Attribution of Sex (BONES)

Reaction of authorities to initial analysis in case study 10

- Law enforcement officials not happy with suggestion that remains possibly represented a male. However, other aspects of the ID matched the missing person: - Skull showed mixture of asiatic and european traits, consistent with hispanic ancestry. - Suture fusion in the skull suggested individual was in late-teens or early-20s at time of death.

The difference between the size and strength of males and females

8% (females are 92% of the size of males), so generally male skeletons are more robust, taller, wider, and more rugged

Accuracy of determining male vs. female

90-100% accuracy in assessing sex based on a full skeleton, 90-95% with only the pelvis, 80-90% with just the skull, and only 80% with only long bones

Mental eminence

An anterior protrusion in the chin region that can best be seen by holding the mandible by the chin using the forefinger and thumb of both hands

Sub-pubic angle

Male: v-shaped Female: u-shaped

Background discovery for case study 10

- 19 ½ year-old Leticia Garcia reported missing in Santa Fe, July 1988. - Skull and partial femur brought home by pet dog near Las Vegas, NM in January 1989. - Santa Fe law enforcement confident that remains were those of Garcia.

Medial aspect of the ischiopubic ramus

- Area of the medial part of the ischiopubic ramus just below the pubic face - This medial edge is relatively wide and dull in males, while it is narrow and sharp in females (but this is the least reliable of the three characteristics)

Overview for sexing sub-adults

- Because most differences in shape and size emerge at puberty, it is difficult to sex individuals who do not express fully adult characteristics - No method has higher than 70% accuracy, but several are used regularly

Using metric methods on the pelvis for determining sex

- Because of the difficulty in measuring the pelvis, there are few methods for distinguishing males and females from metric dimensions of the pelvis - The only widely accepted technique is the ischium-pubic index, a way of quantifying the longer, more stretched character of the pubic bone in females when compared to males

Variations on cranial characteristics used to attribute sex

- Because of the variability of these traits in skulls, there are drawings rated on a scale from 1-5 on each of these characteristics - 1 is female, 2 is probable female, 3 is indeterminate, 4 is probable male, and 5 is male

Concavity of the ischiopubic ramus (sub-pubic concavity)

- Concavity of ischiopubic ramus starting below the pubic faces; best viewed from the posterior side - In females, the ramus in concave (has the subpubic concavity), while it is straight or slightly convex in males

Further investigation of situation in case study 10

- Feeling they had insufficient grounds for a positive ID, family not notified. - Search was conducted the following spring, using cadaver dogs. - Additional remains recovered: vertebrae (inc. fused C2/C3), ribs, clavicle, radius, ulna, scapula, sacrum, ilium, tibial shaft. - Also recovered: a quantity of long blond hair, numerous articles of clothing.

Scars of parturition in determining sex

- Females are more likely to exhibit scars of parturition, appearing as small pits on the dorsal face of the pubis. - There is no one-to-one relationship between number of scars and number of births. - Males and non-parous females also sometimes exhibit scars of parturition.

Sexing sub-adults using the auricular surface

- Females exhibit auricular surfaces with the entire edge of the surface raised above the plane of the ilium, while males display surfaces with all or some of the surface edges in line with this plane - Only a 70% accuracy rate, not used very frequently

Forehead shape in Asians as an example of sexual differences between populations

- Females overall tend to have higher foreheads than males, but Asian males also tend to have high foreheads.

Basic principles of male vs. female

- Humans are sexually dimorphic (two forms) - Skeletally evident in adults but not children (sex hormones increase around time of puberty, leading to secondary sexual characteristics and skeletal changes). - Varies both within and between populations. Robusticity and muscularity are usually more evident in males. - Absolute brain size is similar in the two sexes, but males have larger bodies to feed so masticatory muscle scars on cranium are more rugged in males.

Take home messages for case study 10

- In isolation, cranial material provides less reliability in sexing an individual: gracile males and robust females may confound sex diagnosis from the skull alone (even when metric techniques are employed). - The evidence from the pelvis was, rightfully, given more weight in the sex diagnosis in this case. - Law enforcement erred on the side of caution (and compassion) in waiting to notify the family.

Initial analysis of sex by FA in case study 10

- Initial analysis by Stan Rhine fails to support the identification offered by Santa Fe authorities. - Anthroposcopically, skull had large features, robust bone, and prominent brow ridges, suggesting male sex. - Univariate and multivariate (discriminant function) analyses all put skull into male/female overlap range or just on the male side of the line. - femoral linea aspera delicate, suggesting female sex.

