A COMPARATIVE ANALYSIS OF TERRY COLLECTION BLACK RIBS.

SUSAN R. LOTH

Dcpaıtmem of Aııthropology, Florida Atlarılle University, Boca Raıon, U.s.A.

TERRY KOLLEKS1YONUNDAKİ ZENCi KOSTALARıNIN

KARŞILAŞTIRMALl ANALİzİ

Ozet

Daha önce yapılmış araşıırmalar, kosıa!.ann stemal uçlannın yaş, cınsıyer vr. ırk tayini açılarından oldukça

duyarlı yöntemler olduğunu göstermiştir. Kostaların bel i. rl i gelişme faz.larının standardlarırıa göre yapılan

testler beyazlarda kolaylı.kla uygulanabılmekte ve oldukça doyurucu sonııçlar vemıcktedir. Ancak Amerıkan beyazlan'1da ve. zencilcrimle saptanan ya~lanma sürec, farklLlıkları nedeniyle, beyazlara ait ,tandardların

zencilere uygulanması çok sınırlı kalmaktadır. Üzerinden çok zaman geçmemiş iskeletlerdeki kosıaların adli amaçlı olarak ıncelenmesı, yaşlanma sürecı ıçerisinc!ekı değer ve model farklılıklan kadar, istu!ibel olarak bc.lirgin bir beyazlzenci dimorfizmi (ikişekiJliiiği) de göstermiştir. Örneğin, genç zencikrdeki ossilibsyonun beyazlara oranla daha belirgin olması nedeniyle:, 20'11 yaş[ann son dönemlenndeki bir zenci, beyazlara ait standardlar uygulandığında, gerçek yaşından daha yaşlı bulunmaktadır. Bu farklJıklar beyazlara özgli yaş ve cinsiyet saptanması standardlarının zenciler için kullanmasın: engelleyecek kadar önemlidir. Boy ve yaş sınırları açısından incelenmek üzere topladığımiz modem zenci ömeklerinin sayısal açıdan yetersiz kalması nedeniyle, Terry kolleksiyonundan alınan yaşLarı 19-95 arasındaki 1 LO zenci erkek ve kadın isbletınin kostaları incelendi; böylece, yaş ve cinsiyet saptanmasında zenci iskeletlcrine uygulanacak yöntemLnın

standardları için kullanılabilir bir VCrl tabanı elde cdilmeye çalışıldı. lık sonuçlara göre, Terry kolleksiyonundaki zenci kostalarmill modem toplumdaki beyazlannkine oranla belirgin biçimde kOçlik, modem zencilerin kostalarma oranla ise beklenmedik bir biçimde büyüklük gösterdiği saptandı. 3., 4. ve 5. kostalardaki bazı faz smırlanmalan modem toplumu olıı~turan bireylerd::" elde edilen örneklerde bulunan sonuçlara benziyordu. Terry kolleksiyonundan alınmış olan her iki cinsiyete ait kostalar yaplLırınl, modern zencilerde olduğu gibi, aynı ya:ılardaki beyarililra oranla daha yoğıın jckilde korumaktaydJar. Tcrry kolieksiyü-nu ile modern zcnciler arasındaki yaşlaruna paterni, 6. evre d!~lnda, benzer özellikler ıaşıyordu.

Sonuç olarak, elde edllcn farklılıkların değişken niıelikler içennderi ve bu nedenle, Terry kolJeksıyonun­

daki örneklerin çağda~ toplum bireyleıine uygulanabilea:k standardlaım olu~lUruJma'lIlda kullarıumdma>! ge-rektiğini sapıadık.

Suınmary

Testing on arecent forensic sample of ribs revealed a statisıicaUy significanı dcgree of whiıe/black raeial dimorphi~m a~ well as rMC and pauem differcrıccs in the ngıng process. These diIfercrıc;ıs preclude the use of white b~secl age and sex determination standards on blacks. Sıncc the modem black samplc "':as limited i.n siz.e and age range, ribs from 110 Terry CoUecıion black males and females ranging in age from 19-95 years were analyzed to asccrtain if they followed the same trends and eoııld ıhm providc a sııitabk databasc for black age andliWng sıandards_ Preliminary results indicatc that L~e ribs of Terry blacks are al$o significantly smaller than the ribs of modem whites, buı ,urprisingly, were [ound to be signıficantly larger than L'ıose of modem blacks.

120 S.R. LOTıı Inıercoslal age phase varialion of ribs 3 and 5 from rib 4 was limiıed lo a maximum of one phasc, a resulı

similar lO thal found in modem individuals. Like modem blacks, the ribs of Tcrry black s of both scxes remain much denser with age than whiles. 'The paııem of aging was similar ıo modem blacks, bUl only ıhrough phase

6. iı was therefore concluded thaı the observed differences may indecd be of a ıemporal nalure and ıhus Tcrry

specimens should nol used for the derivalion of conıemporary standards.

