Human migration is deeply embedded in both the history and present<br >functioning of modern society. At the broadest scale international<br >migrations have played a major role in shaping the world cultural map:<br >immigration is at the very root of societies like the United States， Canada<br >or Australia and has profoundly marked many countries of Latin<br >America or Africa. Europe， once the great exporter of people to these<br >countries， became a net importer of labour in recent decades: there are<br >approximately fifteen million labour migrants in Western European<br >countries at present. The numbers of people involved may indeed be<br >enormous: some 67 million people crossed an ocean between 1800 and<br >1950， of whom 60 million were Europeans and of these two out of every<br >three went to the USA; some 10 million Italians left home to settle abroad<br >between 1846 and 1932; there are many more people of Irish origin living<br >outside Ireland， in the USA or Britain especially， than within it. Equally，<br >it has been estimated that some 7.7 million people were involved in intra-<br >