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NUMBER 30 163
pling scheme used. The problem of interdependence
is most significant when the taxon estimate
is taken as a quantity rather than a proportion.
When taxon frequency based on E is taken as a
relative figure, interdependence is significant only
when different species have different degrees of
this bias.
With regard to fossil assemblages, Holtzman
(1979:81-82) has made these remarks about
taxon estimators and interdependence:
It is unfortunate, I think, that the abundance of the most
abundant element has come to be known as the minimum
number of individuals because the latter term leaves the
impression that there is something intrinsically important
about the minimum number of individuals. Its conceptual
insignificance can be appreciated by imagining that specimens
originating from a single once living individual could
somehow be recognized with certainty. For a great many
fossil assemblages the resulting true minimum number of
individuals would equal or nearly equal the number of
specimens. The MNI estimate would then converge on frequency
of specimens, the very estimate that it was designed
to avoid. The common origin of two specimens from a single
once living individual is only of interest when the sampling
procedure is biased so that the collection of one such specimen
increases the probability of collecting the other. The
relationship of MNI (or any other estimate) to this sampling
bias remains largely unknown.
The guess that true MNI probably approaches
total count is considered a reasonable assumption
for faunal samples from Near Eastern tells
(Hecker 1975; Hesse and Perkins, 1974; Perkins,
1973). An example that can be used to extend
this opinion to North American sites has been
presented by Guilday (1970) for historic Fort
Ligonier, Pennsylvania. For the Plains, B. Gilbert
(1969:286, table 7) provides an instructive example.
From ethnographic data, he calculated
the bison meat consumption of a typical villager
at two pounds per day. He then calculated the
total amount of meat represented by the MNI for
bison based on the samples recovered from a
single site. Depending on the length of occupation
and the number of inhabitants visualized (Gilbert
offers three scenarios), the sample recovered only
accounts for between 2 and 6 percent of the bison
meat required.
If interdependence affects the sample for the
various species in a site differentially, it would be
very important to measure this effect. Such a
procedure has long been carried out in Plains
bison kills, but rarely has it been considered for
midden sites anywhere. Exceptions include
Poplin's (1975) painstaking reconstruction of
bone fragments that led to his discovery of
discard units in a trash heap. Coy (1977:129)
offers the least mechanical approach to the problem
of interdependence. She describes a value
called the "probable number of individuals,"
which is defined as "a personal estimate of the
actual number of animals represented, arrived at
after detailed study of the bones themselves and
the groupings in which they were found." This
procedure is analogous to that described by Parmalee
(1977:193) in the corrections he makes to
MNI based on age considerations, though his
final assessment indicates he feels that interdependence
is high in the collections he studied.
Schram and Turnbull (1970:3) stated in the
introduction to their study of the Broom Cave
fauna: "In order to arrive at an estimate of the
actual size of a sample that is comprised largely
(or entirely) of very fragmentary materials, a
means of confining and restricting the spread
between the assessments of maximum and minimum
numbers of individuals must be found."
They propose the calculation of two values in
addition to MNI. One is the "age spread minimum
number of individuals," which is calculated
in the same way Parmalee calculates MNI. The
other value is the "minimal estimate of the maximum
number of individuals." This value is arrived
at by defining skeletal portions likely to be
preserved as units based on an understanding of
the nature of the deposit. This procedure is related
to the point made by Binford (1978:478),
that anatomical units are what are processed by
cultural systems. White (1956:402) points out,
"In certain groups the parents and grandparents
of the man and wife customarily received specific
elements of the carcass such as the left front leg."
It is possible to elaborate on ethnographic observations,
such as White's, to create a list of anatomical
parts likely to be interdependent and to