domingo, 20 de septiembre de 2015

Does a human heart have a finite number of beats?

Yes. At an average of 80 beats per minute, most of us will manage less than four billion beats in our lives. But you don’t die because you run out of heartbeats – you run out of heartbeats because you die. Among mammals, the number of heartbeats over the lifespan of different species is fairly constant. So hamsters’ hearts beat 400 times a minute and they live for about four years, which is 840 million beats, and an elephant manages 35bpm for 35 years, or about 640 million beats total. Those numbers are similar, but that’s just because animals with faster heart rates are also smaller and more at risk from predation and starvation. Their lifespans have evolved to compensate for this by reproducing early and often – they ‘live fast, die young’. Heart muscle can only repair itself very slowly, so eventually every heart will wear out but not after a specific number of beats. 

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