Join me in a little thought experiment.

Suppose some conservative think tank were to propose a Darwinian immigration policy. No longer would people be admitted because they had applied properly and played by the rules; nor yet because they were judged to be in need of political asylum. Instead, as in some dystopian science fiction film, applicants would have to go through an obstacle course designed to weed out the weaklings. Some would die in the attempt. Many more would turn back, defeated. Only the most crafty and determined would win through, bringing their cunning to their new homeland and adding their ruthless DNA to its gene pool.