Results The findings for the test group are summarized in Table 1. According to these findings, the appearance of the investigated features can be applied to the differentiation of gender. The error rate and, thus, the extent to which correct determination of gender is possible vary considerably. Only those features in Table 1 that are printed in bold guarantee a reliable number of correct diagnoses (> 70 percent) and an error rate of less than 10 percent. These features include the arcus superciliaris, crista supramastoidea, glabella, and the overall impression of mandibles and processus mastoideus. See Figure 5. Some features are clearly unidirectional (have a distinctly female or male appearance). These include: a less inclined "steep" forehead is observed primarily in females (present in 45.5 percent EE and 5.1 percent GG); a more inclined forehead is an unreliable male feature (G: 27.3 percent; E: 72.4 percent); the tubera frontalia (E: 63.6 percent; G: 15.5 percent) and parietalia (E: 30.6 percent; G: 6.9 percent) are more pronounced in females; a missing tubera frontalia (E: 21.2 percent; G: 67.3 percent), and the parietalia (E: 36.4 percent; G: 84.5 percent) cannot be regarded as a typical male feature. A conelike protrusion of the protuberantia occipitalis externa is, however, only found in male skulls of the test group (E: 0 percent; G: 22.4 percent). A slight protrusion can be observed on both male and female skulls. (G = 48.5 percent; E = 10.3 percent). The assessment of the correlation between morphognostic features and age (# 49 vs. $ 50 years) led to few notable differences between males and females. The overall impression of the mandibles correlates with age, but it is more prominent in females. With increasing age, and thus with a reduced number of teeth, the lower jaw appears more frail and atrophic. The shape of the orbital cavity is less round in older women (p = 0.045), and this tendency towards virilization of older female skulls can also be observed in the margo supraorbitalis (p = 0.056) and in the reduced size of the tubera parietalia (p = 0.069). The threshold of significance is not reached, however. The five characteristics necessary for reliable gender identification were used to assess 46 skulls of a control group. The gender of 42 (91.3 percent) skulls was correctly determined. The gender of one male and one female skull was incorrectly classified. The results were inconclusive on two male skulls. The determination of gender using the skull is based on morphological features. In the relevant publications, the gender-specific appearance is described almost identically. These descriptions date back to the eighteenth century and arise from observations of a small series of investigations. Broca (1875), for example, examined only 7 EE and 11 GG skulls. Individual descriptions were collected by textbook authors (Stewart 1952; Krogman 1962; Prokop and Göhler 1976; Hunger and Leopold 1978; Bass 1987; Hoyme and Iscan 1989; Herrmann et al. 1990). The morphological descriptions put forward by these authors have remained basically unchanged over the years. No fundamental new findings or features confirmed by more recent investigations have since been communicated. In their investigation on the diagnosis of age and gender using the skull, Ferembach and colleagues (1979) described 17 morphognostic features and oriented themselves according to reports published previously by Acs<di and NemeskJri (1970). The assessment of typognostic features naturally underlies a certain subjective influence. The experience of each investigator with his "internal standard" always leaves its mark, and in addition, the individual features are usually not investigated independently of each other. The skull is assessed in its entirety, subconsciously at least. In cases of doubt, the classification of a single, gender-specific feature can thus be decisively influenced one way or the other. The published data must, therefore, first be interpreted against this background (the significance of the individual features for a certain investigator and the respective sample). Taking these facts into consideration, the features are molded in a gender-specific way. The appearance of certain features differs significantly between female and male skulls. Because of their variability, as demonstrated by the number of false determinations and indifference types, gender-specific features can occasionally lead to different values. The relatively high number (33 percent) of skulls that were either incorrectly determined or which could not be specified according to gender is unsatisfactory. Therefore, the value of features such as inclinatio frontalis, tubera frontalia, and parietalia, processus zygomaticus, height of the os zygomaticum, planum nuchale, upper ridge and shape of the orbitae, and angulus mandibulae for the reliable determination of gender must be critically assessed. In view of the ordinal scaling which consists of five values, a characteristic feature can be guaranteed to determine gender if there is a median difference between males and females of more than one, or even two, combined with a relatively small standard deviation and error rate. These conditions are best met by glabella, arcus superciliaris, processus mastoideus, crista supramastoidea, and the overall impression of the mandibles. In particular, the marks of the muscle insertions at the back of the head (planum nuchae) and the angles of the lower jaw and the os zygomaticum revealed only minor differences in the median values. The high value that is usually attributed to these features cannot be reconfirmed by the findings of the present investigation. It is possible that a tendency towards finer structures in the course of acceleration (Knussmann 1980) is obvious. This can be observed when populations of the migration age are compared (Wahl 1988). In contrast to this are the results gained from mastoid and crista supramastoidea, which should still be regarded as essential features in a reliable determination of gender. The shape of the orbital cavity, which is distinctly different in males and females according to the computer-assisted two-dimensional evaluation (Schleyer et al. 1971; Schiwy-Bochat 1996), proved to be less