Chronological metamorphosis of the auricular surface of the ilium A new method for the determination of adult skeletal age at death.код для вставкиСкачать
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 68:15-28 (1985) Chronological Metamorphosis of the Auricular Surface of the Ilium: A New Method for the Determination of Adult Skeletal Age at Death C. OWEN LOVEJOY, RICHARD S. MEINDL, THOMAS R. PRYZBECK, AND ROBERT P. MENSFORTH Departments of Anthropology and Biology, Kent State University, Kent, Ohio 44242 (C.O.L, R.S.M., R.P M.); Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, Ohio 44106 (C.0.L.); Cleveland Museum of Natural History, Cleveland, Ohio 44106 (C.0.L);Department of Human Anatomy, Northeast Ohio Universities College of Medicine, Rootstown, Ohio 44272 (C.0.L);Cuyahoga County Coroner’s Ofice, Cleveland, Ohio 44106 (C.0.L);Department of Anthropology, Washington University, St. Louis, Missouri 63130 (TR.I?) KEY WORDS Auricular, Ilium, Forensic, Age-determination, Demography, Sacroiliac ABSTRACT A new method for the determination of adult skeletal age at death based upon chronological changes in the auricular surface of the ilium is presented. Formal stages have been constructed following extensive tests and refinements in observations made of such changes. Two completely “blind” tests were conducted to assess the accuracy and bias of the new method. Results show that the system is equally accurate to pubic symphyseal aging (although somewhat more difficult to apply), and also carries the advantages of a higher preservation rate for the auricular surface in archaeological populations and continued age-related change beyond the fifth decade. While the accurate determination of adult age at death is a key element in the description and analysis of skeletal populations and in forensic anthropology, criteria available from which to systematically judge age at death are limited. For some time the pubic symphyseal face has been the principal source of such data with auxiliary input sometimes applied from cranial suture closure and dental wear. During the analysis of age of the Libben population, we noted a strong correlation between age determined by other variables and morphological change of the auricular surface of the ilium. As a consequence we conducted the present study of age changes in the auricular surface of the ilium and their relation to age using both the Todd Collection (Cleveland Museum of Natural History) and the Libben Collection (Kent State University), as well as several forensic cases (Cuyahoga County Coroner’s Office) that became available during the period of the study. Age changes in the auricular surface are relatively well defined and sufficiently regu- 0 1985 ALAN R. LISS, INC lar to provide accurate estimates of age at death. However, they are somewhat more difficult to interpret than those used in pubic symphyseal aging. The reasons for this are twofold. First, there is no definitive “delayed epiphysis” stage as is found in the symphysis (the “ventral rampart”), and second, the age changes in the auricular surface, while regular, are more complex. There are strong advantages of auricular surface aging over that based on the pubic symphysis, however. The survival rate of this region of the innominate is substantially higher than the pubic symphysis in archaeological populations; interpretable changes in the auricular surface extend well beyond the age of 50 (while they generally do not in the pubic symphysis); and based upon the present study, they are equally accurate in the prediction of age at death. Therefore, while auricular surface aging is more difficult to master, the rewards are well worth the effort. Received February 16, 1982; revised January 2, 1985; accepted January 3,1985. 16 (2.0.LOVEJOY, R.S. MEINDL, T.R. PRYZBECK, ANDR.P. MENSFORTH PREVIOUS DESCRIPTIONS OF THE AURICULAR SURFACES AND THEIR CHANGE WITH AGE The sacroiliac joint has received extensive attention in the literature and has been the subject of many anatomical descriptions. The first comprehensive description was by Meckel in 1815. While defined as a n amphiarthrosis in earlier literature, it is now clear that it is a true diarthrosis (Prentiss, 1917; Weisl, 1955; Frigerio et al., 1974; Cohen, et al., 1967; Soholt, 1951; Solonen, 1957; Colachis et al., 1963; Bickel and Romness, 1957; Newton, 19571, the motion of which is greatly increased a s a consequence of the hormones of pregnancy, particularly relaxin (Sashin, 1930; Putschar, 1931). The auricular surface itself has been the subject of several anatomical descriptions (Schunke, 1938; Sashin, 1930; Brooke, 1924). Schunke (1938) examined the thickness of the cartilage