the pelvic girdle of the australian aborigine; sex differences and sex determination

The Pelvic Girdle of the Australian Aborigine; Sex Differences and Sex Determination

V. DAVIVONGS Department of Anatomy, University of Adelaide, South Australia

The collection of the Australian aboriginal skeletons at the South Australian Mu- seum was a main source of material studied in this work. The study of the aboriginal pelvic girdle was done in asso- ciation with that of the humerus and shoulder girdle (R. van Dongen, to be published) and that of the femur (V. Davi- vongs, to be published).

As far as the sex differences and sex determination of skeletons are concerned, it has been universally accepted that the pelvic girdle is the most important part. For this reason the discussion in this report will be mainly concentrated upon the sex differences in the aboriginal pelves as revealed by the metrical characters. The findings will be compared to those of other ethnic groups whenever possible and the sex determination of this skeletal part will be also discussed.

In connection with the sex differences and sex determination of skeletons, the following statements are very important and must be cited here.

1. As a general rule, male bones are more massive and heavier than female ones. The crests, ridges, tuberosities and lines of attachment of muscles and liga- ments are more strongly marked in males. This rule also governs the sizes of joints and articular surfaces as well.

2. In the case of the pelvic girdle, addi- tional sex differentiating features are added. These extra features are due to the different reproductive functions mainly in- fluenced by sex hormones. It has been also accepted that sex differences of the pelvic bone are present from fetal life and onward (Krogman, '62, p. 122). The pres- ence of sex differences of the pelvic girdle has been demonstrated in fetuses (Thom- son, 1899), infants and children (Reynolds, '45, '47); but so far, as can be expected,

sex determination of adult pelvic bones is much easier than that of young ones.

3. HrdliEka (Stewart, '52) points out an important principle, that is, the overlap of ranges of variation of male and female bones on the basis of development of sexual features. Bones in the male series range from hypo- to hyper-masculine, in the female from hypo- to hyper-feminine and the overlap of the two series would take place in the hypo-masculine and hypo- feminine groups. In a series of whole skeletons or any bony parts, the overlapping portion would cause difficulty or even im- possibility of definite sex determination.

In this report, most of measurements and indices that bear the sex distinguishing properties are selected from the previ- ous works. They will be described in the two following sections.

MATERIAL AND METHODS

The material comprises 100 pelvic girdles: 50 males and 50 females. Some of these bones belong to the Department of Anatomy, University of Adelaide but most are in the South Australian Museum. About 80% of skeletons came from South Australia and the rest from Northern Territory, New South Wales, Queensland and Western Australia. All of them are from adults but their ages and sexes were not recorded. Preliminary determination of the sex was mainly based upon the pelvic girdle itself. The subpubic angle and greater sciatic notch were employed in the sexing. The other parts of skeletons such as skulls and long bones were also examined and incorrect determination of the sexes would be assumed in very few cases. All of these bones were taken at

1 On WHO ('61) and Colombo Plan ('62) Fellow- ships in Physical Anthropolo from the Department of Anatomy Siriraj Medicav School, University of Medical Sciehces, Bangkok, Thailand.

443

444 V. DAVIVONGS

random, only damaged bones and those with pathological changes being excluded.

In this study the sacrum and innominate bones were examined and measured separately. The methods of measurements are those described by Wilder ('20) except where stated otherwise. Each linear measurement was recorded to the nearest milli- meter.

I . Measurements of the sacrum 1. Maximum length (or Wilder's mid-

ventral straight length) (fig. 1, AB). 2. Maximum breadth (or Wilder's an-

terior straight length) (figs. 1 and 2, CD). 3. Mid-ventral curved length. The length

from A to B (fig. 1 ) measured along the median line on the curved anterior surface of the bone with a tape-measure.

4. Antero-posterior and transverse diameters of the body of the first sacral vertebra (fig. 2, AE and FG).

C D

Figure 1

Figure 2

Figs. 1 and 2 Measurements of sacrum. AB, Maximum length; CD, Maximum breadth; AE, A.-p. diam. of body of S . l ; FG, Tran. diam. of body of S.1.