significant when inspected visually. Although an investor-associated shift of the threshold value can be questioned in view of a median value within the "male range," the difference in the median value is still too small to lead to a satisfactory diagnosis. Apparently, the visual assessment is inferior to the two-dimensional computer-assisted analysis because of the three-dimensional orbital contour. A "sharpening" of the margo supraorbitalis was defined by Broca (1875) as a female characteristic and has been used as such since then. Palpable findings and thus the strength (thickness) of this ridge were relied upon. Therefore, the value of the margo supraorbitalis for the diagnosis of gender is only minor. If one relies only on the presence or absence of a ridge on the upper, inner edge of the orbital cavity, this feature can be reliably assessed. Presence or absence correlates with gender and is not side-dependent. The probability of correctly determining gender rises to more than 70 percent and, therefore, lies in the order of magnitude of the features mentioned in this investigation (Graw et al. 1997; 1999) The discrepancy between these data and data listed in publications by Krogman (1962), Hunger and Leopold (1978), Novotny et al. (1993), and Ferembach et al. (1979), in particular as regards the value of some features, can be attributed primarily to three reasons: 1. The tables represent summaries of international publications. They are not derived from personal investigations or a specified series of specimens. Shifts in population-dependent validations are generally acknowledged but were neither confirmed nor described. 2. The individual findings were derived from inhomogeneous material of different regional origin and age. Some publications date back to the beginnings of systematic anthropology (Ackermann 1788; Welcker 1866; Ecker 1866; Broca 1875; Rebentisch 1893). In contrast, the German skulls used in this investigation are modern in the forensic sense. Influences due to acceleration are taken into account when the respective findings are compared. 3. Short adjectives such as "small" and "thin" are used to describe certain appearances, but these can cannot be claimed as objective and are based to a great extent on the experience of the investigating researcher. Because of this subjective influence, a shift in the validity is possible. When the individual features (glabella, arcus superciliaris, processus mastoideus, crista supramastoidea, overall impression of the mandibles) are weighted identically, 42 of the 46 skulls of the control group can be determined correctly (91.3 percent). The gender of one male and one female skull was incorrectly determined, and two more skulls could not be assessed (inconclusive results). Compared to the diagnostic reliability of 77 percent (Stewart 1948) and 92 percent (Krogman 1962), respectively, the results are definitely positive and indicate that it is possible to restrict the reliable determination of gender to these five characteristics in forensic anthropological practice. Ackermann, J. F. De Discrimine Sexuum (gber Die k`rperliche Verschiedenheit des Mannes vom Weibe). Inaugural Dissertation Moguntiae, 1788. Acs<di, G. and NemeskJri, J. History of Human Life Span and Mortality. AkadJmiai Kiad\, Budapest, 1970. Bass, W. M. Human Osteology: A Laboratory and Field Manual. Missouri Archaeological Society, Columbia, 1987. Broca, P. Instructions craniologiques et craniomJtriques. MJmoires de la SociJtJ d'Anthropologie de Paris. TII 2. Serie, 1875. Ecker, A. Ueber eine charakteristische eigenthhmlichkeit in der form des weiblichen sch@dels, Archiv fhr Anthropologie (1866) 1:8188. Ferembach, D., Schwidetzky, I., and Stloukal, M. Empfehlungen fhr die alters und geschlechtsdiagnose am skelett, Homo (1979) 30:132. Graw, M., Haffner, H. T., and Czarnetzki, A. Evaluation of the supraorbital margin in investigations for identification of sex: Reliability and validity, Rechtsmedizin (1997) 7:121126. Graw, M., Czarnetzki, A., and Haffner, H. T. The form of the supraorbital margin as a criterion in identification of sex from the skull: Investigations based on modern human skulls, American Journal of Physical Anthropology (1999) 108:9196. Herrmann, B., Grupe, G., Hummel, S., Piepenbrink, H., and Schutkowski, H. Pr@historische Anthropologie: Leitfaden der Feld und Labormethoden. Springer, New York, 1990. Holland, T. D. Sex determination of fragmentary crania by analysis of the cranial base, American Journal of Physical Anthropology (1986) 70:203208. Hoyme, L. E. and Iscan, M. Y. Determination of sex and race: Accuracy and assumptions. In: Reconstruction of Life from the Skeleton, ed. M. Y. Iscan, K. A. R. Kennedy, Liss, New York, 1989, pp. 5393. Hunger, H. and Leopold, D. Identifikation. Springer, New York, 1978. Knussmann, R. Vergleichende Biologie des Menschen. Fischer, New York, 1980. Krogman, W. M. The Human Skeleton in Forensic Medicine. Thomas, Springfield, Illinois, 1962. Novotny, V., Iscan, M. Y., and Loth, S. R. Morphologic and osteometric assessment of age, sex, and race from the skull. In: Forensic Analysis of the Skull, M. Y. Iscan, R. P. Helmer, Wiley, New York, 1993, pp. 7188. Prokop, O. and Göhler, W. Forensische Medizin. Fischer, New York, 1976. Rebentisch, E. Der Weiberschädel, Morphologische Arbeiten (1893) 2:207274. Schiwy-Bochat, K. H. 3-dimensionale Formanalyse der Orbita zur Geschlechtsdiagnose. In: Abstract Volume of the 75th Jahrestagung der DGRM Zhrich, ed. W. Marty, P. Iten, W. B@r, 1996, p. 253. Schleyer, F., Ihm, P., and Bensch, W. gber die Geschlechtsverschiedenheit des Umrisses der knöchernen Orbita, Zeitschrift fhr Rechtsmedizin (1971) 69:168172. Stewart, T. D. Medico-legal aspects of the skeleton: Age, sex, race and stature, American Journal of Physical Anthropology (1948) 6:315321. Stewart, T. D. Hrdlicka's Practical Anthropometrie. Wistar, Philadelphia, 1952. Wahl, J. Shderbrarup. Ein Gr@berfeld der R`mischen Kaiserzeit und V`lkerwanderungszeit in Angeln. II. Anthropologische Untersuchungen, Offa vol. 64. Wachholtz, Neumhnster, 1988. Welcker, H. Kraniologische Mitteilungen. IV. Geschlechtseigenthmlichkeiten des sch@dels, Archiv fhr Anthropologie (1866) 1:120127.
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