Skeletal Sex Determination

Does it belong to a Male or Female?

Once a forensic anthropologist has determined that a human bone has been found, they must try to determine if it belonged to a male or female. This is referred to as sex determination. Note that we are trying to determine sex, not gender.

Sex vs. Gender

Sex is biologically determined by factors like hormones and can be assessed by looking at the morphology of the skeleton. Gender is a cultural construct, meaning that someone's gender is determined by how members of their culture think about roles in society. So when referring to a person's biological sex we will say they are male or female. In contrast, when referring to their gender role, we may use words like guy, girl, lady, gentleman, man, woman, wife, husband, father, mother, etc.

Sex Determination from the Skull

Male

(Source: Smithsonian Institution)

Female

(Source: Smithsonian Institution)

Male

Generally larger than female
Larger brow ridges, with sloping, less rounded forehead
Greater definition of muscle attachment areas on the back of the head
Larger projections behind the ears (mastoid processes)
Square chin with a more vertical (acute) angle of the jaw

Female

Smoother bone surfaces where muscles attach
Less pronounced brow ridges, with more vertical forehead
Sharp upper margins of the eye orbits
Smaller projections behind the ears (mastoid processes)
Chin more pointed, with a larger, obtuse angle of the jaw

Check out these rotating images to see the skeletal differences between the sexes in the pelvis.

Male pelvis -- (Large screen) (Small screen)

Female pelvis -- (Large screen) (Small screen)

Here are some additional resources that may help.

All Things AAFS (Archaeological, Anthropological, and Forensic Sciences)

Smithsonian Institute Written in Bone Activity

Ancestry Estimation

Does it belong to a Caucasian (European), African (Sub-Saharan African/African American), Asian (Mongoloid)?

Once a forensic anthropologist has determined the biological sex of the decedent, they must try to determine the ancestry of the individual. This involves examining the morphology or shape of certain features of the skull that have shown to be commonly associated with the genetic and geographic nature of human ancestry.

Caucasian

Long and narrow face
Sloping eye obits
Larger nasal spine
Narrow, high nasal opening
Sharp inferior nasal border
Spatulate incisors

African

Facial prognathism (facial forwardness)
Smooth and depressed inferior nasal border
Wide nasal chamber
Smaller nasal spine
Rectangular eye orbits
Large teeth, wrinkling of molars
Spatulate incisors

Asian

Rounded eye orbits
Shovel-shaped incisors
Tented nasal bones
Intermediate/triangular nasal opening

(Source: Smithsonian Institution)

Age Estimation (in Adults)

What was the decedent's age at the time of death?

Age estimation is an important part of the biological profile. This involves examining the morphology or shape of joint surfaces such as the pubic symphysis in the pelvic girdle, the sternal rib endings, or the cranial sutures.

Age Estimation from the Sternal Rib End

Generally smooth bone surfaces
Young adults may have a billowy, cloud-like surface
Middle adults have a smoother surface with a slight depression
Rim may be small and rounded with semi-irregular contour (shape)

Generally porous or pitted bone surfaces
Deeply depressed or U-shaped surface contour
Irregular rim with extra bone formation (projections)
Sharp rib with thin walls

Age Estimation from the Pubic Symphysis

young adult pubic symphysis.png

Billowy or cloud-like surface appearance
Irregular or underdeveloped rim

middle adult pubic symphysis.png

Smoother surface with fine texture
Regular rim with oval outline

older adult pubic symphysis.png

Pitted or porous surface
Erosion of rib with extra bone formation

Age Estimation from Cranial Suture Closure

Source: Sibini, RC and Elkowitz, DE (2006) Significant Differences in Patency Among Cranial Sutures. JAOA 106, 600-604.

Here are some additional resources that may help.

All Things AAFS (Archaeological, Anthropological, and Forensic Sciences)

What When How Forensic Science Tutorials: Morphological Age Estimation

Stature Calculation

What was the decedent's approximate height at the time of death?

Stature estimates are an essential part of the biological profile. This involves taking the maximum length measurements of select bones in the skeleton -- usually the long bones of the lower limb -- and using a population-specific formula to produce a stature estimate.

Structure Reconstruction Formulas - Forensics.png

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