Transcript Developing a tool for using Dental Cementum to explore

Developing a tool for using Dental
Cementum to explore seasonality
of the Early-Middle Epipalaeolithic
Azraq Basin, Jordan.
Jennifer Jones: [email protected]
Postgraduate Zooarchaeology Forum (PZAF)
14th November 2009
Cardiff University
Epipalaeolithic in the Azraq Basin
• Early Epipalaeolithic- 22,00014,000BP
• Middle Epipalaeolithic-14,60012,500 BP
• Natufian- 12,500-10,200BP
Key Themes in Epipalaeolthic
• Origins of sedentism
• Length of occupation
• Reason for occupation of sites
(Adapted from Garrard et al, 1994:178)
The ‘Mega Sites’
Kharaneh IV
• 21,000m² in size
• Dates to 20,000-13,000BP
• Originally excavated by Muheisen in 1988.
• Now being excavated by Maher et al (2008present).
• Kebaran and Geometric Kebaran cultural
sequences
• Gazelle most commonly consumed animal
Kharaneh IV
Wadi Jilat 6
•18,200 m² in size
•Dates to 18,000-12,000 BP
•Excavated by Garrard et al (1987), one 2m by
2m trench
• Belongs to the Nebekian cultural sequence
•Gazelle most commonly consumed animal
An example of the level of
deflation at the sites.
‘Mega Site Theories’
• Goring Morris(1998)- Sites used for seasonal exploitation of
migrating gazelle.
• Byrd and Garrard (1990)- Sites represented repeated periods of
occupation with possible periods of longer residency.
The site of Kharaneh IV, an extensive, site,
reminiscent of a tell.
Aims of study
• To explore the potential of using dental cementum analysis
to investigate season of occupation.
• To determine if possible the seasons that each of the
‘Mega Sites’ were occupied.
• To try and understand what the season of occupation at
the sites means in terms of mobility patterns and
territoriality in the Azraq Basin.
• To consider the limitations of using cementum analysis and
how the technique can be developed for future analysis.
• To understand how seasonality studies can be developed in
the Azraq Basin.
• To consider additional ways of understanding more about
territoriality and mobility in the region.
Cementum Analysis
• Grows incrementally on a seasonal basis.
• increments can show:
• Season of Death (from outer
band)
• Age (based on counting rings)
• Possible Causes:
• Variations in nutritional content
of diet in different seasons
• Occlusal stress caused by
seasonal dietary variations
• Biological causes, hormonal
change
• Recognised as a successful technique for
looking at seasonality
• Successfully carried out on gazelle (eg
Lieberman 1990, 1991, Stutz and
Lieberman, 2007).
Dentine
Enamel
Cementum
Mandible
Epipalaeolithic diet of Gazelle
• Environment similar to today.
• Two mains season
– November-March- Main for of
diet low quality grass and forbs
– April-October- Higher quality
browse consumed
• Studies of modern gazelle
(Lieberman, 1993) suggest:
– Wet season growth (NovMarch) approx 2.5µm per
month
– Dry season growth (April-Oct)
approx 4.6 µm per month
Selecting the Sample
• Gazelle most common on Levantine Epipalaeolithic sites.
• M1 used-largest accumulation of cementum.
• Tooth needed to be in situ in the mandible-protects outer band of
cement
Kharaneh IV Mandibles
Wadi Jilat 6 Mandibles
•Taken from 2008 and 2009 excavations.
•Taken from 1984 excavations of a
2m X2m trench.
•Area A (Middle Epipalaeolithic) and
Area B (Early Epipalaeolithic) sampled.
•Taken from a range of different
contexts.
•Total number successfully processed:
12
•Mandibles all from upper levels,
making them contemporary with
the Kharaneh sample.
•Taken from a range of different
contexts.
•Total number successfully
processed: 5
Methodology
• Fully record teeth in mandible including:
• Toothwear according to Payne (1973) and Munro et
al (2009).
• Measurements (Von den Driesch, 1976)
• Photographic record of all sides
• Teeth extracted using Dremel Diamond
edged circular saw.
• Soaked in Resin for 2 weeks
• Resin set in water bath in fridge
overnight
• Blocks of resin sectioned using a Beuhler
isomat diamond tipped circular saw.