Final conclusion of case study 10

- Known PMI considered consistent with condition of skeletal remains. - Initial hunch of law enforcement agents proved correct, but case could not proceed until sufficient evidence had been mustered. - Case highlights difficulty of making positive ID in case of young individuals (since x-rays and dental records less likely to help).

Further analysis of new remains in case study 10

- Lateral head x-ray revealed congenital fusion of C2/C3, matching the recovered vertebrae. - Matching vertebrae, along with consistency in size, robusticity/rugosity, coloration, preservation and weathering indicate skull and femur belong with rest of skeleton - Stature estimation from upper limb bones matched Garcia's height. - Os coxae revealed wide subpubic angle, concavity to ishiopubic ramus, wide greater sciatic notch, and tabled auricular surface, consistent with female sex. - Sacrum had wide alae and slight curvature, female

Mastoid process size in Chumash women as an example of sexual differences between populations

- Males generally have larger mastoid processes than females - However, Chumash females have large mastoid processes

Initial case of case study 9

- Nearly complete skeleton recovered by construction workers outside of TB. - Skeleton was covered by several centimeters of sand and pine needles indicating surface deposition of body, decomposition, then interment from tidal currents and storm winds. - Remains devoid of soft tissue, suggesting relatively long PMI. patterning of pine needles and sand in and around skeleton - Remains recovered w/ rusted zipper and partial upper denture. Based on denture, police focus search on male missing persons, craniofacial characteristics consistent with European ancestry.

Overview and statistics of determining sex

- Pelvis is most diagnostic region of the anatomy (95% for trained osteologist familiar with source population). - Skull is second-best region (90% accuracy). - With pelvis + skull, 99% accuracy. - Techniques exist for sexing other parts of skeleton, with varying (but generally< 80%) levels of accuracy.

Role of relatives in case study 10

- Relatives identify clothing as belonging to Garcia. relatives provide lateral head x-ray and access to dental records. - Skull matches x-ray in pattern of mastoid air sinuses, pattern of arterial branching on endocranial surface, and suture pattern. - Dental match made by forensic odontologist.

Ventral arc of the pubic bone

- Ridge of bone beginning at the superior-medial corner on the anterior surface of the pubis and curving down to the ischiopubic ramus - In males this structure is small to nonexistent, and when it is present it follows the edge of the pubic bone so closely that it occupies the inferior-medial corner of - - Ventral arc is visible in females as young as 14 years (called a precursor arc), but is most easily recognized in women from the mid 20s on

Take home messages for case study 9

- Size is an unreliable diagnostic criterion (too much overlap in male and female body size), thus size related criteria (relative acetabular size, joint sizes) are likely to give incorrect assignation for small males and large females. - Again, given the more stringent criteria of the Daubert standard, metric techniques should be used whenever possible (along with anthroposcopic methods).

Using the scapula to sex adults

- Take two measurements of the scapula: - Maximum length/height of the bone, measured btwn the superior and inferior borders (values < 14 cm are female, values > 17 cm are male, values in between cannot be used to determine sex) - Height of the glenoid cavity (there is overlap but generally >36 mm are male due to the larger size of the humeral head, while those below are female)

Sexing sub-adults using the greater sciatic notch

- The depth of the greater sciatic notch can determine sub-adult sex, more specifically the value of an index relating the depth of the notch to its width - Anthroposcopic evaluations of the notch as "deep" or "shallow" were nearly as effective - No standard method for this measurement has been created

Three notes about cranial discriminant equations for determining sex

- The functions use different sets of measurements to accommodate incomplete crania - The % of correct classification using these formulas are not as high as those attained anthroposcopically by forensic experts, but still popular because it can be performed by those with less experience - Samples may be too old to represent modern humans, so correct percentage is even lower - FORDISC should be used for more accurate samples

Using the femur to sex adults

- The head diameter of the femur is the best single measurement on the bone to determine sex, but must split by ancestral group

Using the radius to sex adults

- The maximum and minimum diameters on the radius are particularly good for determining sex - Radii with a maximum diameter of <21 mm likely female, male diameters >24 mm - For minimum diameters, these values are 20 mm and 23 mm - These may not be accurate for modern populations

Other methods to determine sex for sub-adults

- The skeletons of boys mature more slowly than girls, differences between ages derived from various skeletal structures are more likely to indicate male than female - This can be applied to dental development or eruption and skeletal maturation derived from ossification of wrist bones (but wrist bones are very hard to recover and analyze)

Misc. methods to sex adults

- These other methods use the size differences between sexes to arrive at a sex determination and can be useful when remains are incomplete or as supporting data for the methods previously described - Multiple postcranial bones, scapula, humerus, radius, femur

Purpose of case study 10: Leticia Green

- To explore the difficulties in diagnosing sex sometimes presented in actual cases. - To examine another case involving mixed sexual diagnostic criteria. - To explore the interaction of law enforcement with family members in a case of presumptive ID. - To illustrate another example of working from a presumptive to a positive ID.

