Have you ever wondered why in Quebec they speak French, in Brazil they speak Portuguese, in Mexico they speak Spanish? That is because hundreds of years ago, the Europeans tried to find a trade route to the Orient west of Europe. They accidentally bumped into North and South America, and they took it over and claimed it for their countries. The reason that the Europeans were able to conquer the American Aboriginals and not vice-versa is that they had better food, immunities, and technology.
The Europeans had 13 different types of "eating animals" such as the goat, cow horse chicken etc. The South Americans only had 1, the lama. Animals are a great source of protein which is considered "brain food".
The Europeans also farmed. While the Aboriginals hunted and gathered. Wouldn't it just be great to sit around and do some inventing while someone else farms your food? That's what the Europeans did.
You could produce 10 to 100 times more food by farming than by hunter-gathering. In addition to productivity, forming allowed you to save up food for long trips.
Another reason why the Europeans conquered the Aboriginals is because they had better immunities to germs such as, small pox, measles, mumps etc. The Europeans developed these immunities because they lived in permanent settlements where there were feces on the streets and in the rivers. Animal and human waste is jam-packed with germs, viruses, you name it. With exposure to all these feces, they become immune to almost all the germs in the feces, whereas the Aboriginals on the other hand, kept on moving around and leaving their waste behind. Therefore the Aboriginals had no exposure to germs.
The technology the Aboriginals had was no match to the European technology. The Europeans had guns, horses and steel. The guns were almost no good except for the noise, the noise scared the Aboriginals away because they had never seen or heard a gun before. Horses were so useful in war because you could go faster on a horse than on foot. On a horse you could also get on top of your opponent. Most importantly of all, steel. Steel was useful because it could bend; it was hard but not brittle. Steel was one of the most important European innovations.
I think that the main reason the Europeans conquered the Aboriginals is because they got lucky. They were lucky enough to have life start in their side of the world to give them civilizations that the Aboriginals lacked.
From the outcome of this battle, I recommend that humans should not live in a 100% sanitized environment, or else we will be wiped out like the aboriginals.