The archaeologist Colin Renfrew in his Archaeology and Language links the spread of these languages to the origin of agriculture sometime around 9,000–10,000 years ago in the region of the world known as the Fertile Crescent (roughly present-day Turkey and Iraq). Farming reset the world’s carrying capacity to a higher level, allowing a greater number of people to survive in a given area. The growing populations meant that farmers and their ideas spread out in all directions from the Fertile Crescent. Those that went north and west formed what we recognize today as the Greek, Germanic, and Romance or Latinate languages of Western Europe; those that went north and east produced the Slavic languages; and those that went south gave rise to the languages of Iran, Afghanistan, Pakistan, and India. The Basque language of northern Spain, although in Europe, is not an Indo-European language. In fact, it might be an isolated remant of the languages that were spoken by the hunter-gatherers in Europe before farming and farmers arrived. Russell Gray and his colleagues were later able to confirm Renfrew’s arguments by applying dating techniques to the Indo-European languages, confirming that this family probably did arise sometime around 9,000 years ago. And it is because of descent with modification within the separate branches of this family that today we recognize similarities in the Romance languages of Spanish, French, Italian, and Portuguese, just as we recognize similarities in the Germanic languages of German, Danish, Dutch, and English.
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Wired for Culture: Origins of the Human Social Mind (Mark Pagel)