dentition of a mesolithic population from wadi halfa, sudan

Dentition of a Mesolithic Population from Wadi Halfa, Sudan '

DAVID L. GREENEP GEORGE H. EWING3 AND GEORGE J. ARMELAGOS 2 University of W y o m i n g , Laramie, W y o m i n g ; 3 Universi ty of Colorado, Boulder, Colorado; Universi ty of Utah, Salt Lake City, Utah

ABSTRACT The dentition of a Mesolithic population (8,000-11,000 years old) from Wadi Halfa, Sudan, can be characterized as morphologically complex, massive and relatively free from pathology except that associated with extreme wear.

Maxillary incisors show shoveling. All of the maxillary molars show some development of the hypocone. Supernumerary cusps appear frequently. Almost one-half of the second lower molars observed show distally located third cusps. Over one-half of the maxillary third molars show an extra cusp. A high percentage of mandibular molars show six cusps.

Overall the teeth from this population compare favorably in size with those of an Australian aborigine tribe and are slightly larger than the teeth of the Neanderthaloids from Skuhl.

The teeth show wear of a degree greater than that found in present day Eskimo or Australian aborigine groups.

This data may be intcrpreted as indicating that this Mesolithic group was subjected to rigorous selective pressures favoring large and/or morphologically complex teeth. This pressure was apparently intensive wear, presumably caused by the inclusion of large amounts of grit in the diet through the eating of vegetable food macerated on coarse grinding stones.

During the 1963-1964 field season of the University of Colorado's Nubian Expe- dition, a series of 39 permineralized fossil skeletons were discovered by expedition archaeologists and excavated by the expedition's three physical anthropologists (George Armelagos, George Ewing and David Greene) . Preliminary analysis by the archaeologist directly responsible for this site, Arthur Saxe ('66), indicates that it has Mesolithic affinities and is at least 8,000-1 1,000 years old.

The site from which the skeletons were uncovered, given the designation 6-B-36, lies between 31 and 35 m above the mean Nile level at Wadi Halfa. This is about 151 to 155 m above the mean sea level at Alexandria and back 2.5 km from the Nile into what is now desert. Lithic material recovered from living areas on the site has been included in the Wadi complex of Wheat and Irwin ('65) and appears to be similar to the Quadan complex described by Shiner ('65) and Wendorf, Shiner and Marks ('65).

Most of the 39 skeletons were deliber- ately buried as single and double inter- ments and were oriented with their heads

to the southeast. There was also a large burial complex in which orientation of the skulls varied from east to south. The burials were usually flexed, lying on their left side, except for one individual resting on his back.

Preliminary descriptions of these skeletons have been made elsewhere (Hewes et al., '64; Armelagos et al., '65). Impor- tant aspects of the skeletal morphology with regard to the dentition as part of a functioning morphological complex are the existence of structures that indicate heavy masticatory musculature. Tempo- ral lines on the frontal bone are heavily marked and most of the skulls show a pronounced glabellar protrusion which arches and diminishes laterally to a point approximately above the supraorbital fo- ramina. These cannot properly be called tori but they probably bear a functional relationship to masticatory stress by pro- viding struts against lateral stresses in the frontal bone (Ewing, '66). The mandibles also show features related to heavy mas-

IField work for this study was in part financed through National Scienoe Foundation Grants GS-7, GS-286, and GS-557. (Principle Investigator: Dr. C . W. Hewes.)

41 AM. J. Pays. ANTHROP., 27: 41-56.

42 DAVID L. GREENE, GEORGE H. E W I N G AND GEORGE J. ARMELAGOS

Fig. 1 Typical individual from 643-36 showing marked temporaI lines, gIabelIar protrusion, gonial eversion and a massive mandible all indicative of heavy masticatory musculature.

ticatory musculature. Many show pro- Morphology nounced gOnid eversion and in general are massive with heavy bodies and broad ascending rami.

The dentition from site 6-B-36 can be characterized as morphologically complex and massive. Almost all individuals, where

DENTITION O F A MESOLITHIC POPULATION 43

the observation is possible, show some degree of lingual elaboration, or shoveling, of the maxillary incisors. Because of post- mortem loss and the high degree of dental attrition present in this population, only 11 individuals have incisors on which this trait can be observed. Four of these have deciduous incisors; all have distinct labial ridges and slight fossae which correspond to what Hanihara ('61) calls semishoveled deciduous teeth. Two of the individuals with permanent teeth show no indication of shoveling; five have what HrdliEka ('20) called trace shoveling (distinct traces of the enamel rim); one has a distinct enamel rim plus a shallow fossa (semishoveled), and one has a marked enamel rim and a well developed fossa (shoveled). Most of the maxillary incisors also have finger-like projections running on the lingual surface from the basal tubercle to the incisal edge similar to those on teeth from Jarmo, described by Dahlberg ('60).

