Shannon experienced this first-hand when he and his colleagues were following a herd of elephants in South Africa's Pongola Game Reserve. The researchers kept their car at a respectful distance. But when they rounded a curve, Buga, the herd’s matriarch, stood blocking the road. The driver immediately turned off the engine, which generally causes elephants to move on peaceably. Instead, Buga charged the car. "Next thing we knew, the car was upside down and we were running," remembers Shannon. Buga's extreme reaction, he suspects, was linked to trauma she experienced when she was captured and relocated six years earlier.