5. Indices. i. Sacral index =

maximum breadth maximum length x 100. __..~

ii. Curvature index =

x 100. maximum length mid-ventral curved length - ~

iii. Index of the body of S . l = a.-p. diam. of S.l tran. diam. of S.1 x 100. _ _ ~ -

iv. Corporo-basal index =

tran. diam. of S . l maximum breadth

6. The number of sacral segments, spina bifida and sacralization of the last lumbar vertebra were also recorded.

2. Measurements of the innominate bone

x 100 (Fawcett, '38).

1. Maximum length (fig. 3, AB). 2. Iliac breadth (fig. 3, CD). 3. Length of the pubic symphysis. The

length of the symphyseal surface of the pubis measured with the sliding calipers (fig. 4, PQ).

4. Vertical and horizontal diameters of the acetabulum. These are different from

B

Fig. 3 Measurements of innominate bone. AB, Maximum length; CD, Iliac breadth; EF, Ver- tical d i m . of acetabulum; GH, Horizontal diam. of acetabulum; OM, Pubic length; ON, Ischial length.

AUSTRALIAN ABORIGINAL PELVIS 445

Fig. 4 Measurements of innominate bone. PQ, Length of pubic symphysis; XZ, Chilotic line of ilium; XY, Pelvic part of chilotic line; YZ, Sacral part of chilotic line.

Wilder's. Measured with the sliding calipers; instead of taking the measurement from the middle point of the acetabular notch, it was found more convenient to take it from the marginal points near both ends of the lunate articular surface to the opposite marginal points (fig. 3, EF and GH).

The central point of the acetabulum was located before making any further measurements. In all primates according to Schultz ('30), this point lies approximately at the intersection of the inner edge of the articular surface of the acetabulum with a straight line prolonging the lower part of the acetabular border of the ilium down- ward (fig. 3, point 0). This is the point where the three main pelvic elements; the ilium, ischium and pubis, meet and it is better seen before the union of these bones. Mostly there is a notch in the inner border of the lunate articular surface at this point in adults (Washburn, '48).

5. Pubic length (fig. 3, OM). 6. Ischial length (fig. 3, ON). 7. Greater sciatic notch. As shown in

figure 5, the greatest width (AB) and the greatest depth (OC) were taken with the instrument illustrated in figure 6. The point B is the pyramidal projection located at the termination of the posterior border of the greater sciatic notch. The distance

Fig. 5 Measurements of greater sciatic notch. AB, Greatest width; OC, Greatest depth.

Fig. 6 Instrument for measuring greater sciatic notch.

from the point B to the point at which the greatest depth line intersects the greatest width line (fig. 5, OB) was measured at the same time. The preauricular sulcus was also recorded.

8. Chilotic line of the ilium. First the pubo-iliac and auricular points were located. As described by Deny ("23), the pubo-iliac point (fig. 4, point X) is situated

446 V. DAVIVONGS

RESULTS

1 . Sacrum The measurements and indices of the

aboriginal male and female sacra are shown in table 1.

on the ilio-pectineal line at the site of origi- nal union of the pubis and ilium. Some- times it is ill-defined and the ilio-pectineal eminence is a useful landmark in that case. The auricular point (fig. 4, point Y) is on the anterior margin of the auricular facet where this approaches nearest to the pubo-iliac point. A line connecting these two points is projected to the iliac crest and is called the chilotic line (fig. 4, XZ). The pelvic (XY) and sacral (YZ) parts of the line were measured with the sliding calipers.

9. Indices. i. Coxal index =

Maximum length, maximum breadth and sacral index

Generally speaking, the female sacrum is wider but shorter than the male and in consequence of this the sacral index is greater in the female. In the present aboriginal series, the mean maximum length of the sacrum in males is greater than in females and the sex difference of the mean lengths is highly significant. On the other hand, the mean maximum sacral breadths of the two sexes show no significant difference. Nevertheless, it is clear that the mean sacral index in females is greater than in males; being 115.49 in females and 104.16 in males. The female range of this index is also wider.

