BARKCLOTH, POLYNESIA AND CLADISTICS: AN UPDATE
PAUL TOLSTOY
Université de Montréal
If culture history, by definition, stops short of giving priority to functional
or causal processes, it is because it has enough to do to verify the nature
and extent of the events which it attempts to establish. To neglect that task
risks later raising false problems, neglecting real ones, and, often, becoming
trapped in circular reasoning. Functional analysis and the explanation of sociocultural change depend on the narrative of culture history to specify what
is to be analysed and what is to be explained. If circularity is to be avoided,
that narrative must be constructed on grounds other than those invoked to
justify functional interpretations or causal sequences.
CLADISTICS
Cladistics, commonly associated with evolutionary biology, is a body of
principles and techniques for classifying living forms (taxa) assumed to be
related through common descent. Its product consists of branching diagrams,
called cladograms, or more simply trees, which portray in hierarchical form
the relatedness perceived among the taxa under study. It is the subject of a
large literature, and has been formalised in several computer programmes,
including the two used here, MacClade and PAUP (Maddison and Maddison
2002, Swofford 2002).
Unlike phenetics, which appeals to measures of overall similarity and is
best known in biology as the theory and practice of numerical taxonomy,
cladistics builds trees on the basis of nested sets of traits or characters. In doing
so, groups of taxa are distinguished uniquely by the fact that they, or their
proposed ancestors, share these characters. In this way, cladograms resemble
the keys used in botanical identification more than they do the clustering
schemes more familiar to archaeologists (e.g., Shennan 1988: 190-240).
The rationale behind cladistics, as originally conceived by Hennig (1966)
and his successors, is that nested sets are the expected outcome of divergent
evolution. The individual traits of nested sets are seen as innovations acquired
by descendants from the ancestors in whom they first appear, and for that
reason, absent from all but those descendants. Their appearance therefore marks
differentiation events, shown as internal nodes (forks) in a tree. This reasoning
is shared by linguists who construct trees based on common innovations
(Ruvolo 1987, Sankoff 1987). The technique has also been used successfully
in tracing the ancestry and descent of manuscript copies (Cameron 1987).
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Barkcloth, Polynesia and Cladistics
It is logical, therefore, that cladistics should be applied to other aspects
of cultural change, which in itself has been seen by many as a series of
differentiation events along branching and divergent paths (Flannery and
Marcus 1983, Kirch and Green 1987, Kirch and Green 2001, Kroeber 1948,
Mace and Pagel 1994, O’Brien and Lyman 2003, Sahlins and Service 1960
and Vogt 1964 to mention a very few).
My own interest in cladistics arises from its potential to clarify the
development and differentiation of barkcloth technologies in the tropical
world, a goal I was pursuing before cladistics became current in biology. In
an earlier publication (Tolstoy 1963: 649) I suggested that the tree was one
of three essential ways of representing the events of culture history (the other
two being the unilinear series and the lattice). The appearance of programmes
seemingly capable of representing the events of change in the form of trees
(Fink 1986) naturally led to the kind of analysis presented here.
BARKCLOTH TECHNOLOGY
Contrary to the assertion of Melville Herskovits (1950: 513), barkcloth
making is not a simple process. It consists of many operations, each presenting
ample opportunities for choice. The many options present at each stage of the
process result in a procedure that is highly variable, both within and between
the six major areas of the world where it is practiced: Africa, Southeast Asia
(mainland and island), Near Oceania (Micronesia, Western Melanesia, New
Guinea and Australia), Remote Oceania (Eastern Melanesia and Polynesia),
Mesoamerica, and Central/South America.
The considerable diversity apparent ethnographically within the barkcloth
complex can be measured by plotting the variable presence of 418 traits in
some 177 adequately described barkcloth making procedures. That diversity is
at the core of the larger study still in progress, of which this paper is a partial
outcome (see below, and also Tolstoy 1991). It is a diversity confirmed by
many other less complete accounts and casual observations in the literature.
Further supporting evidence includes the variable morphology of the beaters
used, as known from a file which presently includes over 2700 specimens, and
the large number of tree species from which bark is obtained (157 presently
recorded, belonging to 67 genera).
All of this information reveals not only variability, but a variability patterned
in a manner generally congruent with the cultural geography and the known
prehistory of the areas concerned. This observation raises a number of specific
questions about the history of such technologies, regionally and globally.
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Figure 1. Approximate geographic and linguistic relationships in the Central
Pacific. Subgrouping of languages in the Central Pacific (after Kirch
and Green, 1987).
KPG=Kapingamarangi, FUT=Futuna, UVE=Uvea, FIJ=Fiji,
SAM= Samoa, TON=Tonga, HAW= Hawaii, CCK=Cook
Islands, TAH=Tahiti; AUS=Austral Islands, MRQ=Marquesas,
MAN=Mangareva, EAS= Easter Island.
In answering such questions, the 13 well-described industries from the
Central Pacific (Fig. 1) seemed promising in view of the exceptionally large
amount of information available about them, both from reliable eyewitnesses
and from museum collections (Kooijman 1972). That information reveals
internal homogeneity within the area, as well as expectable and clearcut differences between individual procedures at the level of finer detail.
Diversity and relatedness are thus equally apparent in these technologies
and are in keeping with the prevailing image of Polynesia as a well-defined
“phylogenetic unit” (Kirch and Green 1987: 433 and ff., 2001: 53-91). Central
Pacific barkcloth making, like Polynesian culture as a whole, would thus
seem to be an ideal subject for phylogenetic analysis, in this case an attempt
to trace the branching pattern of evolution leading up to these barkcloth
industries from a common ancestral prototype.
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Barkcloth, Polynesia and Cladistics
THE DATA
The data used to build the various trees here discussed are in the form of a
matrix of 126 rows and 15 columns (Table 1).
Table 1. Trait distribution matrix for Central Pacific and outgroup. Third columns indicate
attribution to transformation type in MX trees: E = Easy Loss type in MX1 trees, e =
Easy Loss in MX1 trees, Standard unordered in MX2 trees, D = Dollo in al MX trees.
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Barkcloth, Polynesia and Cladistics
The columns correspond to 13 manufacturing procedures from the Central
Pacific (Fiji and Polynesia), to which have been added two Indonesian ones
from central Sulawesi, for reasons to be explained shortly. The rows represent
126 traits of barkcloth technology, e.g., those found to occur in two or more
of the 15 procedures represented by the 15 columns.
These 126 traits are recorded as either present (1) or absent (0). Each is
designated by a symbol of three or four characters at the beginning of the row.
A brief translation of each of these code designations is given in Table 2.
Table 2. Code designations for traits occurring in two or more industries (Central
Pacific and/or outgroup).
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Not entered in the data matrix, however, are 85 additional traits (79 found
in one or another of the Central Pacific procedures) occurring in only one of
the 15 industries considered. Though significant for some purposes (e.g., in
judging the relative elaborateness of a given technology) such traits do not
contribute to the construction of a cladogram.
It must be noted also that these traits are not always distributed
independently of one another. Some are linked by relationships of inclusion
(e.g., LQ>LQP, LQK; LP>LPP; LWW>L1W, L2W). The practices they
represent (e.g., LQP, LQK, LPP, L1W, L2W) are thus more heavily weighted
in the analysis than those coded only at a single level of generality. Others
are linked by what I have called elsewhere “statistical” bonds (Tolstoy 1966:
73), e.g., they may tend either to favour each other’s presence (e.g., BGfold to merge layers by beating; Sf-merge thicknesses by beating; SF-splice
sheets by beating together) or, on the contrary, to be mutually exclusive (e.g.,
XDG-dry on ground; XDP-dry hanging). Even in such cases, however, they
were given binary rather than multi-state coding, to make it easier to record
the simultaneous presence of different options sometimes reported within
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Barkcloth, Polynesia and Cladistics
a single procedure. These aspects of the code, though desirable and even
unavoidable, make bootstrapping and other probability-based measures
of signal strength even more inconclusive than they already are (Swofford
1993: 56). Such procedures therefore have not been used here to evaluate
the results obtained.
