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Figure%201.%20Two%20fossil%20skullsClick to Enlarge ImageThe ancestors of modern humans (Homo sapiens) shared the Earth with Neandertals (Homo neanderthalensis) for at least 100 millennia, but some 30,000 years ago Neandertals became extinct, whereas human beings, of course, prospered. Scholars have proposed many possible explanations, including the notion that only human beings developed language. But the archaeological record suggests that the key difference was, in fact, the evolution in Homo sapiens of the mental ability to plan and strategize, which allowed them to find innovative solutions to the many problems they faced as they spread over a harsh, ice-age world.

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