"10. A lifespan is a billion heartbeats. Complex organisms die. Sad though it is in individual cases, it’s a necessary part of the bigger picture; life pushes out the old to make way for the new. Remarkably, there exist simple scaling laws relating animal metabolism to body mass. Larger animals live longer; but they also metabolize slower, as manifested in slower heart rates. These effects cancel out, so that animals from shrews to blue whales have lifespans with just about equal number of heartbeats — about one and a half billion, if you simply must be precise. In that very real sense, all animal species experience “the same amount of time.” At least, until we master #9 and become immortal."
It makes me wonder - I thought that exercising and keeping active were supposed to lengthen one's lifespan, but doesnt your heart-rate increase during activity? Perhaps this is just averaging species' lifespans by scale in general, I cant imagine that a couch potato would have a longer life expectancy than a marathon runner - so it almost seems that on an individual basis the opposite is true, that relative to other individuals within the same species, the more lifetime heartbeats the longer they live on average? Im not sure, but its pretty fascinating and is another demonstration of how numbers affect every part of our world.