Key words : Terry colleclion -Black ribs -Comparaıive analysis -Age - Sex

INTRODUCTION

There are many reasons why it is necessary to carcfully study, then compare populations that differ in terms of race and temporal placement. One must thoroughly understand intrapopulational variation in order to first determine then accurately interpret observable interpopulational differenees. These factors are particularly important in the development of techniques for the determination of demographie characteristics such as

age and sex (1-10).

Earlier research leading to the development of the techniques for the estimation of age at death from the sternal extremity of the rib indicated that this site was very sensitive to the manifestations of age in a strongly sex and race specific manner (6-9). Tests of the rib phase standards showed that they could be easily and rcliably applied to

whites (11,12). However, in a 1987 study by these authors (9), pronounced differences

were documented in the rate and pattern of age related morphological metamorphosis

between modern American whites and blacks. These differences in the aging process

were so distinct that the application of white standards to blacks was severcly limited. Ossification in younger blaeks was notieeably greater than in whites making them appear older as young as the Iate 20s (9). This gap widens with age, especially past 40.

In eontrast, black bones remained much firmer and denser with advancing age than

whites'. Thus, although many ribs looked older, the overall eondition and density of the

bones of middle aged and elderly blaeks of both sex es were comparable to those of mueh

younger whites. it was also found that blacks showed some distinetively different morphological aging patterns that were consistently observed in both sexes. As a result,

these authors published modifications of the existing standards pending the coIlection of alarger sample of black ribs.

When their white based discriminant function sexing formulae (13) were tested on blacks in 1987, Loth and 1 şcan (14) also discovered that the dimensions of the sternal

extremity of the rib showed a marked degree of racial dimorphism, to the extent of effeetively precluding the use of these formulae on blacks. Black ribs were found to be significantly smailer in both the antero-posterior (A-P) and superior-inferior (S-I) measurements than those of whites even though there was no significant difference in

stature. Therefore, when white sexing formulae were applied to blacks, only 20%-50%

classifj-the modifications suggested in 1987 (9), as well as completely new sexing formulae. However, the samp1e of ribs from modern black farensic cases was limited in size, age range and sex distribution. So the author initiated this study to determine if Terry Collection blacks were representative enough to serve as a supplemental database.

The Terry Collection is cmrently housed at the Smithsonian Institution in Washington, D.C. It is composed of about 3,000 skeletons from white and black males and females, all of whom were carefully documented for age, sex and race. Because most of the individuals in this assemblage were bom before the turn of the century, it is necessary to determine if temporal differences exist between the m and their modern counterparts drawn from recent medical examiner's cases.

As with all demographic methods, there are a number of factors besides racial and temporal varialion that ean affeet accuracy. In the case of the rib phase techniques for the estimation of age and discriminant function sexing formulae, there are same very specific considerations that must be made. All standards were derived from the right fomth rib, thus side and pasitional variability must alsa be assessed. Therefore, the purpose of the present research is to carry out a qualitative and quantitative analysis of the ribs of Terry Collection blacks. The results will then be compared with data obtained from modern whites and blacks to assess intra-racial, inter-racial and temporal variation.

METHODS AND MATERIALS

This research was based on a sample composed of the right third, fourth, and fifth ribs of 110 Terry Collection black males and females ranging in age from 19-95 years (Table 1). In order to insure that the correct ribs were chosen, only individuals in which the ribs were intact were used. Unfortunately, in most cases, the rib cage had been sawed through at autopsy making the identification of rib order uncertain. Efforts at obtaining alarger sample size were further hampered because specimens in which the target ribs were obviously diseased or damaged also had to be eliminated.

in eaeh ease, the entire ribeage was first laid out in anatomical order, and examined for side differentials and obvious intercostal variation in the manifesıation of age. Right ribs 3, 4, and 5 were assigned to age phases derived from the fourth rib (7-9). Since ıhe black phase modifications publishcd in 1987 (9) were incomplete, espeeially in females, and are only in the guideline stages, they were further adjusted and supplemenıed by white standards where applicable.

Following phase assignment, eleetronic digital sliding calipers were used to measured the A-P and S-I dimensions at the sternal exırcmiıy of right ribs 3, 4, and 5 as ouılincd /şcan in 1985 (13). Ribs in phase O and phase 8 specimens wcre noı included in the measurements bccause the former are immature and the latıer representing the oldest cases, are of ten seriously deteriorated, especially in white s (13). Mean measuremems of the fourth rib were then compared to those obtained from 339 modem forensic specimens of both sex/race groups which were analyzed by Lolh and /şcan in 1987 (14). The data were analyzed using SPSS-X statistical subroutines (15).