The sacrum can be classified according to the sacral index value as follows:

Sacral index

iliac breadth maximum length x 100. _ _ ___. -

ii. Ischium-pubis index =

pubic length ischial length X 100 (Schultz, '30).

iii. Index I of the greater sciatic notch =

greatest depth Gatest width X 100 (Olivier, '60).

iv. Index I1 of the greater sciatic notch =

x 100. length OB

greatest width -. ~~ Dolichohieric (narrow sacrum)

Subplatyhieric 100 to 105.9

Platyhieric (wide sacrum) 106 and over

up to 99.9

(Comas,'GO)

v. Chilotic index = sacral chilotic line pelvic chilotic line X 100 (Derry, '23). ~~ ~ ~~~

TABLE 1 Measurements and indices of Australian Aboriginal sacra

Male Female S.S.D. Measurements

andindices No. Mean Range S.D. No. Mean Range S.D.

Maximum length

Maximum breadth Sacral index

Mid-ven tr a1 curved length

Curvature index

Body of S. 1 A+. diameter Tran. diameter Index of S. 1 Corporo-basal

index

50

50

50

96.52

99.92

104.16

77-110 8.80

85-109 5.02

86.9-123.2 8.93

50

50

50

88.12

101.24

115.49

71-105

92-113

96.2-140.0

6.87

5.12

10.39

*** n.s. ***

50

50

104.34

92.46

82-115 7.10

81.6-98.2 3.74

50

50

97.08

90.80

81-110

81.C-98.8

6.74

4.22

*** *

50 50 50

50

29.78 47.40 63.03

47.42

25-37 2.29 3 6 5 3 3.99

54.9-72.5 4.40

41.2-55.4 3.24

50 50 50

50

27.58 44.10 62.84

43.62

25-31 3 6 5 0

54.2-72.2

36.4-52.0

1.48 3.68 6.25

3.66

*** *** n.s.

*** All linear measurements in mm. S.D. = standard deviation. S.S.D. = significance of sex difference of means. Degrees of significance: n.s. = not significant, P > 0.05; * = 0.05 > P > 0.01; ** = 0.01 > P > 0.001; *** = 0.001 > P.


In this respect, the mean indices of the Australian aborigine, Japanese Ainu and Fuegian in the male series fall in the subplatyhieric group. In the female series, the means of the sacral indices of these four groups are in the platyhieric range. For the European sacrum, both male and female means fall into the platyhieric group; being 112.4 in the male and 114.8 in the female (Martin, '28).

It should be noted that the ranges of variation of this index in the aboriginal male and female bones extend from the dolichohieric to the platyhieric group (fig. 7). This is also true in other ethnic groups. Therefore, an attempt to use the sacral index for ethnic discrimination is very doubtful.

Mid-ventral curved length and curvature index

On the average the mid-ventral curved length of the aboriginal male sacra is longer than that of the females. The female range is also narrower and falls almost entirely within the male range. The mean curvature index in males is slightly greater than in females indicating that the longitudinal curvature of the anterior surface of the female sacrum is more pronounced.

The body of the first sacral vertebra According to the general rule, the size

of the body of the first sacral vertebra should be larger in males than in females. The mean antero-posterior and transverse diameters of this part are greater in the aboriginal males, i.e. supporting the rule. Unfortunately, the female ranges of both measurements are narrower than those of males and all fall within the male ranges. The result is that the separation of any female sacrum from the males by these measurements alone is impossible.

The means and ranges of variation of the index of this part in both sexes are quite comparable and the means show no significant sex difference.

C orporo- bas a1 index Fawcett ('38) has shown that there is

a sex difference in the ratio of the transverse diameter of the body of the first sacral vertebra to the maximum sacral

breadth, expressed as the corporo-basal index. The index is generally greater in the male sacrum. In the present aboriginal series, it has been shown that the mean transverse diameter of the body of the first sacral vertebra is greater in males and the mean maximum breadths in males and females are almost equal. Therefore, the mean corporo-basal index in this series is greater in males and the difference is not expected to be more than that of the transverse diameter itself (fig. 8).

The sacral and corporo-basal indices are selected for a further discussion on sex determination.

Number of sacral segments From the aboriginal male series of 50

sacra, there were ten six-segmented bones ( 2 0 % ) and 40 five-segmented bones (80% ). Only two six-segmented sacra (4% ) were observed in the female series of the same number and the rest, 48 bones (96% ), were five-segmented. The higher percentage of the six-segmented sacrum in males should be noted.