covering the opposing sacral and iliac surfaces. He found sacral cartilage to vary in thickness from 1 to 3 mm., while iliac cartilage was usually less than 1 mm thick. He also noted distinctive differences in the nature of the cartilage covering the two halves of the joint, a n observation borne out by this study (see below). He described the sacral cartilage as being primarily hyaline with “surface cells arranged in compact, parallel layers,” while the cartilage investing the iliac portion of the joint was primarily fibrous with occasional islands of hyaline cartilage. He described the fibrocartilage as having a columnar arrangement along the dorsoventral axis of the surface. Schunke observed that after the third decade the surfaces of the joint became “roughened, furred, and frayed.” Sashin (1930) attributed this process to a n age-related increase in the proportion of fibrocartilage in the joint (see below). Schunke took issue with this observation, attributing it instead to the more typical process of degeneration seen in other movable joints with synovial cavities. He noted, however, that in none of his sample of 200 joints did any eburnation occur, a n observation suggesting that surface changes are in fact primarily a consequence of a n increase in the proportion of fibrocartilage as suggested by Sashin, whose work with the joint was much more extensive and systematic. Observations of the subchondral bone surface made during the present study tend to support Sashin’s view, since they progressively accumulate with age in a regular way, usually without any asso- ciation with significant osteoarthritic degeneration or marked osteophytosis. Brooke’s (1924) observations on ankylosis of the joint are of some interest to the present study. He found that ankylosis was common in males above the age of 50 but always rare in females. Thirty-seven percent of his sample of 105 males were ankylosed, and 76% of the sample of 44 joints above the age of 50 years showed ankylosis. No ankylosis was observed in his sample of 105 females of all ages, and he concluded that it was primarily a male trait. He did not provide a n age-specific report of his sample, so that his data are of limited value in the determination of age, nor did he specify whether he was reporting fibrous or true bony ankylosis. Sashin also reported ankylosis to be a frequent occurrence in older male joints that he reviewed (1930). His data were more systematically reported and are reproduced in Table 1. He also documented the well-established increase in mobility of the sacroiliac joint with pregnancy. This factor, along with preauricular sulcus formation (also associated with pregnancy) must be considered in auricular aging, although on the whole these factors seem to introduce only minimal bias in age determination. Use of the auricular surface proper for determination of skeletal age a t death was included by Kobayashi in his general review of indicators available for age assessment (1967). He provides brief descriptions of some changes with age. HISTOLOGICAL CORRELATES OF AGING IN THE AURICULAR SURFACE Sashin’s extensive review of histological changes that occurred with age in his sample of 257 postmortem examinations of the auricular surfaces (sacrum and ilium) clearly document the regular changes that take place in this joint with increasing age. It is important to note that his paper did not come to our attention until after the age changes described below were prepared from osteological material. The similarity in his description of age changes observed histologically and those of the present study (observed grossly) are striking. His work was based upon a sample of 43 cases between the ages of birth and 29 years (group 0, 111cases between 30 and 59 years (group and 103 cases 60 years or older (group IID. For group I he provided the following description of the appearance of the auricular cartilage of the ilium: a, 17 AURICULAR SURFACE AGING TABLE 1. Osteoarthritic changes and bony ankylosis of the sacroiliac joints (data from Sashin, 1930) Age hr) Males Up to 29 30-39 40-49 50-59 Females Up to 29 30-39 40-49 50-59 No. Beginning Osteophytes Moderate 6 5 7 23 0 0 1 12 5 6 0 0 0 2 4 7 The cartilage lining the ilium is slightly bluish, dull, and striated. The surface is grooved by transverse radiating lines, giving it a striped appearance. The articulating cartilage is thin, in places membranelike, and varies in thickness from one-half to two millimeters. For group I1 he found the following changes to have occurred normally: The iliac cartilage . . . becomes irregular, granular, often very roughened, and coated here and there with yellow plaques. When the joint of a man in the