  Phylogenetic methods have broad potential in linguistics beyond tree
inference. Here, we show how a phylogenetic approach opens the possibility of
gaining historical insights from entirely new kinds of linguistic data--in this
instance, statistical phonotactics. We extract phonotactic data from 111
Pama-Nyungan vocabularies and apply tests for phylogenetic signal, quantifying
the degree to which the data reflect phylogenetic history. We test three
datasets: (1) binary variables recording the presence or absence of biphones
(two-segment sequences) in a lexicon (2) frequencies of transitions between
segments, and (3) frequencies of transitions between natural sound classes.
Australian languages have been characterized as having a high degree of
phonotactic homogeneity. Nevertheless, we detect phylogenetic signal in all
datasets. Phylogenetic signal is greater in finer-grained frequency data than
in binary data, and greatest in natural-class-based data. These results
demonstrate the viability of employing a new source of readily extractable data
in historical and comparative linguistics.
