Quite who they were and what they were like remain matters of disagreement and uncertainty. Right up until the middle of the twentieth century the accepted anthropological view of the Neandertal was that he was dim, stooped, shuffling, and simian—the quintessential caveman. It was only a painful accident that prodded scientists to reconsider this view. In 1947, while doing fieldwork in the Sahara, a Franco-Algerian paleontologist named Camille Arambourg took refuge from the midday sun under the wing of his light airplane. As he sat there, a tire burst from the heat, and the plane tipped suddenly, striking him a painful blow on the upper body. Later in Paris he went for an X-ray of his neck, and noticed that his own vertebrae were aligned exactly like those of the stooped and hulking Neandertal. Either he was physiologically primitive or Neandertal's posture had been misdescribed. In fact, it was the latter. Neandertal vertebrae were not simian at all. It changed utterly how we viewed Neandertals—but only some of the time, it appears.

It is still commonly held that Neandertals lacked the intelligence or fiber to compete on equal terms with the continent's slender and more cerebrally nimble newcomers, Homo sapiens. Here is a typical comment from a recent book: "Modern humans neutralized this advantage [the Neandertal's considerably heartier physique] with better clothing, better fires and better shelter; meanwhile the Neandertals were stuck with an oversize body that required more food to sustain." In other words, the very factors that had allowed them to survive successfully for a hundred thousand years suddenly became an insuperable handicap.