The New York Times – New research is intensifying the debate — with profound implications for the future of the planet. “…Humans have never belonged to the select society of the everlasting. We most likely inherited fairly long life spans from our last common ancestor with chimpanzees, which may have been a large, intelligent, social ape that lived in trees away from ground predators. But we never out-evolved the eventual senescence that is part of being a complex animal with all manner of metabolically costly adaptations and embellishments. As the years pass, our chromosomes contract and fracture, genes turn on and off haphazardly, mitochondria break down, proteins unravel or clump together, reserves of regenerative stem cells dwindle, bodily cells stop dividing, bones thin, muscles shrivel, neurons wither, organs become sluggish and dysfunctional, the immune system weakens and self-repair mechanisms fail. There is no programmed death clock ticking away inside us — no precise expiration date hard-wired into our species — but, eventually, the human body just can’t keep going. Social advances and improving public health may further increase life expectancy and lift some supercentenarians well beyond Jeanne Calment’s record. Even the most optimistic longevity scientists admit, however, that at some point these environmentally induced gains will run up against human biology’s limits — unless, that is, we fundamentally alter our biology…”