Consider comparatives and plurals; we could imagine combining the two to form the meaning of 'even more than previously mentioned'. Thus,
our side had soldier-s, they had soldier-s-er
our side had soldiers, they had more soldiers
This goes on to things like
I had students, and they had student-s-er
I had students, and they in turn had students
Now we're getting to the point where the plural comparative may be losing its comparative sentiment. Originally, it signifies |S1| < |S2|, but slowly, the meaning is turning into |S1| < |S1 + S2|, i.e. the comparative's frame of comparison no longer is S1 but the size of the whole set of things - i.e. we're no longer comparing the number of my students to the number of "my grand-students", we're comparing the number of everyone who can trace their educational lineage to me to the number of my direct students.
As this meaning is slowly entrenched, the comparative form's comparative meaning is lost, and the meaning turns more into 'here, new nouns of a type previously mentioned are introduced', so student-s-er simply means '(more) new (as far as the discourse goes) students'.
At this point, the comparative might turn into a marker that is basically an indefinite article for nouns, maybe restricted to nouns of types already participating in the discourse?