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.