Papio cynocephalus Age Determination 0. M. REED Southwest Foundation f o r Research and Education, San Antonio. Texas 78284

ABSTRACT The age of non-domesticated primates has always been a ques- tion to the scientific investigator. This question was magnified in the early 1960's when primate research hit a new peak. Age development standards became nec- essary to conduct many projects demanding developmental information. This project utilized known aged Papio cynocephalus baboons. Skull, muzzle, long bone and tooth development measurements were taken on a linear growth pro- gram for five years. These data, when programed for the computer, gave a re- liable regression curve age predictability of one month up to 40 months and a three month age predictability up to 72 months for P. cynocephalus. Data taken from known-aged animals not in the survey proved the reliability of the project.

Early efforts to determine the age of the baboons in the Southwest Foundation for Research and Education colony were based on weight measurement alone. Dental examinations revealed that animals with deciduous or primary teeth present weighed the same as those with worn third molars. The dental formula of eruption, although unknown for the baboon at that time, indicated the validity of expending efforts to establish such a formula for age determination.

Review of the literature indicated at that time no comprehensive program was be- ing used or had been developed to formu- late age or growth patterns of the baboon.

Many investigators, Schultz ('60), Zuck- erman ( '60) , and Garn ( '60) , had made single item evaluations; some of these were dry skull evaluations, first molar eruptions, wear patterns and deciduous teeth wear and eruption patterns on rhesus monkeys.

This project was started in 1963 utiliz- ing the known-aged baboons Papio papio and Papio cynocephalus, of the domestic and African colonies existing at Southwest Foundation for Research and Education at that time. This study also utilized the in- fants of the breeding colony established 18 months later. Early results indicated that the domestic or interbred colony were slower in development and reproduction. These baboons were followed through their

AM. J. PHYS. ANTHROP., 38: 309-314.

growth cycles, but sufficient numbers were not available for statistical reliability; the data reported here is based on P . cyno- cephalus.

MATERIALS AND METHODS

Examination and study of the animal and the literature indicated that head (skull and muzzle), teeth, long bones, hand and wrist were the reliable indica- tors of growth and development.

A program of monthly radiographs of head, humerus, and wrist-hand was in- stituted. The cephalometric unit consisted of a Wehmer cephalostat and a 90 Kv fixed x-ray, with a 60 in. target distance. The Ce unit allowed a repeated fixed posi- tion reproduction of the head for compara- tive readings. The hand and long bone ex- posures using an unrestricted dental x-ray were on 40 in. target distance chosen be- cause x-ray distortion is at the minimum.

Radiographic films were then measured utilizing the following reference points. The horizontal reference line chosen was the plane evidenced by the occlusal of the posterior teeth of the maxilla. The animal has a flat rather than the curved occlusal plane exhibited by the human.

Skull measurements were obtained by measuring between the vertical lines, dropped to the horizontal line from the posterior pole or external occipital pro- tuberance, whichever was the most prom-

309

310 0. M. REED

TABLE 1 Papio cynocephalus age determination table in months (condensed) skull

Length Age in months

Male Female

African Domestic African Domestic

mm 72.0 81.0 93.0 98.5 107.5

1.76 4.31 6.73 23.12 37.34 68.72

1.44 3.78 14.11

29.59 55.72 53.40 85.32

TABLE 2 Papio cynocephalus age determination table muzzle

Length Age in months

Male Female

African Domestic African Domestic

mm 20.5 31.5 43.5 50.0 67.0 74.0 88.0 100.0 111.0

6.14 7.70 16.59 18.25 22.88 24.52 40.75 48.59 64.93 79.56 93.40

9.39 1.50 22.73 10.45 30.98 27.88

40.36 82.46

TABLE 3 Papio cynocephalus age determination table long bone (humerus)

~ ~

Length Age in months

Male Female

African Domestic African Domestic

mm 67.0 1.29 0.99 73.0 1.34 2.17 1.32 1.96 86.0 3.62 4.67 3.73 5.04 97.0 6.25 7.38 6.52 8.63 108.0 9.47 10.59 9.95 13.09 116.5 12.32 13.39 13.01 17.11 125.0 15.49 16.46 16.40 21.61 137.5 20.70 21.45 21.98 141.5 22.50 23.16 23.91 150.5 26.77 27.20 28.50 159.5 31.36 33.43 166.5 35.13 37.48 175.5 40.25 183.0 44.74 191.5 50.07 200.0 55.65 21 1 .o 63.24 219.5 69.38 229.5 76.91 238.0 83.57 245.5 89.63