fourth decade is examined, the changes are likely to be more pronounced. . . . The articular cartilage is usually very irregular and coarsely granular; around its margins are erosions and bony irregularities, or osteophytes. In some cases, too, fibrotic changes appear in this cartilage and loose strands may be seen free in the joint space. In a male at the fifth decade, one very frequently finds the cartilages irregular. There are erosions, tears, and fibrotic changes, with connective-tissue strands connecting the joint surfaces. . . . His description of cases beyond the age of 60 continues to emphasize the further degeneration of the joint and its articular cartilage. Both joint surfaces become “deeply icteric; the surfaces were rough and very irregular; coarse fibrous strands passed from surface to surface.” Osteophytosis, with fibrous and bony ankylosis became progressively more frequent with age. While Sashin’s descriptions of the cartilaginous changes do not correspond exactly with those described below for auricular subchondral bone, the general correspondence be- Advanced Beginning Bony ankylosis Moderate Advanced tween the two is excellent, and correlation between these separate observations is usually obvious (see below). METHODS The present study is based upon detailed observation of over 250 well-preserved auricular surfaces from the Libben population and systematic observation of approximately 500 specimens from the Todd Collection. Fourteen forensic cases with confirmed identity and age were also used. The method was then tested independently using two carefully screened samples from the Todd Collection whose ages a t death were unknown to the investigators and that had not been used in the development of formal aging standards (see Lovejoy et al., 1985).The two sample sizes were 98 and 108, respectively. Results of these blind tests are reviewed after presentation of the system itself. Terminology The following terms and definitions (Fig. 1) will prove useful in the descriptions and discussion that follow: Auricular surface: This is the area of subchondral bone forming the iliac portion of the sacroiliac joint. The sacral portion or surface taking part in this joint does not reflect the age changes described below and cannot be used to determine age. This is most likely a consequence of the greater tendency of iliac cartilage to become fibrotic with age, and its thinner covering to reflect more distinctive changes in the subchondral bone. Demifaces: The form of the typical auricular surface is in the general shape of a “boomerang” with the apex occurring a t the junction of the surface and the posterior termination of the arcuate line of the innominate. The superior portion relative to this 18 Retroauricular Area C.O. LOVEJOY, R.S. MEINDL, T.R. PRYZBECK, AND R.P. MENSFORTH 1‘ \ Preauricular Sulcus Inferior Demiface Fig. 1. Region utilized in auricular surface age determination. For discussion see text. apex will be called the superior demiface, while that below this point will be called the inferior demiface. Since the term “demiface” (adopted from traditional pubic symphysis aging description) is somewhat cumbersome, all future references will simply be to the upper or lower face with the prefix “demi” understood. Apex: As just described this is the portion of the perimeter of the joint in immediate contact with the posterior terminus of the arcuate line. Retroauricular area: This shall be considered the general area posterior to the auricular surface from which the lumbosacral and sacroiliac ligament complex arises. It may be considered to extend from the auricular surface posterior to the posterior inferior iliac spine, and superiorly as far as the insertion of the iliocostalis. Porosity: Perforations of subchondral bone of the auricular surface will be generally termed porosiy . This is not to be confused with those that arise as a consequence of hyperostosis or osteopenia. With respect to the auricular surface, there frequently occur small to large perforations that are to some extent associated with age changes (see be- low). These will be referred to with respect to their size as “microporosity” (fine, just optically visible perforations) and “macroporosity” (less regular, large, generally oval perforations ranging from 1 to 10 mm in diameter). Grain: Reference will be made below to changes in the “grain” of the surface. This refers to the gross appearance of the surface with respect to its fine structure as far as can be judged by the unaided eye. Stereomicroscopic inspection of this feature does not enhance (in our experience) its value as an age indicator. A heavily “grained” surface is one that resembles closely the