SEARCHING FOR TREES
The objective in converting these data to tree form is to find the nested sets of
traits and the nested taxonomic groups which result in the shortest (optimal)
tree. Treelength is defined as the number of steps (acquisitions or losses of
traits in the course of evolution from a reconstructed ancestor) summed over
the entire tree (it is expressed by the topmost or single number to the right
of the trees shown in Figures 3 and 6-8, and to the left of trees in Figures 4
and 5). The rationale of searching for the optimal tree is to avoid postulating
ancestral traits or changes that are superfluous, and to retain only those that
are needed to account for the traits present in the taxa on the tree’s terminal
branches (i.e., the 15 procedures listed as abbreviations at the top of each of
the columns of the matrix in Table 1 and across the top of the trees shown
in Figures 2-8). The guiding principle of such tree construction is therefore
simplicity or parsimony. The expectation is that many or most of these traits
or characters were transmitted to their present possessors by inheritance from
their precursors and, ultimately, from their common ancestor.
As Maddison and Maddison (2002: 45) put it: “the clarity of this logic is
unquestionable, but it does not fully prepare us for the real world.”
In the first place, characters or traits often do not appear distributed in
a manner that is perfectly nested, either because of flawed data (missing
taxa, incomplete descriptions, inappropriate coding) or trait acquisition by
means other than inheritance (borrowing from neighbours, spontaneous and
coincidental innovation). The calculus of treelength thus becomes the search
for a compromise between more or less conflicting and variously flawed
distributions. Such a compromise, in turn, requires a yardstick and underlying
assumptions for comparing imperfect behaviours. As we shall see, different
assumptions usually lead to different results.
Secondly, the data may admit of more than one solution and produce a set
of several optimal (equally short) trees. True, even a thousand trees usually
will be an infinitesimal fraction of all possible ones (13 taxa can be arranged
to create more than 316,000,000,000 different trees [Rohlf 1982: 142]) and
will narrow considerably the range of relationships that reasonably can be
claimed between taxa.
Paul Tolstoy
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Finally, in most cases, the number of taxa to be fitted to a tree will be
large enough to preclude an exact search, i.e., one in which all possible trees
are examined, and one that is wholly certain to find the shortest tree (though
constraining assumptions can help with this problem; see Sankoff 1987,
Swofford 1993: 42). Consequently, the methods most commonly used are of
heuristic type. They are thought to be quite effective, and incur a measure of
empirical testing whenever they converge repeatedly on the same result from
different initial conditions. They contain nonetheless a number of weaknesses
and difficulties, fully covered
by Swofford (1993: 32-40) and can, at times,
2
fall short of their objective.
ASSUMPTIONS
It is of interest therefore to build trees using key traits alone, and to compare
them with trees based on the full set of traits in the matrix. Such comparisons
provide the opportunity not only to determine which of the two inclusion
sets generates the most credible tree, but also to identify invariant elements
of tree structure which appear under either option.
Under some conditions (when standard, freely reversible traits are used; see
below) programs PAUP and MacClade calculate indices which measure the
fit between traits and the trees in which they occur. Such measures formalise
the contribution of each trait to the tree in a comparable manner and thus
differ from the inspection-derived recognition of key traits as in Table 3.
Arguably, such index-derived measures are not altogether satisfactory on
cultural grounds. Nonetheless, I have used one of them (RC, the rescaled
consistency index, as defined in Maddison and Maddison 2002: 388) to
create a second restricted inclusion set, consisting of 23 characters with
RC’s ≥ 0.25, its membership overlapping only in part with the set of key
traits chosen by inspection.
The need to root a cladogram arises from the fact that, with 13 cases or
terminal branches (i.e., the 13 manufacturing procedures under comparison from
the Central Pacific), it is generally possible to build 23 (2N-3) equally short
versions of the optimal tree, differing only in the placement of the root node.
The latter is the initial point of divergence at the base of the tree (indicated by
an arrow for each tree in Figure 2). If the tree is taken to represent phylogenetic
history, the root marks the first differentiation event in that history, and,
determines completely and unavoidably the nature and sequence of all other
such events to follow. Four of the 23 possible rootings of the same tree (a tree
in which no other changes have been made) are shown in Figure 2 as examples,
and they obviously imply very different culture-historical scenarios.
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Barkcloth, Polynesia and Cladistics
Table 3. Central Pacific key traits. A-Industries arranged in order of terminal branches
of tree D42; B-Industries arranged in order of terminal branches of tree MX1-126.
Figure 2. Different rootings of the same tree (Tree U-109 of Fig. 7).
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Barkcloth, Polynesia and Cladistics
Two approaches are commonly used to root trees. The one generally
preferred is to postulate an outgroup, i.e., a set of one or more taxa assumed
to be related to the study group but not part of it. Postulating an outgroup
makes it possible to contrast features that are evolutionary novelties in the
study group with those that are not, and provides a direction of change away
from the common ancestor shared with the outgroup. The point of attachment
of the outgroup to the ingroup is thereby fixed and determines the optimal
position of the root node of the ingroup. Their procedures are entered in the
two right-hand columns of Table 1. The fact that their technology is related to,
yet different from, that of the Central Pacific has been evident for some time
on grounds of shared traits, beater forms (Tolstoy 1963: Fig. 5a-d) the motifs
used to decorate their barkcloth (Kooijman 1972: 442-56), and even the term
for beater (ike) which they share with the technologies of Polynesia.
Including the outgroup in some of these searches brings to 15 the number
of terminal branches on the tree. It also raises the total number of traits in the
data matrix from 109 to 126, enlarges the set of key traits from 34 to 42, and
increases the number of traits in the restricted inclusion set from 23 to 28.
In the ideal case, a tree obtained in a search which includes the outgroup
should be identical to one of the several (in the present case, 23) built from the
ingroup alone. In practice, the two are often very close, but identical only in
some cases (as in trees 1 and 2, 3 and 4, 5 and 6 in Table 4). Since both cannot
be right, the difference between them is one measure of noise in the data and
helps identify the less reliable characteristics of the trees compared. Their close
resemblance, in any event, invariably indicates where the root should be placed
if it is accepted that the outgroup is indeed a distant relative of the ingroup.
Another manner of rooting a tree is one that is entailed by some
transformation assumptions, though that option should be considered less
reliable (see below). Finally, a tree may be pictured as unrooted (an example
is shown in Figure 9), in which case it conveys degrees of relatedness but
little information as to the chronology of the events it represents.
The choice of transformation type (or character type) is without doubt
the most fundamental assumption to be made prior to a search, though its
importance is too often underrated in practice. It specifies the expected
common rules of behaviour of any or all traits as they are seen to be acquired,
passed on, or lost on the branches of the phylogenetic tree. In its present
application, it amounts therefore to a model of cultural change, and defines
just what is understood by “parsimony”, and how it is to be measured.
Three transformation types, alone and in combination, have been
programmed in the 18 searches of the Central Pacific data discussed here.
These are: (i) the Standard, unordered, undirected, and freely reversible type
(“Standard” for short), generally favoured by biologists and presumed to be
Table 4. Searches and resulting trees – Central Pacific technologies.
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Barkcloth, Polynesia and Cladistics
the least burdened with questionable assumptions about the process of change,
(ii) the Dollo type, and (iii) the Easy Loss type. Each will be defined as the
trees based on them are presented and discussed below.
Table 4 summarises the assumptions, indicates the number and treelengths
of the optimal trees generated by each of 18 searches, and identifies the figures
illustrating the trees produced. It should be noted that not all the trees found are
here illustrated. As much as possible, those illustrated (Figs 3, 6-8) have been
configured to make it easy to compare them and to judge the correspondence
of the relationships portrayed between the 13 industries and their geographic
positions (Fig. 1). Trees obtained with the outgroup excluded (those produced
by odd-numbered searches) are rooted for optimum treelength when the
outgroup is grafted onto them. Their consequently augmented treelengths
by such grafting are given in brackets in Table 4. Conversely, the reduced
treelengths of trees from which the outgroup is pruned are shown in brackets
in the rows corresponding to even-numbered searches.
It will be noted that the augmented lengths of trees found by searches
originally undertaken with the outgroup excluded are sometimes identical to the
reduced lengths obtained by pruning the trees in which the outgroup originally
was included. Such cases provide support for the results of both searches.
THE TREES OF SEARCHES 1-6 (FIGURE 3)
The Standard transformation type, shared by the trees of Figure 3, embodies
the assumption that traits can be lost or gained any number of times in the
course of evolution, and that losses and gains in all cases are equally possible
in principle, the ones found and accepted being the ones which, taken together,
result in the shortest treelength overall.
In calculating treelength and seeking optimality, therefore, the “cost”
of a gain equals that of a loss, e.g., one step. In a sense, this is a minimal
assumption, implying a model of evolution in which “anything can happen”
(Maddison and Maddison 2002: 60). Given that assumption, the finding of
single origin or homology for any character is likely to be robust, i.e., to hold
up under the other transformation assumptions applied later in this study. That,
in the end, may be the main merit of this transformation type.
