INTRODUCTION

Current researches arcoss a variety of disciplines have demonstrated that language is a complex adaptive system（Holland，1992；Steels，2000；Beckner et al.2009；Bybee，2010）.The main features of such a system involve the following key features：adaptation through interaction and competition of factors，self-orgnazition and aggregation，distributed control and collective emergence，intrinsic diversity，perpetual dynamism，and phase transition and non-linearity.The advantage of viewing language as a complex adaptive system is that it reveals the commonalities in many areas of language research，including first and second language acquisition，historical linguistics，psycholinguistics，language evolution，and computational modeling（Ellis，2009：1）.

As far as languguge evolution concerned，however，it is a huge research area，even though under the unified account of the CAS approach.Therefore，the theories we can seek for the understanding of language evolution include so many different theories，such as Game theory，Collective Behavior，Networks，Evolution ＆ Adaption，Pattern Formation，Systems theory，and Nonlinear Dynamics and so on.In this study we will first examin some different perspectives on language evolution，and cast out some doubts and questions about those views.Next，a detailed discussion will cover some basic factors that language evolution involved.Finally，based on the discussion，a theory will be proposed to try to account for language evolution.