[PeterWhittaker]

You may be interested in http://www.sciencedaily.com/releases/2007/10/071010132314.ht...

tl;dr - infrequently-used irregular verbs get "regularized", frequently-used irregular verbs, e.g., "be", "think", will likely stay irregular forever.

(I remember reading about changes to the English language that happened to be underway about the time the printing press arrived, and how the press "froze" that process, leaving us with the mess of pronunciation, spelling, and verb endings we have today, but I've been unable to find an appropriate reference, so I offer the article about the Lieberman study in its place.)

[ranit8]

Would that be a sign Americans have been reducing usage of the learn verb? I guess that correlates with the amount of posts here about the problems of American education.