Comparing the trees in Figure 3 reveals common characteristics, regardless
of rooting or of the inclusion set adopted. They include a perceptible segregation
of eastern and western industries (though not always from monophyly, i.e.,
in consequence of sharing a common ancestor exclusive to them), the close
relatedness indicated for FIJ, TON and SAM on the one hand and of TAH,
HAW and MRQ on the other, and a relatively stable pattern of the number of
branching events intervening between these cases. Differences are mostly in
the positioning of EAS, KPG and, less often, of CCK and AUS.
Figure 3. Trees produced by searches 1-6 (all traits are of Standard type).
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Barkcloth, Polynesia and Cladistics
Implied scenarios include several in which the earliest to diverge from
the rest are some eastern technologies (AUS in U109, U123, U23 and U28,
as well as CCK in U109 and U23). Though not inconceivable, these events
receive no support at this time either from other trees or from other data. Also
disturbing are repeated portrayals of KPG and EAS as a close pair (U109,
U126, U23, U28).3
On both counts, U34 and U42 are more believable than the others. They
are basally bifurcate, clearly separating western from eastern industries as
monophyletic sister clades (i.e., hierarchically equivalent groups, each with its
own exclusive ancestor). Geographically, they suggest a total of 10-11 discrete
and redundant dispersal events radiating outward from central locations in
each sub-area, presumably Fiji or Tonga and Tahiti. Phylogenetic parsimony
is here achieved at the cost of its geographic equivalent, i.e., the principle of
least moves, particularly as the earlier of these dispersals tend to take place
over the greater distances: in the west, to Kapingamarangi before reaching
Tonga or Samoa, in the east, to Mangareva and Easter Island before reaching
the Marquesas or the Cook Islands.
Alternatively, reading these trees to represent serial down-the-line
transmission between nearest neighbours leads to a model even less plausible
in appearance: that of series of centripetal moves from the peripheries of the
Central Pacific homing in on central locations such as Fiji and Tahiti.
In either scenario, the trend over time in both clades tends to be from simple
to complex, the more elaborate industries being the latest to emerge. Though
common enough in general cultural evolution in the long term, additive trends
of this sort must be viewed critically, particularly at the shorter space and
time scales of regional culture history.
In this connection, notwithstanding Eldredge and Cracraft’s (1980: 158-64)
classic injunction to avoid “non-A” classes, it is evident empirically that the
commonly used Standard undirected transformation type is prone, at least
when dealing with cultural inventories notably different in size, to create
some classes more notable for the characters they lack than for those they
contain. In the present case, relatively poor or less completely described
inventories such as those of KPG, FUT and UVE in the west, or AUS, MAN
and EAS in the east, are favoured to represent the more conservative and
distant relatives of taxa with larger and more elaborate inventories such as
FIJ, SAM, TAH and HAW.
In the trees of Figure 3, the tendency of Standard characters to portray
cultural evolution as highly additive finds expression in the high number
of trait acquisitions or gains over time that constitute 59 to 85 percent of
all changes. In this respect, even the most satisfactory of these trees differ
sharply from those produced for the Central Pacific by other searches, in
which losses invariably outnumber gains (Table 5).
Table 5. The eight most satisfactory trees of searches 1 to 18.
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Barkcloth, Polynesia and Cladistics
Reconstructions and estimates listed topmost in each cell of columns 4
and 5 assume the 109 trait inclusion set and 13 taxa regardless of the original
sets used in the search. The middle entry in these cells also assumes the 109
inclusion set but is based on the distributions of those 109 traits over 15 taxa,
thereby including occurrences in the outgroup. The bottom entry enlarges the
inclusion set to include all 118 traits shared by the outgroup with one industry
at least in the Central Pacific. All estimates and calculations, however, reflect
the differing transformation types used in creating these trees, as designated
by their prefixes (U, D, EL, MX1 and MX2).
The high ratio of gains to losses in turn reflects the stringent criteria
inherent in the Standard transformation type for recognising continuity and
transmission between tree nodes.
Particularly when applied to data of uneven quality (or reflective of high rates
of actual trait loss), such criteria create a considerable number of interrupted
character trajectories, and thus inflate the number of apparently independent reacquisitions or reversals of traits to account for their reappearance in industries
with larger inventories. The result therefore is to enlarge seeming phylogenetic
distances between industries despite their shared traits, and to show many of
the latter as having multiple independent origins. These often seem implausible
and at variance with our understanding of cultural distributions in general,
and of Polynesian culture history in particular.
Thus, of 15 traits recorded in no other area of the world, nine are shown
in all trees of Figure 3 as having multiple origins in the Central Pacific. They
include such relatively frequent traits in the area as using one’s teeth to strip off
the bark (LTH, N=5), rolling up the stripped bark against the grain to prevent
it from curling (LRB, N=5) and scraping the bast from the outer bark with a
shell (LXS, N=6). Of the 34 key traits confined to the east or to the west in
Table 3, 16 (almost half) are shown likewise as arising spontaneously more
than once within the group to which they are confined, thereby seemingly
nullifying their value as indicators of relatedness through common descent.
This phenomenon is illustrated in Figure 4, which represents the trajectories
of four traits (shown as filled branches), as reconstructed on the second
(U126) and fourth (U42) of the six trees of Figure 3. By the criteria commonly
used to interpret distributions in ethnography or archaeology, the histories
reconstructed for WLF (fermenting before beating) and SX (perfuming
barkcloth) are not realistic: despite their occurrence in eastern industries judged
to be close relatives, each is given two separate origins in Eastern Polynesia.
The calculus designed to create the shortest tree in this case appears to work
against the acceptance of commonalties that deserve routinely to be interpreted
as reflecting common origin. The same can be said of the trajectories of LRB
and LXS (see above), both of them bast removal techniques unique to the
Central Pacific and unreported anywhere else in the world.
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Figure 4. Trajectories of traits on trees U-126 and U-42 (traits are of Standard type).
In all these cases, it is also evident that the accounting rules for measuring
treelength make no allowance for the variable size of the phylogenetic gaps
observed between seemingly disconnected occurrences, which are smaller
in the cases of WLF and SX than of LRB and LXS. Should one wish to
overlook or bridge such gaps to infer continuous character trajectories, as
implied in the preceding paragraph, one might hope that the size of any gap
being bridged would find its reflection in its cost in treelength.
The shortcomings of the Standard undirected transformation type as noted in
this section can be mitigated to a degree by choosing the Dollo transformation
type, which proposes an altogether different model of change.
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Barkcloth, Polynesia and Cladistics
THE TREES OF SEARCHES 7-10 (FIGURE 6)
Unlike a Standard reversible trait, a character of Dollo type by definition is
uniquely derived, i.e., arises only once. Like a Standard trait, it is reversible,
i.e., it may be lost after being acquired. Unlike it, however, it cannot be reacquired once lost (Maddison and Maddison 2002: 72, Swofford 1993: 8).
Lest postulating such behaviour seem altogether arbitrary, it might be pointed
out that it is eminently compatible with the concept of culture as a means of
avoiding the costs of generating the same innovations over and over again
(Boyd and Richerson 1985: 14-16). That claim cannot be made for the contrary
assumption, that frequent re-acquisition of cultural elements after their loss
is the unproblematic norm.
Obviously, the Dollo assumption makes both for a very different portrayal
of character trajectories in a tree, and for a different calculation of overall
treelength. The difference can be seen in Figure 5, which illustrates the same
trees and the same distributions as Figure 4, but posits that each of the four
traced traits is of Dollo type by connecting all their occurrences.
From Figure 5, it should be evident that: (i) the summing of steps to
calculate treelength is now, to a much greater extent, a summing of losses
rather than of gains; and (ii) in appraising the behaviour of individual traits, the
prominence of losses in summary calculations is accompanied by sensitivity
to the size of the distributional gaps being bridged.
Thus, the formerly split distributions of LXS (second stripping with shell)
and LRB (rolling bark against the grain), now made continuous, nonetheless
count as five and seven steps respectively, and are rated accordingly as the
least parsimonious. The paths of the other two traits (WLF-fermenting and
SX-perfuming), which have more concentrated distributions, consist of four
steps each. This means, of course, that, once the Dollo type is adopted, the trees
themselves must be re-built (as shown in Figure 6 but not in Figure 5) to reflect
4
the differing contributions of these and other traits to optimal treelength.