• Polished on 3 µm and 1 µm- ‘mirror
polish’ achieved
• Light microscopy- at 40X magnification
• Photomicrographs taken using a Nikkon
E995 microcam.
Examples of the Cementum
Photomicrographs
Dentine-Cement
Junction
Dentine-Cement
Junction
thin translucent
band.
Opaque band
Translucent band
Opaque
outermost band
Opaque band
Outermost thin
translucent
band.
Dentine
Void
dentine-cement junction of
the outer edge of the distal
root edge of Specimen 4
A photomicrograph of the
dentine-cement junction
of the distal root of
Specimen 2
Summary of Kharaneh IV Results
Specimen Number Area
Approx. Time range, BP,
Age at death of
Uncal. (From Maher, 2009)
individual (Months)
Season of death
2
A
14,600-12,500
54 +
Spring/Summer
4
A
14,600-12,500
36-54
Autumn/Winter
7
A
14,600-12,500
18-36
Spring/Summer
8
A
14,600-12,500
18-36
Spring/Summer
9
A
14,600-12,500
54-96
Spring/Summer
11
A
14,600-12,500
54-96
Spring/Summer
12
A
14,600-12,500
54+
Spring/Summer
6
B
22,000-14,600 BP
3-7
Spring/Summer
10
B
22,000-14,600 BP
18-36
Autumn/Winter
13
B
22,000-14,600 BP
54+
Autumn/Winter
15
B
22,000-14,600 BP
18-36
Not possible to
determine
17
B
22,000-14,600 BP
18-36
Spring/Summer
Summary of Wadi Jilat 6 Results
Specimen
Deposit
Number
Approx. Time
Age at death of
Season of death
range BP (Martin, individual
2009)
(Months)
18
2
17,000-15,000BP
3-18
Autumn/Winter
19
5
17,000-15,000BP
3-18
Autumn/Winter
20
5
17,000-15,000BP
7-46
Autumn/Winter
22
2
17,000-15,000BP
18-48
Spring/Summer
24
4
17,000-15,000BP
unknown
Not possible
21
12
18,000-20,000
7-18
Not possible
23
12
18,000-20,000
unknown
Not possible
Discussion
• Multiple seasons of occupation at both sites.
• Likely that the sites were being occupied for
prolonged periods of time.
• Possible aggregation of populations during
times of hardship.
• ‘mega sites’ way of staking claim over a specific
area.
Further avenues of Research
• Kharaneh IV- potential for study of new mandibles
excavated over next few years.
• Wadi Jilat 6- available sample exhausted, need to
look at other seasonality indicators:
•
•
•
Age profiles of gazelle.
Presence of migratory birds.
Archaeobotanical remains
• Understanding site function:
•
•
Skeletal representation
Butchery marks
• Non zooarchaeological investigations
• Tools types represented and their
function
• Other material culture eg shell beads
Evaluation of Pilot Study
• Sample size small (but
comparable to other cementum
studies).
• Temporal resolution an issue.
• Freshly excavated samples worked
better.
• Thin sections and higher
magnifications may enable more
detailed resolution of seasonality.
• Not possible to tell effects of
chemical digenesis on the
samples.
• Need to use several different lines
of evidence.
Specimen 24, Wadi Jilat 6. The
resin did not impregnate the
tooth well, leaving air gaps, and
causing the cement to pull away
from the root, meaning that
cement banding was obscured.
Conclusions
• Cementum Analysis can be applied to the ‘mega sites’.
• Patterns suggest sites were occupied for extended
periods of time, rather than repeatedly at a specific
time of year
• Larger samples required in future.
• More detailed analysis may enable greater seasonal
resolution.
• Important to use a range of seasonality indicators.
• Need to consider other aspects of zooarchaeology and
material culture, to understand more about site
function, and relationship between sites.
Acknowledgements
Many thanks to:
• Louise Martin (UCL)
• Sandra Bond (UCL)
• Lisa Maher and Tobias
Richter
(Cambridge/UCL)
...and all members of the
Epipalaeolithic Foragers
in Azraq Project (EFAP).