Is there a link between Earth's geomagnetic reversals and extinctions? Nobody has proven it, despite their efforts. But the idea just won't go away.

The Earth's magnetic poles haven't remained consistent over the planet's 4.5 billion year history. It's experienced multitudes of pole flips, or geomagnetic reversals, where its north and south poles swap positions.

Scientists rely on paleomagnetism to detect them. Paleomagnetism detects the orientiation of Earth's poles across geological time in lava and sediments. The orientation of magnetic minerals in lava and ancient sediments record the locations of the poles at the time they solidified or accumulated.

Scientists think reversals are triggered by changes in the heat that flows across Earth's core-mantle boundary, but finding a pattern in geomagnetic reversals is a daunting task. They seem to occur about once every 450,000 years; evidence shows 183 of them in the last 83 million years.…