Many or most Indic languages possess voiceless aspirated stops. Cross-linguistically, such stops often turn into fricatives: e.g., in Indo-European, this happened in Greek, in Iranian, and probably in the prehistory of Latin. There are dozens or perhaps hundreds of Indic languages, and they've possessed voiceless aspirates for millennia, so you'd think many of them should have undergone this sound change.
- Have any Indic languages changed their voiceless aspirates into fricatives?
- What might explain the non-occurrence (or at any rate rarity) of this change in Indic, when it seems to be common elsewhere?