Humans are a striking exception; even though we're bereft of natural weapons – claws, ripping teeth and so on – we easily protect ourselves from even large predators. There are the occasional "bear in the woods" stories, but those come when we leave our constructed environments.

The reason we're so able to keep ourselves safe is simply that we can think. Humans have, since long before recorded history, figured out how to master wild animals. And so we have no natural predators… or at least none of the usual type.

Our Predators Are Intellectual Predators
In case anyone is pounding a desk, screaming "war," don't worry, I'll get to that in a minute.

Humans are not destroyed by claws and teeth, they are destroyed by ideas. In fact, they are highly vulnerable to ideas. In particular they are suckers for authority, for idols and for promises of free stuff. 

We see these vulnerabilities from one end of human history to another. Here's just a brief explanation:

Authority: A large number of humans will obey a well-presented authority without critique. The doctor in a white lab coat, the politician wearing a fine suit and podium, the monarch with a crown and a retinue… people turn off their minds when confronted with them and simply comply. The fact that so many order-givers play up their authority proves the point: they wouldn't take pains to create such images if they didn't work. People will also reflexively defend authority, if for no other reason than they've already obeyed it and they don't want to look stupid.
Idols: Humans find psychological comfort in holding to a great and powerful entity. It makes them feel safe. If you frighten people, then supply them with a powerful figure (Mussolini makes a nice example) and they'll line right up. It's no accident that the communists made giant images of Lenin, Stalin, Mao and the others: It works.
Free stuff: From the plunder of enemies to robbing the rich to technical incarnations of the same principle, humans are easy marks for this scam. We've all watched it in action, and so I won't elaborate further.