surface of fine sandpaper. Billowing: This term has also been adopted from one used in descriptions of pubic symphyseal age changes. However, it does not have quite the same meaning in the present description. Herein it is meant to represent the presence or absence of transverse ridging (usually running transversely across upper and lower faces). The “billows” vary from large regular surface features, to fine grained just-visible ridges. Density: Reference will be made below to the density of the auricular surface. This refers only to the surface appearance and not to the amount of bone actually present (which would require sectioning). A “dense” surface is one in which the subchondral bone appears compact, smooth, and shows a marked absence of “grain.” GENERAL NATURE OF SURFACE CHANGES WITH AGE Grain and density Most surfaces retain a granular appearance until it is lost to other surface features. Granulation, however, becomes more coarse with increasing age. Thus a fine granular appearance is a n indicator of youth, and is usually associated with billowing and striae. Loss of granularity increases with age. Such loss may occur as early as 27 years, but in such cases the loss does not cover the entire surface. Complete loss of granularity may occur as early as the middle of the fourth decade, but does not become a modal condition until about 45-50 years, even though many auricular surfaces of this age retain a partially granular appearance. The general sequence, then, is from a fine to coarse condition, with eventual loss to densification (the subchondral bone becomes highly compact and exhibits no grain). AURICULAR SURFACE AGING Macroporosity Many older auricular surfaces do not demonstrate this feature, but when present, it is a general indicator of age. Its first occurrence in our sample was at age 38, but it remains rare until age 50, after which it becomes much more frequent. It should not be confused with occasional subchondral defects that can be present at any age. A general clue is that macroporosity usually covers a significant portion of the surface, while subchondral defects are intermittent and not systemic. Billowing This feature is never as marked as in the pubic symphysis but is present in most younger individuals. It may be defined as regular, generally transverse, undulations of the surface. It generally declines with increasing age between 25 and 40. The oldest age of occurrence in our sample was 50. It should not be confused with surface irregularities, which do not show a definite transverse pattern. It tends to reduce between 25 and 30 and to be replaced by striations (see below). Striations (striae) Transverse striations tend to remain as billowing decreases and to characterize individual surfaces in the fourth decade. They may be retained after the age of 50 but are rare. They tend to be more marked on the lower face. Thus, a granular and slightly striated auricular surface without marked billowing (and other changes discussed below) is typical of age 35. Striae differ from billows only in degree. Thus billows tend to become striae with age, and this feature remains generally until the age of 40. Above this age, billows/ striae are rare. The oldest age of occurrence in our sample was 50 years. Apex The edge of the auricular surface in the region of the apex is a diagnostic feature. It tends to be sharp and distinct until age 35, after which it may become more broad (as a consequence of arthritic lipping) and vaguely triangular in form, or become blunted by the formation of a “rim.” Most arthritic changes are first seen here (those which can be most clearly interpreted). The degree to which the surface is raised from the innominate is not a reliable indicator of age and is more pronounced in the female. Formation of the 19 preauricular sulcus causes the anterior lip of the lower face to become isolated and distinct. This should not be considered an indicator of age. Retroauricular Area Activity in this area is an indicator of age. Young specimens show very smooth and undifferentiated surfaces posterior to the auricular surface (but may have significant surface features that are themselves “inactive”). The term “activity” includes an increase in porosity, fine to large osteophytes, and general surface irregularity. While not a good indicator of age by itself, in conjunction with other features of the auricular surface proper, it contributes valuable information for the age estimate. Transverse Organization One of the principal features of younger auricular surfaces is a definitive anteroposterior organization of the surface. Both billows and striae show this definitive feature. As aging progresses such organization