Immigration

Most people are technically immigrants. Take the U.S. for instance. Unless you are a Native American, called that for a reason, then you are an immigrant. And for the most part, if you want to go that far back, most of them walked here from somewhere else. Not sure what you were really asking, but I hope I answered it.

I think we have been immigrants ever since. Our ancestors and all native ancestors we have have been migrating due to change of season, looking for food or just trying to find the perfect settlement. I think it is just normal. The world is a big place for all of us. Just not enough means.:)

Scientifically speaking, humans were originally nomadic tribes, and hunter gatherer societies. We may have an instinctual inclination to go where there is better food and climate for our own survival. So there may be a natural instinct towards migration - allowing us to seek a more prosperous place to live.