Upload
willis-andrews
View
214
Download
1
Embed Size (px)
Citation preview
Sometimes less is moreComparison of rapid and traditional recording methods
Bantycock Mine, Balderton
Recording methods
Easily identifiable and non-reproducible parts
• Like epiphyses
• Excludes ribs, vertebrae, limb shaft fragments, etc.
• Saves time by recording fraction of excavated assemblage
• Developed by Watson (1979) because NISP highly susceptible to specimen fragmentation & interdependency (one bone counts once)
Reason for comparison: Worry that important information will be lost if entire assemblage not recorded
Traditional – record everything, including ‘Unidentified’ and ‘-Sized’
Rapid – diagnostic zone system, records limited pre-defined set:
Background: Shaft anxiety
Examples have shown rapid methods can be problematic:
• Some Paleolithic sites: Intense bone processing and carnivore gnawing can selectively remove limb bone epiphyses (which are zones)
• Meaty limb bones appear absent because epiphyses missing and limb shafts not counted
• If absence not recognized as artifact of method = incorrect interpretation of human economy, hence anxiety
Rapid methods not appropriate for every research question, but
But can they be confidently applied to English commercialassemblage and effectively address changes in animal husbandry ?
Evaluation of recording & quantification method
• To evaluate methods re-recorded and re-quantified assemblage second time:
Bantycock Mine, Balderton, Newark, Notthinghamshire
• Commercially Excavated by Pre-Construct Archaeology, Lincoln
• Faunal Report by J. Richardson (2008), Archaeological Services WYAS
Bantycock Mine
Gypsum Mine
Chronological periods
Iron Age
Early Roman
Early 2nd to mid/late 4th century AD
mid 4th century or later
Unknown (nearly ¼ assemblage)
Evaluation of recording & quantification method
Richardson’s original method recorded all specimens, but also identified ‘diagnostic zones’
Thus rapid system can be compared to 2 levels to the original report:
1) Evaluate value of recording all specimens
2) Investigate affect of different zone criteria on analysis
ALL SPECIMENS
ZONESRAPID ZONES
ORIGINAL REPORT
ORIGINAL METHOD Recording & Zone Criteria
• All material recorded, including unidentified and indeterminate
• 38 post-cranial measurements & basic aging and sex data
Zones
• 34 post cranial zones
• 3 zones on each limb bone
• 2 teeth
Recording & Zone CriteriaRAPID ZONE METHOD
• Only specimens with zones are recorded (with exception)
• 57 post-cranial measurements + tooth measurements
• Presence or absence of ribs/vertebrae
Zones
Present/absent
Not counted – proximal epiphyses
Method summary
• All material recorded
• Zones:
• 34 post cranial zones
• 2 teeth
• 38 post-cranial Measurements
• Only material with zones is recorded:
• 22 post-cranial zones
• all teeth
• zones on prox. epiphyses not included in quantification
• 57 post-cranial measurements and tooth measurements
ORIGINAL METHOD RAPID ZONE METHOD
Evaluation of recording & quantification method
Comparison:
• Total amount of specimens recorded (Time)
• Total number of measurements recorded (useful information)
• Taxa absolute frequency & relative frequency
• Body part distribution
• Age and sex data
Recording comparison Total Recorded Material
5000 + more specimens ~ 800 more measurements
ORIGINAL METHOD RAPID ZONE METHOD
Both in MS Access Database
Quantification comparison Absolute Frequency
ORIGINAL METHOD RAPID ZONE METHOD
NISP – number of identified specimens
Zone count – number of zones
More material recorded than counted
Instead of NISP use NCSP –number of counted specimens
NISP = 6965NCSP = 1218.5
Includes ‘animal-sized’ material
Only 2 teeth
Includes all teeth
ZONE COUNT = 1498
n = Original zones – Rapid zones
More in Rapid Zones
More in Original Zones
Absolute Frequency Difference in zone count
Different zone criteria emphasize different body parts
Absolute Frequency Difference in zone count
• 3 zones on limb shafts
• Only 2 teeth
ORIGINAL ZONE METHOD RAPID ZONE METHOD
• 1 zone per bone
• All teeth
HYPOTHESIZED BIASES
Fragmentation bias more equal: only 1 zone per bone
More conservative system better describes recorded material
Bias against animals not eaten (no dP4s)
Bias toward animals with less-fragmented limbs zones (smaller)
Relative Frequency Common taxa
Iron Age (153.5)
Early Roman (158.5)
Early 2nd to mid/late4th century (319.5)
Mid-4th century or later (100)
Unphased(246)
010203040506070
%
Relative Frequency
Rapid MethodNCSP
CATTLE SHEEP/GOAT PIG
Original NISP
Iron Age (375)
Early Roman(482)
Early 2nd to mid/late4th century (946)
Mid-4th century or later (261)
Unphased(615)
0
20
40
60
80
%
Original Zones
Iron Age (153)
Early Roman(181)
Early 2nd to mid/late
4th century (346)
Mid-4th century or later (117)
Unphased(288)
0
20
40
60
%
Relative Frequency Common taxa
Iron Age (153.5)
Early Roman (158.5)
Early 2nd to mid/late4th century (319.5)
Mid-4th century or later (100)
Unphased(246)
010203040506070
%
Relative Frequency
Rapid MethodNCSP
-20
-10
0
10
20
dif
fere
nc
e
Original Zones
Original NISP
-20
-10
0
10
20
dif
fere
nc
e
DIFFERENCE in relative frequencies (Original – NCSP)
CATTLE SHEEP/GOAT PIG
Absolute & relative frequency summary
•Relative frequency both systems generally very similar
• Relative frequency from Original NISP most different
• Zone methods show small difference across Iron Age – Roman transition
• Rapid system is more conservative in counting absolute frequency with 1 zone per bone and all teeth
• Better description of assemblage
Body part distribution
• Original report did not quantify body part distribution, but noted that no element was over or underrepresented
• Rapid method quantified MAU (minimum animal units) for domestic taxa by period, also found entire skeleton fairly evenly represented
• MAU like MNI but doesn’t involve side = total for element / 2
Because of shaft anxiety – look at how shafts are represented…
Body part distribution summary
• Both systems concluded near equal skeletal part distribution
• Closer investigation of limb shaft fragments indicates some bones (radius) may be missed in rapid system
• But not to a significant degree – and if included simply reinforces equal skeletal part distribution
Age and Sex Data• Highly similar in both systems since each records fusion and tooth wear
Comparison summary
At Bantycock:
No significant loss of useful data on species representation, body part distribution, or age and sex data
But Rapid method is faster, has more measurements and better controls for interdependency (point of zones).
In analysis, the problem is not that information is missing, but not knowing what information is missing.
Strength of Rapid methods is accurately describing what material is recorded.
Therefore the method of recording used should be based on its ability to effectively answer research question in time available.