declines and the surface becomes more amorphous with no clear directional structure. This is an important factor, since vestiges of billowing or striae may be seen in some areas of older surfaces, but the age of these specimens will be detectable by their lack of a clear transverse organization. In order to illustrate the general behavior of each of the above types of chronological change, we qualitatively assessed (presenceabsence) 102 ilia from the Todd Collection. The results are shown in Figures 2-5. Each shows the percentage of the sample by decade that exhibited each of the various traits described above. As no sex differentials were detected in any of these characters, they were not graphed separately by sex. DESCRIPTION OF GENERAL AGE-CHANGE PROCESS Before a series of stages that can be used t o estimate age at death are presented, it will be useful to describe age changes in the form of a general progression. Five basic phases may be isolated in age transformation of the auricular surface. Early post-epiphyseal phase An irregular, plate-like epiphysis appears and fuses quickly to the sacral portion of the sacroiliac joint shortly after puberty (although it is occasionally substantially de- 20 C.O. LOVEJOY, R.S. MEINDL, T.R. PRYZBECK, AND R.P. MENSFORTH 100- 80- 60- % i t ,, I I I 40- i I , 20- -- Granularity c 18 - Density 3’0 50 40 i0 i0 AGE IN YEARS Fig. 2. Results of qualitative assessment of granularity and density by decade. Correlation between decade and percent displaying trait is .87 for density, but nonsignificant for granularity. The latter reflects the fact that type of granularity (smooth-coarse) is the age related feature, while simple presence/absence of granularity is only slightly correlated with age. N = 102. layed). There is no similar epiphysis in the development of the auricular portion of the joint, but a “youthful” appearance is retained, which is somewhat similar to the more striking “subepiphyseal” surface of the pubic symphyseal face prior to the fusion of the ventral rampart. This surface is quite distinctive and easy to recognize and will be described in more detail below. It generally lasts until the mid-20s. Young adult phase This extends from the mid-20s to the mid30s or slightly older. During this period most of the periauricular features remain unchanged, but the surface exhibits loss of billowing and a coarsening of granulation. Mid adult phase During this period, age changes in the surface continue, and those in associated peri- auricular areas (such as the retroauricular area) are more marked and also become useful in interpreting age (range: mid-30s to mid40s). Early senescent phase Between the mid-40s and mid-50s the surface becomes more dense, and periauricular activity is further increased. Changes are mostly in grain, porosity, density, and the condition of the apex (see below). Breakdown After the approximate ages of 55-60, the surface begins to undergo progressive destruction of its subchondral bone. The process is highly variable, as will be described below, but in all cases it involves increased porosity and irregularity, with marked periauricular changes. 21 AURICULAR SURFACE AGING 1OC 80 6C \ % 40 20 - Transverse Organization 0 Striae r - - - -Billowing * 8 AGE IN YEARS Fig. 3. Results of qualitative assessment of transverse organization, the occurrence of striae, and the degree of billowing. Correlations between decade and percent displaying each trait are -.98, -.96, and -.97 respectively. N = 102. their use in age determination prior to our knowledge of their actual age. Figure 6 shows modal auricular stages for the third and The following are formal standards for age fourth decades; Figure 7 shows modal auricassessment using the auricular surface. A ular stages for the fifth and sixth decades. It series of modal age phases are illustrated for should be noted that only the actual auricreference in Figures 6 and 7. Relevant data ular faces are shown; final age estimates for the specimens illustrated in these figures should also incorporate data from the remay be found in Table 2. The specimens troauricular area and apex. shown were selected after photography, be20-24 cause the photographic appearance of many The surface displays fine granular texture specimens differed significantly from their gross appearance (e.g., shadow effects dis- and marked transverse organization. There guised billowing or striations, etc.). Thus each is no retro-auricular activity, apical activity, photograph illustrates the modal appearance or porosity. The surface appears youthful beof a n auricular surface of its prescribed cause of broad and well-defined billows, “modal age,” even though some specimens, which impart the definitive transverse orgaif studied directly, would yield slightly older nization. Billows are well-defined and cover or younger age estimates. Table 2 also lists most of the surface. Any subchondral defects the age assessment made by one of us (C.O.L.) are smooth-edged and rounded (Fig. 6A). Note during the second blind test (Todd Sample distinct transverse billows and very fine gran11-Lovejoy et al., 1985) as a n illustration of ularity. CHRONOLOGICAL STAGES OF THE AURICULAR SURFACE 22 C.O. LOVEJOY, R.S. MEINDL, T.R. PRYZBECK, AND R.P. MENSFORTH - Macroporosity a-.