Paleolithic Continuity Theory

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The Paleolithic Continuity Theory (PCT) suggests that the Indo-European languages originated in or nearby Europe and have existed there since the Paleolithic. It argues that the appearance of Indo-Europeans coincides with the first regional settlement of Homo Sapiens in the Middle/Upper Paleolithic age.
Its main proponents are the Italian linguists Mario Alinei, Gabriele Costa and Cicero Poghirc as well as the German and Belgian prehistorians Alexander Hausler and Marcel Otte.

Continuity Theory
The Continuity Theory proposes that Indo-European speakers arrived in Europe tens of millennia ago, and that by the end of the Ice Age, had already differentiated into Celtic/Italic/Germanic/etc. speakers occupying territories within or close to their traditional homelands. It also suggests that the glaciers and pre-glacial basins that compartmentalised Europe during the Ice Age may actually have been the mechanisms for this process of differentiation of Indo-European into its component families.
The Continuity Theory also draws radically different conclusions about the rate of linguistic change from those of the traditional theories of Colin Renfrew and Gimbutas. Clearly, if a homogeneous proto-Indo-European people appeared in Europe 6,000 years ago, then firstly, all subsequent language evolution will necessarily be compressed into the 6,000 years between then and the present, and secondly, the projection of this rapid rate of linguistic change back into the Palaeolithic will lead to the evident conclusion that no useful inferences can be drawn about languages spoken at that time, since it will impossible to distinguish genuine cognates in extant languages from chance similarities.
It is based on a synthesis of linguistic studies, the archaeogenetical studies of Brian Sykes indicating that some 80% of the genetic stock of Europeans goes back to the Paleolithic, as well as on archaeological data indicating European cultural continuity.
Proponents point to a lack of archaeological evidence for an Indo-European invasion in the Bronze Age; to the lack of substantial genetic change since the Paleolithic; and to analogy with a theory of a Paleolithic origin of Uralic peoples and languages in Eurasia. Moreover, the continuity theory is much more parsimonious in comparison with classical approaches to the IE developments.

Criticism
The mainstream position of historical linguistics is that genetic continuity does not imply linguistic continuity and that theories of a literal "military conquest" have fallen into disfavour with most supporters of the theory of a Chalcolithic origin of Indo-European.

Proponents
Jonathan Morris reviewed Alinei's favourably in Mother Tongue, a journal dedicated to the reconstruction of Paleolithic language, judging Alinei's theory as being
"both simpler than its rivals and more powerful in terms of the insights it provides into language in the Meso- and Palaeolithic. While his book contains some flaws I believe that it deserves to be regarded as one of the seminal texts on linguistic archaeology, although given its lamentable lack of citation in English-language circles, it appears that recognition will have to wait until a translation of the original Italian appears."[1]