The emergence of new languages out of languages in contact is a phenomenon that can be observed with a naked eye on the African terrain (see Abidjan French, Sango, Swahili for example). Relexification by borrowing of the lexicon of one of the languages in contact and nativization of the new vehicular language are processes of creolization which seem to have also presided over the emergence of Eastern Yiddish. In this contribution, we would like to reconstruct the glottogenesis of historically attested Indo-European languages by using the model of creolization that may be observed in the genesis of Creoles in the colonies of the Caribean Islands and the Indian Ocean. We will begin by examining some mechanisms of linguistic emergence which are deemed to have participated in the development of Creole languages during the European colonial expansion (16th-19th centuries). We will then consider an even older phase in the history of nativized hybrid languages by reconstructing analogous processes of grammaticalization induced by contact and relexification during the second half of the 3rd millennium BC. The emergence of French Creole languages between the end of the 17th and 18th centuries provides a fine illustration of the interweaving of socio-economic and cultural factors and linguistic data. The origin of slaves in the French colonies of the Caribbean and Indian Ocean differs. A majority of speakers of Bantu languages were present in the early years of the founding of Martinique whereas Saint Domingue-Haiti was primarily populated by speakers of Gbe languages. In the Creoles of the Indian Ocean, the Bantu and Malagasy languages were strongly represented among the slave population. Thus, the languages brought into contact with varieties of French in the two colonial settings belonged to partly distinct linguistic types. Structural convergences between the languages in contact favored the emergence of new structures, different from their source languages. Convergence, conservation understood here as the maintenance and reanalysis of units and functions of substrate or superstrate languages, and hybridization conspired to produce new or partly new linguistic units and functions. Thus, the personal object pronouns of Reunionese Creole exhibit a remarkable analogy with the equivalent pronominal series in Malagasy, hence the idea that convergence could be at the inception of the Creole system. The successors of the preposition “avec” (with) in Seychellois Creole (and in Mauritian Creole) show the influence by convergence with the Bantu source languages. The absence of opposition between /s/ and /ʃ/ in all Indian Ocean French Creoles testifies to the role of Malagasy, where this phonemic distinction is unknown, in the development of Indian Ocean Creole systems. The organization of various dimensions of noun phrases in French Creole languages, including nominal agglutination, provides fine examples of convergence, conservation and hybridization. At an earlier phase in the history of hybrid nativized languages, it is possible to reconstruct analogous processes of grammaticalization induced by contact and relexification. The second half of the 3rd millennium BC saw the spread of late Indo-European (or perhaps already different dialects of late Indo-European) following an expansion which was accompanied by contacts with people speaking very different languages from Indo-European. From these contacts between the intrusive language of the invaders and the epichoric languages of the regions where Indo-European spread, new languages arose which are the historically attested Indo-European languages. Their structure bears the trace of the hybridization of their grammatical systems. As for the lexicon of these languages, the large proportion of words with an Indo-European root suggests that the emergence of historically attested Indo-European languages involved relexification processes that could be two-fold. On the one hand, epichoric substratic languages were partially or totally relexified by means of an Indo-European vocabulary that created totally new languages in their context of emergence. Thus, we can consider Armenian the product of the relexification of substratic Hurro-Urartian or more probably Proto-Kartvelian languages by means of a lexicon provided by Proto-Armenians, Indo-European-speaking people who came from the Balkans, gained a foothold in Asia Minor around 1200 and progressed towards the east until their installation in the Armenian high plateau around 590 BC. On the other hand, it is also conceivable that the various ramifications of late Indo-European were in part relexified by means of the vocabulary of the epichoric languages. This would explain the high proportion of words of non-Indo-European origin in most of the ancient Indo-European languages: Hittite; Sanskrit; Avestan; ancient Greek; Italic languages; Celtic languages; Germanic languages; Slavic languages; Baltic languages; Tocharian. This study carried out jointly by two Creolists and a specialist in historical and comparative grammar makes it possible to recall what is at stake in the notion of glottogenesis: not only an awareness of the fact that languages have a beginning, which may be more or less calculated, but also that these beginnings, far from being creations ex nihilo, result from new syntheses obtained from pre-existing languages. The dynamics perceptible to the naked eye in an African context (Nouchi ; Sango ; Lingala) allows us to reconstruct the processes of the emergence of Creoles in the context of European colonies founded overseas in the 17th and 18th centuries. In turn, the scenarios proposed to understand the genesis of Creoles make it possible to question the linearity of the lineage of historically attested Indo-European languages compared to the common stock of Proto-Indo-European. These languages, some of which were particularly called upon to reconstruct Proto-Indo-European (Hittite; Sanskrit; Ancient Greek; Lithuanian) would not be the direct extensions of the proto-language but rather innovative syntheses whose grammar and even vocabulary testify of the impact exerted by substratic languages. Traditional Indo-Europeanism viewed these underlying influences as marginal remnants. In our approach, inspired by the study of linguistic hybridizations of a more or less recent past, the part of the alloglot environment of endolectalized Indo-European languages is certainly much more than a slag resistant to analysis: it allows not only to take into account the emergence of the specific grammatical systems of the first attested Indo-European languages but also to understand that the lexicon inherited from the Proto-Indo-European strain is not a static heritage but rather the product of partial relexification of a non-Indo-European language using Indo-European vocabulary. The fact that the Indo-European languages never completely continue the reconstituted system of Proto-Indo-European even when they share, each in its own way, a common lexical reservoir, leads to consider these various Indo-European languages mixed creations whose latent structure is not necessarily Indo-European even though the morphemic and lexical signifiers undoubtedly continue the morphology and lexicon of Proto-Indo-European.