---.e 80 MICroporOsity 1 ." I / I r , I I I ""1 18 i0 i0 <O 60 i0 AGE IN YEARS Fig. 4. Results of qualitative assessment of macroporosity and microporosity by decade. Correlations between decade and percent displaying each trait are .84 for macroporosity and .96 for microporosity. N = 102. 25-29 Changes from the previous phase are not marked and are mostly reflected in slight to moderate loss of billowing, with replacement by striae. There is no apical activity, porosity, or retroauricular activity. The surface still appears youthful owing to marked transverse organization. Granulation is slightly more coarse (Fig. 6B,C). Note slight reduction of billows in Figure 6B and demonstrable replacement by striae in Figure 6C. Distinct transverse organization is evident in both specimens. 30-34 Both faces are largely quiescent with some loss of transverse organization. Billowing is much reduced and replaced by (definite) striae. The surface is more coarsely and recognizably granular than in previous phase, with no significant changes a t apex. Small areas of microporosity may appear. Slight retroauricular activity may occasionally be present. In general, coarse granulation supercedes and replaces billowing (Fig. 6D-F). Note smoothing of surface by replacement of billows by fine striae, but distinct retention of slight billowing on the lower face of all three specimens. Loss of transverse organization and coarsening of granularity is evident. 35-39 Both faces are coarsely and uniformly granulated, with marked reduction of both billowing and striae, but striae may still be present under close examination. Transverse organization is present but poorly defined. There is some activity in the retroauricular area but this is usually slight. Minimal changes are seen a t the apex, microporosity is slight, and there is no macroporosity. This 23 AURICULAR SURFACE AGING ,.A, '.\ , **.* I ',\ . , ,, -...' \ I I *. - lschial 4 e- - - - e Apical c-----* Retroaurtcular 30 30 40 40 60 50 1 70 AGE IN YEARS Fig. 5. Results of qualitative assessment of auxiliary features (those not employed in formal descriptions of the auricular surface itself) by decade. Qualitative assessment of osteophyte formation around the ischial tuberosity is also included. Correlations between decade and percent displaying trait are 35 for ischial changes, .80 for apical changes, and .92 for retroauricular activity. N = 102. T A B L E 2. Figure reference Todd No. 6A 854 1851 1243 1245 1139 1313 690 612 1319 1468 1431 1409 1476 1687 1174 1422 1549L 1549R 1132 1852 6B 6C 6D 6E 6F 6G 6H 61 6J 7K 7L 7M 7N 70 7P 7Q 7R 7s 7T Modal age 20 25 28 30 32 34 35 36 38 40 41 42 44 45 47 50 55 55 49 60 + Blind age est. Stated age 18 27 26 34 33 29 23 33 44 37 41 42 40 54 54 59 68 68 47 63 19 33 24 31 31 35 35 36 39 37 42 38 44 49 54 50 54 54 51 63 Sex F M F M M M F F M M M M M M M M F F M M Fig. 6. Modal changes in the auricular surface with age: third and fourth decades (A-J). These may be considered standards for the surface itself, but final age determination should also incorporate auxiliary features as well. Modal, estimated, and stated ages are given in Table 2. Fig. 7. Modal changes in the auricular surface with age: fifth and sixth decade (K-T). See legend of Figure 6 and Table 2. 26 C.O. LOVEJOY, R.S. MEINDL, T.R.PRYZBECK, AND R.P.MENSFORTH is the primary period of uniform granularity (Fig. 6G-I). Note coarse granularity, absence of striae (still slightly visible in Fig. 6G and in one area of lower face of Fig. 61). Further reduction of distinct transverse organization is evident. 