"Humans have no natural predators. Zero." As a group yes. As individuals - no. Go in alone somewhere where other big predators like wolves, bears or whatnot an

"Humans have no natural predators. Zero." As a group yes. As individuals - no. Go in alone somewhere where other big predators like wolves, bears or whatnot and hold your ground for a few weeks. I bet that unless you build some kind of fortress for yourself to sleep at night, not even firearms will help you in the long run. "Even with stone-aged levels of technology we spread to every corner of the world, in every known climate and ecology, in large numbers, and thrived." Actually, we've managed to thrive only in the places where there was enough air (no underwater humans), water (not many thriving communities in the deserts), food (which was a hard limit for the level of development, famine was a regular regressing factor), warmth (no people in Antarctica), and other such useful things. In this regard we are no different than other animals.