Syntactic Phylogenetic Trees

TL;DR

This paper examines the challenges of using SSWL syntactic data for linguistic phylogenetic reconstruction, proposing methods to improve reliability through additional information and algebraic geometry techniques.

Contribution

It identifies problems in naive approaches and introduces phylogenetic algebraic geometry to assess data reliability and improve phylogenetic tree accuracy.

Findings

Restricting analysis to smaller language subfamilies improves data match

Using fully mapped parameters enhances reliability of phylogenetic trees

Phylogenetic invariants effectively evaluate tree consistency

Abstract

In this paper we identify several serious problems that arise in the use of syntactic data from the SSWL database for the purpose of computational phylogenetic reconstruction. We show that the most naive approach fails to produce reliable linguistic phylogenetic trees. We identify some of the sources of the observed problems and we discuss how they may be, at least partly, corrected by using additional information, such as prior subdivision into language families and subfamilies, and a better use of the information about ancient languages. We also describe how the use of phylogenetic algebraic geometry can help in estimating to what extent the probability distribution at the leaves of the phylogenetic tree obtained from the SSWL data can be considered reliable, by testing it on phylogenetic trees established by other forms of linguistic analysis. In simple examples, we find that, after restricting to smaller language subfamilies and considering only those SSWL parameters that are fully mapped for the whole subfamily, the SSWL data match extremely well reliable phylogenetic trees, according to the evaluation of phylogenetic invariants. This is a promising sign for the use of SSWL data for linguistic phylogenetics.