As would be expected (HrdliEka, ' 20 ) , shoveling is not as prominent in the mandibular incisors. Two out of eight individuals with permanent teeth show very slight development of marginal ridges that might be classed as trace shoveling.

Lingual elaboration or shoveling con- tinues into the maxillary and mandibular canines. This observation has been made in other populations (Hanihara, '61 ). Gen- erally, both upper and lower canines are monocuspid teeth with noticeable mesial and distal lingual marginal ridges which produce the shoveled contour. Of the eight individuals with maxillary teeth and a similar number with mandibular teeth, none show noticeable development of cinguli.

Ten individuals have observable maxillary premolars. In both the first and second premolar, the lingual and buccal cusps are almost equally developed with the buccal being only slightly larger. Most have well marked mesial and distal marginal ridges which are occasionally bisected by a central groove.

Mandibular first premolars are bicuspid with a noticeable lingual cusp. Two individuals out of nine have lingual cusps ap- proximating the size of their buccal cusps. All have well marked mesial and distal pits and those with larger lingual cusps

have well developed triangular ridges con- necting with the buccal cusp.

All nine individuals observed with mandibular second premolars have well developed lingual cusps. Five of these exhibit bilaterally a third distal lingual supernumerary cusp. In general, these teeth have mesial and distal pits, but the triangular ridge is not as well developed as in the first premolars.

Permanent molars are also morphologically complex. All ten of the individuals observed have well developed hypocones on their maxillary first molars. Second maxillary molars show more variation. Only one individual has a well developed hypocone, five show a slight reduction in the size of the hypocone and three show reduction of the hypocone to a cuspule. Although third molars show a wide range of morphological variation, (Dahlberg, '45) this sample of 12 individuals is relatively homogene- ous. Two individuals have molars with only a slight reduction in the hypocone, two show only a cuspule for a hypocone, while one has no hypocone. Seven have fifth cusps which were probably produced by a splitting of the hypocone. In the three cases where both right and left teeth were present, this morphological variant was bilaterally expressed. In a very large sample from historic Nubian populations, this oc- curred bilaterally with a highly significant association (0.01 2 P 2 0.001) between left and right sides of the jaw (Greene, '65). Such mirror imagery in a bilateral structure suggests that this split hypocone variant has a genetic basis.

Some of the maxillary molars present show elaboration of the lingual side of the protocone in the form of cusps, pits and grooves. Some dental anthropologists feel that the pits and grooves that occur a t this location are not part of the same morphological complex as the cusps. They restrict the term Carabelli Trait or Carabelli Cusp to the various gradations of cusps that may occur (Weidenreich, '37; Hanihara, '63). Other dental anthropologists (Korenhof, '60; Kraus, '51) include cusps, pits and grooves in the same complex. Carabelli phenomena when iound are not restricted to any particular maxillary molar. They can occur on any of the maxillary molars including the second deciduous molar

,44 DAVID L. GREENE, GEORGE H. EWING AND GEORGE J. ARMELAGOS

Fig. 2 Mandible showing second premolar with a supernumerary third cusp located distally on its lingual surface. The right third molar, and possibly the second and first as well, has six cusps.

(Dietz, '44; Tsuji, '58). In this sample, 4 out of 12 individuals with first maxillary molars display some elaboration of the lingual side of the protocone (one pit; one slight cusp with groove; two medium cusps). Two individuals out of ten show pits or grooves on their second molars. And 2 out of 12 have slight cusps on their third molars.

Cusp number and fissure pattern in mandibular molars are probably indepen- dent morphological and genetic variables (J@rgenson, '55; Greene, '65); so their occurrence is listed separately. With regard to the first mandibular molar, all 11 individuals with relatively unworn cusps show

five distinct cusps. Six of these individuals have supernumerary sixth cusps located between the metaconid and hypoconulid. Supernumerary cusps in this location have been termed C6 (Nelson, '38). In the three cases where individuals retain both left and right teeth, this variant is bilateral, Out of 11 individuals with second mandibular molars, five have at least five cusps with two of these also having supernumerary C6 cusps. Out of ten individuals with third mandibular molars, five have five cusps with three of these also having C6 supernumerary cusps. The remaining five individuals have only four cusps on their third mandibular molars.


Fig. 3 Maxilla showing incisor shoveling, slight canine shoveling, and left first molar with a small Carabelli Cusp.

Fissure patterns on the mandibular molars can vary from a Y pattern (Dryopithe- cine) to a + (crucilorm) pattern (Hell- man, '28). The Y pattern occurs in seven out of nine individuals with first molars, 5 out of 11 with second molars, and none out of six with third molars. All of the re- mainder show cruciform patterns.

Two individuals with maxillary third molars and two each with mandibular first, second, and third molars have wrin- kled enamel comparable to that found in the dentition of a Neanderthal child described by Carbonell ('65 j .

