War, while horrifically cruel, does spur technological advance, and not just in killing people. Nowhere is that seen better than 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.
Surgical amputation as a life-saving measure began to spread in 1500s, but the real inflection point came in the American Civil War, where the introduction of the anesthesia chloroform allowed doctors to better shape surviving limb tissue.
Not surprisingly, mass manufacturing of artificial limbs likewise took off in the Civil War.
Confederate soldier J.E. Hanger, an early amputee, went on to found the world's first great prosthesis factory. His namesake company remains a global industry leader to this day.
Along the same line, the world's single biggest consumer of artificial limbs is the U.S. Department of Veterans Affairs, which dispenses thousands of new ones each year to its aging service population while replacing tens of thousands more.
Following our military interventions in Afghanistan and Iraq, U.S. military hospitals have also cared for hundreds of soldiers who've lost limbs in combat, mostly from close explosions.
Casting our net more widely, we see that the vast majority of the roughly 2 million Americans who've suffered a loss of limb did so as a result of infections, circulatory diseases and cancer, causes often associated with relative affluence.
In the world's less developed regions, the main culprits are congenital defects, accidents (industrial and vehicular) and land mines. For example, there are an estimated 400,000 land-mine survivors spread across roughly 80 postwar countries.
Nonetheless, the future market for prosthetics is far more tied to global aging than to regional conflicts. As globalization raises incomes in emerging markets, a larger share of the world's population lives longer lives - the ultimate affluence.
Extended lives translate into far higher rates of cancer and heart disease. So, if one out of every 150 Americans today employs some form of prosthesis, by 2050, a world populated by 9 billion-plus humans could easily produce a pool of 50 million or more users.
Now let's switch over to modern science, where the U.S. Defense Department has recently pumped in tens of billions of research dollars in response to our first extended overseas conflicts since Vietnam.
Thanks to recent advances in material sciences, the construction of artificial limbs has improved dramatically in the last few years. That means not only heightened functionality but lower cost.
For example, the stunningly sturdy Jaipur foot, so named for the Indian town in which it was developed, combines advanced materials with elegant engineering at the affordable price of $40. But it's the interface of man and machinery to which I most want to draw your attention.
Up to now, about the best we've been able to accomplish is using healthy neighboring tissue to signal, through muscle contractions, desired motion in robotic limbs. While that gets you simple actions, like squeezing an object, a lot of desired articulation is clearly lost in that crude translation.
But here are two promising research efforts that suggest we're approaching far more profound capabilities.
The first involves MIT research into advanced computer algorithms that directly convert brain signals into actions by prosthetic devices - mental intention electronically recast as code. Huge translation challenges remain, especially at the exact point of tissue-machine interface.
That takes us to some exciting work being done at Oak Ridge National Laboratory, where scientists have spent the last half decade coaxing manmade carbon nanofibers into integrating directly with cells.
These infinitesimally small spiked structures actually penetrate neural cells to the point where electrical signaling is possible in both directions, meaning we effectively tap into the body's internal communications network.
Darth Vader meets the Six Million Dollar Man? It's not at all fantastic.
But here's hoping it doesn't take too many more lengthy wars to keep this ball rolling. The quickest route to biological limb regeneration shouldn't run through a minefield.