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PPMP > 2. Abiotic Factors and Physical Processes > Flashcards

2. Abiotic Factors and Physical Processes Flashcards

1
Q

Biotic factors

A

living organisms found in an ecosystem

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2
Q

Abiotic factors

A

non-living organisms found in an ecosystem

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3
Q

Examples of biotic factors

A 
Insects
Root and fungal tunnelling
Bacterial action
Rodent gnawing
Small carnivore damage
Large carnivore damage
Human modification
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4
Q

Examples of abiotic factors

A

Winnowing

Aggradation

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5
Q

How do insects and predators affect decomp?

A

In correct circumstances, maggots can reduce a body to bones within days
Cold weather slows maggot activity
Flies can being laying eggs within minutes of death occurring if access is not blocked
Predators cause loss of soft tissue and increased access for insects

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6
Q

How does scavenging impact remains?

A

Reduces soft tissue very quickly
Predators cause loss soft tissue and increased access for insects
Can damge bone (may not)
Depends on access

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7
Q

How does animal activity affect bone?

A

Can cause loss or damage to bone which mimics perimortem trauma
-8% spiral or green fractures caused by carnivore activity
-5% spiral or green fractures caused by trampling
Smaller species can cause up to 50% bone fracturing

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8
Q

Examples of canidae scavengers?

A 
Domestic dogs
Fox
Wolf
Coyote
Jackal
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9
Q

Examples of felidae scavengers?

A 
Domestic cat
Lynx
Lion
Tiger
Leapord
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10
Q

Examples of ursidae scavengers?

A

Brown/black/grizzly bears

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11
Q

Examples of hyaenidae scavengers?

A

Brown/spotted/striped hyaena

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12
Q

Properties of canid scavenging?

A

Feeding begins at face and neck
Moves to thorax (especially chest)
Upper extremities disarticulated from trunk
Lower extremities disarticulated from trunk
Finally trunk disarticulated and eaten

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13
Q

How does plant activity affect decomposition?

A

Roots can ‘etch’ the surface of bone since they secrete humic acid
Roots can perforate cortex causing mechanical damage as they grow
Roots may be attracted to dug area because soil is looser or due to decomposition process
Can stain the surface of bone brown(plant decomp) or green(algae)
Can move bones

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14
Q

Abiotic effects on decomposition

A 
Physical/Chemical processes: temperature, humidity, oxygen, pH acid/alkali
Winnowing/Aggrading: water, gravity
Fracture patterns
Post-depositional damage
Burning/thermal effects
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15
Q

Examples of different climates

A

Hot and wet (fastest decomposition gets rid of soft tissue in 6/7 days)
Hot and dry
Cold and wet
Cold and try

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16
Q

How does weather affect decomposition?

A

Temperature/humidity affects insect activity
Cold slows bacterial reproduction and chemical proceses
Heat/high humidity speeds processes
Low humidity = mummification
Indoors/outdoors heat increases decomp of soft tissue
10 degree rise in temp doubles rate of chemical reactions

17
Q

Define mummification

A

Mummification involves the transformation of a once-living body or tissue into a state of arrested decay

18
Q

Define dessication

A

Removal of all water from tissues via heat, osmosis and evaporation

Requires warmth/cold and no predation
Dry conditions mean no putrefaction occurs

19
Q

How do chemicals effect decomp?

A

Heavy metals can help to preserve tissue e.g. mercury, arsenic, lead and copper
Chelating agents can combine with heavy metals making them unavailable to bacteria e.g. sphagnum produced by moss in bogs

20
Q

Define bone weathering

A

The process by which the original microscopic organic and inorganic components of bone are separated from each other and destroyed by physical and chemical agents operating on the bone either on the surface or within the soil zone

e.g. loss of collagen and hydroxyapatite

21
Q

What are Behrensmeyer’s 5 stages of bone weathering?

A

Stage 0 - fresh, defleshed bone
Stage 1 - cracks to appear along the length of the bone, some soft tissue may still be present
2a - top layer of bone begins to flake, some soft tissue may still be present
2b - top layer of bone almost completely flaked off
3 - top layer of bone gone, deeper layers of compact bone are fibrous (1-1.5mm)
4 - compact bone continues to look fibrous, rough to touch, splintering of bone may occur, inner cavity begins to show wear
5 - inner trabecular bone exposed, bone falling apart and losing original shape

22
Q

Other factors affecting decomposition

A

Burial - slows rate of decomp, restricts access of carnivores and insects
Mass burial - produces differentiating rates of decay, faster on edges
Water - slows rate of decay, temperature and salinity are both important

23
Q

How does shallow water/floods affect decomp?

A

Can act to move disarticulated remains or single bones

24
Q

What are the effects of immerision in water on soft tissue?

A 
Goose skin (anserina cutis) - roughening or pimpling of skin
Skin maceration (washer womans skin) - swelling and wrinkling of skin
Adipocere - transformation of fatty layer beneath skin into soap like material (requires 3 or more weeks)
25
Q

How do bodies in water lie?

A

Face down

Head hanging when bloating brings them to surface

26
Q

How does depth affect burial?

A

Less than a foot = insects can access body

Over two feet = temperature drops and becomes consistent

27
Q

What factors of soil type affect burial?

A

pH
Type - clay/sand etc
Moisture content
Soil organisms

28
Q

Define the process of saponification

A

Hydrolysis of triglycerides by bacterial enzymes which separates the fatty acids from the glycerol molecule which continues until there are no triglycerides left
Produces mixture of saturated and unsaturated fatty acids
Hydrogenation of unsaturated fatty acids into saturated fatty acids occurs

29
Q

Examples of unsaturated fatty acids

A

palmitoleic
oleic
linoleic

30
Q

Examples of saturated fatty acids

A

myristic
palmitic
stearic

31
Q

What does saponification produce?

A

Formation of a waxy, fatty substance (adipocere)

32
Q

Properties of adipocere

A

Off white in colour but can be reddish, greyish or grey/green
Needs the presence of adipocere
Can occur in dry conditions as well as amp conditions

33
Q

What conditions slows/speeds saponification?

A

Speeds up - body covered in clothes, early activity by anaerobes
Slows down - in cold water

34
Q

How does burning affect remains?

A

Reduces body to relatively small fragments
Destroys DNA evidence at moderate temperature
Leads to heat-induced morphological change - warping/distortion/fracturing/cracking
Destroys odontological evidence and many personal markers of identity

PPMP (14 decks)

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