An examination of a varied set of linguistic phenomena that can be understood as processes of complexification at work in Ur-Aeolic as a variety of Greek that took shape in the context of an isolated speech community –specifically one situated in western Anatolian locales during the Bronze Age.

A linguistic investigation of the Aeolic dialect group, examining linguistic traits of the Lesbian, Thessalian, and Boeotian dialects and those traits common to all three and thus traits belonging to ancestral Aeolic.

The chapter discusses contact-induced phenomena, the models used in linguistics to represent processes of diffusion, and the principles that govern them. It explains several cases of diffusion across language barriers, borrowing and substrate effects, dialect contact, and new-dialect formation.

This chapter is about the evolution of language contact as a research area from the late nineteenth century to the present. It underscores the catalyst part that the discovery of creoles and pidgins by European philologists and other precursors of modern linguistics played in highlighting the roles of population movement and language contact as actuators of language change and speciation. It draws attention to the significance of the study of language evolution in European colonies in making evident the realities of language coexistence. These include the possible competition that can cause language shift and the death of one or some of the coexistent languages, a process that has affected competing European vernaculars faster than it has, for instance, Native American languages. It underscores the expansion of the field as linguists became interested in phenomena such as interference, codeswitching (or translanguaging), codemixing, diglossia, language diasporas, and linguistic areas, as well as factors that facilitate or favor the evolution of structures, sometimes of the same language, in divergent ways, owing to changes in population structures.