122 S-R. LOHI

Tahle i. Frequency distribution of specimens by decade. N= 110

D=de Males Females

10-19 1 O 20-29 7 11 30-39 14 8 40-49 8 14 50-59 7 10 60-69 5 8 70 and over 8 9 Totals 50 60

Table II. Intercosta1 phase variation in Terry b1acks. Phase devialion from Rib 4:*

Rib 3 Rib 5

N +1 O -1 +1 O -1

Males 50 O 40 8 5 41 4

Females 60 49 9 3 43 10

T o t a 110 1 89 17 8 84 14

(*) +1

=

i phase older than Rib 4; O

=

same phase as Rib 4; -1

=

ı phase younger than Rib 4.

RESULTS

Assessment of intereostal age phase variation produeed the results summarized in

Table 1. The overwhelming majority of these ribs were in the same phase as the fourth rib, and no eases exhibited a deviation of more than ı phase. Overall, the direction of

differenee for both ribs wasyounger, but this was mueh more pronouneed in the third rib. Examination of both sets of ribs 2 through 7 revealed no apparent differenees between the right and left sides, and no major phase deviation if the strongly sex linked

variation between ribs classified as phases 6 and 7 especially in males, and despite the fact that there were 17 individuals age 70 and older, only four (2 males and 2 females) resembled a white phase 8.

Table II prcsents a comparison of mean rib dimensions to gauge intercostal size differentials. S-I and A-P dimensions diflered in all three ribs. However, the differenees were greater in males.

Table III show s the results of a Student's (-test on intergroup size differentials between Terry blacks and modem black s and whites. Surprisingly, there appears to be a negatiye secular trend in that the ribs of Terry blacks from the tum of the centuryare consistently larger than lheir modem counterparts. As can be seen from the data presented in this table, the differences between blacks are statistically significant (p< 0.05) except in the A-P dimension in females. It can also be seen that although Terry blacks are larger than modem ones, they' are still significantly

smaııe~

than modem whites, especially in the S-I dimension in which both sexes differ at a very high levc1 of probability (p< 0.001).

Table III. Intercosta! size variation in Terry b!acks (mm).

Males Females Mcan SD Mcan SD Rib3 S-I 16.3 1.69 13.6 1.64 A-P 7.4 1.32 6.8 1.66 Rib4 S-I 17.1 1.75 13.4 1.77 A-P 8.0 1.41 6.9 1.47 Rib S S-I 16.2 2.29 13.0 1.74 A-P 8.8 1.37 7.6 1.43 AGE 46.7 18.19 48.6 19.20 N 42 45

124 S.R. LOTH

Table IV. Deseriptive statisties of the rib dimensions (mm) and Stodent's t-test of intergroup differentials.

Variable/Sample N Mean SD elf _P

A-P Modem BM 47 7.26 1.10 -2.50 89.42 0.014 Terry BM 48 7.90 1.38 S-I Modem BM 47 16.19 2.10 -2.23 88.50 0.028 Terry BM 45 17.09 1.76 A-P Modern BF 14 6.23 0.86 -1.64 30.33 0.112 Terry BF 57 6.70 1.32 S -I Modern BF 14 12.44 1.30 -2.16 27.40 0.040 Terry BF 52 13.36 1.77 A-P Modem WM 133 8.37 1.31 2.06 79.92 0.043 Terry BM 48 7.90 1.38 S-I Modem WM ₁₃₃ 18.10 1.83 3.31 78.41 0.001 Terry BM 45 17.09 1.76 A-P ModernWF 73 6.91 1.03 0.97 103.24 0.336 Terry BF 57 6.70 1.32 S-I Modern WF 73 14.75 1.57 4.54 101.77 0.000 Terry BP 52 13.36 1.77

Analysis of the results of this study has revealcd several important eharaeteristies of the ribs of Terry Collection black males and females. The most notable finding was the deteetion of what appears to be a negatiye seeular trend in stemal extremity rib dimensions. This was surprising in light of the investigations of Trotter and Gleser (16,17) that revealed a trend toward inereasing stature especially since early in the 20th century. The ribs of Terry blacks were determined to be significant1y larger than those of

today's blacks. Y ct despite the measurable gap between the two black groups, the significant gap between Terry blacks and modem whites was even greater. It is possible

that the negatiye secular trend in black rib size refleets an increase in the limb to torso

ratio. Another consideration is that this may denote robustieity arising from the much more strenuously physicallifestylc Terry blacks are pres um ed to have led. At this point, however, these suppositions, along with other explanations of this rather unexpeeted finding have yet to be investigated.

