Degredation

Question 1

Describe the macrostructure of teeth

Answer 1

• Teeth are made up primarily of collagen: calcium phosphate mineral material
• Structurally very different to bone, each tooth has a central cavity, blood cells, and nerves connecting them to the soft tissues going to the gums
• Surrounded by a layer of dentine (no blood supply)

Question 2

Bone composition

Answer 2

• 60-70% inorganic material, mostly calcium phosphates
• 30-40% organic material, mostly collagen
• 20% Water

Question 3

Osteoblasts do what

Answer 3

Secrete proteins and collagen

Question 4

Principle cause for tissue decomposition

Answer 4

• Microbial attack
• The gut microbe, which secretes collagenase plays a vital role
• Human bone is observed to be affected by bacterial attack 2x as often as animal bone
• Butchering/de-fleshing may increase preservation

Question 5

Cooking and biomolecular preservation

Answer 5

• Cooking is detrimental to the preservation of some biomolecules
• E.g. when collagen reaches temp over 58c the helix structure unravels and is more exposed to further damage
• Melting point of DNA is 75-80 degreesC
• Heating at low temperatures may destroy DNA and proteins but not result in visible alteration to bone structure

Question 6

Cremation

Answer 6

• Cremation is generally immediately evidenced through bone fragmentation and changes to structure and appearence
• Dehydration and oxidation result in shrinkage and cracking
• There will be no DNA or proteins preserved in fully cremated bone
• Lipid may be preserved in the fabric of unglazed ceramic vessels

Question 7

Example of strontium isotope analysis on cremated bone

Answer 7

• SIA on cremated human bone from Stonehenge indicated that they are not from the immediate area

Question 8

3 main factors affect the preservation of mineralised and keratinaceous tissue

Answer 8

• Soil pH and hydrology, ambient temperature
• Soils with low moisture content, alkali/neutral pH
• Soil calcium and phosphate is in equillibrium with the bone which limits mineral dissolution

Question 9

Teeth diagenesis

Answer 9

• Teeth are generally accepted to be less susceptible to diagenesis than bone
• No vascular network in dentine
• Have a protective layer of enamel
• Can occur through openings at the tips of the roots