Human Skeletal Biology

[S] Human Skeletal Biology #

Tuesday, April 7, 2020 — 12:49 PM

What is Skeletal Biology? #

Study of the skeleton

• human osteology: general, descriptive analysis of the skeleton
• bioarchaeology: (more recent term) integrates skeletal biology with archaeological contexts
• forensic anthropology: applied skeletal biology to medical/legal context (identify individuals)

What can we learn? #

• human evolution
• past social behavior
• modern biology/physiology
• identify individuals (forensics)

Features – Terminology #

★ everything leaves marks!

Projections #

• muscle/tendon ridges

Depressions #

• grooves or fossa (wells) for organs, etc

Foramen and canals #

• holes for nerves, blood vessels

Function of Bone #

1. Structural #

• framework for muscles
• protects vital organs

2. Physiological #

• bone marrow produces red blood cells

• stores calcium, phosphorous, fat, blood cells, etc

• 2/3 bone is hydroxyapatite crystal – gives strength

• 1/3 bone is collagen, ground substance (organic)

2 main types: #

• woven bone

• lamellar bone (adult/mature)

  • cortical (compact) – external bone surface
  • trabecular (cancellous) – spongy insides

• cortical (compact) — external bone surface

• trabecular (cancellous) — spongy insides

Spongy structure: trabecular, filled w/ marrow, fat

Outer hard structure: one circle = osteon, made of collagen, center: canal — blood canals

Compact bone

Bone Cells #

• Osteoblasts: bone formation
• Osteocytes: maintenance
• Osteoclasts: bone removal

→ bone remodelling — a constant cycle

Entire skeleton renewed every 10 years

Why does bone remodel? #

• Extract calcium and phosphorus (can take out of skeleton if needed)

Repair damage #

• Macrodamage: fracture

• Microdamage: small damages → tiny fractures/microcracks

  • Woven bone → bony callus
  • If accumulated, would break bone

• woven bone → bony callus

  • if accumulated, would break bone

• respond to functional stress/damage

  • bigger muscles = bigger bones needed
  • reduce size of bone when not needed (space, lying in bed…)

• normal bone growth

The Skeleton #

• long bones → levers (femur)
• flat bones → skull, shoulder
• short bones → tight, cube-like (wrist, ankle)
• irregular bones → specialized, complex (pelvis, vertebrae)

[T] Forensic Anthropology #

→ Applies biological anthropology to identify individuals for forensic/legal purposes

Protocol #

1. human or animal?
2. how many?
3. age at death
4. sex
5. ancestry
6. stature
7. Pathologies → antemortem (before) or perimortem (near death)
8. Postmortem interval → time since death

1. human or animal #

• use joint surfaces to differentiate
• compare to other animal bones

2. # of individuals #

• minimum number (MNI)
  • present elements
  • overlapping/duplicate elements (e.g. two left femurs)
  • articulation: see if bones fit together, match left/right
• no two skeletons are alike

3. Age #

• developmental — ossification, dental development (up to 20yrs) → little variation in tooth development time
• metamorphosis — changes in appearance of bones → lots of variation, especially in adults
  • epiphyseal fusion

Tooth wear #

• for any refined foods that grind enamel

4. Sex #

Can only determine after puberty

• Size: males taller, more robust (but very subtle)
• Shape: pelvis, cranium ← variation from population

Not definite — on scale: F! → F → F? → ? → M? → M → M!

Pelvic Sexing Traits #

Male vs Female pelvis comparison:

• Male: curved tail bone, smaller subpubic angle
• Female: vertical tail bone, pelvic inlet, subpubic angle much larger
• Pubic bone: 95% accurate sexing
• Sciatic notch: wider in female

5. Ancestry #

• race is a social classification but biology can make broad categories
• metric traits: measurements/stats directly from skeleton
• nonmetric traits: general characteristics (e.g. shovel shaped incisors)

6. Stature #

height measurements based on size of long bones

• femur length
• arm bones

Misc #

• occupations: changes in mandible in instrument players etc
• handedness
• dental work
• sinus cavities are unique

7. Pathology #

Antemortem: before death #

• sinus infection
• fractures that have healed
• cavities

Perimortem: around the time of death #

• wounds
• choking/strangulation

Manner/Cause of Death #

Manner #

the events that occur at/near death, determined by forensic anthropologist

Cause of death #

precise biological explanation, determined by coroner

Time since Death #

• very difficult to determine
• variable in environment
• rely on surroundings (bugs, plants)