From Popular Mechanics: "We've long regarded aging as something almost mystical or supernatural, and it's easy to see why. ... But research demonstrates that aging isn't a supernatural process; it's a physical one that gradually occurs as systems wear out beyond the body's ability to repair them. Cells fill up with metabolic debris called lipofuscin that they can't digest, accompanied by decreasing functionality. They also undergo glycation, gumming up and caramelizing with sugars that have bonded to proteins. Mitochondrial DNA can suffer mutations, and the body slowly loses stem cells, which weakens healing and repair. Aging is breakdown, but broken things can be fixed. After all, cars and airplanes tend to wear out as they get older, but with sufficient maintenance they can last far beyond their design life. ... Americans now live longer, healthier lives by several decades than the majority did a century ago. Most of us think it's a good thing. Would extending this phenomenon by several more decades be good, too? Seems like it to me."