Automated languages phylogeny from Levenshtein distance

Languages evolve in time according to a process in which reproduction, mutation and extinction are all possible in a way which is similar to haploid evolution. Exploiting this similarity it is possible, in principle, to verify hypotheses concerning their relationship. The key point is the definition of the distance among pairs of languages in analogy with the genetic distance among pairs of organisms. This concept seems to have its roots in the work of the French explorer Dumont D'Urville which, in his work about the geographical division of the Pacific, proposed a method to measure the degree of relation among languages. The method used by modern glottochronology, developed by Morris Swadesh in the 1950s, measures distances from the percentage of shared cognates. The weak point of this method is that subjective judgment plays a relevant role. Recently, we proposed a new automated method which has some advantages: the first is that it avoids subjectivity, the second is that results can be replicated by other scholars assuming that the database is the same, the third is that no specific linguistic knowledge is requested, and the last, but surely not the least, is that it allows for rapid comparison of a very large number of languages. The distance between two languages is defined by considering a renormalized Levenshtein (or edit) distance among words with the same meaning and averaging on the words contained in a list of 200 features. The renormalization, which takes into account the word's length, plays a crucial role, and no sensible results can be found without it. We applied our method to the Indo-European and to the Austronesian groups considering, in both cases, fifty different languages.