Language Evolution and Computation Bibliography

Deacon has suggested that one of the key factors of language evolution is not characterized by an increase in genetic contribution, often known as the Baldwin effect, but rather by a decrease. This process effectively increases linguistic learning capability by organizing a novel synergy of multiple lower-order functions previously irrelevant to the process of language acquisition. Deacon posits that this transition is not caused by natural selection. Rather, it is due to the relaxation of natural selection. While there are some cases in which relaxation caused by some external factors indeed induces the transition, we do not know what kind of relaxation has worked in language evolution. In this article, a genetic-algorithm-based computer simulation is used to investigate how the niche-constructing aspect of linguistic behavior may trigger the degradation of genetic predisposition related to language learning. The results show that agents initially increase their genetic predisposition for language learning—the Baldwin effect. They create a highly uniform sociolinguistic environment—a linguistic niche construction. This means that later generations constantly receive very similar inputs from adult agents, and subsequently the selective pressure to retain the genetic predisposition is relaxed.

Through a constructive study of grammaticalization as a potentially important process of language evolution, we have found two findings. One is that linguistic analogy, which applies linguistic rules extendedly, is a very critical for language acquisition and meaning change. The other is that inferences based on the recognition of similarity and contingency among particular meanings can realize unidirectional meaning change, a remarkable characteristic of grammaticalization. We discuss the significance of these findings in the context of the origin and the evolution of language, especially the role of linguistic analogy in creativity. Based on the discussion, a hypothetical scenario of the origin and the evolution of language is proposed.

Creole is a new born language emerging in most cases where language contact takes place. Simulating behaviors that creole communities are formed in some environments, we could contribute to actual proof of some linguistic theories concerning language acquisition. Thus far, a simulation study of the emergence of creoles has been reported in the mathematical framework. In this paper we introduce a spatial structure to the framework. We show that local creole communities are organized, and creolization may occur when language learners learn of ten from non-parental language speakers, in contrast to the non-spatial model. The quantitative analysis of the result tells us that emergence of local colonies at the early stage tends to induce the full creolization.

Language change is considered as a transition of population among languages. The language dynamics equation represents such a transition of population. Our purpose in this paper is to develop a new formalism of language dynamics for a real situation of language contact. We assume a situation that memoryless learners are exposed to a number of languages. We show experimental results, in which contact with other language speakers during acquisition period deteriorates the learning accuracy and prevents the emergence of a dominant language. If we suppose a communicative language, when learners are frequently exposed to a variety of languages, the language earns relatively higher rate of population. We discuss the communicative language from the viewpoint of the language bioprogram hypothesis.

Creole is one of the main topics in various fields concerning the language origin and the language change, such as sociolinguistics, the developmental psychology of language, paleoanthropology and so on. Our purpose in this paper is to develop an evolutionary theory of language to study the emergence of creole. We discuss how the emergence of creole is dealt with in the perspective of population dynamics. The proposal of evolutionary equations is a modification of the language dynamics equations by Komarova et al. We show experimental results, in which we could observe the emergence of creole. Furthermore, we analyze the condition of creolization in terms of similarity among languages. We conclude that a creole becomes dominant when pre-existing languages are not similar to each other and rather similar to the newly appeared language (would-be-creole); however the new language must not be too similar, in which case pre-existing languages remain and coexist.

Children will develop their parental languages correctly, since language learners come to obtain the one which they contact most in the community. At the same time, children would be affected by other languages, the influence of which is proportional to the population of those languages. In this paper, we revise the foregoing evolutionary theory of language, that is differential equations of the population dynamics. We propose that the transition rate in languages is sensitive to the distribution of population of each generation. In addition, we introduce the exposure probability that is the measure of influence from other languages. We show experimental results, in which we could observe the emergence of creole. Furthermore, we analysed which language would be dominant, dependent on the initial distribution of population, together with the exposure probability.

Evolution of symbolic language and grammar is studied in a network model. Language is expressed by words, i.e. strings of symbols, which are generated by agents with their own symbolic grammar system. Agents communicate with each other by deriving and accepting words via rewriting rule set. They are ranked according to their communicative effectiveness: an agent which can derive less frequent and less acceptable words and accept words in less computational time will have higher scores. They can evolve by mutational processes, which change rewriting rules in their symbolic grammars. Complexity and diversity of words increase in the course of time. The emergence of modules and loop structure enhances the evolution. On the other hand, ensemble structure lead to a net-grammar, restricting individual grammars and their evolution.