A 6,000-year-old story
The consensus view on the origin of Indo-European languages, a family that includes English, Spanish, Russian, and Hindi—is the "Steppe hypothesis". The model, supported by extensive genetic and archaeological evidence, posits that Proto-Indo-European (PIE) was spoken by the Yamnaya people. These nomadic pastoralists expanded from the Pontic-Caspian steppe, modern Ukraine and Russia, around 4,000-3,000 BCE, spreading their language and genes across Europe and Asia. Genetic studies show a massive population shift in Europe during this period, with a significant influx of "Steppe ancestry".
This narrative places the birth of PIE in the Copper or early Bronze Age, associating it with innovations like horseback riding and wheeled wagons that facilitated the Yamnaya expansion. For decades, this has been the dominant explanation for how over 400 languages spoken by nearly half the world's population came to be.
An older voice from the caves
The Paleolithic Continuity Theory (PCT) offers a radically different timeline. First proposed in detail by linguist Mario Alinei in the 1990s, the PCT argues that Proto-Indo-European is not a recent import but has been spoken in Europe since the Upper Paleolithic. This pushes its origins back by thousands of years, suggesting that the ancestors of Indo-European speakers were the Homo sapiens who repopulated Europe after the last Ice Age.
The theory finds its physical anchor in the Franco-Cantabrian region of northern Spain and southern France. This area was a major human refuge during the Last Glacial Maximum (c. 20,000 years ago). The caves here, such as Altamira and El Castillo in Cantabria, show evidence of near-continuous human occupation and artistic production for tens of thousands of years. The oldest art in El Castillo—a simple red disk—dates back at least 40,800 years, making it the oldest known cave art in Europe. A symbol in Altamira is over 36,000 years old.
Proponents of the PCT argue that this deep continuity in settlement and symbolic culture implies a continuity of language. They propose that the major language families of Europe evolved in situ as populations expanded out of these Ice Age refugia. The theory challenges the mainstream view by asserting that stability, not constant replacement, is the default state for languages over long periods. It also reinterprets the non-Indo-European Basque language, spoken in the same region, and not a remnant of a pre-Indo-European world, but as a language that evolved alongside PIE from Paleolithic times.