PAPIO CYNOCEPHALUS AGE DETERMINATION

TABLE 4

Papio cynocephalus tooth stage table Age in months

TABLE 4 (continued) Papio cynocephalus tooth stage table

Age in months

Tooth Staee Male Female

Upper Central 1 2 3 4 5 6 7

Lower Central

Upper Lateral

Lower Lateral

Upper Canine

Lower Canine

1 2 3 4 5 6 7 8

1 2 3 4 5

1 2 3 4 5

1 2 3 4 5 6 7

1 2 3 4 5 6 7 8

Upper 1st Premolar 1 2 3 4 5 6

02-05 06-08 09-

02-05 06-08 09-

03-07 08-

03-08 09

04-07 08-

03-08 09

05-

01-04 0 5-0 7 08-21 22-27 2 8 4 0

41 -

01-04 05-07 08-20 21-27 28-38 3 9 4 0 41-45 46-

08-10 11-25

30- 26-29

08-1 1

27-29 12-26

30-

06-08 09-13 14-30 31-36 37-44 45-45 46-

06-08 09-13 14-29 30-33 3 4 4 4 45-45 4 6 4 9 50-

10-1 1 12-16 17-25 26-28 29-30 31

31 1

Tooth Stage

Lower 1st Premolar 1 2 3 4 5 6 7

Upper 2nd Premolar 1 2 3 4 5 6

Lower 2nd Premolar 1 2 3 4 5 6

2 3 4 5 6 7 8

Lower 1st Molar 1 2 3 4 5 6 7 8

2 3 4 5 6 7

Lower 2nd Molar 1 2 3 4 5 6 7

Upper 1st Molar 1

Upper 2nd Molar 1

Male

05-

08-16 1 7-2 1 22-33 34-35 36-40 41- 08-15 16-21 22-32 33-34 35-38 39-

-01 02-05 06-10 11-16 17-20 21-38 39-

- 01-03 04-1 1 12-14 15-18 19-24 25-

12-15 16-20 21-32 33-35 36-37 3 8 4 8 49- 12-15 16-19 20-30 31-33 34-37 38-44 45-

Female

10-1 1 12-16 17-25

28-30 31-34 35- 10-15 16-19

26-27

20-28 29-32 33-36 37- 11-15 16-19 20-27 28-3 1 32-36 37- 02-04 05-13 14-15 16-1 8 19-25 26-32 33-

- 01-02 03-12 13-14 15-17 18-24 25-32

13-14 15-19 20-27 28-31 32-34 3 5 4 1 42-

-13 14-18 19-26

30-32 33-40 41-

32-

27-29

inent, to glabella. Muzzle length was mea- sured from vertical lines dropped from glabella to the most anterior spine of the pre-maxilla.

The planes and points of reference uti- lized in this study were not the standard orthodontic analysis points used in human growth studies. To be useful, this aging

program had to have points of reference that a technician could locate and utilize easily. Standard orthodontic reference points were determined, measured and used in a test sampling of the baboons. These points when analyzed gave results comparable to those obtained from our chosen reference points. However, techni-

312 0. M. REED

TABLE 5 Papio cynocephalus age determination table measurement ,sum of skull, muzzle, long bone

Sum Age in months

Male Female

African Domestic African Domestic

mm 93.0 98.5

104.0 108.5 116.0 124.5 132.5 138.5 141.5 150.0 156.5 162.0 168.0 175.0 183.0 190.0 200.0 211.0 220.0 230.0 239.5 245.5 260.0 271.5 284.0 291.0 302.5 314.0 318.5 327.0 337.0 345.5 360.0 375.0 384.5 397.0 411.0 419.5 428.5 440.0 454.5

1.36 2.20 3.05 4.45 6.19 7.78 9.70

11.66 12.96 16.33 19.21 22.52 24.46 27.78 31.25 32.65 35.36 38.65 41.52 46.61 52.10 55.69 60.55 66.18 69.68 73.47 78.41 84.81

1.01 1.41 1.92 2.61 3.50 4.38 5.79 7.53 9.11

11.03 12.99 14.31 17.73 20.67 24.09 26.11

-

cians who were not dentally trained could consistently utilize the reference points set up by this study more correctly and with less error than the standard orthodontic reference points. The hand radiograph was obtained by taping the hand in a palm up position. The humerus radiograph was a modified posterior-anterior view that was selected for best view of joint and epiphy- sis viewing.

