question: Why did natives consider Africans to have a ` Great Medicine ' ?
answer: because Africans were virtually immune to the Old-World diseases
turker_answer: Natives considered Africans to have a ` Great Medicine ' because Africans were virtually immune to the Old-World diseases .
rule-based: Natives considered Africans to have a ` Great Medicine because Africans were virtually immune to the Old-World diseases ' .