Passage Summary: Some experts say humans survived because they could adapt to different environments, but the author says that's wrong because another species was adaptable and still died out.

Conclusion: The claim that the ability to handle diverse environments was necessary for human survival is incorrect.

Reasoning: A related species, Australopithecus afarensis, possessed the ability to thrive in diverse environments but went extinct anyway.

Analysis: The author is confusing a 'necessary condition' with a 'sufficient condition.' The anthropologists claimed that adaptability was required for survival (necessary), not that it guaranteed survival (sufficient). The fact that a different species had this trait and still went extinct only proves that adaptability isn't enough to guarantee survival; it doesn't disprove the idea that you need it to survive. Look for an answer that identifies this confusion between what is needed to stay alive and what ensures staying alive.