Omotic languages are heavily agglutinative, often forming entire sentences with one word.
 There seems to exist a preferred evolutionary direction from agglutinative synthetic languages to fusional synthetic languages, and then to non-synthetic languages, which in their turn evolve into isolating languages and from there again into agglutinative synthetic languages
Language contact may also lead to a variety of other linguistic phenomena, including language convergence, borrowing, and relexification (replacement of much of the native vocabulary with that of another language)

