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Bone Density
Measurements
Photon Densitometry
Bone Survivorship
Human Bone Density
100
What is Density-mediated destruction?
The intrinsic properties of individual types of bones and portions of bones have in part determined their survival after undergoing these processes.
100
What is density?
Mass/Volume
100
Why was PD developed?
the technology was developed to measure bone mineral loss in PMP women
100
How do you calculate percent survivorship?
the # of elements (or portions thereof) present as a percentage of how many were present for a given MNI.
100
Gallowey et a. 1997 utilized what at multiple loci on long bones.
photon absorptiometry
200
Do studies take bone shape into account?
In the past, no; currently, yes.
200
What is true density?
mass/volume without the pore space included
200
True of False. Lyman (1984) used multiple scan sites throughout a bone.
True
200
How does acidic soil react with the surface area of bone?
It dissolves the mineral portion.
200
what is bone mineral density by circumference?
BMDc is the calculation of the circumference at each scan site divided by pi.
300
How does bone density affect the distance of water transport?
Denser items are less likely to be moved and lighter items travel further.
300
What is bulk density?
mass/volume with the pore space included
300
How does a photon densitometer measure density?
The more bone that is present, fewer photons reach the collector.
300
What type of taphonomy was present in the acidic soil of SE Asia
Boot taphonomy.
300
What is the one detriment to Gallowey et al.'s experiment?
still assumed a uniform structure across the measurement points in the bone.
400
Is bone density relevant to bone survival when undergoing burning or butchery?
No. In burning, soft tissue shielding is more relevant to survivorship, and in butchery, denser midshaft portions are often targeted.
400
True or False. when specific gravity is over 1, the bone will sink.
True. specific gravity is density of material/density of water; therefore, when the density of the material is greater than the density of the water, the object will sink and vice versa.
400
Name one problem to PD
1. value derived is an average across that scanned section so it ignores the amount of variation in the amount of bone. 2. it measures bone mineral content across an area and not a direct measure of density 3. the overall shadow of the bone is the entire scan area, regardless of its cross-sectional shape
400
This part of the bone survives the longest when submerged in acidic soil
long bone shafts
400
True or False. Willey et al. 1997 analyzed approximately 100 individuals before reburial occurred.
False, approximately 500 individuals.
500
What are the taphonomic factors that Pokines mentioned in discussing the relevance of bone density to survivorship?
What are trampling/tumbling, acidic soil attach, scavenging by large mammals, some types of massive blunt force trauma, and weathering.
500
What are the true densities of hydroxyapatite and bone tissue, respectively?
hydroxyapatite = 3.1-3.2 g/cm^3 bone tissue = 1.9-2.0 g/cm^3
500
Name two more problems to PD.
1. value derived is an average across that scanned section so it ignores the amount of variation in the amount of bone. 2. it measures bone mineral content across an area and not a direct measure of density 3. the overall shadow of the bone is the entire scan area, regardless of its cross-sectional shape
500
Describe the process of destruction to the bone by acidic soil.
Thinner areas of cortical bone will be destroyed first. Thicker areas of cortical bone will have their surface layer removed but still persist.
500
Describe the Crow Creek Site.
It is a Native American village located in South Dakota that underwent a massacre of of its population in the 1300s. There was a lot of evidence of scalping and trophy parts taken.