Black Do Slack

AITOOW wonders how Europeans arrived at the conclusion that Africans were the best option in the new world? Anyone that watches a Mexican solemnly slave in the sun for peanuts can't believe that they weren't a better option. I know they say that the indigenous people couldn't take the heat, but, they can't be talking about Mexicans. Today's African ancestors are the progeny of the toughest/best of the bunch. How bad were the others?