In German Southwest Africa the term “Verkafferung” is understood as meaning the sinking of a European to the cultural level of the Native […] Lonely life in the field, in continual contact with Africans, but more especially mixed marriage – these things encourage the regrettable degeneracy of the white settler. In spite of his occasionally active personal intelligence the degenerated European is always a lost member of the white population, since even in the best cases one of the basic demands of his own culture, the active drive and adherence to a definite plan, is completely lacking in him. Even in employment such unfortunates are frequently less useful than an intelligent native. Only by means of legal (prohibition of mixed marriages) and social action can this scourge be controlled in the long-term. The safest remedy for this not to be underestimated danger lies in facilitating marriages with white women.
Source: Karl Dove in, Heinrich Schnee (ed.) Deutsches Kolonial-Lexikon edited by (Leipzig : Quelle & Meyer 1920) – 3 volumes. Largely finished around 1914, but not published until after the war.