Two individuals show some evidence of the protostylid. One has pits on the mesial buccal surface of the protoconid of its second mandibular molars which are not in contact with the buccal groove. The other shows a medium-si7ed cusp on the left third mandibular molar and a pit on the right third mandibular molar.

Comparing the dental morphology of incisors and molars of the 6-B-36 population with that of a later Meroitic population from the same geographical area which

dates from 350 B.C. to 450 A.D. indicates that the Mesolithic population displays a higher frequency of supernumerary cusps in both maxillary and mandibular molars, a higher frequency of maxillary molars with well developed or just slightly reduced hypocones, and a higher frequency of shoveling in the maxillary incisors.

Odontornetry Two basic measurements were taken on

individual teeth (following Moorrees, '57) : ( 1 j Mesiodistal crown diameter: the

greatest mesiodistal diameter of the tooth crown, measured parallel to the occlusal and labial surfaces.

(2 j Buccolingual or labiolingual crown diameter: the greatest distance between the labial and lingual surfaces at right angles to the mesiodistal crown diameter.

Crown height was not measured since the majority of teeth show extensive occlusal wear. Also, root length measurements were not obtained since most of the teeth were still in alveoli. Measurements were not taken in any case where wear

46 DAVID L. GREENE, GEORGE H. EWING AND GEORGE J. ARMELAGOS

TABLE 1

Comparison of t h e morphological complexi ty of the dent i t ion f r o m the Mesolithic populat ion (64-36) with t h a t f o u n d in a Meroitic populat ion

Maxilla

6-B-36 Meroitic

Mandible

Meroitic 6-B-36

I Shoveled Normal

M' 4 4-

M2 4 4- 3 + 3

M3 4- 3 + + 3 + 3

% n % n 88 ( 9 ) 31 (22) 12 ( 2 ) 69 (48)

100 (10) 69 (33 ) 31 (15)

% n % n 25 ( 2 ) - - 75 ( 6 ) - -

Mi 6 54 (6) 8 ( 3 )

4 12 (4 ) 5 46 (5 ) 80 (29)

Mz 6 18 ( 2 ) 5 2.7 ( 3 ) 15 ( 7 ) 4 55 (6) 85 (41)

Mt 6 30 ( 3 ) 3 ( 1 ) 5 20 ( 2 ) 50 ( 1 7 ) 4 50 ( 5 ) 47 (16)

n, the number of individuals with a specific trait. 4, maxillary molar with well developed hypocone. 4 -, maxillary molar with reduced hypocone. 3 + maxillary molar with hypocone reduced to cuspule. 3 +I+, maxillary molar with split hypocone. 6, manibular molar with six cusps. 5 manibular molar with five cusps. 4: mandibular molar with four cusps. Shoveled, some trace of shoveling in the incisors. Normal, no shoveling in the incisors. The Meroitic data is from Green ('65) and this study did not include data on shoveling in the

mandibular incisors.

could have produced noticeable error. In those measurements taken, the greatest error is probably in the mesiodistal diameter of the incisors since occlusal wear of any degree can change this dimension. It should also be noted that, since the number of measurements in each class is very small, no attempt is made to deal with sample variance aside from listing the range for each measurement. Only one proportional index was computed - the Crown Index obtained by dividing the me siodistal diameter by the buccolingu al and multiplying by 100 to give a measure of the length-width relationships of the tooth crowns.

Measurements were made on a vernier sliding caliper accurate to 0.1 mm. All measurements are entered in millimeters. All measurements are from left teeth.

A comparison of the teeth from 6-B-36 with those of other populations gives an indication of their relative size. The populations used in this comparison are Sinan- thropus (Weidenreich, '37), Skuhl (Coon,

'62), Australian Aborigine (Campbell, '25), Bantu (Shaw, '31), Pecos Indians and American Whites (Nelson, '38). in order to approximate overall bulk, buccolingual and mesiodistal mean diameters are summed for all teeth in a class (i.e., all incisors, all premolars, all molars). No distinction is made between the sexes since none was made in several of the com- parative studies. Since these samples vary in number, ranging from 4 to over 100, it is not practical to apply statistical tests of significance to the differences observed.

The mean for the summed measurements of all tooth classes is 256.5 which is close to the median populational value of 256.8 represented by the Skuhl material. Generally, if the samples are representative, the population from 6-B-36 with a value of 262.5 has above average size teeth when compared with the size variation present from Middle Pleistocene (Sinan- thropus) to modern populations. Teeth of all classes in 6-B-36 are almost as massive as those of the aboriginal Australian popu-

DENTITION OF A MESOLITHIC POPULATION 47

lation which has the largest teeth of the recent populations considered. Overall, the teeth from 6-B-36 are larger than those from Skuhl. However, anterior teeth from 643-36 are smaller than Skuhl anterior teeth, while its posterior teeth, especially the mandibular premolars, mandibular molars and maxillary molars, are noticeably larger.

