<P> The Germanic substrate hypothesis is an attempt to explain the distinctive nature of the Germanic languages within the context of the Indo - European languages . It claims that the elements of the Common Germanic vocabulary and syntactical forms, which do not seem to have cognates in other Indo - European languages, suggest that Proto - Germanic may have been either a creole or a contact language that subsumed a non-Indo - European substrate language or a hybrid of two quite different Indo - European languages, from the centum and satem types, respectively . </P> <P> The non-Indo - European substrate theory was first proposed by Sigmund Feist in 1932, who estimated that roughly a third of Proto - Germanic lexical items came from a non-Indo - European substrate and that the supposed reduction of the Proto - Germanic inflectional system was the result of pidginization with that substrate . Which culture or cultures may have contributed the substrate material is an ongoing subject of academic debate and study . Notable candidates for possible substrate culture (s) are the Maglemosian and Funnelbeaker culture but also older cultures of northern Europe like the Hamburgian or even the Lincombian - Ranisian - Jerzmanowician culture . </P>

Give one cause of the introduction of many non-indo-european words into english
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