Smith ('03) describes a graduated series in the Australian aboriginal sacra from four segments, which is not uncommon, through four and a half, five, five and a half, to six segments. He also suggests that they illustrate the transitional char- acter at the junction of the lumbar and sacral regions.

It should be also mentioned that the longer mean maximum length in the male series is not due to the more common six- segmented sacrum in this sex. When the maximum length of the sacrum of this type was measured, the sixth sacral seg- ment was excluded.

Spina bifida and lumbar sacralization

Two types of abnormalities of the sacrum were recorded in this survey. Spina bifida in which the sacral canal is open posteriorly for its whole length was found in four male sacra (8% of the male series) but in none of the female series. Bilateral lumbar sacralization was found in a male sacrum and one of the female bones had unilateral sacralization of the right side.

In fact, lumbar sacralization differs from the six-segmented sacrum merely in

448 V. DAVIVONGS

TABLE 2

Measurements and indices o f Australian Aboriginal innominate bones ~ ~ ~ ~ ~ ~

Female Male S.S.D. Measurements

and indices No. Mean Range S.D. No. Mean Range S.D.

Maximum length 99

Iliac breadth 97

Coxal index 96

Length of pubic

Ace t abulum

symphysis 84

Vertical diam. 99 Horizontal diam. 95 Pubic length 89 Ischial length 89 Ischium-pubis

index 89

Gr. sciatic notch Greatest width 100 Greatest depth 100 Length OB 100 Index I 100 Index I1 100

Sacral part 97 Pelvic part 97 Chilotic index 97

Chilotic line

197.65

147.99

74.77

36.25

51.47 50.75 63.31 81.18

77.98

45.23 24.97 6.11 55.68 13.45

64.01 49.91 129.26

178-221 9.39

133-167 7.12

70.1-80.9 2.46

27-44 3.41

45-58 2.79 45-57 2.86 54-73 4.53 74-91 3.92

70.9-86.8 3.76

37-55 4.06 18-31 3.02 -2-+13 2.93 37.5-77.5 8.54 -4.0-+28.6 6.55

50-77 5.24 36-58 4.09

94.3-197.2 16.46

96 181.96

94 142.16

91 78.04

62 34.52

100 45.92 89 45.53 72 69.24 72 74.72

72 92.72

100 50.86 100 26.05 100 17.27 100 51.38 100 33.78

97 56.74 97 58.23 97 98.16

165-195

126-161

71.1-83.7

29-42

41-50 40-50 60-80 64-83

8 1.1-107.4

42-60 21-34 9-2 7

37.9-67.3 19.6-50.9

47-68 49-70

73.1-138.8

7.27 *** 7.24 *** 2.83 ***

3.09 * *

2.00 *** 1 .89 *** 5.07 * * * 3.57 *** 5.99 ***

3.84 * * * 2.68 * * 3.78 *** 5.54 * * * 6.34 * * *

4.66 *** 4.64 *** 12.41 *I*

All linear measurements in mm. S.D. = standard deviation. S.S.D. = significance of sex difference of means. For degrees of significance see footnote to table 1.

the degree of transformation from the characters of the fifth lumbar vertebra to those of the first sacral vertebra. If the transformation was complete or nearly complete, it was recorded in the present work as a six-segmented type of the sacrum. If only the transverse processes of the fifth lumbar vertebra were enlarged and articulated with a part of the upper surface of the lateral mass of the sacrum, it was recorded as the lumbar sacralization. Furthermore, the sacralization might be limited to one or other side.

Sacral spina bifida was observed by Smith ('03) in a female aboriginal sacrum together with the unilateral sacralization on the left side of the same bone.

Innominate bone The measurements and indices of the

aboriginal innominate bones of both sexes are listed in table 2.

Maximum length, iliac breadth, coxal index and length of

pubic symphysis The means of the maximum length and

iliac breadth in males are greater than in females and they show high degrees of significance of sex differences. For the coxal index, the mean in the female series is greater than that in the male, indicating the relatively wide ilium in the female. Although the means of the maximum length, the iliac breadth and the coxal index are highly significant for sex differences, the male and female ranges overlap so widely that the three features have very low value for sex determination.

