Text: Robert Wright  Anyone who doubts that male chimpanzees spend lots of time fighting over females should read Frans de Waal's book Chimpanzee Politics . Though the chimp colony de Waal studied was not in a purely natural setting, as were the chimps at Gombe studied by Jane Goodall, de Waal, for that very reason, got a clearer look at daily life within a colony than Goodall did.
Entailment: The chimp colony de Waal studied was not in a purely natural setting
Contradiction: The chimp colony de Waal studied was in a purely natural setting