From a Cameroonian refugee.
A reporter interviews a Cameroonian refugee.
What he says in the video sounds like, "The sky is open and only one thing, why do we divide it and have borders ?"
"Why should we forbid a human being from crossing a border ?"
So yes, indeed. Why do we have borders ?
P.S.
I truelly feel that I don't know for what exact reasons we have borders.
I feel that it is so fundamental and natural but I feel this inability to list out the reasons into words.
The perspective of the question seems inverted. We don't have borders per se, because we like to cut through things. We have Countries that exercises their authority on an specific area. The perimeter of that area is called a border.
The area that each Country control is limited fundamentally because there are disagreements on how to best run the thing or who should run the thing. If you allow everybody to enter your Country you lose control and bad things may happen: economic troubles, political crises, loss of political authority, violence, etc.
Just like many people like to have their own houses, many people like to have their own Country.
The Westphalian sovereignty doctrine is accepted for the definition of states and their territorial sovereignty:
From wikipedia: https://en.wikipedia.org/wiki/Westphalian_sovereignty
Westphalian sovereignty is the principle of international law that each nation state has sovereignty over its territory and domestic affairs, to the exclusion of all external powers, on the principle of non-interference in another country's domestic affairs, and that each state (no matter how large or small) is equal in international law. The doctrine is named after the Peace of Westphalia, signed in 1648, which ended the Thirty Years' War, in which the major continental European states – the Holy Roman Empire, Spain, France, Sweden and the Dutch Republic – agreed to respect one another's territorial integrity. As European influence spread across the globe, the Westphalian principles, especially the concept of sovereign states, became central to international law and to the prevailing world order.[1]
The farthest reference i have for the history of borders is the Bible. You find stories that had nothing to do with Governments. What maybe started out as disagreements between 2 brothers and the two agreed to part ways and one would take the hill country and the other the valley beyond a river. So they used geographical boundaries and separated their families that later became villages and through the generations became tribes and later cities and then empires. I know everyone doesn't agree that the Bible is fact but even still i think this paints a fairly accurate depiction on how boundaries could have started. I would imagine in the early days borders were very necessary in dealing with disputes on who could let their livestock graze on what land, where you could cultivate the land and later, by whom a city could tax and who were forced to join the military. But ultimately i think this all started by families and their different bloodlines.
Because humans evolved from apes, and thus bottom line is, we are not as intelligent as we'd like to think we are. Apes, like most animals, are territorial, and so are humans. Territorial on the individual level (MY house, MY land, MY property), territorial on the group level (my town / my region / my language / my country / my continent). And to denote the limits of your territory, you need a border. Borders therefore are a natural byproduct of territorialism. Humans just document/record borders in a more sophisticated manner.
Why animals have to be territorial ==> ask Darwin / evolution
Apparently it's beneficial for the survival of the one owning the territory.
The most-likely reason is, that if food sources are scarce, and the world is overpopulated, you need the territory for yourselfs to survive. Defending territory is therefore crucial for survival.
==> evolution is in favour of borders
