I recently read (in Steven Johnson's Where Good Ideas Come From) about Kleiber's Law, which is that as things get bigger, they tend to slow down. Among the many applications of this theory is the heart-rates of larger animals are slower than smaller ones. Further, larger animals live longer than smaller ones--a fly might live for a day, while an elephant lives for 50 years. But neither of these relationships is linear, unless you combine them. Then you find that if you plot mass vs. metabolism on a logarithmic grid you get a straight line from sparrows to whales.
An interesting corollary is, as science writer George Johnson observed, that the number of heartbeats per lifetime tends to be stable from species to species, it's just that some species use them up more quickly than others. I think there's something very elegant in this, and almost poetic.
(I'm reminded of a similar theory about caloric intake--that the body is meant to process only so many calories, whether consumed in forty years or a hundred.)
I would like to live longer and well, but not at any price. I don't intend to slow my pulse so I can live more years. I'd prefer to sprint to the finish line, where I collapse flushed with exertion and sustained by adrenaline. I would rather my heart beat wildly than keep a dirge-like time from a dusty metronome. I hope I go with a white-knuckle grip on the handlebars of adventure, and not resting comfortably in the armchair of caution.
"Do not go gently into that good night. Rage, rage against the dying of the light." Dylan Thomas
