Tabitha M. Powledge returns to her weekly science blogs roundup with a piece about a Spanish cave that has yielded the oldest human DNA yet found — along with some thoughts about why the news media keeps treating such discoveries as a big surprise: "These discoveries seem surprising in part because many of us are still in the grip of a now-untenable idea: That human evolution (or, actually, evolution of many organisms) is lineal, a straight line of descent."
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