The dazzling feats of Olympic and professional athletes depend on top-notch performance by their powerfully conditioned muscles. But conditioning can only go so far; recent research suggests that on a biological level, some athletes really are born, not made. Future genetic breakthroughs could change even that. This month's cover story, "Muscles and Genes," addresses the possibilities. Also in this issue: "Searching for Shadows of Other Earths," "Who Were the First Americans," "From Protocols to Language," and James Burke on "The Last Word."
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