Biology Reference
In-Depth Information
before death. This method of sampling from the remains ensured that they had samples from
three points during each individual's life. In this way, a sort of personal life history could be
reconstructed for the individuals.
Results indicated that the hunter
e
gatherers had maintained a nearly consistent diet and
residence during their lives, whereas the possible soldiers had distinct differences between
the earlier and later isotopic signatures between their bones and teeth, as would be
expected for one traveling and dying quite a distance from their birthplace. The possible
enslaved woman also demonstrated a marked change in isotope ratios during her life,
particularly following the development of her third molar in her twenties and the subse-
quent uptake in her bones in the later years of her life that indicated a sharp shift from
a more arid environment to one where seafood made up a larger portion of her diet (
Sealey
et al., 1995
).
MICROWEAR
Since the surface of the tooth is subject to contact with the food eaten during life, teeth bear
evidence of the diet of the individual in the form of tiny, microscopic scratches and pits
referred to as microwear. Studies of microwear enable researchers to place individual spec-
imens into broad dietary categories. Although specific records of foods eaten are not possible
as microwear in an individual changes nearly weekly, assignment to broad dietary categories
(e.g., frugivore vs. folivore) is possible. Studies analyzing microwear in archaeological pop-
ulations have also noted differences in the macrowear patterns (grossly visible wear) between
pre- and post-agricultural and industrial populations. Macrowear is often associated with
agricultural diets or those diets that involve ingestion of plant materials containing high
levels of silicates. Macrowear also includes occupational wear (e.g., using the teeth as tools)
and bruxism (teeth grinding).
The chewing cycle places different amounts of wear and tear on different cusps and tooth
surfaces, so an understanding of the basic chewing cycle mechanism and wear facets is
crucial in order to compare wear on like facets in order to have an accurate basis for compar-
ison. The chewing cycle begins with the closing stroke where the teeth of the upper and lower
jaws first come into contact. This is followed by two power stroke phases, where in phase I,
the lingual and buccal cusps of the maxillary molars come into contact and shear against the
cusps of the mandibular molars. In phase II of the power stroke, the grinding action is
continued with the lingual swing of the mandibular molars relative to the maxillary molars
resulting in the inward facing mandibular buccal cusps grinding against the outward surface
of the maxillary lingual cusps (
Hillson, 1996
). Given the different stresses being applied to the
respective cuspal surfaces, wear facets involved in phase I and phase II are considered sepa-
rately in microwear studies.
Initial studies of dental microwear examined the surfaces of teeth using optical light
microscopy. Scanning electron microscopy (SEM) was then used due to the increased clarity
and depth of field, with the most commonly used standards being those developed by
Gor-
don (1988)
and Walker and Teaford (
Teaford and Walker, 1984; Walker and Teaford, 1989
).
Data collection using SEM is a costly and time-intensive endeavor. Some investigators
have begun to return to low-level magnification analyses to make good use of the low cost
