Some say the world will end in fire, some say in ice; still others say in a nuclear apocalypse that will annihilate humanity while leaving cockroaches intact. It’s an unhappy picture, homo sapiens being completely wiped out by its own technology as the little pests inherit the Earth, but is the possibility fact, or just science fiction?
Unfortunately, it looks like the bugs win this one. They’ve already survived one nuclear attack: The cockroach survival theory surfaced in the wake of the 1945 atomic bombings at Hiroshima and Nagasaki, when reports began to circulate that the only signs of life remaining between the two cities were cockroaches scurrying among the ruins. With that kind of evidence, it’s reasonable enough to infer that even more nuclear weapons won’t be enough to keep them down, but it always helps to test a hypothesis. As usual, that’s where the Mythbusters stepped in.
The Discovery Channel team conducted an experiment on German cockroaches to see just how much radiation they can stand before kicking the tiny bucket, and it’s a lot—more than we frail humans can handle, for sure. A month after their initial exposure to 1000 radon units (rads) of cobalt 60—an amount sufficient to kill a human in just 10 minutes of exposure—about half of the cockroach sample was still alive and thriving, which is all the more impressive considering the normal mortality rate of insects with only a 6-to-9-month life span. The second condition upped the dose of radiation to 10,000 rads, about the equivalent amount of exposure that would result from an atomic bomb, and 10 percent of the cockroaches were still around to tell the tale a month later. The 100,000 rads condition, thankfully, proved that at least cockroaches aren’t invincible: None of them made it through, which would be more tragic if they didn’t still possess superhuman levels of radiation immunity.
Detractors from the theory that roaches will someday rule the Earth don’t disagree with the findings that the little creepy-crawlies would easily outlive us after nuclear fallout; their argument is that there are other, even more radiation-resistant insects out there. Wood-boring insects, as well as their eggs, can survive exposure to as much as 68,000 rads, while it would take about 64,000 to take out the common fruit fly. The Habrobracon, a type of parasitic wasp, easily takes the radiation-resistance championship with its ability to survive up to 180,000 rads—somewhere around 200 times as much resistance as any human possesses.