Figure 6 shows optimal trees for the Central Pacific data set based on the
Dollo constraint, with the trajectories of all traits, including those tracked in
Figure 5, now somewhat modified (not shown but easily traced), and shorter
in three of the four cases previously illustrated (three steps for LRB, four
steps for LXS, and two steps for SX).
It is evident at once that all D trees exhibit a degree of resemblance to
those earlier found using the Standard transformation type. All show a strong
tendency to oppose east and west. The pattern of internodal distances is, on
the whole, familiar, though, in this respect and in others, the 126 character tree
with outgroup (Fig. 6: D126) is the most aberrant. As in earlier searches, the
root node is found to be located either centrally (D34 and D42) or somewhat
off centre (D109, D126) among eastern taxa.
Paul Tolstoy
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Figure 5. Trajectories of traits traced in Fig. 4 on trees U-126 and U-42 assuming they are
of Dollo type.
Two novel configurations are present: a close-knit grouping of TAH, AUS
and CCK in trees based on key traits alone (D34 and D42), and a linking of
SAM to UVE, FUT and KPG in the trees based on complete inclusion sets
(N= 109 or 126). EAS is now placed most often in the eastern group. In D34
and D42 the eastern clade has a structure compatible with geography, and
does not seem merely to rank its members by order of elaborateness (number
of traits present). Searches based on key traits with and without the outgroup
produce two overlapping sets of highly similar trees (not all shown), some of
them identical in both sets. Their agreement with each other and with D109
gives all a measure of credibility.
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Barkcloth, Polynesia and Cladistics
Figure 6. Trees produced by searches 7-10 (all traits are of Dollo type).
Trees based on full inclusion sets (109 and 126 traits) again have some
eastern technologies (e.g., HAW and TAH) branching off earlier than all
other members of either group. Among other members of the eastern group
(or within the eastern group as a whole, in the key-feature trees), MAN
and EAS are the earliest to differentiate. In all trees, separate moves out
of Fiji can be made somewhat fewer (four in the key-feature trees, two in
D109). However, in the west as in the east, some of the earlier dispersals are
redundant and cover greater distances (KPG, MAN, EAS) than later ones
(TON, SAM, CCK).
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One disquieting characteristic of Dollo trees, moreover, is the elaborate
ancestral technology which they generally imply. It is an obvious outcome of
the assumption that all traits must go back to a single origin. Understandably,
this results in a minimum of 88 to 92 percent of the number of reconstructed
changes being shown as losses rather than gains.
The complexity attributed to ancestral Central Pacific (*CP) technology
is particularly marked in the symmetrical basally bifurcate key-feature trees,
e.g., D34 and D42, which represent *CP technology 5 as having 75 to 84 of the
109 traits recorded at least twice in the Central Pacific, and in consequence
inferred to have been part of *CP technology before the emergence of its
eastern and western variants. These are high figures, considering that the five
most elaborate recent industries of the area possess ca. 68 traits on average,
and that HAW, the most elaborate, is coded by 84 traits (these include 66
shared with at least one other industry of the area and 18 not otherwise
reported in the Central Pacific). In the asymmetrical full-feature trees, that
effect is somewhat less pronounced, with D109 and D126 reconstructing 6684 and 74 *CP traits, respectively (ranges in these figures reflect differing
equally parsimonious reconstructions of the trajectories of some traits [see
Maddison and Maddison 2002: 68-70, 97-101]).
It is difficult to choose the most satisfactory among these trees, though
D126 probably should be eliminated on such grounds as linking EAS and
CCK, classifying both as western and identifying the initial divergence within
the Central Pacific as that of HAW from all the rest. D109 does have the merit
of linking SAM to KPG, and of requiring relatively few primary moves out
of Fiji (N=2) and out of an eastern centre of dispersal which could be Tahiti
or the Marquesas. Again, however, the implication that TAH and HAW were
the first to differentiate from an ancestor common to all others is difficult to
accept. In this respect the symmetrical key-feature trees seem marginally more
plausible, particularly D42 which can be read to mean that, for barkcloth to
achieve its recent distribution, four primary moves had to take place out of
Fiji (albeit in counter-intuitive order) and five out of Tahiti.
THE TREES OF SEARCHES 11-14 (FIGURE 7)
Searches using an Easy Loss character type represent an attempt, more
informative than successful, to moderate some of the excessive effects of the
Dollo assumption, which erases any possible effects either of borrowing or of
spontaneous re-acquisition (convergence). As a user-defined type, Easy Loss
is one for which the user can specify his own assumptions. It is inspired by
the example provided by Maddison and Maddison (2002: 291).
The Easy Loss type has been defined here as one in which the number
of steps counted as the cost—in treelength—of losing a trait is half that of
38
Barkcloth, Polynesia and Cladistics
acquiring it. Though arbitrary (a different cost ratio could have been adopted),
this assumption attempts to be less radical than the Dollo, which prohibits
re-acquisitions altogether. Its aim and effect, however, is similar, i.e., to be
more indulgent in its criteria for defining continuity and thus to “mend”
some trajectories which seem implausibly fragmented when portrayed by
Standard characters. Unlike the Dollo type, it is an assumption that aims to
discourage rather than to preclude altogether the proliferation of unlikely
multiple reversals.
Like the Dollo constraint, the Easy Loss assumption seems reasonable in
principle, particularly since losses through the founder effect are expectable
in an island area such as the Central Pacific (Kirch and Green 1987: 44041, 2001: 21, 73), and uneven reporting (which can create the appearance
of losses) is a certainty in all ethnographic description. That the three most
elaborate industries in each of the two groups (the western and the eastern) of
the Central Pacific, e.g., FIJ, TON, SAM, TAH, HAW and MRQ, should share
many (N=30) traits absent from their simpler, yet probably closer relatives
might be seen as empirical support for either possibility.
Traits illustrating this observation would include some reported only
from the “big six” (TT-young trees preferred, LXS-scraping bast with shell,
XDA-multiple soak and dry, XDB-drying to bleach, SC-storing as roll, DUsteam-dyeing, UAG-wide girdle, UFQ-mosquito curtain), others current in
the east but confined to the more elaborate industries in the west (LRB-rolling
up against grain, LX-second strip by scraping, PR-rolling up before working,
BG-folding to merge layers, BOG-multi-stage beating, WK-sprinkling,
XW-weighting with stones, SI-oiling, Sw-sewing thicknesses together,
DIM-dipping in mud, DPK-pinking, UCP-poncho, UDM-mat, UMS-shroud,
UYS-signal, UMG-burial offering, USB-post-partum dress) and yet others,
inversely, occurring in the west but confined to the more elaborate industries
of the east (L1W-wetting for first strip, PT-drying before processing, WMsoaking in sea water, BF-folding to beat, then unfolding, XDP-hanging to
dry). Taken together, such distributions suggest that less-than-thorough
descriptions or the impoverishment of originally richer inventories may
account for some at least of the differences observed between industries that
are geographically close. Though not all the trees obtained in these searches
(Fig. 7) are believable, they help again to relate results to assumptions.
The familiar east-west opposition is once more shown to be robust, though
EL126 unaccountably places TAH in the west (from which it can be removed
and placed at the root of the eastern industries at a cost of two steps). The
pattern of nodal distances also remains a familiar one, especially in the west,
where trees with full inclusion sets support the SAM-KPG-UVE-FUT clade
(EL109, EL126) previously noted in D109. More importantly, the structure
Paul Tolstoy
39
Figure 7. Trees produced by searches 11-14 (all traits are of Easy Loss type).
of the western clade is compatible with a single primary dispersal event
from Fiji to Tonga (or conceivably the reverse), initiating an island to island
transmission in keeping with geographic and cultural relationships in that
part of the Central Pacific. In EL109, the structure of the eastern group is
less easy to read in as simple a manner,
despite a geographically suggestive
6
“backbone” (HW-MRQ-MAN-EAS).
40
Barkcloth, Polynesia and Cladistics
Rooting again is central in EL109, though not in EL34. In both cases,
however, rooting is inherent in the use of the Easy Loss transformation type,
inasmuch as Easy Loss characters are intrinsically “directed”, entailing an
overall direction of change by virtue of weighting gains and losses unequally
(Maddison and Maddison 2002: 50, Swofford 1993: 15). This property creates
difficulties not entailed by using the two other transformation types so far
examined.
As Swofford notes (1993: 10), “while the ability to obtain rooted trees
without assuming an outgroup may seem appealing, it comes at a high price”.
In the present case and in others, that price has two components which, taken
together, make the use of the EL type by itself disappointingly inconclusive.
