"The Only Known Animal That Lives Within Borders"
Actually, not so. Chimps have borders, too. Groups of male chimpanzees patrol in the areas that border the areas of neighbouring groups. If they see chimps from the other groups & if they are more numerous, they may attack.
Not to forget that lots of other animal species are also very territorial & attack intruders. Humans are not so special, they just do it on a greater scale.
Sure, but their borders are not fixed at exactly the same place with fences, passports and this for centuries. Of course I've choosen the title to be quite provocative, and if you take it seriously there are borders everywhere. But not that kind of bureaucratic and totalitarian borders as in the world of humans. In the world of animals it's more about who is nice to who. In the world of humans it's just about which flag you are "part of", and the border is created by someone autoritharian hundreds of years ago, in a completly different world than now.