40-44 No billowing is seen. Striae may be present but very vague. The face is still partially (coarsely) granular and there is a marked loss of transverse organization. Partial densification (which may occur in islands) of the surface with commensurate loss of grain is present along with slight to moderate activity in the retroauricular area. Occasional macroporosity is seen, but this is not typical. Slight changes are usually present a t apex. Some increase in microporosity is seen, depending upon the degree of densification. The primary feature is the transition from a granular to a dense surface (Fig. 6J,7K-M). Note distinct presence of microporosity in Figure 6 J and simulation of billowing (this specimen does not display true billowing because it lacks transverse Organization). Microporosity is also clear in remaining specimens. Note densification of lower face of Figure 7L and upper face of Figure 7M. Minor striae are still visible on upper face of Figure 7L and lower face of Figures 7K and M, but in both cases expression is very slight and secondary to more distinctive age features. 4549 Significant loss of granulation is seen in most specimens, with replacement by dense bone. No billows or striae are present. Changes at apex are slight to moderate but are almost always present. There is a distinct tendency for the surface to become dense. No transverse organization is evident. Most or all of any microporosity is lost to densification process. There is increased irregularity of margins with moderate retroauricular activity and little or no macroporosity (Fig. 7N,O,S). Note distinct densification of these three specimens and the almost complete lack of transverse organization. These surfaces are markedly irregular because of the densification process. Some microporosity is present in Figure 7s. 50-60 This is a further elaboration of previous stage, in which marked surface irregularity becomes paramount feature. Topography, however, shows no transverse or other form of organization. Moderate granulation is occasionally retained, but is usually lost during previous phase and is generally absent. No striae or billows are present. The inferior face generally is lipped at inferior terminus, so as to extend beyond the body of the innominate bone. Apical changes are almost invariable and may be marked. Increasing irregularity of margins is seen. Macroporosity is present in some cases but it is not requisite. Retroauricular activity is moderate to marked in most cases (Fig. 7P-R Q and R are opposite sides of same specimen; despite distinct differences in shape, age features are symmetrical). Note irregularity of surface, macroporosity of lower faces of all three specimens, marked density, and absence of any youthful criteria. + 60 The paramount feature is a nongranular, irregular surface, with distinct signs of subchondral destruction. No transverse organization is seen and there is a definitive absence of any youthful criteria. Macroporosity is present in about one-third of all cases. Apical activity is usually marked but is not requisite for this age category. Margins become dramatically irregular and lipped, with typical degenerative joint change. The retroauricular area becomes well defined with profuse osteophytes of low to moderate relief (Fig. 7 T typical 60+ auricular surface). There is clear destruction of subchondral bone, absence of transverse organization, and increased irregularity. Older specimens display further directional changes of this type. METHODS OF APPLICATION The preceding set of phases has been constructed to serve as age modes in a n idealized metamorphosis of the auricular surface. It is designed to be diagnostically applied in the same manner as the Todd ten-phase system for the pubic symphyseal face. However, while many auricular surfaces will clearly conform to one of the above stage descriptions, many will not, the latter containing combinations of features from two or more phase mode descriptions. For the purposes of seriation and final age assessment, the observer should seek out from each auricular surface the paramount age criteria that best represent the biological aging process and correspond to the designated phase of the formal method. Auxiliary indicators (e.g., apical and retroauricular activity) may then be 27 AURICULAR SURFACE AGING used to raise or lower the estimate of age within the age mode, or in some cases, to raise or lower the age mode itself. In general the age modes are best represented by the following paramount characters: 1. 20-24: billowing and very fine granularity. 2. 25-29:reduction of billowing, but retention of youthful appearance. 3.30-34 general loss of billowing, replacement by striae, and distinct coarsening of granularity. 4.35-39:uniform coarse granularity. 5. 4044: transition from coarse granularity to dense surface; this may take part over islands of the surface of one or both faces. 6.45-49: completion of densification with complete loss of granularity. 7.50-59: dense irregular surface of rugged topography and moderate to marked activity in periauricular areas. 8. 