The mean length of the pubic symphysis in males is also greater than in females. Sex difference of the mean lengths is significant in a moderate degree. However, the female range is narrower and falls entirely within the male range. So in this

AUSTRALIAN ABORIGLNAL PELVIS 449

Number of Sacra

Female

a Overlap

85-89 95-99 105-109 115-119 It5429 135-139

90-94 100-I04 l l O - l l 4 120424 IS0454 140-144

Sacral Index Fig. 7 Distribution of sacral index.

Number of Sacra

15 I-

= Female

Overlap n

36-37 40-41 44-45 48-49 52-55

38-39 41-43 46-47 50-51 54-55

Corporo-Basal Index Fig. 8 Distribution of corporo-basal index.

case, the separation of the female bones from the males by this length alone is impossible.

Diameters of acetabulum According to the general rule, the hip

joint tends to be larger in males and thus the male acetabulum is expected to be larger than the female one. This is proved to be the case in the vertical and horizontal diameters of the acetabulum. The mean diameters in the aboriginal males are much greater than in the females and the sex differences of the means are highly significant. It should be also noted that in both sexes the mean transverse diam-

eter is slightly smaller than the mean vertical diameter.

Pubic length, ischial length and ischium-pubis i ndex

At puberty and certainly after that, the pubic length in females is much greater than in males. This is the reason why the more obtuse subpubic angle and the tri- angular form of the obturator foramen are common in females (Washburn, '48). The pubic length compared with the ischial length in the form of the ischium-pubis index, is also greater in females. In the aboriginal series, the mean pubic length is obviously longer in females and on the

450 V. DAVIVONGS

Number of Innominate Bones

20 k

1 n

70-71 74-75 76-79 82-83. 86-87 90-91 94-95 98-99 ILn-403 10647

72-73 76-77 80-81 &-85 88-69 $2-93 96-97 100-101 104-105

Ischium-Pubis Index Fig. 9 Distribution of ischium-pubis index.


1 0 t-

*I 42 43 44 4 5 46 4 7 48 4 9 50 51 52 53 54 5 5 56 57 58mITle

Vert ical Diameter of Rcetzbulum Fig. 10 Distribution of vertical diameter of acetabulum

contrary the mean ischial length in females is shorter. As can be expected, the mean of the ischium-pubis index in females is much greater than in males; the mean index being 92.72 in females and only 77.98 in males. The male and female ranges of variation of this index also show a rather small overlap suggesting a high value for sex determination. The latter problem will be discussed later.

Greater sciatic notch In comparison with other primates, man

has a more developed sciatic notch with sex differences. The sex difference is not found in the sciatic notch of the others (Straus, '29). Washburn ('48) points out that the sex difference in the greater sciatic notch belongs to a different system from that in the pubic bone and that it is not correlated with the subpubic angle.


It was found that the notch is wider in females (Thomson, 1899; Derry, '23 and Letterman, '41) and this is confirmed in the present aboriginal series. The sex dif-

ference of the mean greatest widths in this series is highly significant.

Derry ('23) and Letterman ('41) found that the mean greatest depth of the notch


30 I- n l l I I

-Female

-2-4 2-3 6-7 10-11 14-15 18-19 22-23 26-27 m, 0-1 4-5 8-9 11-13 16-17 20-21 24-25

Length OB of Greater S c i a t i c Notch Fig. 11 Distribution of length of greater sciatic notch.

Number of

10 t

-6-4 0-2 6-8 12-14 16-20 24-16 30-32 36-38 42-44 48-50

-3-4 3-5 9-11 15-17 21-23 27-24 33-31 39-41 4547 51-53

Index I1 of Greater S c i a t i c Notch Fig. 12 Distribution of index I1 of greater sciatic notch.

452 V. DAVIVONGS

is greater in males which means that the notch is deeper in this sex. The result is different in the present series; being probably due to the different technique of measurement. In this aboriginal series, the mean greatest depth of the notch is greater in females and the sex difference is moderately significant.

The index I of the notch which is the ratio of the greatest depth to the greatest width per 100 is greater in males by the means. The range of this index is narrower in the female series and all female cases fall within the male range.

