Immigrant groups lose usefulness once emigration stops and homegrown generations lack old-world skills

Evidence

In doing so they replaced the Jews. Jews had come from Europe in the fourteenth, more especially in the fifteenth and early sixteenth centuries. They came with a knowledge of languages and countries and for a while were very useful. But they lost their usefulness; no new ones were coming, and the second generation born in Turkey no longer possessed the skills and knowledge that their parents had brought from Europe. — Bernard Lewis, From Babel to Dragomans, 164

Categorization

• XREF: Parallels the arc of any immigrant-skill labor pool — e.g. Dominican baseball players, Irish navvies — and mirrors the blood-and-culture transmission argument in The Namesake about second-generation assimilation. — connects to: Random loss of skilled elders can erase a group’s entire complex tool repertoire — Joseph Henrich, The Secret of Our Success: How Culture…, 685
• DEEPTHINKING: A compact general theory of skilled-diaspora decay: the skills are not transmitted generationally because they’re tied to the old country, and once emigration stops the pool fossilizes.