so i don't know exactly why (or hwy) i got onto this topic this morning, but i decided to look into the etymological origins of the "wh" digraph, for words like "what", "when", etc
so first of all, the digraph used to be "hw", which explains the h-first pronunciations we've all probably heard. my dad pronounces them with the h first, apparently a common thing in the Southeastern United States. there's a shift called the "wine-whine merger" that explores the verbal pronunciation change, but that started me wondering as to how the digraph switched from hw to wh. the answer is, as is often the case, material history and in particular
Norman French
basically, it was just decided to match the pattern of other digraphs such as ch, sh, th. that's all. human want thing match pattern. and thus we switched it to "wh", and that probably contributed to the change in pronunciation.
further more well cited reading on this topic: