Investigating Cultural Evolution Using Phylogenetic Analysis: The Origins and Descent of the Southeast Asian Tradition of Warp Ikat Weaving

The warp ikat method of making decorated textiles is one of the most geographically widespread in southeast Asia, being used by Austronesian peoples in Indonesia, Malaysia and the Philippines, and Daic peoples on the Asian mainland. In this study a dataset consisting of the decorative characters of 36 of these warp ikat weaving traditions is investigated using Bayesian and Neighbornet techniques, and the results are used to construct a phylogenetic tree and taxonomy for warp ikat weaving in southeast Asia. The results and analysis show that these diverse traditions have a common ancestor amongst neolithic cultures the Asian mainland, and parallels exist between the patterns of textile weaving descent and linguistic phylogeny for the Austronesian group. Ancestral state analysis is used to reconstruct some of the features of the ancestral weaving tradition. The widely held theory that weaving motifs originated in the late Bronze Age Dong-Son culture is shown to be inconsistent with the data.


Warp versus weft axis
Weaving geometry differs from regular Cartesian plane geometry in one important respect: the two axes (x,y in the Cartesian plane, weft, warp in the weaving plane) are not equivalent on woven textiles. As an illustration of this consider these two simple shapes, which are equivalent in a Cartesian sense but different from a weaver's perspective (imagining the warp lying in the same direction as this line of text): The basic shape that must be tied on the warp (shown in color) is different: in one case the weaver must tie resist knots along a row of warp threads and then along several bunches of warp threads lying at right angles. In the other case, it involves tying two diagonal rows of knots on the ikat frame. Another way of looking at this is that an older weaver must teach a younger weaver a different procedure for making these two motifs, and that the 'instruction' that is passed from one generation to another is different. In the classification system, primitives are labeled A, B, C etc, in approximate order of increasing complexity. They are shown in color on the left hand side of the following pages. The motifs that are made up from them are given unique labels based on the symmetry operations used to create them: r = reflection in weft axis d = reflection in warp axis i = rotation through 180 degrees n = glide Motifs that are composed of two or more simpler motifs are indicated by hyphens, for example, Ed-ITSN is the star shape ITSN enclosed by brackets Ed. This motif is found on textiles from Kisar and neighboring islands.
This labeling system is used in a semi-systematic way to differentiate motifs, since a fully systematic nomenclature would be too cumbersome for practical use, particularly with more complex motifs.
In many cases this approach reveals that motifs that look superficially different are actually similar from a weaver's perspective, because they are made up of similar shapes. For example the distinction between the "line" form of a motif and the "block" (filled in) is generally of no great significance to a weaver tying ikat resists, since the shape that must be remembered is the same in the first instance, even though the final result looks different. Duplication by reflection in the warp axis is also a trivial matter for the weaver, since in most cases this can be done by tying several two (or more) sets of warp bundles together and then separating them into mirror image halves after tying and dyeing. These features explain why (for example) the group of simple motifs labeled Gr and Grd, some of which appear different at first sight are actually very similar as far as weavers are concerned, and often appear together in the same textile or in similar textiles: Van Vuuren drew attention to this phenomenon in her account of interviewing Tanimbar weavers [12]. She noted that they paid little attention to the shapes that she recognized as 'motifs' on finished textiles, instead preferring to discuss the shapes that they needed to remember when tying resists onto the warp.
Not all of the differences in primitives correspond to meaningful differences from a weaver's point of view. For example, in many cases square curls, hexagonal shaped curls and smoothly curved curls are essentially equivalent. For this reason motifs that occur interchangeably on textiles of a tradition or closely related traditions are grouped together into a single character, since the differences between them convey no useful information. This has been done on a pragmatic basis, based on analysis of a large set of textiles and observation of weavers in the field.
A degree of familiarity with weaving motifs and textiles generally is required in order to make these judgments and others like them, and the challenges involved are quite analogous to the decisions that must be made when coding linguistic data or morphological characteristics in biology.

Conservatism and copying in warp ikat decoration
As mentioned, weavers use a limited vocabulary of primitives to construct motifs. These are simple shapes that are used in building-block fashion to construct more complex motifs. The use of this vocabulary and the conservative nature of most traditional weaving is particularly apparent in cases where warp ikat weavers have consciously copied motifs from external sources. The cloths most commonly imitated by Indonesian weavers in the past few centuries have been Indian imported silk patola (made using a complex double ikat technique), and the Indian printed cotton trade cloths that were themselves imitations of patola designs. These cloths had high status amongst Indonesian families and were often used as heirloom and bridewealth items, and their designs were sometimes copied into locally made warp ikat. For example, the biboek'sa motif of the Biboki weavers of West Timor has been correctly identified by Barrkman [46] as a patola-inspired creation, with the characteristic patola features of white designs outlined in black on a dark red ground. The biboek'sa motif successfully evokes patola textiles and includes some innovations in layout and coloring, but, remarkably, the motif itself has been re-constructed from primitives that were already familiar to Biboki weavers. It has also been modified from an all-over design to a linear format suited to motifs organized into bands in Biboki sarongs:

Contemporary Biboki sarong with biboek'sa design, based on Indian trade cloths
A rough impression of the overall shape of the Indian motif is recognizable in the Biboki sarong, together with the floral feature at the center and presence of hooks, but the Biboki version is actually composed of hook-and-rhomb shapes that were familiar to the Biboki weavers. The original Indian design falls outside the classification system for warp ikat presented here since it is composed of entirely different shapes, but the Biboki version is classifiable as the motif Mnrd-IN, which is grouped with other similar motifs into the character JnrdIN.
Barnes, in her classic study of Lamaholot textiles [4], also reviewed a number of instances of motifs that were said to be "patola" derived. She found that in most cases these had also been re-interpreted by Lamaholot weavers, to the extent that she found it difficult to identify the Indian prototypes, so thoroughly had they been assimilated into local tradition.