Purpose of Case Study 9: Tampa Bay skeleton

- To explore the difficulties in diagnosing sex sometimes presented in actual cases. - To provide a worked example of discriminant function analysis in an actual case. - To explore the interplay of anthroposcopic and osteometric analyses in an actual case.

Sexual variations between populations

- Variation exists between populations in sexually diagnostic traits. - For example: forehead shape in Asians, mastoid process size in Chumash women - Thus determination of ancestry should precede determination of sex, and FAs should be familiar with relevant populations.

Three characteristics of the pubic bone that are over 95% accurate in sexing

- Ventral arc - Concavity of the ischiopubic ramus - Medial aspect of the ischiopubic ramus

Using the humerus to sex adults

- Vertical head diameter of the humerus is particularly good at determining sex - Below 43 mm = certainly female - 43 to 44 mm = probably female - 46 to 47 mm = probably male - Over 47 mm = certainly male - Measurement doesn't work for Hispanic individuals

Ischium-pubic index

- Very accurate but measurements are hard to obtain - Base point for measurement is inside the acetabulum where the ilium, ischium, and pubis fuse (difficult to see, represented either by a raised area, an irregularity, or a notch inside the acetabulum) - Measurements can be taken by holding a caliper on this base point in the hip socket and swinging it to the end of the pubic bone and to the bottom of the ischium - Index is obtained by dividing the pubic length by the ischium length and multiplying by 100 - But the area of overlap is 32%, so the index will only be right 68% of the time if ancestry is not known

Ischiopubic ramus

Composed of the lower parts of the pubis and ischium, the subpubic concavity is at the lower end

Reason for the main architectural differences between sexes

Females carry and birth children so their pelvises are designed to accommodate the passage of infants, and other architectural differences are based on this main difference

Lateral view, male vs. female

Male = left, female = right

Browridges on skull

Male: Large Female: small, none

Mastoid on skull

Male: Large, projecting Female: Small, non-projecting

Chin

Male: broad Female: pointed

Pelvic inlet male vs. female

Male: heart shaped Female: circular or elliptical

Ilium

Male: high and vertical Female: low and flat

Obturator foramen

Male: large and ovoid Female: small and triangular

Pelvis size

Male: large and rugged Female: small and gracile

Size of skull

Male: large and rugged Female: small and smooth

Shape of sacrum

Male: long and narrow Female: short and broad

Greater sciatic notch

Male: narrow Female: wide

Pubic shape

Male: narrow and rectangular Female: broad and square

Preauricular sulcus

Male: rare Female: well developed

Supraorbital margin on skull

Male: rounded Female: sharp

Nuchal area on skull

Male: rugged with hook Female: smooth, hook uncommon

Frontal bone on skull

Male: slanted Female: high, rounded

Discriminant function analysis of sex in case study 9

Near sectioning point but always below, so female

Two primary biological differences between male and female

Size and architecture

Pelvic inlet

The area enclosed by the os coxae and sacrum when viewed superiorly

Discriminant function for determining sex from the skull

The logistical discriminent functions can predict the sex from the five characteristics listed above, where if the result is less than zero the skull is male and if it is over zero the skull is female

Curving of the sacrum

The male sacrum is more evenly curved when viewed laterally, while in females this bone often exhibits a marked angle between segments two and three

The pelvis in determining sex

The pelvis contains the greatest number of characteristics for determining sex because it is the bone the most affected by birthing

Sexing the skull through anthroposcopic methods overview

The skull is the second most useful way of determining sex, but these factors often vary among ancestral groups, which is why it is better to determine ancestry before sex

Gradations in pelvic size

There are an infinite number of gradations between pelvis size, with males at the high end and females at the low end, but there is considerable overlap in the middle → thus sexing is often much more difficult than described

Discriminant functions/metric methods for determining sex

Using a discriminant function with 9 measurements of the skull, sex can be determined 85% of the time

Using postcranial bones to sex adults

• Virtually all long bones, the pelvis, foot bones, vertebrae, and even ribs have been measured to attempt to determine sex from postcranial bones • Indeed, many of these have proven to be more accurate than determinations from the skull, as cranial measurements can be confounded by traits that alter by ancestral group