The Basics of a Biological Profile in Forensic Anthropology

Expert Profile

Dr. William R. Belcher is currently working as an Assistant Professor at Nebraska-Lincoln University, United States. He is a forensic anthropologist and archaeologist, but also an environmental archaeologist with a speciality in animal bones from archaeological sites-zoo archaeology. He is interested in understanding the application of forensic anthropological methods to the identification of human remains. As the Coordinator for the Graduate Certificate in Forensic Anthropology, he welcomes students at the undergraduate and graduate level to learn the identification techniques and processes as a service-based discipline as UNL. He has worked in two disparate areas of research, one as an environmental archaeologist and the other as a forensic anthropologist/archaeologist. His environmental archaeology program focuses on the analysis of ancient (3rd and 4th millennium BCE) fish remains and their modern counterparts. This will allow them to examine significant changes in fishing, butchery, ancient trade, as well as climate change. After retiring from the Defense POW/MIA Accounting Agency, his primary focus at UNL is to provide opportunities to learn and conduct research related to the identification of missing US service members in conjunction with the Scientific Analysis Directorate Laboratory at Offutt Air Force Base in Omaha, NE.

Forensic Anthropology

Anthropology – The study of humans. Forensic – Pertaining to legal matters.

Forensic anthropology, application of physical anthropology to legal cases, usually with a focus on the human skeleton. Forensic anthropologists can assess the age, sex, and unique features of a decedent and are invaluable in documenting trauma to the body and estimating how long a corpse has been decomposing. Forensic anthropologists work closely with individuals in law enforcement and medical science—and especially with specialists in ballistics, explosives, pathology, serology (the study of blood and bodily fluids), and toxicology—and are often expert witnesses in murder trials.

Biological Profile

A biological profile is an individual's identifying characteristics, or biological information, which include the following:

• Sex
• Age
• Stature
• Ancestry
• Skeletal
• Variation
• Trauma
• Pathology

There are certain aspects when we are dealing with biological sex determination: -

1. Robust: The strength of a skeletal element relative to some mechanically relevant measure of body size.
2. Gracility: It is slenderness, the condition of being gracile, which means slender
3. Pelvic girdle
4. Cranial Characteristics
5. Muscles Attachments

Difference Between Male and Female Pubic Bone

The basic difference between male and female pubic bone is given in the following table

Figure 1- Difference between male and female pubic bone

Difference Between Male and Female Cranial Morphology

Figure2 - Female Cranial Bone

Figure 3- Male Cranial Bone

Difference Between Male and Female Muscle Mass

Points to be considered when we are studying the difference in the muscle mass of males and females: Larger the muscle mass, the rougher the bone surface.

The main areas are: -

1. Nuchal Region (Neck).

2. Linea aspera of the femur (Posterior).

3. Pelvic Girdle (Muscles Attachments).

Attribution of Ancestry or Geographic Origin

When we are studying ancestry or geographic origin we focus on these things.

1. Morphological features of the skull

• Visual or Macroscopic Assessment: -

• Macroscopic sex estimation has between 70% and 98% accurate.
• Macroscopic sex estimates are accurate when applied to medieval material.
• Individually, traits showed differences in the degree and scaling of sexual dimorphism between the medieval sample and that of the original collections used to create the standards, especially for skull traits.
• Commonly used macroscopic traits for sex estimation produced accuracy rates similar to those achieved on known‐sex post-medieval and modern material when assessed in a sample of medieval skeletons.
• Presence or absence of traits.

2. Craniometrical Measurements of the skull.

• The craniometrical analysis involves measuring the dimensions of the skull, such as the maximum and minimum length or width, or measurements between anatomically defined landmarks.
• The metric analysis, therefore, helps identify patterns in skull shape and size that may not be appreciated visually.
• Ancestry estimation is often more accurate and straightforward, however, when sex can be assessed by other methods first (Postcranial methods such as pelvic morphology and postcranial metrics are better for estimating sex than cranial features).

