Nearly 42,000 years ago, when Earth’s magnetic fields reversed, this triggered major environmental changes, extinction events, and long-term changes in human behavior, a new study reports. The findings, made possible by a new radiocarbon record derived from New Zealand’s ancient kauri trees, raise important questions about the evolutionary impacts of geomagnetic reversals and excursions throughout the deeper geological record, the authors say. “Before this work,” says author Chris Turney in a related video, “we knew there were a lot of things happening around the world at 42,000 years ago, but we didn’t know precisely how… For the first time, we’ve...