period following.

RECENT HUMAN DENTAL
EVOLUTION:
Poetry from Brace et al, 1991.
Now dental reduction is fast,
And Man shall be toothless at last;
He eschews his chews,
And will choose to lose,
The teeth that he had in the past.

The ‘lithic’ time frames
 Anthropologists and others have divided the
time periods since the advent of stone tools 2.5
million years ago into three 'lithic' (Gr = of
stone) time frames.
 The Paleolithic (the 'old stone age') encompasses
the late Pliocene and all of the Pleistocene up to the
end of the last Ice Ages about 12,000 years ago.
 The Mesolithic (the 'middle stone age') which
began at the end of the Pleistocene, is seen as a time
of transition leading to the
 Neolithic (the 'new stone age).

Tooth size reduction:
 Tooth size began a gradual reduction during the
Upper Paleolithic at the rate of roughly 1% per
2,000 years until the end of the Pleistocene about
10,000 years ago.
 Beginning about 10,000 years ago, the rate of
reduction seems to have doubled to about 1%
every 1,000 years.

 Australian aborigines have not followed an
identical path. Even though Australian tooth size
has been decreasing since the late Pleistocene, that
tooth size has remained larger in proportion to
body size than was true even for 'classic'
Neanderthals of Western Europe.

 There are major
differences in tooth
size between the living
populations of the
world.

Why has reduction occurred?
Probable theories:
 Dental reduction is a result of facial reduction.
 Smaller teeth are an economic advantage; fewer
resources go into making smaller teeth.
 As early humans acquired culinary skills, teeth
ceased to have survival value
 Probable Mutation Effect.
When selection is suspended, the structure simply
deteriorates to a lesser version of its original
condition.

The Impact Of Technology On Tooth
Size:
 Improvement in Food preparation technology.
 Lack of paramasticatory functions--such as
processing animal skins.
 Cooking of meat. .
 Development of pottery and efficient stone
pounding and grinding
Accelerated the reduction of tooth size.

Other changes in teeth
 Decrease in sexual dimorphism in tooth size.
 More related to changes in male dentitions than
to changes in female tooth size.
 During the Upper Paleolithic and Mesolithic, males
become more gracile (slender, slim, or slight) at a
faster rate than females.
 This trend in males may be related to changes in
hunting patterns and the types of animals exploited.

Traits In Modern Human Dentition
 In the modern world, with convenient and rapid
travel, human populations are becoming more
diffuse. Yet, in many parts of the world,
boundaries are vigorously maintained by a variety
of social, cultural, and economic reasons
Variation in teeth:
 Metric variation is evaluated by making
measurements of teeth.
 Non-metric variation is the subjective judgement
of certain features. Ex. Carabelli trait

Metric Variation
1) Overall Tooth Dimensions,,
 Mesiodistal
 Buccolingual
 Crown height
1. Metric measurements have normal (Gaussian)
distributions.
2. In modern populations, it has been shown that
anterior tooth diameters vary inversely with
posterior teeth diameters.

2) Asymmetry in crown diameters
 Dental traits ordinarily exhibit a high degree of
symmetry.
 Directional asymmetry:
 Is where one side is consistently larger in a
population.
 A component of directional asymmetry
averaging + or - 0.06 mm is common in human
dentitions.

 Fluctuating (random) asymmetry
 It is where the largest side varies between
individuals.
 Greater than directional asymmetry.
 It appears to be slightly larger for the upper
dentition than the lower,
 And more so for boys than girls.
 Within one class of teeth, the more distal
members of a class are more asymmetrical than
the mesial members
 Asymmetry is more marked in children lacking
one or more of their third molars.

 Many animal studies have suggested that
bilateral symmetry is a key index of health in
choosing a biologically fit mate.

 Odontometric fluctuating asymmetry has been
associated with
 Congenital abnormalities,
 Genetic syndromes,
 Elevated levels of inbreeding.
 Stress caused by nutritional or disease factors
during development
Ex. Children of Tristan da Cuhna

Agenesis and variation of teeth:
 Agenesis of one or more teeth is one of the most
common of human developmental anomalies.
 Failure of one or more of the third molars to form
occurs in 20% of the population, upper& lower
second premolars (3.4%) maxillary lateral
incisors (2.25%).