In searches that include the outgroup, the most obvious “price” commonly
takes the form of a conflict between the rooting imposed by the character
type and the one posited by specifying an outgroup. For reasons which
Swofford (1993: 10) clearly explains, the result, in such cases, is that “the
taxa that would ordinarily be assigned to the ‘outgroup’ may spring from
within the ingroup”. As Maddison and Maddison (2002: 51) point out, it is
the responsibility of the investigator “to maintain [the outgroup] apart from
the ingroup and impose any phylogenetic structure” he wishes to assume.
In the present analysis, this has meant imposing a topological constraint on
searches (as provided by the PAUP program), i.e., a programming instruction
to override the placement of BAK and POS within the ingroup in trees EL126
and E42, and to keep only trees in which the outgroup is kept separate. The
outcome is predictably several steps longer than it would be otherwise (five
and two steps longer in EL126 and E42, respectively). It is reassuring, if
deceptively so, that this manoeuvre, justifiable on technical grounds, does
not yield outgroup-rooted trees that differ greatly from their self-rooted
counterparts (compare EL109 with EL126, and EL34 with EL42).
A second and more insidious component of “price” remains, one entailed
by the mere use in all these trees of a transformation type for which loss is
programmed as less costly than acquisition. As Swofford (1993: 10) points
out, its effect predictably is to root the tree “nearest the taxa that have the
fewest derived states. This may in fact be what you want, but you should at
least be aware of the reasons why the program places the root where it does.”
In the end, the rooting thus produced “is still likely to be more artifactual
than meaningful”.
The effect noted by Swofford is startlingly evident in the ladder-like trees
EL34 and EL42 built with key traits alone (searches 13 and 14). In these,
industries emerge in an order that closely matches their inventory size. As
configured in Figure 7, the order from left to right is that of the declining
Paul Tolstoy
41
number of their eastern key traits, then of the increasing number of their
western ones. A similar pattern is detectable, if less overwhelming, in each
of the clades of basally bifurcate full-trait trees EL109 and EL126, as can be
verified from the following table of inventory sizes.
Like trees built entirely with Standard or Dollo characters, the outcomes
of searches 11-14 are unevenly plausible, with EL109 the most appealing
and EL 126 in second place. The latter resembles EL109 though flawed by its
placement of TAH. Both trees somewhat unexpectedly show AUS and EAS as
a close pair, though conceivably because transmission of the technology out
of Mangareva took place in two opposite directions: one eastward to Easter
Island, one westward to the neighbouring Australs.7 The fully ladderised
trees produced by searches 13 and 14, on the other hand, seem transparently
to be “artefacts” created by the application of the Easy Loss assumption to
a reduced and therefore malleable inclusion set of 34 key traits, and seem
difficult to reconcile with geography.
The proto-technologies reconstructed for the Central Pacific in these trees
are not appreciably poorer than the ones derived from the Dollo assumption.
As in the latter, different equally parsimonious reconstructions of ancestral
inventories create broad ranges for their possible elaborateness, variably
estimated as between 63 and 95 of the 109 traits recorded at least twice in
the area. The lowest estimates (63 and 66) suggest a degree of elaboration
comparable to that described by the more complete accounts for HAW (N=84),
TAH (N=69) and FIJ (N=68). However, reconstructions for EL109, a tree
preferable on other grounds, suggest 79 to 85 ancestral traits, a number that
might seem uncomfortably high.
Table 6. Inventory size (N traits in each industry).
42
Barkcloth, Polynesia and Cladistics
THE TREES OF SEARCHES 15-18 (FIGURE 8)
Some justification can be found for using each of the character types so far
described. Yet it is doubtful whether any one of them by itself yields a fully
convincing phylogeny of the Central Pacific barkcloth technologies or that
any is appropriate for all 126 characters listed in the matrix.
Both PAUP and MacClade, however, make it possible to assign different
transformation types individually to different traits. That option was used
in the four final searches of this study. These are based on the supposition
that certain transformation types may be more appropriate than others for
particular subsets of characters.8
Specifically, the Dollo type was attributed to characters whose single origin
(homology) seemed assured: (i) by their universality or high frequency in
the area considered (N=26), (ii) by their presence nowhere else in the world
(N=15), or (iii) by their confinement, in the Central Pacific, to the western or
to the eastern group (the previously listed key traits, N=34). These partially
overlapping subsets contain a total of 69 characters (marked “D” in Table 1,
totalling 77 when the outgroup is included).
The Easy Loss type was assigned to traits earlier noted as present in
the most elaborate industries of the Central Pacific, yet absent from their
geographically closer and simpler relatives. This was taken to mean that
incomplete data or actual loss might have contributed at least locally to
their broken distributions (N=24, marked “E” in Table 1 [six of the 30
earlier mentioned in section 8 are pre-empted by the first set]; N=33 with
the outgroup included).
The 16 traits thus unaccounted for (marked “e” in Table 1) were treated
as Standard reversible in searches 17 and 18, and as Easy Loss in searches
15 and 16.
The trees based on these mixes of character types are, in many ways,
the most satisfactory (Fig. 8). Since all contain a number of characters
programmed as Easy Loss, they are naturally rooted. The results in this
respect are interesting and acceptable in the outcomes of the two searches
run with the outgroup excluded: trees MX1-109 and MX2-109, which are
self-rooted between FIJ and all other taxa. Both of those with a designated
outgroup (MX1-126 and MX2-126) were run with topological constraints
to maintain the outgroup separate, and are consequently longer by seven and
nine steps, respectively, than the trees run without that constraint. Gratifyingly,
the structure of the trees obtained in either manner resembles significantly
that of the self-rooted trees based on 13 taxa.
The two trees in Figure 8 built with the outgroup included (MX1-126 and
MX2-126) are identical, and thus tend to support one another. Like some trees
found earlier, they are centrally rooted and portray three subclades or small
Paul Tolstoy
43
Figure 8. Trees produced by searches 15-18 (traits attributed to Dollo and Easy Loss types in trees
MX1-109 and MX1-126, and to Dollo, Easy Loss and Standard types in trees MX2-109
and MX2-126).
monophyletic groups: one within the more inclusive western clade, the other
two within the eastern one.
The western clade consists of the series SAM>KPG>(UVE-FUT) (which
also appears in D109, D126, EL109, and EL126) and is part of a larger unit
which also includes TON and FIJ, i.e., all the western industries. In the east,
one subclade includes TAH, AUS, and CCK (as in D34 and D42, where it
44
Barkcloth, Polynesia and Cladistics
also includes HAW). The other is formed of MRQ, MAN, and EAS (as in
EL109 and EL 126, where it additionally contains AUS). MRQ, EAS, and
MAN also appear as a group in D34 and D42, though a paraphyletic one, i.e.,
one not sharing an ancestor exclusive to it, though MAN and EAS do form a
close pair or subclade in D42, as in three of the four MX trees.
Trees MX1- and MX2-126 require only three moves out of Fiji or Tonga,
one of them to eastern Polynesia (perhaps to Tahiti). As might be expected,
the tree in which 16 traits are programmed as Standard reversible (search
18) exhibits a larger number of re-acquisitions (homoplasias) among Central
Pacific traits (18 traits vs. 14), some of them less likely than others (e.g.,
SU-gluing layers, DFG-fringing, DPL-pleating), and a higher percentage of
gains as opposed to losses (15-33% of changes vs. 14-27% in MX1-126).
Unlike its twin, which is one of two optimal trees found by search 16, MX2126 is one of five found. The other four (not shown) are identical in their
western branches, but differ in small ways in their portrayal of the eastern
group. Three are one to three steps longer if the outgroup is excised or if its
treelength is measured in MX1 currency. The remaining tree is identical to
the other produced by search 16 but, like the latter, is two steps longer than
the preferred one when pruned of its outgroup.
The tree illustrated as MX1-126, though identical in form to MX2-126,
predictably reconstructs a somewhat larger ancestral inventory (63-73 traits
vs. 46-66). For tracing changes through time it is more appealing in view of
the lower number of homoplasias it postulates and its greater determinacy,
being one of only two found.
Of the trees produced without outgroup, the one programmed with 16
Standard traits (MX2-109) is interesting in being rooted in the west and in
requiring only one move out of Fiji, with Tonga or Samoa as plausible staging
locations for later moves both westward (Uvea, Futuna, Kapingamarangi)
and eastward (perhaps to the Cooks, Tahiti or the Marquesas). MX2-109
implies an ancestral technology of lower complexity (59-66 traits), and a
higher ratio of trait acquisition to loss (25-31% of recorded changes) than
its equivalent MX1-109, built with Dollo and Easy Loss traits alone. Of all
trees based on a mix of types, however, MX2-109 also shows the highest
number of re-acquisitions (N=22), including many of those posited by MX2126 and others comparably doubtful (e.g., PR-rolling up before processing,
Sw-sewing layers together, DL-pronged liner, UMG-burial offerings). In this
respect, MX2-109 compares unfavourably with MX1-109.