Attrition Wear was assessed using a scale devel-

oped by Brothwell ('63) for molars. This was modified for the anterior teeth. Cate- gories of wear in the premolars and possibly the canines are equivalent to those in the molars because basically these are cusped teeth. Wear for the incisors is more difficult to assess, but a n approximation was made which we believe to be adequate.

Individuals from 6-B-36 fall into three dental age groups : those with deciduous molars; those with all permanent teeth but with unerupted third molars; and those with all permanent teeth erupted. Chrono- logical ages for these groups are estimated following Scott and Symons ('64).

Three individuals have deciduous molars. Of these, one represented by the right half of its mandible shows a completely developed first permanent molar crown still unerupted in its crypt, indicating an age of from two and one-half to three years of age. Its deciduous incisors and canines were lost post mortem. Its deciduous molars show no indications of wear. The other two individuals in this group have permanent first molars, lateral and medial incisors, as well as both deciduous molars, and are somewhere between six

TABLE 2 iMasiElary huccolingual, mesiodistal diameters a n d crown indices f rom t h e

Mesolithic populat ion (6-B-36) in mill imeters

33-L M-D c-I - I X 11 r X n - - n 1 X

I' male 1 - 8.1 1 - 10.3 1 - 78.6 2 71.1- 74.0 72.6 5 71.1- 78.6 75.1

I2 male 1 - 6.8 1 - 8.1 1 - 84.0 female 3 6.5- 7.4 6.9 3 6.9- 7.9 7.6 3 89.0- 96.1 90.8 all 5 6.5- 7.4 6.8 5 6.9- 8.1 7.6 5 84.0- 96.1 90.1

C' male 2 8.4- 8.9 8.7 2 7.2- 7.8 7.5 2 107.7-123.3 115.5 female 2 7.9- 8.7 8.3 2 7.3- 8.0 7.7 2 108.2,108.8 108.5 all 4 7.9- 8.9 8.5 4 7.2- 8.0 7.6 4 107.7-123.3 112.0

P3 male 4 9.1-10.9 10.0 4 7.3- 8.3 7.7 4 118.2-143.8 130.5 female 4 8.1-10.1 9.4 4 7.4- 8.0 7.7 4 108.0-132.4 122.9 all 9 8.1-10.9 9.7 9 7.4- 8.3 7.6 9 108.0-143.8 127.1

P4 male 4 9.0-10.9 10.2 4 7.1- 8.0 7.7 4 112.5-149.3 134.1 female 4 9.1-10.6 9.8 4 6.5- 7.5 7.1 4 135.6-141.3 138.0 all 8 9.0-10.9 10.0 8 6.5- 8.0 7.4 8 112.5-149.3 136.1

female 2 6.9- 7.1 7.0 2 9.6- 9.7 9.7 all 5 5.5- 8.1 7.3 5 7.2-10.3 9.8

M' male 3 12.2-13.0 12.7 3 10.4-12.0 11.4 3 108.3-117.3 111.6 female 4 11.5-12.5 12.2 4 10.1-12.1 11.2 4 102.5-114.7 106.4 all 8 11.3-13.0 12.3 8 10.1-12.1 11.3 8 97.4-117.3 107.2

MZ male 5 12.0-13.2 12.6 5 9.7-11.5 10.5 5 114.8-126.5 120.1 female 4 11.2-12.5 11.9 4 9.7-11.7 10.8 4 104.6-116.8 110.9 all 9 11.2-13.2 12.3 9 9.7-11.7 11.1 9 104.6-126.5 116.0

M3 male 4 10.6-13.2 12.0 4 8.3-10.7 9.4 4 123.4-133.7 127.5 female 6 10.8-13.4 11.7 6 8.3-10.5 9.3 6 117.2-130.1 125.1 all 10 10.6-13.4 11.8 10 8.3-10.7 9.4 10 117.2-133.7 126.0

n, number of teeth measured. r, range. x, mean. The all category contains at times more than the sum of the males and the females because in

- some cases individual sex determination was not possible and these are included.


TABLE 3

Mesolithic population (6-B-36) in millimeters andibular buccolingual, mesiodistal diameters and crown indices from the

B-L M-D c-I - n r X r X n r X n - - - - - - - - - - 11 male -

female 3 6.2- 6.5 6.3 3 5.4- 5.9 5.6 3 106.8-120.4 112.6 all 4 6.1- 6.5 6.3 4 5 . 4 6.0 5.7 4 101.7-120.4 109.9

- - - - - - - - Iz male - female 2 6.7- 6.7 6.7 2 6.1- 6.4 6.2 2 104.7-109.8 107.2 all 3 6.5- 6.7 6.6 3 6.1- 6.4 6.2 3 104.7-109.8 107.0