Garn’s eight stages are as follows: Stage 1 Earliest appearance of follicle. Stage 2 Fully developed follicle, no

calcification of cusp.

1.61 3.55 6.20 8.88

14.35 22.04 30.69 38.06 42.03 54.29 64.66 74.11 85.12

1.58 2.48 3.40 4.92 6.87 8.66

10.86 13.14 14.67 18.68 22.14 26.18 28.57 32.68 37.03 38.80 42.22

Stage 3 Beginning calcification of cusp. Stage 4 Calcification of crown surface. Stage 5 Extension of root below crown. Stage 6 Further root development be-

Stage 7 Root completed except for

Stage 8 Apices closed. These films were taken for a total time

of five years. Adult films were obtained from a cross section of the known-aged colony animals, while all infant and juve- nile data were a longitudinal report from one month to termination of study.

low “cleft” stage.

apices.

PAP10 CYNOCEPHALUS AGE DETERMINATION 313

CeXCENTRAL INCISOR LAT: LATERAL INCISOR 3

I O M : I t 1 OECIOUOUS MOLAR 2 0 M z 2 n a OLCIOUOUS MOLAR f

I cA =CANINE 0

2 ' o LZLOWER UzUPPER

I M i I MOLAR Ce: CENTRAL INCISOR LIT= LATERAL INCISOR 2nd PM: 2nd PREMOLDR

80 l P M : i i l PREMOLAR CA=CANINE 3 M c 3 r d MOLAR

701 L:LOWER U = UPPER

601

9 50

zz 40

c z 0

30

20

10 Fig. 2 Papio cynocephalus permanent tooth Fig. 1 Papio cynocephalus deciduous tooth eruption sequence 18-75 months,

eruption sequence 0-223 days.

90-

80-

70-

60- I I- 6 50- 5

W

v

40- a

30-

20-

IO-

0

o-- ACTUAL DATA FROM REED - COMPUTED REGRESSION

20 60 100 140 180 220 260 300 340 380 420 460 500 MEAN SUM of SKULL, MUZZLE, and LONG BONE in MM's Fig. 3 Papio cynocephalus 2 age VS. Z measurements.

For converting these data (utilizing age utilized to develop the regression curve of in months for eruption of teeth, measure- monthly growth and/or development ments of the skull, muzzle and humerus, standards. in millimeters, and the teeth development

ment) a sum total of each monthly mea- surement was produced. This was then

utilizing Garn's eight stages of develop- RESULTS

The results are best demonstrated by utilizing the tables and graphs derived

314 0. M. REED

from the computer analysis of the four years of data.

In figures 1 and 2 the mean eruption date was the first day or month respec- tively that the crown penetrated the gingiva. The eruption process averages three months for all but the maxillary canine, in the male, which may take six to eight months for complete eruption.

In figure 3 a regression curve determin- ing the predictability occurring from 0-85 months, was tested upon completion of the project on ten known aged P. cyno- cephalus, juvenile baboons. Results were accurate within one month up to 36 months and within a three month range up to 60 months. No tests were conducted, due to lack of available known aged ani- mals, on baboons over 60-62 months old.

DISCUSSION

When using primates obtained from the African Bush Country, a method of age determination is essential for experimenta- tion in sexual development, arteriosclero- sis projects, and in any study demanding a normal development stage in which growth or development variables may be involved.

It is this investigator’s opinion that this project demonstrates that the oral growth and development and the growth of the humerus give the researcher an accurate tool to determine a baboon’s age from birth to 60 months.

ACKNOWLEDGMENTS

This study could not have been com- pleted without the dedicated help of Evelyn Reed, Horace Coleman, Ignacio Gomez and Joe Marin. This crew measured the trac- ings and handled and maintained the ani- mals throughout this study.

This research project was totally sup- ported by National Institute of Dental Re- search grant DE-020-73-0351.

LITERATURE CITED Garn, S. M., C. G. Rohmann and F. N. Silverman

1967 Radiographic standards for postnatal ossification and tooth calcification, Medical Radiography and Photography, 43: 45-66.

Schultz, A. H. 1960 In: The Jaws and Teeth of Primates. W. W. James, ed. Pitmans Medical Publishing Company, London, pp. 246, 248 and 314.

Zuckerman, S. 1960 In: The Jaws and Teeth of Primates. W. W. James, ed. Pitmans Medical Publishing Company, London, pp. 110, 246, 251, 311 and 314.