War extends frontier on man-machine interface War, while horrifically cruel, does spur technological advances, and not just in killing people. Nowhere is that seen better than in medical care of the wounded, especially those who've suffered amputations. Recent breakthroughs suggest that scientists are on the verge of redefining the human-machine interface, with significant repercussions for an aging global population. A bit of history first, then some sense of the current challenge. Artificial body parts (e.g., noses, ears, eyes) began appearing more than 4,000 years ago, with history recording in 500 B.C. that the first artificial limb belonged to a Persian soldier whose wooden foot replaced one that he himself had hacked off to escape chained captivity.