MX1-109 portrays the lowest number of multiple re-acquisitions (N=14),
most of them quite credible (BL-beating on log, LD-sequential stripping from
trunk, LS-first strip by scraping, WO+=beat/soak/beat sequence, WW-soak/
beat/soak sequence), but appears unacceptable in linking KPG with EAS as
Paul Tolstoy
45
a close pair, an aberration noted earlier in the trees of Figure 3. The required
number of separate moves out of Fiji appears to be one, perhaps to Samoa
or Tonga, from which secondary dispersal could be seen as taking barkcloth
elsewhere in the Central Pacific. However, making it acceptable would entail
two additional steps in treelength, by inserting KPG in its more usual position
between SAM and FUT-UVE and linking CCK to EAS in its stead.
In sum, the better choice would appear to be between trees MX2-109 and
MX1/2-126. The latter tree is more conformist in its sub-grouping, but seemingly
postulates one more move out of Fiji. In its MX1 variant it is somewhat more
appealing in its reconstruction of ancestral Central Pacific technology, implying
a fairly elaborate common ancestor (63-73 traits of the 109 set, a few more if
the 126 set is included) and fewer re-acquisitions (16 rather than 21). MX2-109,
however, is attractive in its clear natural rooting in the west (FIJ vs. TON-SAM),
the suggestion of two stages of transmission within the western sub-area (1>TON-SAM; 2->KPG>(FUT-UVE)), and its compatibility with an eastward
dispersion of the technology from Tonga or Samoa to one of several possible
eastern centres such as the Cooks, Tahiti or the Marquesas.
CONCLUDING REMARKS: SUBSTANTIVE
\Thus, western industries are invariably set apart from eastern ones, whatever
their hierarchical ranking. The simpler procedures of the smaller western
islands (Uvea, Futuna, Kapingamarangi) are generally shown as related to,
and often as derived from, the more elaborate technologies of the three larger
island groups, and of Samoa in particular. In the east, a subgroup consisting
of TAH, CCK and AUS is often detectable. The other eastern technologies
sometimes form a single second group, or else are divided so that HAW is
set apart from the rest.
More precise claims require the choice of a specific tree. Such a choice can
be narrowed by eliminating trees which deviate markedly from the composite
drawn above. Beyond that, realism becomes a crucial consideration, and brings
in what Sober (1988: 58-69) has called “empirical background assumptions”.
Are the kinds and number of uniquely derived traits believable? Are the
ancestral industries implausibly poor or implausibly elaborate? Is the ratio of
gains to losses during evolution extreme? Are reasonable numbers, kinds and
orders of geographic moves indicated to disperse the technology from its point
of entry, here presumed to be Fiji, to other parts of the Central Pacific?
Preceding sections have shown that many trees, produced under a variety
of auxiliary assumptions, fail the test of realism by all or some of these
criteria. By the same token, eight trees deserve to be “shortlisted” as providing
phylogenies and scenarios worthy of consideration. Their main characteristics
are summarised in Table 5 above.
46
Barkcloth, Polynesia and Cladistics
In the end, MX1-126 would appear to be the most satisfactory, inasmuch
as it postulates a relatively low number of homoplasias (losses followed by
re-acquisitions), an ancestral industry of an elaborateness comparable to
that of recently observed technologies of the area, a ratio of gains to losses
which avoids the extremes of the Standard and Dollo models, and requires
only three primary moves out of Fiji or Tonga to initiate a neighbour-toneighbour dispersal over the remainder of Polynesia. It is also among the
more compatible with the linguistic tree commonly accepted for the Central
Pacific (see Fig. 1) and with current reconstructions of culture history in the
area based on a mass of other evidence (Kirch and Green 2001: 89-90).
MX1-126 implies a scenario which begins with the introduction, probably
to Fiji, of an industry no less sophisticated than those reported in recent times
from Fiji, Tahiti or Hawai‘i. Many of its characters (c. 60%) are inherited
from a common ancestor shared with manufacturing procedures reported in
Island Southeast Asia, which I have called “East Indonesian” (Tolstoy 1963).
However, it innovates such distinctive practices as LTH-removing bark with
the teeth, LRB-rolling bark against the grain after removal, LXS-separating
the bast from the outer bark with a shell scraper and perhaps TL-raising barkproducing trees, most commonly Broussonetia papyrifera, in plantations. This
industry was probably that of the Lapita culture (Kirch and Green 1987: 438,
2001: 185), though it is likely that it was not the only one.
Subsequently, a western and an eastern variant emerge. The west abandons
such practices as harvesting the bark of tree branches (TB), fermenting the
bast (WLF), initial beating with a distinctive preliminary beater (BOP)
and mixing basts of different trees in the final product (XX), but innovates
delaying the work (for less than 24 hours) after bast detachment (PW), gluing
on patches to mend rents (Sfg) and decoration by printing or rubbing, using
a board or a tablet (DK). Eastern practice is both more retentive and more
innovative, losing fewer traits initially, adding such steps as alternate drying
and moistening with dew (XDD), introducing several novel decoration
techniques (DB-tube impression, DG-deliberate beater groove impression,
DMB-appliqué beaten-on patchwork, DPF-cut-outs and perforation) and
seemingly broadening the inventory of finished products to include UCC
(capes), UYG (wrappings for cult objects), UYM (masks) and UXI (kites).
Data gaps in Melanesia and Indonesia, however, leave open the possibility,
particularly in the case of the latter four items, that some of these traits
are retentions from a pre-*CP stage and were lost later by proto-western
technology. The geographic locus of the initial eastern industry may have
been the Cook Islands, Tahiti or even the Marquesas.
According to MX1/2-126, the first modified version of this proto-eastern
technology (HAW) retains the changes enumerated, loses 15 other traits
Paul Tolstoy
47
(among them LTH, PR, WMF, SU and DFG) and innovates 18 idiosyncratic
ones (not discussed here), the largest number of any industry described for the
Central Pacific. This may reflect, above all, the extreme attention Hawaiian
barkcloth has received from Brigham (1911), Buck (1957) and others. It
should be noted, moreover, that the early differentiation of this industry need
not imply its immediate introduction on Hawai‘i.9
The *TAH+ and *MRQ+ subclades diverge at about the same time or
slightly thereafter, possibly in the Society group. Their internal differentiation
then takes place largely through differential loss, a process which leads
ultimately to the simplified procedures described for its members on the
Australs, Mangareva and Easter, though the effect of incomplete reporting
on our knowledge of them is uncertain and possibly important. A limited
number of innovations, however, do mark both the common ancestor of all
six industries (SE-re-beating after use, UHC-caps, USV-priestly vestments)
and those of the *TAH+ and *MRQ+ clades individually (Sfx-felted-on repair
patches, DP-plant impression, and UAH-sashes in the first, UVO-ceremonial
offerings and UYF-effigies/cut-outs in the second). Each of the six industries
also acquires idiosyncratic traits, ranging in number from 11 in the MRQ, nine
in TAH and seven in EAS and AUS to four in CCK and two in MAN.
The geography of these events can be read in several ways, the divergence
of MAN and EAS perhaps most likely to follow serially from the isolation
of these technologies on Mangareva and Easter Island respectively. The
locations of ancestral industries such as *TAH+, *MRQ+ and HAW before
their descendants assumed their present locations seem more uncertain and
could plausibly be seen as the Cooks, the Societies or the Marquesas.
In the west, loss and simplification over time are more marked. TON
technology, the first to separate, loses some 13-20 traits of proto-western
technology in the process. Two traits (SK-decoration by smoking, EEparticipation of both men and women in making cloth) arise in the common
ancestor of the remaining five, but subsequent evolution is also mostly through
loss, with FIJ retaining the greatest part (N=54) of the original inventory.
Three innovations appear in *SAM+ technology. If spontaneous, these
represent parallelisms with Easter Island (LS-initial stripping by scraping,
BL-beating on log, UAB-belts). KPG is the most deviant of this group, with
seven idiosyncratic traits. It seemingly shares with FUT and UVE the loss of
BOG (multistage beating), a practice otherwise near-universal in Polynesia
and inherited from earlier stages in island Southeast Asia. In the light of these
trait histories, geography can be read to mean Kapingamarangi received its
technology from Samoa, as did Uvea and Futuna.
