ABSTRACT
In Africa, out of Africa, into Europe, Asia, the Americas, human beings might be characterized, as some archaeologists have put it, an “invasive species”. They leave ecological niches to which they had adapted. Until the middle of the 20th century, people who left any “old country” for the Americas had almost no opportunity to return, or keep ongoing contacts with those they left behind. By the 1960s, cheap air travel changed all that, and people on the move used this new opportunity. With the turn of the 21st century, new technologies opened newer opportunities. As far back as history and pre-history can trace humanity, people around the world have been on the move. Longer historical perspectives confirm that human beings move, or are moved, and find themselves having to deal with people moving or being moved in and out of what some imagined were stable, closed, communities.
