As the article says (but I initially overlooked it) it was discovered in 1972. Instead of actually reading that, I went looking for the oldest scientific refer

As the article says (but I initially overlooked it) it was discovered in 1972. Instead of actually reading that, I went looking for the oldest scientific reference, and finally found a Wikipedia entry in French that said: "En 1972, le physicien français Francis Perrin découvre à l'usine d'enrichissement militaire de Pierrelatte les traces de ce phénomène dans de l’uranium provenant de la mine d'uranium d’Oklo exploitée par la Compagnie des mines d'uranium de Franceville (Comuf). Il s'agit des seuls réacteurs nucléaires naturels connus au monde à ce jour."