The examination of the Australian aboriginal innominate bones reveals that a large number of the male bones have a form of the greater sciatic notch different from that of the female bones. The typical male notch is J-shaped whereas the typical female one is parabolic. One of the metrical characters that would express the difference is the length OB (fig. 5). On the average this length is shorter in males (Letterman, '41) and this is true in the aboriginal series. The sex difference of the means is highly significant and the overlap of the male and female ranges is


25

20

10

also very small. The similar result to this was also found in the index I1 of the greater sciatic notch.

Chilotic line In the Australian aborigines, the mean

length of the sacral part of the chilotic line in m'ales is longer than that in females. This is in contrast with the mean length of the pubic part which is longer in females. Consequently the mean chilotic index is smaller in females than in males; being 98.16 in females and 129.26 in males. The female range of this index is also narrower than the male range.

The mean value of the total length of the chilotic line in the aboriginal males is 113.92 mm and 114.97 mm in the females. It is slightly longer in females. This result is different from Derry's findings ('23). He found that the mean total lengths of the line in the English innominate bones from the Whitechapel and the Egyptian bones, both dynastic (2500-2000 B.C.) and predynastic, are longer in males than in females. However, in the series of Kerma from the Sudan, the male and female means are nearly the same.

Female

Overlap

0 Male

1 70-79 90-99 l l O l l 9 130-139 WIW no-179 I90499

80-89 IOl-lW 12042~ I40449 160-169 180469

Chilotic Index Fig. 13 Distribution of chilotic index.


Preauricular sulcus In 100 aboriginal male innominate

bones, a small and shallow preauricular sulcus was found in 49 while the remain- ing 51 showed no trace of the sulcus. In contrast, from the same number of female bones, absence of sulcus was observed in only ten, the small and shallow sulcus was found in 31 and 59 had a deep and wide sulcus. It must be concluded that while the male and female innominate bones have the small shallow sulcus or absence of the sulcus in common, only the female bones ever have the deep and wide one.

DISCUSSION

All measurements and indices listed in tables 1 and 2, except for the maximum breadth of the sacrum and the index of the body of the first sacral vertebra, show significant sex differences of the means. Those which bear a high degree of significance and have a small overlapping range between the sexes are selected for analysis in sex determination. They are as follows:

I. Sacrum 1. The sacral index. 2. The corporo-basal index.

I I . Innominate bone 3. The ischium-pubis index. 4. The vertical and horizontal diameters

5. The length OB of the greater sciatic

6. The index I1 of the greater sciatic

7. The chilotic index. Evaluation for sex determination of

these measurements and indices can be carried out by application of histograms showing frequency distributions in the male and female series and the percentage of overlap between both series will be as- certained. The value for sex determination of any measurement varies inversely with the percentage of overlap; that is, when the percentage is small, the value is high and vice versa.

The frequency histograms of the sacral and corporo-basal indices (figs. 7 and 8 ) show very wide overlaps between the male

of the acetabulum.

notch.

notch.

and female groups. The overlapping range of the sacral index is from 95 to 124 and the sacral bones in this range number up to 82 (82% ). The range of the overlap for the corporo-basal index is from 40 to 53 and the number of bones in this part is 92 (92% ). Therefore, very low value for sex determination would be expected from both indices of the sacrum. Other measurements of this bone yield more extensive ranges of overlap than these two indices.

The distribution of the ischium-pubis index of the innominate bone in figure 9 betrays a specially small overlap between the male and female series. From the total of 161 innominate bones of both sexes, 45 bones (28% ) fall within the overlap which ranges from 80 to 87. At the index level of 80-81, there are 17 male bones and only one female, which means the chance to be male is much greater than to be female by a ratio of 17 to 1. If this aberrant female bone is removed the percentage of overlap drops to 17%. This index for sex determination is very valuable.

As seen from the frequency histograms of the vertical diameter of the acetabulum (fig. lo ) , the overlap between the two sexes extends from 45 to 50 mm and the overlapping bones are 112 in number (56% ). A similar result would be expected in the horizontal diameter. About 45% of the bones can be sexed by these two diameters.

