00:00Two billion years ago, Earth built a nuclear reactor.
00:04Not humans. Nature did.
00:07Deep in what is now Gabon, Africa, in a place called Oklo,
00:12deposits of uranium became so concentrated and so pure that they did what shouldn't be possible.
00:19Groundwater seeped in.
00:21The water acted as a moderator, slowing neutrons down just enough to trigger a real fission chain reaction.
00:29It turned on.
00:30It boiled the water away, which shut it down.
00:33Then more water seeped back in, and it turned on again.
00:38For a hundred and fifty thousand years.
00:41We know there were sixteen of these natural reactors.
00:45And no, nothing used them.
00:47There were no humans, no dinosaurs, no animals at all.
00:51Just microbes.
00:52It had no purpose.
00:54It just ran.
00:55It produced heat, power, and radioactive waste, and then perfectly contained that waste in the surrounding rock.
01:03We didn't even know they existed until 1972, when scientists in France noticed uranium from Gabon was strangely depleted.
01:12Someone had already used it.
01:14Nature had beaten us to nuclear power by two billion years.
01:19And it also solved nuclear waste storage long before we did.