 Polygenesis, the formation of one or more
supernumerary teeth occurs much less frequently
than agenesis.
 Agenesis and polygenesis has been reported for the
apes and Old World monkeys.
 The frequency of agenesis amongst the hominoids
is highest in humans and is found most frequently
in the molar region.

 More than 49 syndromes categorized in the On-line
Mendelian Inheritance in Man (OMIN) are
associated with tooth agenesis.
 This implies that there are common molecular
mechanisms for tooth or other organ development.
 Agenesis of numerous teeth is often associated
with congenital ectodermal dysplasia

Third molar agenesis:
 The absence of third molars has been associated
with an increased incidence (13 times) of other
missing teeth..
 Also predisposes for reduced size of the remaining
teeth and the delayed development of certain teeth.
 If a third molar is absent, the molars and premolars
of the same quadrant are delayed in formation and
eruption. This is especially true for the most distal
tooth in each class.

 Associated with crown-size reduction, particularly
of the lateral incisors, the second premolars. This is
more true in the female than the male.
 There is even evidence of reduced body size and an
increased incidence of prematurity, suggesting a
reduction of prenatal growth rates in affected
individuals.

 Third molar agenesis has also been linked to
diminished stability of specific molar cuspal
patterns.
 Reduction of the Carabelli cusp has been
associated with third molar agenesis.
 It is the anterior teeth, not the posterior teeth that
are the most affected by third molar agenesis.

EVOLUTION AND AGENESIS
 Teeth destined for evolutionary loss anticipate that
condition by increased variability in size, shape,
and/or agenesis.
 Butler's field theory and tooth agenesis
 Odontogenesis and epithelial-mesenchymal
interactions
 Molecular markers of odontogenesis

Non-metrical Variation in Tooth Form
 Metric traits vary in their expression, so
standardization is necessary.
 Non-metric traits have been especially useful in
tracking human migrations.
 Metric traits and non-metric traits are polygenic.
Several genes appear to be responsible their
production.

Sinodonts: Tracing Native American Origins
 It is a pattern of dental features that includes shovel-shaped
incisors, single-rooted upper first premolars, triple rooted lower
first molars and other attributes.
 Three-rooted lower first molars are reported in 25-40% of Eskimo-
Aleuts and 6% for most North American Indian groups.
 Earliest evidence for sinodonty comes from northern China in
about 18,000 B.C.. According to his calculations, the Sinodonts
migrated into Mongolia about 20,000 years ago and across the
Bering Strait about 14,000 years ago.

The Carabelli Trait
  Caucasoid populations
with a low level of frequency
of shovel-shaped incisors Vs
the Mongoloid populations,
which possess a high
frequency of shovel-shaped
incisors
 Used to Estimate times of
evolutionary divergence
between local races, their
ancestry, and migration
patterns of populations

Other commonly recorded variants
(1) Shovel Shaped Incisors
 In incisors, the marginal ridges
may be especially prominent and
enclose a deep fossa in the lingual
surface.
 90% Asians and Native
Americans  and lowest amongst
Europeans.
 Appears in Homo erectus,
suggesting that this is a very
ancient trait.

2) Uto-Aztecan Upper Premolar
 In the permanent upper first
premolar, the buccal cusp may
bulge out to the buccal with a
marked fossa in its distal
shoulder.
 Found only in Native Americans

(3) Protostylid of Lower Molars
 The protostylid is a feature on
the buccal side of the lower
molar crown
 It is seen especially on the
first or third permanent
molars or in deciduous lower
second molars.
 40% of a population.

4) Taurodontism
 The term was coined by Sir
Arthur Keith to describe the
'bull-like' condition in cheek
teeth
 .In living people it may appear
up to 5% in some populations; it
is prominent amongst the
Krapina Neandertal specimens

Some of the dental diseases affecting
modern man:
 Dental caries
 Periodontal diseases
 Malocclusion
 Enamel defects
 Third molar impactions
 All these conditions
were also present in the
stone age man, but to a
lesser degree when
compared to modern
man.
 What could be the
reasons?

