My issue with r/k selection theory as it pertains to humans is that we would be the only species known to man that not entirely on a single side of the coin.
All rabbits are r-selected. All elephants are k-selected. Humans are a mix? I suppose you could argue that different ethnic groups (black=R and white =K) have different r/k designations but that seems unlikely because although we are different we due share immense genetic similarities, enough for liberals to claim "one human race."