Interestingly, the constraints on the geography and chronology of
divergence events suggested by MX2-109 are very similar to those implicit
48
Barkcloth, Polynesia and Cladistics
in MX1/2-129, with the difference that MX2-109 (i) allows an introduction
of barkcloth into Eastern Polynesia from Samoa, and (ii) that the closer
relationship of AUS to MAN than to CCK in that tree implies, as in EL109
and EL126, that the Australs received their technology (or elements of it?)
from Mangareva in the east rather than from the Cooks to the northwest .10
Finally, it may be noted that the eight most acceptable trees examined
here (Table 5) fall into two groups on the basis of the dispersal geography
they propose.
Trees built with Easy Loss (EL) characters, including those in which such
characters are in a minority (MX1, MX2), suggest dispersal scenarios largely
of the “stepping-stone” or down-the-line kind. These require relatively few
primary (radial) moves from entry points in the west (Fiji or Tonga?) and in the
east. In the west, such scenarios, suggested by EL109, MX2-109, MX1-126
and MX2-126 (the latter two identical in form), imply primary moves to such
destinations as Samoa and/or Tonga and eastern Polynesia (Tahiti?). In the east,
one or two central locations (depending on whether entry was via the Cooks,
the Societies or the Marquesas), Hawai‘i and possibly the Australs require
primary moves, the remaining three or four islands or island groups deriving
their technology by secondary transmission from nearer neighbours.
Such a model contrasts with the scenarios implicit in trees U34, U42, D34
and D42. Like the preceding, they imply single initial points of entry in the
west and east, perhaps Fiji and Tahiti respectively, though Tonga in the west
and Australs in the east are possible candidates in the D trees. Remarkably,
however, subsequent dispersal is almost entirely by direct transmission
radially out of these centres, the earliest ones generally taking place over the
greatest distances (to Kapingamarangi, Mangareva, Easter Island), the latest
being to closer neighbours (Tonga, Samoa, the Cooks).
Such patterns prevent these latter four scenarios from achieving what might
be called inclusive parsimony. Together with unrealistic proportions of reacquisitions (very high or null) and extreme reconstructed inventories (very
small or unduly large), these redundant and unparsimonious dispersal patterns
would appear to justify a preference for trees in the first group, i.e., EL-109,
MX2-109 and MX1/2-126. These seem more reflective of geography and
of prevailing notions of the internal and external relationships of Polynesian
culture (Kirch and Green 2001: 184-87).
Reservations as to the reliability of all scenarios considered here can and
should be made. Their credibility or lack thereof rests on configurations
which, if made one or two steps longer, could tell a different story. It also
relies on the quality of available reports, on sensible coding and on the
ability of the method used to trace correctly the trajectories of 126 traits. In
this respect, the scattered and seemingly unconnected occurrence of some
Paul Tolstoy
49
14-15 “homoplasic” traits even in MX1-129 may equally well represent a
failure of available information to link their various presences rather than
their spontaneous re-acquisition in the course of evolution.
In the end, the more important implications of these reconstructions may
be the following:
(1) The relative complexity of the ancestral technology from which all recent
industries are best derived.
(2) The strong connections of the latter with Island Southeast Asia, also
evident from beater types, decorative motifs, and other evidence, some
of it lingustic and botanical, not presented here but covered in Kirch and
Green 2001: 184-87 and in the monograph I am currently preparing.
(3) The fundamental contrast between their western and eastern variants.
(4) The importance of reduction and loss in the evolution of many of these
technologies over time. Like Polynesian culture as a whole in Kroeber’s
(1948: 760) view, many of these industries appear to illustrate what today
would be called “the founder effect” (Kirch and Green 2001: 21, 73).
CONCLUDING REMARKS: METHOD
The present study is part of a broader project the goals of which are above
all substantive. Cladistics furthers these goals by clarifying the assumptions
required for culture-historical inference. It is not proposed here as a standalone means of demonstrating a thesis, nor was its use in the present case
conceived primarily as a methodological exercise.
Often implicit, and sometimes explicit, the notions, though not the terms,
of tree, outgroup, inclusion set and transformation type have a long albeit
often hidden history in our thinking about cultural distributions (see Sapir
1916). It is impossible, in fact, to seek time depth in a body of ethnographic
data without prior choices or preferences as to likely directions of change,
the sets of elements best suited to reveal them, and the frequency or ease with
which cultural elements are acquired or lost over time. Cladistics compels
an awareness of these choices and illustrates, in a replicable manner, their
effect on results.
In the first place, the attempt to represent evolution as a tree compels
the realisation that, at a minimum, the number of equally short rooted trees
linking a given set of terminal branches is almost double the number of those
branches. True, 23, in the present case, represents a staggering reduction of
the roughly 300 billion possible trees that could be built with these data.
Moreover, these 23 arrangements share a basic plan, the “unrooted” tree
50
Barkcloth, Polynesia and Cladistics
(Fig. 9), which in itself provides a classification of sorts, based on the mutual
closeness or remoteness of individual taxa which it reveals. The need remains
nonetheless to choose one of those 23. The required choice is comparable
to that of the archaeologist who must decide which end of a seriation is the
upper one. If that choice is not made, we lack the hierarchy needed to inject
time depth into an otherwise flat ethnographic picture.
Figure 9. Tree MX1-126 represented as unrooted. The number of unequivocal
changes (gains and losses) are indicated by numbers on each branch, as
calculated by MacClade version 4.05 for the rooted version.
Paul Tolstoy
51
Rooting is preferably achieved by choosing an outgroup, though overall
similarity measures and an inherent directedness attributed to individual
traits have both been used for that purpose, not always convincingly. Rooting
determines branching order and character distributions over the tree’s forks
and branches.
The choice of root, however, is not the only assumption on which these
particulars depend. To produce MX1-126 (Fig. 8), a model of cultural change
had to be assumed. This was done by attributing 77 characters in Figure 2
to the Dollo type, and the remainder to the type defined as Easy Loss. Like
the choice of root, these attributions must and can be justified (see sections
discussing trees of searches above). Their perceived merit, however, turns on
pre-existing beliefs, e.g., that these technologies are indeed genealogically
related (both to each other and to the outgroup) and that relatedness is
something which translates into distributions in interpretable ways. Cladistics
makes it possible to operationalise such beliefs, but provides no independent
proof that they are valid.
Tree MX1-126, with which this study concludes, therefore is not, in any
sense, proof ab nihilo either of the degrees of relatedness of these technologies
or of the homologous status of 93-95 non-homoplasic traits or of the presence
of 63-73 ancestral traits in the version of barkcloth technology initially
introduced into the Central Pacific, probably over 3000 years ago. In fact,
the relatedness of all Central Pacific industries is assumed from the start, as
is the homologous status of 77 traits. MX1-126 does, however, provide the
simplest chronicle of events that will account for the ethnographic present,
given the “auxiliary” assumptions which, in Sober’s view (1988: 58-69), no
inductive hypothesis can do without.
Other similar bodies of data may require specifically different strategies
and assumptions. The likely ratio of gains to losses, the number of parallelisms
(independent re-acquisitions) considered acceptable, and the realism of the tree
model itself may be appraised differently in areas where the founder effect was
less important, or when less elaborate technologies and/or longer time spans
are considered (as in Southeast Asia), or where uneven coverage is less of a
problem, or in an area such as post-colonial Africa where occasions for contact
and borrowing have been numerous. As in botany, “reticulistics” may in such
cases have more to contribute (see Stevens 1987, and articles by W.H. Wagner,
H.-E. Wanntorp, C.J. Humphries, and G. Nelson, in Platnick and Funk 1983).
All of these considerations suggest that the experiments here described
provide no easy lessons, and that cladistics is more of an invitation to
disciplined conjecture, or perhaps, an improved filing system for phylogenetic
purposes, than a straightforward algorithm ensuring a correct answer.
As Stevens has pointed out (1987: 162), the taxonomic process is one of
“continual reevaluation”.
52
Barkcloth, Polynesia and Cladistics
CONCLUDING REMARKS: ETHNOLOGICAL THEORY
As Sober remarks (1988: 144, 146), the “incantation” is often repeated that
all our observations and inferences are “theory laden”, including presumably
such primary ones as whether or not Hawaiians practiced preliminary
beating (BOP). Perhaps. But “theory-neutrality and theory-ladenness are
matters of degree”, and though “our description of the data may depend on
some theory or other, ... it had better not depend on the very hypotheses we
intend to use the data to evaluate”. Regrettably, that is precisely what often
happens when data are assembled only to “test hypotheses” of a functional
or explanatory nature.
