No. 32: Mar-Apr 1984
A decade ago, French scientists discovered the remains of a natural nuclear reactor at Oklo, Gabon, in Africa. Somehow nature had concentrated enough uranium-235 in one place to start a chain reaction, with the attendant production of heat and radiation. Now U-235 is radioactive, and there is now much less around than in past geological eras. This has led some scientists to speculate that many more Okla phenomena may have flamed momentarily in earlier times, especially Precambrian days. The mutagenic radiation from such natural reactors could have been a major driving force in evolution.
(Anonymous; "Natural Reactors Helped Evolution," New Scientist, 100:737, 1983.)
Reference. For details on the Oklo Phenomenon, see category ESP13 in our Anomalies in Geology. For a description of this Catalog, visit: here.