It is clear that the overlaps between the male and female distributions are very small for the length OB and the index I1 of the greater sciatic notch. The overlapping range of the length OB (fig. 11) is from 8 to 13 mm and contains 49 bones from the total of 200 (24.5% ). This rather high percentage of overlap is due to three aberrant bones which are two male bones of 12-13 mm and a female bone of 8-9 mm. If these bones are rejected, the bones that overlap will be only 17 (8.5% ). The originally overlapping part of the index I1 ranging from 18 to 29 (fig. 12) contains 55 bones (27.5% ). After removal of four aberrant bones, a female bone of 18-20 and three male bones of 27-29, the bones left in the overlap are 20 in number (10%). It can be concluded that the

454 V. DAVIVONGS

length OB and the index I1 of the greater sciatic notch are useful sex determinants.

The chilotic index is less valuable for sex determination because the sexual overlap is extensive (fig. 13). The overlap ranges from the index of 90 to 139 and the bones in this range are 150 in number (77% ). It means that only 23% of the total can be definitely sexed by the chilotic index alone.

For sex determination the data of four useful sexual criteria are given in table 3.

Because of some degrees of ethnic differences, these figures are special for the Australian aborigines only. They cannot be used in other groups without modifi- cation.

So far as the ethnic differences are concerned, the most distinguishing feature of this bodily part of the Australian natives is the narrowness of their hips (Campbell et al., '36 and Abbie, '51). In the Central

Australian aborigines, mostly of the Njalia (Wailbri) tribe, Abbie ('57) found that the mean of the bicristal (or biiliac) diameter for adult males was 258.64 mm and for adult females, 246.15 mm. The relative pelvic breadth was 15.2 in males and 15.7 in females. He concludes that there is obviously no great sexual distinc- tion, and comparison with Martin's figures for other groups puts the aborigines de- cidedly in the narrow-hipped class. In fact, the study on the assembled bony pelves is the best way of approach to this problem. Measurements of the separate pelvic bones, as in the present report, do not afford adequate evidence. Neverthe- less, the shorter pubic length in the Aus- tralian aborigines is more or less a reflec- tion of the narrow pelves they possess. This can be seen in table 4 which presents the ethnic comparisons of the pubic and ischial lengths and the ischium-pubis in-

TABLE 3 Important sex determinants of Australian Aboriginal innominate bone

Definitely female Definitely Overlap male Measurements and indices

Ischium-pubis index Vertical diam. of acetabulum (mm) Length OB of gr. sciatic notch (mm) Index 11 of gr. sciatic notch

< 80 80-87 > 87 > 50 45-50 < 45 < 8 8-13 > 13 < 18 18-29 > 29

TABLE 4

Pubic length, ischial length and ischium-pubis index in various ethnic groups

Measurements, index and groups Sources

Pubic length (mm) Eskimo American White American Negro Bantu Australian aborigine

Ischial length (mm) Eskimo American White American Negro Bantu Australian aborigine

Ischiurn-pubis index Eskimo American White American Negro Bantu Australian aborigine

Hanna and Washburn ('53) Washburn ('48) Washburn ('48) Washburn ('49) Present series

Hmna and Washburn ('53) Washburn ( '48 ) Washburn ('48) Washburn ('49) Present series

Hanna and Washburn ('53) Washburn ('48) Washburn ('48) Washburn ('49) Present series

- No.

129 100 50 82 89

129 100 50 82 89

129 100 50 82 89

Male

Mean Range

74.1 63-85 73.8 65-83 69.2 60-88

63.3 54-73 66.2 57-78

88.4 79-98 88.4 75-98 86.6 79-96

81.2 74-91 80.3 71-92

83.9 73-92

79.9 71-88 83.6 73-94

82.5 70-91 78.0 71-87

- No.

95 100 50 70 72

95 100 50 70 72

95 100 50 70 72

Female

Mean Range

80.1 73-90 77.9 69-95 73.5 63-86 73.2 66-84 69.2 60-80

81.0 72-89 78.3 69-93 77.5 67-86 74.8 68-84 74.7 64-83

98.8 91-109 99.5 91-115 95.0 84-106 98.1 87-107 92.7 81-107


dex. In all cases, the figures for the Aus- tralian aborigines seem to be smaller than those of the others. It should be also noted that these differences are not great and they cannot be used successfully for ethnic discrimination.

