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.

Origins of contact varieties are at the center of language contact research, focusing on the dynamics between the population structure’s social ecology and the linguistic phenomena that emerge. This chapter proposes an alternative hypothesis to the emergence of Andean Spanish, a macro-dialect spoken in several countries in western South America and product of contact between Spanish and Andean languages, particularly Quechua, the most spoken in the Americas. It argues that contrasts between the linguistic evidence present in colonial documents authored by Indigenous individuals and those present in the speech of Andean Spanish speakers in the twentieth and twenty-first centuries reveal different types of contact phenomena. The colonial data include linguistic evidence of lexical borrowing (primarily cultural) and grammatical phenomena proper of second language speakers (e.g., number and gender agreement, vocalic alternation). The post-colonial data include evidence of grammaticalization phenomena, revealing a case of contra-hierarchical grammatical influence (from the minoritized Indigenous language to the hegemonic language). The contrast between these two historical periods’ internal social ecologies reveals specific (types of) social conditions that help explain the focusing and emergence of the contact (macro-)dialect known as Andean Spanish.

This chapter situates plurilingualism (at the individual level) and multilingualism (at the societal level), depending on the researcher’s approach to language contact, as enablers of various consequences of language contact. The relevant phenomena include language endangerment and loss (through language shift), codemixing and codeswitching (or translanguaging), the emergence of creoles, other mixed language varieties (including urban youth “stylects”), colonial varieties of European languages (such as Spanish), super-diversity, as well as structural change, borrowing, and the emergence of lingua francas. Concepts such as foreign workers’ interlanguages are contrasted with creoles and pidgins. Differences in their emergence are grounded in second language learning, degree and type of exposure to the hegemonic language, language shift, and the emergence of communal norms. The presentation in the chapter is generally grounded in population movements and changing population structures, therefore in speakers'/signers’ social history. It is also diachronic, explaining how domains of interest have evolved and expanded in language contact as a research area since the late nineteenth century, focusing on phenomena not elaborated in the chapters of Volume 1.