1) Dental caries
Causes;
 Tooth morphology
 Diet
 Microorganisms
 Dental caries also occurs -- the great apes
( chimpanzees), have a diet most similar to our own
 Gorillas, primarily leaf eaters, lower rate of dental
caries.
 The orangutan in intermediate between chimpanzees
and gorillas.
 In the most ancient hominins, the incidence of caries is
less than 1%.

 There has been a sporadic, but generally
increasing caries prevalence over the past 5,000
years.
 During the first 4,000 years there is a gradual
increase in caries prevalence ranging from 2 to
10/100 teeth
 Followed by a sharp rise at about the year 1000
A.D. to 24 /100 for 3 out of 4 populations.
 The year 1000 A.D. is the approximate date for the
introduction of sugar cane to the Western world.

 In SAM these areas do not retain food as they are
being constantly agitated by hard, coarse, fibrous,
gritty food leading to occlusal and proximal attrition
of the teeth and loss of food retentive areas.
 But in civilized man
 Cariogenic soft and pappy diet.
 Lack of occlusal attrition
 Lack of proximal attrition

2)Malocclusion
 There is a tendency amongst non-technologic
human societies for virtually all individuals to
show a nearly ideal occlusion.
Malocclusion arises from the lack of chewing
stress with the modern processed diet. This disuse
has reduced jaw growth and increased the
incidence of occlusal variation.
 Ex. A rural community in the Mammoth Cave
region of central Kentucky

 In 1954, Begg  low incidence of
malocclusion in SAM  reduction by more
than half an inch in the total length of each of
his dental arches.
 This was caused by tooth attrition so that the
smaller crowns (in mesiodistal diameter) could
be more easily accommodated into the jaws.

 Though Begg overestimated the amount of tooth
material lost as a result of attrition, his concept of
attrition occlusion can be considered to be one of
the contributing factors in the development of
malocclusion.
 There are two reasons for the lower incidence of
malocclusion in SAM:
 Attrition of the teeth which eliminates tooth
irregularity and crowding
 Severe forms of these malocclusions were
detrimental to their survival

Types of malocclusion and the extent of
severity in SAM
 Class 1 malocclusion: a minor handicap.
 Similarly for class 2 div 1.
 Class 2 div 2deep incisor overbite inhibits lateral
masticatory movements of the jaw and hence he
cannot masticate his food properly, Faster and
rapid attrition  bacterial infection.
 Class 111 malocclusion is also detrimental because
of the low survival value.
 X-occlusion

THIRD MOLAR IMPACTIONS
 Humans evolved in a high dental attrition
environment. Though there was tooth material
excess, Mastication of tough foods caused
occlusal and proximal attrition+ physiological
mesial drift,  increasing retromolar space as they
age.
 The delayed eruption of the third molar 
evolutionary adaptation to interproximal wear of
the cheek teeth.

 The recent secular trend in increasing impactions is
not related to genetic change in humans.
 But is a response to a soft food diet  lack of
interproximal wear of the teeth,
 Narrower dental arches  disuse  shorter dental
arches
LESS SPACE AVAILABLE DISTAL TO SECOND
MOLARS

Other causes for impaction and malocclusion
 Increasing brain size
reduces space available
for oral features.
 The influence of
language on the oral
system

Periodontal diseases:
 Diet change  lack of continual friction on
gums
 Lack of occlusal wear added on by physiologic
eruption of teeth
 Lack of proximal attrition

Enamel defects:
Transition from hunter-gatherer subsistence to
agriculture.
 Increased reliance on one food resource carries risk
of seasonal nutritional deficiencies.
 Increased sedentism might enhance transition of
childhood diseases.
 Settled life, development of social stratification,
and concentrations of wealth and power in society
that higher status individuals had fewer dental
defects. They were better fed

Social and political causes of disease:
 In anthropology, four levels of political organization
are recognized.
 (1) Bands are just dozens of people, a small group of
related people, who are typically nomadic and do not
have formal leadership. Band organization is
historically ancient; all of the humanity lived this
way before 12,000 years ago. They subsist on
hunting and gathering. Nature is their storehouse.
 (2) Tribes are largely loosely knit groups of a few
hundred of people with informal leadership in an
organization based on kinship by blood or marriage.

