The first migration led some groups away from the African continent to colonize the rest of the planet and, ever since, geographical displacement of individuals or groups has remained constant throughout history (despite the restrictions currently imposed by border-control policies).

Planetary geography and bird migration «Mobile organisms occupy territories with abundant resources, take advantage of them in order to breed, and leave when unfavourable conditions occur. Migration is nothing more than that» It is well known that seasonal climate alternation in mid and high latitudes of the

The end of the Civil War also ended a period of scientific and cultural development, which had taken place during the Republic. Scientists and intellectuals who had been part of academic life, and often political life too, were faced with the choice of staying in Spain or going into exile abroad after the Francoist victory.