(Photo: Getty Images)

Last weekend, I left my rental car parked overnight in a remote location in northern South Africa, where I have been working on a story. When I got back to the car the following afternoon, there was a freshly shed snakeskin on the ground by the rear bumper.  The biologist I was with (OK, he was a mammals guy) examined the head and ventured, “It could be a young black mamba.”

I contemplated that as I drove for the next four hours south to Pretoria. Off and on, I wondered whether the snake had sought shelter, as animals sometimes do, in the engine compartment of the car. In case you’ve somehow never heard of black mambas, they are among the deadliest snakes in the world and can grow to 15 feet in length. They generally use their considerable speed to escape rather than to attack, but they…