Smallpox is the best example. Today, it exists only in closely-guarded labs. In prehistory, we also wiped out all the megafauna outside Africa --- partly becaus

Smallpox is the best example. Today, it exists only in closely-guarded labs. In prehistory, we also wiped out all the megafauna outside Africa --- partly because they were delicious, I'm sure, but also partly because they found us delicious.