> some linguists have hypothesized that analytic languages are easier for foreign speakers to learn as adults, and that this causes languages with lots of geographic spread and inter-language contact to become more and more analytic.
That's an interesting theory, and certainly fits with Mandarin (aka "Common Speech"); but how well does it fit with the prevalence of Greek in the ancient world, Latin during the Middle Ages, and Arabic in the Middle East and North Africa now? Those are all towards the "synthetic" scale, aren't they? Did/have those languages drift/ed to become more "analytic"?
Yeah, Latin and Greek became somewhat more analytic during the time periods where a lot of foreign speakers were adopting them as their main languages. (That was during the Roman period, not the Middle Ages, for Latin; Latin in the Middle Ages was a dead language used only by learned people in non-everyday contexts, so its grammar was mostly preserved.) I don't know about Arabic.
Standard Arabic is similar to Latin in Medieval Europe - it is a second language that is used for formal education and communication, but that no one speaks as a native language. All the Arabic languages that people speak as first languages are much more analytic.
It's a similar phenomenon to Latin, where the formal written Latin used in Europe preserved things like case endings and flexible word order, while the Vulgates that later became the Romance Languages dropped a lot of that and started relying much more heavily on word order.
That's an interesting theory, and certainly fits with Mandarin (aka "Common Speech"); but how well does it fit with the prevalence of Greek in the ancient world, Latin during the Middle Ages, and Arabic in the Middle East and North Africa now? Those are all towards the "synthetic" scale, aren't they? Did/have those languages drift/ed to become more "analytic"?