It would be easy, for example, to claim that making barkcloth is a “simple”
process, or that it is linked to the availability of a few suitable species, or that
the bast must be soaked before beating and that the beater must be grooved
because that makes the process more rational and more effective. Support
could be found for such statements in “relevant” evidence. A comprehensive
culture-historical synthesis, carried out independently of these questions, will
reveal, however, that all of these statements are inaccurate.
The present paper and its larger parent study are thus squarely in the domain
of culture history. As biologists Eldredge and Cracraft (1980: 20) have said of
tree building, “the initial primary question is exactly what happened, not why
or how”. Such a question does not exclude incidental attention to problems
of function or of causation, and indeed is essential in preparing the ground
for their examination, provided it is not allowed to bias findings or subvert
the main objective, that of finding out “what happened”.
It should be particularly clear that culture history is essential for setting the
stage for the difficult questions of “why”. Opinions differ as to the appropriate
manner of answering them in our field (see Flannery 1986: 518). In the light
of earlier debates on that subject, the application of cladistics to represent past
events may appear “theory-laden” to some, in the sense of favouring evolutionary
causation. It is clear, among other things, that it is uniquely suited to represent
divergent evolution as “descent with modification” and to reveal differentiation
events that call for explanation in selectionist, adaptive or other terms.
However, before exaggerating the commitment that phylogenetic trees
imply to a narrowly Darwinian view, it is well to recall that linguists and
epigraphers also use tree diagrams. For such users, trees embody little more
than the belief that information is modified in the course of transmission, for
whatever reason, and is modified in different ways in separate instances—
whence divergence.
As the earlier quotation of Eldredge and Cracraft illustrates, some
biologists also can take such a position, and they are able, in principle at
least, to leave open the question of “why” during the tree-building process, a
Paul Tolstoy
53
manoeuvre that anthropologists still seem very reluctant to endorse. Perhaps
for this reason, C. Loring Brace has claimed that in cladistics “mechanism
and process are simply regarded as irrelevant” (Brace 1994: 485).
In the present case, Brace’s claim would be an overstatement. Tree-building
does not aim here, any more than do the traditional classifications and
distribution studies of culture history, to make function or cause irrelevant. It
does aim to assure that patterns are real before the attempt is made to account
for their permanence or their causation.
The construction of trees, detached as much as possible from considerations
of function or adaptation, can be expected, in fact, to free the concepts of
adaptedness and evolution from the confusion, lamented by Dunnell (1980:
50-51) between what is to be explained and explanation itself. It can do so
by not prejudging whether a given change is adaptive or not and, above
all, not allowing such judgment to influence the determination of whether
it occurred. It can thus portray change as descent with modification, while
avoiding the circularity of such platitudes as they invented, or borrowed it,
because they needed it.
ACKNOWLEDGMENTS.
I am most particularly grateful to Roger C. Green, whose interest in this research
stimulated me to update it and who encouraged me to submit it for publication in
the JPS. I wish also to thank Judith Huntsman, Editor of JPS, and two anonymous
referees, all of whom did much to make this text more intelligible, but who should
not be blamed for any remaining obscurities.
NOTES
1.
2.
Curiously, “transformed” cladists have claimed that cladistics does not need the
justification of evolutionary history, and is to be seen merely as the search for a
natural order, independent of, or prior to, its possible use to support phylogenetic
hypotheses or scenarios (Scott-Ram 1990: 133-45). This distinction between
observation and theory, when not overstated, is a useful reminder that any
pattern does indeed require theoretical support to be interpreted, and that its
meaning cannot naively be taken to derive from the existence of the pattern itself.
Nonetheless, it would seem evident that cladistics “is unintelligible except in the
light of evolutionary theory” (Scott-Ram 1990: 141).
In the searches presented here, I have used a random sequence for stepwise
addition, a TBR branch swapping algorithm, on occasion supplemented by SPR,
and replicated at least 50 times in each search. I have generally avoided the
COLLAPSE option, but have used MULPARS, less often STEEPEST DESCENT.
Running times with recent versions of PAUP on a not-so-recent Power Mac
were usually on the order of minutes with characters programmed as Standard
reversible or as Dollo, and only slightly longer for Easy Loss.
54
3.
4.
5.
6.
7.
8.
Barkcloth, Polynesia and Cladistics
This surprising linkage may be a random effect of the relatively small and largely
non-idiosyncratic inventories of these two industries (N=38, 27), and their few
informative commonalities (N=6). These consist of BL (beating on a log), BOS
(simple one-stage off-stem beating) and UAB (belts), rare in the area but common
worldwide, and others rare worldwide as well (LS-initial stripping by scraping,
XSM-smoothing by hand before drying). With the exception of WMF (soak in
sea water, then in fresh water) all are primarily western when reported at all in
the Central Pacific.
In absolute number of steps, Dollo trees tend to be substantially longer than trees
built with Standard traits. The lengths of trees created on different assumptions,
however, cannot be compared directly. Comparisons across types are possible
using an index based on minimum and maximum possible lengths given a
particular character type. Unfortunately, for Dollo and user-defined types, there
appears to be some uncertainty as to how such an index should be calculated.
Hereafter, an asterisk preceding the designation of an industry or technology
indicates a reconstructed hypothetical ancestral form rather than one of the 15
industries described by recent observers and listed in Table 1 or 3.
A “backbone” structure is a relative pattern of relationships shared by several
trees, occurring independently of taxa which do not conform to it. When these
are pruned, that pattern is revealed as invariant (Swofford 1993: 43).
Such a possibility is seemingly supported by linguistic evidence (Green and Weisler
2002: 36-37). Like the latter, it might justify an amendment of the tree model,
in this case the one here preferred (MX12-126), to allow for “lateral transfer”
between the technologies of MAN and AUS, otherwise less directly connected.
As pointed out by one reviewer, the theory behind these and other transformation
types deserves attention, and involves understanding how such types treat
variability arising from other causes than descent, e.g., convergence, inadequate
data and, of course, borrowing. I have not attempted here systematically (though
see note 9) to identify individual instances of borrowing or to distinguish them
from other kinds of departure from the tree model. As in linguistics, the task is
an important one and one which I hope to address elsewhere.
It is worth noting, however, that estimation and recognition of the effects
of borrowing, wholesale “blending” or missing data do not face precisely the
same challenges in the various disciplines that make use of the tree model.
Thus, in biological applications, particularly when dealing with fully-described
non-interfertile living species, the Dollo model threatens to do little violence to
the data. By the same token, it may also be the least needed in practice: lateral
transfer of characters is not a major problem and full anatomical characterisation
of species is possible from museum specimens.
On the other hand, the combined threat of lateral transfer and missing data
is much greater in many cultural applications, missing data being particularly
critical when dealing with behaviour rather than objects. It is a major reason in
the present study for comparing the effects of different assumptions, if only to
establish the extent of their agreement and the alternatives they might suggest.
Paul Tolstoy
55
In the Central Pacific, differences and similarities due to borrowing between
technologies can be no means be excluded (Kirch and Green 2001: 85-89), even
if they might be less pervasive than they seemingly are in Africa or parts of
Southeast Asia, where contacts between distinct traditions of barkcloth making
may have been geographically easier, more frequent and/or longer in duration.
As in linguistics, identifying such effects has its own uncertainties, though
there again the challenges differ according to discipline: sound changes provide
assistance in linguistic comparisons, whereas ethnography must rely more on
spatial analysis and on cross-cultural data.
9. Cladograms place restraints on the geographic locations of the events they
represent but cannot situate them unequivocally, for two reasons. One, ancestral
taxa may diverge long before they occupy the locations in which we find them
today. Thus, the technologies of Tonga (TON) or Samoa (SAM) in tree MX2-109
could have had a joint or a separate existence on one or more islands of the Fiji
group well before reaching their present locations. Two, a cladogram cannot tell
us which of two divergent sister taxa continued to occupy the location in which
their divergence occurred. In principle, any path of connected branches from
root to terminal branch, whether that of EAS or of TAH, may represent an in situ
evolution of the technology we find on Easter Island or Tahiti in historic times.
In either case, all other technologies would have been emplaced by moves away
from that location. In discussing the relationship of taxa to particular locations,
it is therefore essential that designations of present and past industries (“HAW”,
“FIJ”, “*TAH+”) be kept distinct from those of the locations (Hawai‘i, Fiji,
Tahiti) with which they are associated today.
10. See Note 7.
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