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Quantification
Quantification has probably had more written
about it than any other methodological aspect of zooarchaeology
(O’ Connor 2000:208) because there is no consensus as to which
method is the most efficient (Crabtree and Monge 1990:114). The
two most common approaches include the use of NISP and MNI.
These are presented in
Table 1
and reflect species abundance and
diversity for the 8th Century BCE occupation at Mudaybic.
NISP stands for the number of identified
specimens and refers to the number of bones attributed to the
assemblage in general, or to a species in specific. For example,
the NISP count for the total assemblage is 2575 bones, 8 for
equids and hare (Lepus sp.), etc. NISP counts are easy to
calculate once all identifications have already been carried
out. NISP is additive across time and space, so adding new data
to an existing database is straightforward. The term Total
Number of Fragments (TNF) also refers to the same bone count
(O’Connor 2000:54). Considering all the destructive (taphonomic)
agents to which animal bones have been exposed for centuries or
millennia, it should be assumed that NISP counts reflect only
the archaeological sample rather than the death sample from
which the assemblage is derived (O’Connor 2000:55).
There are a few problems with using NISP.
First, this approach does not account for the fact that the
number of skeletal elements differs between species (Grayson
1984:21), which inflates some taxa by overestimating their count
(Klein and Cruz-Uribe 1984:25). NISP introduces an additional
bias because it over-represents those species with robust
diagnostic bones that are more easily identifiable (Klein 1980).
NISP is sensitive to fragmentation (Klein and Cruz-Uribe
1984:25); therefore, an assemblage comprised mainly of
fragmentary bones will result in artificially inflated NISP for
a given species, making it appear to be more abundant than it
is. The method ignores the effects of differential preservation
on the bones of different taxa, a process that undoubtedly skews
perceptions of relative species abundance (Grayson 1984:22).
Although NISP values may not be an accurate measure of absolute
species abundance, they can be used to estimate relative animal
use (Redding 1994:280). NISP can show the rank order of taxa,
which is sufficient when the top ranked taxon comprises the vast
majority of the assemblage (O’Connor 2000:57). This situation
particularly applies to the Near East where ovicaprines commonly
dominate most faunal assemblages. This is also true of the Iron
Age Mudaybic assemblage, of which ovicaprine remains account for
nearly three quarters.
MNI (minimum number of individuals) is based
on the most abundant sided element. The state of epiphyseal
fusion and bone portion are taken into consideration, and the
count is determined for individual species. MNI counts are
unaffected by fragmentation, a problem associated with NISP.
There are a few inherent problems with MNI counts, though. A
main drawback to the method is its unpredictable response to
aggregation, that is, how archaeological contexts are defined,
grouped, then excavated, to form isolated units of study
(Crabtree 1990:159; Grayson 1984:29; O’Connor 2000:212-3).
Therefore, a study of MNI numbers is really a study of the
decisions made relating to a particular approach to aggregation
(Grayson 1984:49). Also, determining MNI counts for small
samples will over-represent rare or uncommon species (Dayan
1999:481), an observation that confirms Grayson’s (1981)
position that MNI, and NISP for that matter, are functions of
sample size. An example of this can be seen in Table 1. NISP for
gazelle (Gazella sp.) remains account for less than 1 % of the
assemblage, but with at least two animals present, its MNI jumps
to over 6 %. An even greater jump can be seen on the data from
goat bones. Definitional and arithmetic problems are also
associated with using MNI, and MNI results are not additive as
they are with NISP counts. Therefore, when new information is
added to an existing database, the entire assemblage must be
completely reexamined in order to arrive at a new MNI value
(O’Connor 2000:61). This is a tedious, time-consuming procedure
(Klein and Cruz-Uribe 1984:26). For these reasons, the use of
MNI has not been enthusiastically endorsed by some (Gautier
1984:245; Horwitz and Tchernov 1989:144). Since both methods
have their merits and problems, it is probably safe to assume
that there is no single technique that can adequately measure
the relative proportions of archaeological animals. Since the
actual number of animals that form any faunal assemblage lies
somewhere between NISP and MNI (Hesse and Wapnish 1985:114),
using both measures of abundance is the best approach to
overcome quantification problems (Crabtree 1990:159-60; O’Connor
2000:217).
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