All mammals get the same amount of heartbeats, very broadly speaking.
Take humans, for instance. For simplicity’s sake, let’s say your heart beats once a second. On average, this probably isn’t too far off.
Sixty seconds are in a minute, and sixty minutes are in an hour. That’s 3,600 heartbeats per hour, or 86,400 in a 24-hour day. 365 days in a year means 31,536,000 heartbeats per year. After 32 years, you will have produced a little over a billion heartbeats.
Put another way, if you have 32 years left to live, you’ve got a billion heartbeats ahead of you.
Mice and elephants each get roughly a billion heartbeats, and so do most mammals in between.
I wrote a bit about Kleiber’s Law, and the biology that underpins why other mammals also get roughly the same number of heartbeats, even when their lifespan is longer or shorter than average:
Back over to us (humans): we seem to be a notable exception, since our lifespans are just over double the figure I used (32 years; average human life expectancy is now 73). We certainly are notable: humans have steadily expanded our average lifespan from the prehistoric and ancient world, where infant mortality, famine, and preventable diseases effectively culled humanity.
In sum, we take good care of the biological machines we call our bodies, and we have managed to steal time from nature, in a manner of speaking, thanks to our social structure and (especially) due to our technology.
A mouse’s billion beats go by quickly, and mice live very short lives. Elephants’ hearts go much slower, and they can live longer lives than prehistoric humans. If we paid elephant health care the same attention as we pay to human health care, could we get their lifespans to be longer than ours?
Regardless of biological differences, we each get a finite amount of heartbeats to use. It’s not precisely a billion for any of us, but it might be helpful to have a specific number in mind, and a billion is the right order of magnitude.
The question for today is: what are you going to do with your billion heartbeats? If you’re terminally ill or much older, maybe that number is much lower, but I want to emphasize the concept: each of us has a finite number of heartbeats remaining.
Well, this is the starkest case I've ever read against high-intensity exercise.
I will no longer be wasting my precious heartbeats on frivolous stuff like staying in shape!
Goodbye, running. Hello, living to 120 years!
Thought-provoking article as usual. Still, it won't stop me from continuing my daily exercises.