 (3) Chiefdoms are thousands of people with power
consolidated in a council or a single leader. Such a
society now has classes with differences in wealth,
prestige, and power. Wealth held by the elite is often
accumulated by tribute, a technique just short of
taxation.
 (4) States have, since their origins 5300 years ago
They have social classes with extreme differentials
in wealth, prestige, and power. They have armies,
taxes, the power to coerce, bureaucracies, and a
leadership based on religious or secular ideas.

Politics has shaped human destiny.
 Human conflict results between peoples out of phase
in history.
 It is what happened when Europeans reached out
into Africa, the Americas, and the farthest corners of
the globe.
 They went armed with their technology, military
skill and political power. Unknowingly they were
also armed with their epidemic diseases, but they
thought it was the will of their Almighty God when
disease decimated aboriginal peoples.

CULTURAL CAUSES OF DISEASES:
Cultural modification of teeth
 The Unintentional
Alteration Of Teeth
1) Habits
Clay-stemmed pipes

2) Teeth as Tools
(Paramasticatory Behavior)
 used their teeth when their
fingers couldn't do the job.
 When distinctive occupational
wear of the teeth is reported, it
is often described as task-
related wear.

Intentional Modification Of Teeth
Ablation (L = ablat, to remove), the intentional
removal of teeth.
 This has been recorded for a number of
contemporary societies, especially in Africa and
Australia.
 Usually with a pointed stick, often the sharp hard
end of a spear, struck with a rock.

 Deliberate staining of teeth has been documented;
a cultural ideal totally different from our own.
 In French colonial Annam (now Viet Nam),
every Annamese of either sex was expected to
have his/her teeth blackened by a process said to
be very painful. "Any dog can have white
teeth," they say. To them, white teeth are not
only ugly but immoral!
 The Iban people of Borneo both blacken and file
their front teeth.

Chipping of teeth
 The filing of anterior teeth for cosmetic reasons.
African cultures
 An unusual permanent canine abnormality in
Uganda has been traced to the folk belief that
infantile fever originates in the deciduous canine
teeth. The deciduous teeth, usually the lower, are
removed in a crude fashion with resulting damage
to the developing tooth germ

Cross-hatch pattern
 labial surface of the tooth.
 Done carefully, this
technique was probably the
least likely of the techniques
to involve the pulp of the
tooth.

 Incrustations of
the teeth. (Jewel
inlays)
 This technique required
great skill, and probably
began in the Pre-Classic
(100 BC-300 AD).
Pyrite, jadeite, turquois,
or gold would be set into
the labial surface of the
teeth.

Conclusions:
 Inquiry is what anthropology is about. It is a
search, an investigation into what we are now,
from whence we came and how we got to be the
way we are today.
 To divine the future of man it is necessary to look
back into past and search for clues left behind in
the sands of time.
 The study of man and his evolution is not complete
and additional knowledge will only help us
understand ourselves better.

Bibliography:
1. Various websites on Anthropology and human
evolution and changes in oral health
2. Begg orthodontic theory and technique 2nd
edition P.R Begg, P.C Kesling 1971
3. A Colour Atlas and Textbook of Oral Anatomy
B.K.R Berkovitz, G.R Holland et al

Bibliography…
4. An update on the refinements in Begg treatment:
course conducted by: Indian orthodontic society
S.D.M college of dental sciences June 1993.
Attrition occlusion today -A contemporary
reassessment by Dr. K Jothindra Kumar
5. The anthropology of modern human teeth, Dental
Anthropology and its Variation in Recent Human
Populations – G. Richard Scott and Christy G.
Turner
6. Oral Diseases of the Tropics – Prabhu

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