C1 male 2 8.3- 8.3 8.3 2 6.9- 8.5 7.7 2 97.6-120.3 108.9

all 4 7.7- 8.3 8.1 4 6.9- 8.5 7.4 4 97.6-120.3 109.7

Pa male 3 8.9- 9.5 9.3 3 7.3- 7.9 7.6 3 112.7-130.2 122.1 female 2 8.3- 8.5 8.4 2 7.4- 7.5 7.5 2 110.7-114.9 112.8 all 5 8.3- 9.5 8.9 5 7.3- 7.9 7.6 5 110.7-130.2 118.4

female 1 - 7.7 1 - 7.1 1 - 108.5

P4 male 3 9.6-10.2 9.8 3 7.9- 8.1 8.0 3 118.5-125.9 121.9 female 2 8.0- 8.8 8.4 2 6.7- 8.1 7.3 2 111.4-119.4 115.4 all 5 8.0-10.2 9.2 5 6.7- 8.1 7.7 2 111.4-125.9 119.3

MI male 1 - 12.7 1 - 12.5 1 - 101.6 female 5 10.1-12.5 11.7 5 10.9-13.2 12.1 5 92.7-100.0 96.2 all 9 10.1-12.7 11.5 9 10.9-13.2 12.1 9 89.2-101.6 95.3

M2 male 4 11.2-13.2 12.0 4 11.1-13.4 12.2 4 95.8-100.1 99.0 female 4 9.5-11.7 11.0 4 9.9-12.2 11.2 4 95.8-100.9 98.0 all 8 9.5-13.2 11.5 8 9.9-13.4 11.8 8 95.8-100.9 98.5

Ma male 4 10.7-12.4 11.7 4 10.9-13.5 12.1 4 89.6-113.8 97.3 female 2 10.9-11.6 11.2 2 11.2-11.3 11.2 2 96.5-104.6 100.5 all 6 10.7-12.4 11.5 6 10.9-13.5 11.8 6 89.6-113.8 98.3

n, number of teeth measured. r, range. x, mean. The all category contains at times .more than the sum of the males a?d the females because in

- some cases individual sex determinatlon was not possible and these are included.

TABLE 4

f rom the Mesolithic population ( 6 - B 3 6 ) with those f rom other selected populations

Population Imax Iman Pmax Pman Mmax Mman Sum

White 28.4 23.7 31.9 29.9 61.9 62.8 238.6 Pecos 29.5 23.6 33.5 30.9 63.4 65.8 246.7 Bantu 29.6 23.9 32.3 30.6 63.3 64.3 244.0 Skiihl 32.2 26.0 36.0 31.6 65.7 65.3 256.8 6-B-36 31.5 24.8 34.8 33.0 68.2 70.2 262.5 Australian 31.3 25.6 35.4 33.0 70.5 71.4 267.8 Sinanthropus 34.7 27.1 39.4 37.2 68.4 72.3 279.1

Ranked metric comparison o f the summed meun buccolingual and mesiodistal diameters

Note: In this comparison sample sizes used in determining mean buccolingual and mean mesiodistal diameters for each todth vary for each population listed from 4 I1 (Sinanthropus) to 100 I1 (Pecos Indians). Approximately the same range in sample size exists for the other teeth. The assumption is made in this paper that the means based upon these samples are representative of the populational means.

and nine years of age. Both of these show wear on their deciduous molars equal to Brothwell's scale 4 with dentin exposed and linking the cusps. None of their permanent teeth show wear.

Davies and Pedersen ('55) report that Eskimo children subsisting on the native diet of meat and fat show wear by the age of eight to nine that only exposes dentin on the tips of molar cusps in the decidu-

DENTITION OF A MESOLITHIC POPULATION 49

TABLE 5

Wear scale

1 - no wear

2 - enamel abraded

3 - dentin barely exposed on cusp tips (or occlusal surface of incisors)

4 -dentin exposure links most of the cusps (occlusal surface of incisors medium worn)

5 - Most of cusp area enamel worn away only leaving enamel in deep fissures (occlusal surface of incisors very worn)

6 - crown worn away

(Intermediate grades indicated by +.)

ous dentition. The children from 6-B-36 apparently were subjected to greater degrees of attrition than the Eskimo children. In several cases coarse grinding stones were found associated wtih the burials (Saxe, '66). It may be presumed that they were used for macerating vegetable foods and as they were used they produced grit which mixed with the food and acting as an abrasive wore away the teeth.

Two individuals have all permanent teeth but with unerupted third molars that have completely developed crowns. This indicates that they are between 12 and 16 years of age. One of these shows wear on his maxillary and mandibular medial incisors equal to Brothwell's scale 2 with abrasion of enamel surfaces. None of his other teeth are worn. The other individual shows greater wear. His canines, second molars and premolars show wear equal to scale 2 while his third molars and incisors show wear equal to scale 3+ with dentin moderately exposed on occlusal surfaces. Beyron ('64), in analyzing dentitions of the Walbiri tribe in Australia, found that 12 out of 24 individuals between the ages of 15 and 24 showed no enamel abrasions (Broca's Stage I ) and that the other 12 showed at most some enamel abrasion but no exposure of dentin (Broca's Stage 11). Wear found in the 12- to 16-year-old individuals from 6-B-36 is greater than that found in a somewhat older Australian group.