One important aspect of this study is the question of intercostal variation in the rate of age related metamorphosis. Earlier work by Michelson (18), Semine and Damon (19) and

1

şcan and Loth (20) reported prominent differences between the first and lower ribs and to a lesser extent, among the lower ribs themselves, but these observations had not been quantified. The results of the present study verify this phenomenon, but indicate that intercostal age phase variation is, in fact, relatively minor between ribs three, four, and five. This means that even if the fourth rib is unavailab1e, a good estimation of age can still be obtained from the phase technique. However, S-I and A-P dimensions do vary considerably. Therefore, sexing formulae must be rib speeifie.

In many respects, the aging pattem seen in Terry blacks are similar to those in the modern black sample. It is so consistent and recognizably different from the white

metamorphosis that it may be possible to separate the raees to some degree based on their characteristic shapes. Like the ir modern counterparts, the bones of Terry blacks remained mueh firmer and denser with advancing age than whites'. Bone deterioration in

males was bare1y detectable even in many individuals past the age of 70. Although some thinning was noted in elderly black females, it never approached the paper

thinness characteristic of advancing age in the majority of white females. lntriguingly, this phenomena is very similar to what Todd (21) noted in the black pubic symphysis, namely that rarefication did not advance to the same degree as in whites.

The author's observation that blacks exhibit much leSs of the progressive deterioration in the over 50 groyp that allows good age diserimination throughout life in whites indieates that very different standards must be established for the last two phases.

In conclusion, the present study has again eonfirmed the results of earlier research

indicating that significant skeletal differences do exist between white and black

Americans, and thus must be accounted for in the development of demographic methods. Furthermore, this work has resolved a number of questions about the ribs themselves.

126 S.R. LOTH

First, there is no evidence of side differentials. Ribs 3 and 5 are most of ten within the same age phase as the fourth rib, and no case has been more than one phase away. This is consistent with the results of arecent study of modern whites (lO, 22).

Finally, one major temporal difference was unearthed by this study, and that was the

negative secular trend in black rib dimensions. Although Terry black ribs show

morphological aging patterns that are virtually identical to the modern blacks studied thus far, the final judgment must waİt until sufficient modern blacks over the age of 60 can be collected for comparison. Therefore, it would be wise to defer the use of the Terry blacks as a supplementary population for the delineation of age phases. This project as well as the development of discriminant function sexing formulae for blacks, is currently underway. The results of this study have also raised some questions, and future research should be aimed at further elucidation of the factors responsible for racial and temporal variation.

Acknowledgements

The author is very gratefu! to Dr. M. Yaşar İşcan for his unwavering support, valuable advice, and use of modem forensic data. The author also wishes to thank Dr. Douglas Ubelaker of the Smiıhsonian Instiıution

for his gracious assistance that enabled me to obtain access to the Terry Collection, as well as his "open door" during the data collection phase of this project. The warrn and generous hospitality of his research assistant, Kathy Murray, was very much appreciated, as was the full cooperation of the Smithsonian faculty and staff, notably, Terry Collection Curator D. Schmidt, Department Chair D. Ortner, D. Owsley, A. Stix, and secretary Luwann Tyson. This research was funded by a Short Terrn Visitors Grant from the Smilhsonian

Institulion and a Grant-in-Aid of Research from Sigma Xi, The Scientific Research Society.

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4 Schranz, D. (1959) Am. J. Phys. Anlhropol., 17, 273-278.

5 Krogman, W.M., İşean, M.Y. (1986) The Human Skeleton in Forensic Medicine, Second Edition, Charles C. Thomas, Springfield, IL.

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LO Lotlı, S.R, İşean, M.Y. (1989) In Age Markers in ıhe lluman Skelelon, (Işean, M.Y., ed) Charles C. Thomas, Springfield.

11 Işean, M.Y., Loth, S.R. (1986a) 1. Forensic Sci., 31, 122-132. 12 Işean, M.Y., Loth, S.R (1986b) J. Forensic Sci., 31, 990-999.

16 Troııer, M., Gleser, G.c. (1951) Am. J. Phys. Anıhropol., 9,311-324. 17 Troııer, M., Gleser, G.c. (1958) Am. 1. Phys. Anllıropol., 16, 79-123.

18 Michelson, N. (1934) Hum. Biol., 6,543-557.

19 Semine, A.A., Damon, A. (1975) Hum. Biol., 47, 101-116.

20 Işean, M.Y., Loth, S.R. (1986c) in Forensic Osleology: Advances in Ihe Idenıificaıion of Human Remains, (Reichs, K.J. ed) pp. 68-89, Charles C. Thomas, Springfield, ID.

21 Todd, T.W. (1921) Am. J. Phys. Anlhropo!., 4,1-70.

22 Işean, M,Y., Loth, S.R., Scheuerman E.H (1989) Am. J. Phys. Anlhropol., 78, 245 (abstract).

Reprints request to: Susan R. Loth

Department of Anthropology,

Florida Atlantic University, Boca Raton, FL 33431-:991, U.s.A.