Racial-purity survival doctrine in Europe predates modern immigration panics

Evidence

The fear of cultural and racial extinction has a long pedigree in European history, which can be traced back to the racial Darwinism of the nineteenth century, articulated by writers such as Count Joseph-Arthur de Gobineau, who argued that only races that maintained their racial purity would survive. — Matt Carr, You Are Now Entering Eurabia, 56

Categorization

• QUESTION: How direct is the intellectual lineage from Gobineau to Huntington and the Eurabia authors — citation, paraphrase, or convergent independent logic?