The diet of the Walbiri tribe consists of 70 to 80% vegetable food of which most consists of wild seeds. These seeds are

ground on stones to form a coarse meal which is then consumed (Meggitt, '57). This type of diet is likely to introduce a certain amount of abrasive material (stone particles) aside from hard seeds into mas- tication. The 6-B-36 diet must have con- tained a greater proportion of abrasive material than the Australian one. Again a possible source of this abrasive material could be the very coarse grinding stones found associated with some of the burials.

The third dental age group is much larger than the first two. It consists of all those individuals that have or had their complete sets of permanent dentition erupted. It includes individuals from 17 years of age and older. Ideally, this group of adults should be analyzed for wear with regard to age groups. Unfortunately non- dental information for the assessment of wear is not available for most of the speci- mens. Pubic symphyses are missing or shattered. Stresses produced by soil over- burden and geological action at the site have opened many cranial sutures. And, the process of permineralization has in some cases obscured the degree of cranial suture fusion. Age could be assessed on the basis of degree of tooth wear; but, if these assessments were then used to assess the rate of wear, the analysis would be circular. Consequently, the adults are dealt with as a single group.

Since first permanent molars normally erupt first and are thus exposed to forces of attrition for the longest period of time, the average degree of wear found on an individual's first molars is used to estimate the maximum degree of attrition found in his dentition. Out of 20 adults, 8 (40% ) show wear equal to Brothwell's scale 4-4+ on their first molars with dentin exposure linking most of their cusps. Another six (30% ) show wear even greater than this. Summing, 14 out of 20 (70% ) show wear which exposes a t least enough dentin to link some cusps.

Beyron ('64) found in a sample of nine Australian aborigine adults between the ages of 25 and 44 that four showed only enamel abrasion and five (55% ) showed wear exposing islands of dentin (Broca's Stage 111). In a sample of thirteen adults aged 45 and over he found that one (8% ) showed only enamel abrasion (Broca's

50 DAVID L. CREENE, GEORGE H. EWING AND GEORGE J. ARMELAGOS

Fig. 4 Maxilla showing extreme wear and post-mortem tooth fractures.

Fig. 5 Maxilla showing extreme wear on first and second molars and an unworn left third molar showing five cusps (3++).


Stage 11), eleven (84% ) showed some exposure of islands of dentin (Broca’s Stage 111) and only one (8% ) showed complete exposure of the dentin (Broca’s Stage IV).

Comparing the wear found in 6-B-36 with that found in Beyron’s Australian sample indicates that the lumped adult sample from 6-B-36 has 3 greater proportion of individuals with wear at least exposing islands of dentin than Beyron’s 25- to 44-year-old age group (70% vs. 55% ). It is only when Beyron’s group of individuals over 45 is compared to the lumped 6-B-36 sample that the proportion of individuals with wear at least exposing some islands of dentin is greater in the Austra- lian group (91 c/o vs. 70% ).

Assuming that the 6-B-36 sample is not completely comprised of individuals over 45 years of age, which seems reasonable since Vallois (’37) estimates from other Mesolithic material that 95.5% of Meso- lithic people were dead by the age of 40, then the degree of wear found at 6-B-36 is similar to that found in Beyron’s Aus- tralian aborigine population.

Briggs (’55) found in his North African Mesolithic series that 58.8% of his sample showed pronounced wear and 23.5% showed medium wear throughout their dentitions. Since Briggs’ standards of wear assessment were not identical to those used in this study a direct comparison with the wear found in 6-B-36 should not be made. However, Briggs data along with that from 6-B-36 indicates that African Mesolithic populations were subject to a considerable amount of dental attrition.

Anderson (’65) has suggested that an analysis of the degree of wear and patterns of attrition in dentitions can at times give insights into specific cultural practices. He noted erratic wear on thc teeth of the El Riego and Coxcatlan phases at Tehuacan, Mexico which produced oblique occlusal surfaces set in different planes. He ex- plained this as the result of pulling sand covered plant material through the teeth in order to strip off the more edible parts. Most of the wear observed in 6-B-36 is horizontal with little angulation. There is little evidence that this population had specialized cultural practices such as those found at Tehuacan.

Different degrees of wear in different portions of the dental arcade has at times been used to infer cultural practices. For example, some investigators (Brothwell, ’63) point out that the Eskimos show more wear on their anterior teeth, incisors, than on their posterior teeth, molars, and interpret this as being the result of the Eski- mo practice of using their anterior teeth extensively for chewing hides and biting thongs.