Skull of Different origin

1. Caucasoid Skull: -

• Also known as Europid.
• Found in Caucasian race.
• First introduced in the 1780s by members of the Gottingen School of history.
• Caucasoid traits are recognized as thin nasal aperture ("nose narrow"), a small mouth, facial angle of 100–90°, and orthognathism.
• Have small teeth, with the maxillary lateral incisors often shrunken in size or replaced with peg laterals.
• Have prominent supraorbital ridges and a sharp nasal sill.

2. Negroid Skull: -

• Less commonly called Congoid.
• It was introduced in the  1780s by members of the Gottingen School of History.
• Cranium is long in length,  narrow in breadth, and low in height.
• The sagittal contour is flat and the occipital profile is quite rounded.

3. Mongoloid Skull: -

• It was introduced in the 1780s by members of the Gottingen School of History and further developed by Western scholars in the context of "racist ideologies.
• Roundhead shape with a medium-width nasal aperture.
• Rounded orbital margins and massive cheekbones.
• Weak or absent canine fossae and moderate pragmatism.
• Absent brow ridges.
• Simple cranial sutures, prominent zygomatic bones, broad, flat, tented nasal root and short nasal spine.
• Shovel-shaped upper incisor teeth (scooped out behind).
• Straight nasal profile, moderately wide palate shape.
• Arched sagittal contour, wide facial breadth and a flatter face.

Craniometrical measurements to access Ancestry

• Craniometric analyses are often used in the estimation of ancestry because geographic variation in cranial size and shape is known to exist, but is difficult to assess with the naked eye.
• The metric analysis, therefore, helps identify patterns in skull shape that may not be appreciated visually. In some cases, analyses may involve one or two measurements or a ratio of two measurements, but the most accepted approach is the use of the discriminant functions.
• Ancestry estimation is often more accurate and straightforward, however, when sex can be assessed by other methods such as pelvic morphology and postcranial metrics are better for estimating sex than cranial features.
• The use of Fordist for the estimation of ancestry begins by taking the relevant and available skeletal measurements, inserting them into the electronic data forms and selecting the appropriate groups for comparison.
• Two examples of Fordisc results and interpretations of likely ancestry classification are shown in the Figures below.

Stature

Forensic Estimation of stature is part of the identification process necessary when dismembered body parts are found. It is also possible to estimate the stature from bones. Stature estimation is obtained from measurements of long bones; namely the humerus, femur, and tibia. We generally focus on knowing the sex and ancestry when we deal with stature in forensic and anthropology terms.

Metric traits of long bones

Stature is mainly calculated from the measurements of long bones humerus, femur, and tibia. Incomplete fragments can be used to estimate height, by first estimating the length of the long bone of a  regression equation before applying the original formula to estimate stature.

Adult age estimation.

In the case of unidentified skeletal remains, estimation of age-at-death is part of the biological profile used to narrow the list of potential missing persons.

• The estimation of age from sub-adult remains can be accomplished through the assessment of the degree of dental development,  dental eruption, long bone growth,  and epiphyseal union.
• The pubic symphysis is one of the most reliable areas of the skeleton for adult age estimation.
• Other methods include changes in the morphology of the auricular surface and the sternal rib end.
• Morphological age estimation is the process by which a skeletal biologist or forensic anthropologist examines skeletal characteristics to obtain an estimate of biological age.
• Teeth undergo age-related morphological and biochemical changes. Morphological changes include attrition, secondary dentin deposition, gingival recession, cementum apposition, root resorption, dentin translucency, and color.
• Age estimation from the sternal rib end is based upon the premise that bone at this joint adopts an increasingly irregular morphology with advancing age.

Conclusion

As a meticulous examination of any death scene is imperative, forensic anthropologists are frequently involved at the earliest stages of investigating a human skeleton. Forensic anthropologists focus on human skeletal traits, such as skull features, dental characteristics, and subcranial bone sizes and shapes, that vary from individual to individual and from population to population. An examination of the skeleton may reveal evidence concerning pathology and any antemortem (before death), perimortem (at the time of death), or postmortem (after death) trauma.

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