Biology Reference
In-Depth Information
describe an assemblage of naturally mummified human remains recovered from a cave in
southern Bolivia. These individuals were recovered with artifacts in the Tiwanaku style,
which is centered some 600 km away from the cave site in northern Bolivia. The presence
of extra-local artifacts suggested nonlocal individuals; however,
87
Sr/
86
Sr analyses demon-
strated that these individuals were in fact from the local area in southern Bolivia. Such find-
ings led the workers in this study to question the sphere of influence of Tiwanaku in southern
Bolivia.
Oxygen
Like strontium, oxygen isotopes have been used by skeletal biologists to reconstruct
mobility in prehistoric populations (
Sponheimer and Lee-Thorp, 1999; Knudson, 2009; Knud-
son et al., 2012
). Stable oxygen isotopes (
d
18
O) in biological apatite echo the isotopic compo-
sition of water in the body,
d
18
Oat37
C. In turn, body water
d
18
O itself is influenced by the
isotopic composition of imbibed water, as well as the oxygen in the air and food sources
(
Sponheimer and Lee-Thorp, 1999; Turner et al., 2009
). The isotopic composition of imbibed
water is influenced by a host of ecological variables including latitude, altitude, aridity,
seasonal temperature fluctuations, and rainfall (
Gil et al., 2011
). Under this assumption, skel-
etal biologists have used
d
18
O values from biological apatite to infer an individual's
geographic location at the time that the apatite was laid down (
White et al., 1998; Prowse
et al., 2007
). Similar to strontium isotope analysis, skeletal biologists must also understand
the
d
18
O variation of potential water sources before making inferences about an individual's
migratory status. Utilizing examples from the
Andes, Knudson (2009)
cautions that the
complex movement of water through diverse ecological zones might complicate or even
prevent interpretations derived from
d
18
O data.
CASE STUDY: ARCHAEOLOGICAL RESEARCH QUESTIONS
WITH STABLE ISOTOPE DATA
Echoing my earlier comments, as well as those of Cabana and co-workers (Chapter 16),
this volume, the intention of this case study is to provide a general overview of how an inter-
ested skeletal biologist might actually perform stable isotope analyses on bones and teeth. As
has been mentioned, numerous steps are involved with both sample procurement and anal-
ysis. Once samples are physically located in the laboratory, researchers must first extract
collagen and/or biological apatite from them. After this has been accomplished, those
samples are analyzed on the mass spectrometers. It should be emphasized here that both
wet chemistry extractions and mass spectrometer work should only be initiated under the
supervision of highly experienced personnel. In my experience, it was necessary to travel
to another institution and learn from a mentor who was exceptionally generous with his
time. Extensive treatment of methodological techniques can be found by reviewing articles
in the
Journal of Archaeological Sciences, Archaeometry,
and
Archaeological and Anthropological
Sciences.
The Society for Archaeological Sciences' (
http://www.socarchsci.org/
) triannual
publication might prove useful, as would resources gathered from attending the yearly Inter-
national Symposium on Archaeometry. In the remaining portions of this section, I will high-
light how stable isotope analysis of carbon, nitrogen, and strontium was utilized to