In order to compare anterior wear with posterior wear, individuals with one or more incisor and one or more first permanent molar were examined. Permanent incisors erupt between seven and eight years of age and first permanent molars erupt around six years of age (Anderson, ’62). On the average, the length of exposure to forces of attrition will be similar for incisors and molars from the same individual.

The distribution of degrees of wear is similar with regard to incisors and molars. This indicates that the individuals found at 6-B-36 did not engage in cultural practices that produce differential wear between anterior and posterior portions of the dentition.

Naturally, wear throughout the dentition is dependent upon the length of time that an individual tooth is subjccted to attrition. Anderson (’62) gives the following sequence of average ages of eruption for the permanent teeth.

Age in Years Tooth 6 First molars 7 Central incisors 8 Lateral incisors 9 First premolars

10 Second premolars 11 Canines 12 Second molars

Those teeth that erupt earliest are exposed to attrition for the longest period of time.

Grouping the teeth into three eruption classes -- Class I : first molars, incisors, first premolars; Class 11: second premolars, canines, second molars; and Class 111 : third molars - gives the following distribution of average wear in these classes for the adult sample.

Wear on Class I teeth is extensive with 18 out of 23 individuals showing wear averaging scale 4 or better. Wear is not as

17-25 Third molars

52 DAVID L. GREENE, GEORGE H. EWING A N D GEORGE J. ARMELAGOS

TABLE 6 Wear found i n individuals possessing permanent

incisors and first molars

Incisors First molars

n 1-1 + 0 2-2 + 1 3-3 + 2 4 4 + 6 5-5 + 5 5+ $4 1 Total 15

n 0 1 3 6 2 3

15

n, number of occurrences of wear of a specific degree out of a sample of 15 individuals.

TABLE 7 Wear found in different eruption classes

Degrees of wear Class I Class I1 Class I11

n 1-1 + 0 2-2 + 2 3-3 + 3 4 4 t 10 5-5 t 4 5+ +-6 4 Total 23

n n 1 5 5 8 5 3 6 4 2 0 3 0

22 20 n, number of individuals with wear in a particular

class and of a specific degree.

severe on Class I1 teeth; 11 individuals show wear of less than 4 and 11 show wear greater than 4. Class I11 teeth display the least amount of wear; 16 out of 20 individuals show wear less than 4. Ap- parently the longer a tooth is exposed to attrition forces, the greater the wear. Pro- gressive wear such as this, related to in- creasing exposure to forces of attrition, might be produced by grit created by grinding vegetable food on coarse stones. Grit evenly distributed in chewed food could produce uniform wear on all teeth.

Wear analysis also indicates that most of the individuals in this population had an edge-to-edge bite. Out of a sample of nine individuals with both maxillary and mandibular incisors, eight show horizontal wear on the occlusal surfaces of these teeth while only one has any noticeable wear on the lingual surface of the mandibular incisors indicating some degree of overbite. Brace ('62) argues that in human evolution the overbite first appears after a group reaches the Neolithic level of cultural development which, with its de- pendence upon cultivated grain, puts more masticatory stress on the molars changing

the occlusal relationship of mandible to maxilla. If this is the case, then a Meso- lithic population with dietary habits tend- ing toward those found in a Neolithic cultural level (the utilization of ground vegetable food) might well show the tran- sitional distribution of overbite and edge- to-edge bite found in 6-B-36.

Abscessing Briggs ('55) and Poitrat-Targowla ('62)

suggest that the extreme wear observed in African Mesolithic populations contributes to a very high frequency of apical abscessing. Wear exposing the dental pulp opens up a pathway for infection. Out of 29 individuals with permanent dentitions either completely erupted or just lacking third molars, eight show alveolar abscessing cen- tered around one or more root apices. All of these seem to be the result of a con- centric spread of infection from the root apices and would be classified as alveolar abscesses by Weinmann and Sicher ('47).

Looking at teeth instead of individuals, 25 teeth out of 397 observed have apical abscesses. All of these abscessed teeth show wear equal to Brothwell's scale 5 or better with most of the occlusal enamel worn away. This indicates that, in this population, teeth do not become abscessed until they are severly worn, supporting Briggs' and Poitrat-Targowla's contention. However, other factors aside from wear are also important in the genesis of apical abscesses in this population since 55 other teeth show wear of scale 5 or better but they are not associated with abscesses. In- dividuals possessing these teeth may not have had dental flora that initiate infection through the pulp.

Other Mesolithic populations from Africa show as high or higher frequencies of alveolar abscessing. Briggs ('55) found that 64.5% of 39 individuals in his series had one or more abscesses. Poitrat-Targowla ('62) found that 28.7% of sixty-six max- illae showed some abscessing.

Caries Although the rate of abscessing is high

in this population, the incidence of caries is quite low. Only four cases were found.

