Why has the general evolution of indoeuropean and ugric languages

>>1474823

Languages generally cycle from isolating, to agglutinative, to fusional, back so isolating again.

At the isolating stage languages mainly rely on word order and function words like auxiliary verbs or particles to indicate grammatical information. At the agglutinative stage, these function words start becoming inflectional affixes. At the fusional stage sound changes blur the boundaries between morphemes, "fusing" them together, so to speak, packing more and more grammatical information into smaller affixes. Eventually sound change erodes the inflectional affixes altogether and the language is isolating again.

https://en.wikipedia.org/wiki/Morphological_typology#Cyclical_evolution