60+: breakdown with marginal lipping, macroporosity, increased irregularity, and marked activity in periauricular areas. While each auricular surface will be distinguishable as falling into one of the above eight categories, the remaining details must then be used to refine the age estimate. For example, billowing is occasionally retained well into later life. In the case of a coarsely grained surface, but one that still retains some billowing, the former indicator is paramount, but the latter should be used to reduce the age estimate slightly (within the mode). Partial breakdown may occasionally occur prior to its typical age mode. An auricular surface in the transitional phase between granulation and density that also showed a small area of breakdown or unusually marked apical or retroauricular activity, would be placed in the late portion of the age mode (43 or 44 years) or moved to the succeeding one (i.e., the specimen might be aged 4547 years). Practice and experience in the application of the above modes will make their use more clear. Some mention of sex-specific application should also be made. In general the above age modes may be applied in the same fashion to both male and female auricular surfaces. The single exception is female innominates which show clear and marked pre-auricular sulcus formation. In these cases age changes along the inferior margin and apex are accentuated, the effects of these must be disregarded in the age estimate. TESTS OF ACCURACY AND RELIABILITY Two questions are clearly paramount in judging the usefulness and validity of an age indicator. The first is interobserver reliability, and the second is its accuracy in the prediction of real age at death. The system presented above has been exhaustively tested and retested using both the Libben and Todd collections. In earlier phases of development of the system, several tests were made using random Todd samples of 100. In each of these, correlations with stated age ranged from .55 to .75. However, during these applications the system was not fully developed, nor were the Todd specimens used screened for accuracy of stated age. Two final tests of the system were made using Todd material for which the stated age at death had been screened for accuracy, and that did not utilize any of the specimens used in the development of the formal system. Slight modifications were made in the system between the conduction of these two tests (see Lovejoy et al., 1985).These latter two tests thus compose a completely blind and objective evaluation of the auricular aging technique. Partial results of these tests are presented in Table 3. A complete description of the methods used to construct the tests and of selection of the samples used, and a more complete presentation of results (including Pearson correlation coefficients,comparisons with other age indicators including TABLE 3. Actual age (years) Test I auricular surface Test I1 auricular surface 18-29 Inaccuracy' Bias2 3.3 0.9 3.2 2.6 7.6 0.9 7.2 1.6 30-39 Inaccuracy Bias 40-49 Inaccuracy Bias 9.4 7.7 -5.9 -2.9 50-59 Inaccuracy Bias Over 60 Inaccuracy Bias All ages Inaccuracy Bias All ages normalized3 Inaccuracy Bias N 9.9 -8.3 11.1 9.0 -6.2 7.2 -5.8 7.8 -3.5 7.0 0.0 7.8 -3.7 98 1.9 7.3 -0.5 108 'Inaccuracy is mean error without regard to sign. *Bias is mean error incorporating sign of error. %ormalization consisted of equating the weight at each age class. 28 C.O. LOVEJOY, R.S. MEINDL, T.R. PRYZBECK, AND R.P. MENSFORTH pubis, Komolgorov-Smirnov tests with real age distributions, etc.) may be found in Lovejoy et al. (1985). In addition, several observers were given the above descriptions, and without further comment (following some practice for familarization) or further instruction, were asked to apply them to the second of the above samples. The results of these tests of observer reliability and accuracy of age prediction demonstrated that the technique is highly replicable. Correlations between observers for a sample of 110 ranged between .76 and .81, which were comparable to similar tests performed using pubic symphyseal aging. Thus, the accuracy and reliability of the present system compares favorably with other systems utilizing the pubic symphyseal face. These data, in conjunction with the much higher rate of preservation of the auricular surface in archaeological material, make the auricular surface a new and valuable tool in estimates of age a t death. When used systematically in conjunction with other age indicators (including the pubic symphyseal face), they will also improve the reliability of estimates of age a t death in forensic anthropology (see Lovejoy et al., 1985). ACKNOWLEDGMENTS The research reported in this paper was funded by the National Science Foundation, Award No. BNS-77-07958. 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