A premolar cavity is on a maxillary right first premolar; it is very large and


TABLE 8 Summary of ca7ies incidence

Type of tooth No. with caries No. of teeth observed

61 Maxillary and mandibular incisors 0

110 Maxillary and mandibular premolars 3

42 Maxillary and mandibular canines 0

184 Maxillary and mandibular molars 3

Total 397

apical in nature, eroding away the mesial half of the crown. The three cavities found in molars are all interproximal in nature. One is exceptionally large, eroding away the mesial portion of the occlusal surface of a left mandibular third molar.

Other Mesolithic populations also show high frequencies of peridontal diseases. Briggs ('55) found a frequency of 66.7% in his series while Poitrat-Targowla ('62) found a frequency of 59% at Taforalt.

Onlv 1% of all the teeth observed Crowdincr show caries which is slightly lower than that observed in other Mesolithic populations. Portuguese and other North African Mesolithic populations show frequencies of 3.8% and 3.4% (Clement, '58). Poitrat- Targowla ('62) reports that the Taforalt population had a caries frequency of 5.9%.

Above the Mesolithic level of cultural development the frequency of caries in- creases (Brothwell, '60; Clement, '58). New diets containing soft foods and new bacterial variations probably introduced with the domestication of plants and ani- mals are alleged to have brought about this rapid increase (Brothwell, '60).

PERIDONTAL DISEASE

Intensive tooth wear can expose some of the soft tissues of the mouth to infection which may eventually involve alveolar bone (Brothwell, '63). This seems to be borne out by the 6-B-36 dental pathology. Twenty-four out of 28 individuals where the observation was possible show some signs of alveolar recession that is indicative of alveolar infection. Of these with regard to a t least one tooth, seven show recession past root bifurcations, five show recession to the root bifurcation, and 12 show recession just below the gingival margin. If we assume that all of these instances are evidence of peridontal disease, then 85.7% of the population were infected. If we exclude the 12 with recession, the frequency is still 42.8%.

- Four individuals out of 29 with perma-

nent dentitions show slight crowding. This was most evident in the anterior portion of the dentition, particularly with regard to the incisors. One individual showed anterior crowding i n addition to compres- sion in the mandibular molar row pro- ducing aberrant third molars. Briggs ('55) found 12.5% (of 37 individuals) crowding which is similar to the 13.7% (of 29) found in 6-B-36.

Resorption and evulsion Actual resorption and restructuring of

the mandible and maxilla was extremely rare, Only two such instances were noted. One burial had its right mandibular first molar alveolus completely resorbed. An- other burial shows partial resorption in connection with a large apical abscess of the mandibular left first molar. This indicates that very few people lost teeth ante mortem.

In this connection, i t is interesting to note that there are no instances of evulsion of incisors. Cabot Briggs ('55) reports that incisor evulsion is common among his North African Mesolithic series. Ferembach ('62) also notes a high frequency of incisor evulsion in the Taforalt epipaleolithic people. It is apparent that the Mesolithic people at Wadi Halfa dif- fered from the other two groups with regard to a cultural trait - incisor evulsion.


Rotated premolars Three individuals show rotated second

premolars out of 110 premolar observa- tions. One case shows a 45" rotation in the buccal-mesial direction in a left lower premolar. Another shows a 90" rotation in the buccal-mesial direction in a left lower premolar. And another shows a 90" rotation of its upper left second premolar in the lingual-mesial direction. None of these instances are bilateral.

Third molars Out of 27 reasonably intact sets of den-

tition, all have at least one third molar either erupted or still in its crypt. Twelve of these individuals have all four third molars - 11 completely erupted and one with all four unerupted. Three individuals show one molar in the maxilla. In these three cases, both mandibular molars are present. Seven individuals had both mandibular molars. Three of these still had their third molars in crypts. Two individuals had one maxillary molar - one left and one right. One individual had a maxillary left molar and a mandibular left molar. And two individuals had only mandibular left molars.

In all of the above instances, there was no way of assessing whether or not the missing teeth were congenitally absent since the other third mular alveoli were shattered and missing. However, the available evidence strongly indicates that the incidence of third molar agenesis is quite low if not zero since the occurrence of bilateral agenesis in either mandible or maxilla generally is quite high (Garn et al., '63).

CONCLUSIONS

It is possible to interpret this data in the following way. The Mesolithic population from 6-B-36 was subjected to rigorous selective pressures favoring large and/or morphologically complex teeth. This pressure was apparently intensive wear presumably caused by the inclusion of large amounts of grit in the diet. Morphologi- cally simple teeth that are large, or teeth that are morphologically complex through the addition of supernumerary cusps and additional ridges and wrinkles provide more material for resistance to attrition.

In 6-B-36, attrition pressures maintained large teeth and apparently also favored dentitions with complicated morphologies. Shoveling is found in the anterior teeth and numerous examples of supernumerary cusps are found in the posterior teeth.

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