SUMMARY

1. Australian aboriginal pelvic girdles, 50 males and 50 females, were examined and measured in this work. About 80% of the material was found in South Aus- tralia without any record of the age and sex. This paper is concerned mainly with the sex differences of the bones and their value for sex determination. Some comparison with other ethnic groups is made.

2. The narrowness of the pelves was discussed as the most distinguishing feature of the aborigines. This probably bears upon the shorter pubic length found in this ethnic group. In this connection it is sug- gested that study of the assembled pelves is better than study of the separate bones.

3. With the exception of the maximum breadth of the sacrum and the index of the body of the first sacral vertebra, all the measurements and indices taken in this work show statistically significant differences between the male and female means.

4. Sex determination by the sacrum alone is never satisfactory. The overlap of the male and female ranges is very extensive in every measurement of this bone, even in the sacral and corporo-basal indices.

5. For sex determination by the innominate bone, the useful sex determinants are :

i. The ischium-pubis index. ii. The diameters of the acetabulum. iii. The length OB of the greater sciatic

iv. Index I1 of the greater sciatic notch. notch.

ACKNOWLEDGMENTS

I am greatly indebted to Professor A. A. Abbie for his valuable advice and helpful criticism of this work. I am very grateful to Mr. N. B. Tindale, Curator of Anthropol- ogy of the South Australian Museum, for his kind permission to examine the mate-

rial. Grateful thanks are also due to Mr. P. D. Kempster for providing certain in- struments.

LITERATURE CITED Abbie, A. A. 1951 The Australian aborigine.

Oceania, 22: 91-100. 1957 Metrical characters of a Central

Australian tribe. Oceania, 27: 220-243. Campbell, T. D., J. H. Gray and C. J. Hackett

1936 Physical anthropology of the aborigines of Central Australia. Part. I. Anthropometry. Oceania, 7: 106-139.

Comas, J. 1960 Manual of Physical Anthro- pology. Revised and enlarged English ed. Charles C Thomas, Springfield, Illinois, U S A .

Derry, D. E. 1923 On the sexual and racial characters of the human ilium. J. Anat., Lon- don, 58: 71-83.

Fawcett, E. 1938 The sexing of the human sacrum. J. Anat., London, 72: 633.

Hanna, R. E., and S. L. Washburn 1953 The determination of the sex of skeletons, as illustrated by a study of the Eskimo pelvis. Human Biol., 25: 21-27.

Krogman, W. M. 1962 The Human Skeleton in Forensic Medicine. Charles C Thomas, Spring- field, Illinois, U.S.A.

Letterman, G. S. 1941 The greater sciatic notch in American Whites and Negroes. Am. J. Phys. Anthrop., 28: 99-116.

Martin, R. 1928 Lehrbuch der Anthropologie. 2te Auf. Gustav Fischer, Jena.

Olivier, G. 1960 Pratique Anthropologique. Vigot FrBres, Paris.

Reynolds, E. L. 1945 The bony pelvic girdle in early infancy. Am. J. Phys. Anthrop., n.s.,

1947 The bony pelvis in prepuberal childhood. Am. J. Phys. Anthrop., n.s., 5: 165-200.

Schultz, A. H. 1930 The skeleton of the trunk and limbs of higher primates. Human Biol., 2: 303438.

Smith, W. R. 1903 Abnormalities in the sacral and lumbar vertebrae of the skeletons of Aus- tralian aborigines. J. Anat. and Physiol., Lon- don, 37: 359-361.

Stewart, T. D. 1952 HrdliEka’s Practical An- thropometry. 4th. ed. Wistar Institute, Phila- delphia.

Straus, W. L., Jr. 1929 Studies on primate ilia. Am. J. Anat., 43: 403460.

Thomson. A. 1899 The sexual differences of

3: 231-354.

the foetal pelvis. J. Anat. and Physiol., London, 33: 359-380.

Washburn, S. L. 1948 Sex differences in the pubic bone. Am. J. Phys. Anthrop., n.s., 6:

Sex differences in the pubic bone of Bantu and Bushman. Am. J. Phys. Anthrop., ns . , 7: 425-432.

Wilder, H. H. 1920 A Laboratory Manual of Anthropometry. P. Blakiston’s Son & Co., Phila- delphia.

199-207. 1949

the pelvic girdle of the australian aborigine; sex differences and sex determination

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