> The conditions under which a natural nuclear reactor could exist had been predicted in 1956 by Paul Kazuo Kuroda.[1] The phenomenon was discovered in 1972 in Oklo, Gabon by French physicist Francis Perrin under conditions very similar to what was predicted.

So not only did we not learn by observing the natural phenomena in this case, we actually predicted it (accurately, it seems).

I think the thesis being debated in this thread is the possibility of learning based on observation. No one was claiming that all discoveries were actually made this way.