650,000 Hours/3 Billion Heartbeats

There are many ways to quantify a human life. Here are two.

The first comes from Bill Bryson’s A Short History of Nearly Everything:

[F]or you to be here now trillions of drifting atoms had somehow to assemble in an intricate and intriguingly obliging manner to create you. It’s an arrangement so specialized and particular that it has never been tried before and will only exist this once. For the next many years (we hope) these tiny particles will uncomplainingly engage in all the billions of deft, cooperative efforts necessary to keep you intact and let you experience the supremely agreeable but generally underappreciated state known as existence.

[…]

The bad news is that atoms are fickle and their time of devotion is fleeting – fleeting indeed. Even a long human life adds up to only about 650,000 hours. And when that modest milestone flashes past, or at some other point thereabouts, for reasons unknown your atoms will shut you down, silently disassemble, and go off to be other things. And that’s it for you.¹

And here is physicist Sean Carroll’s:

Our finite life-span reminds us that human beings are part of nature, not apart from it. Physicist Geoffrey West has studied a remarkable series of scaling laws in a wide range of complex systems. These scaling laws are patterns that describe how one feature of a system responds as some other feature is changed. For example, in mammals, the expected lifetime scales as the average mass of an individual to the 1/4 power. That means that a mammalian species that is sixteen times heavier will live twice as long as a smaller species. But at the same time, the interval between heartbeats in mammalian species also scales as their mass to the 1/4 power. As a result, the two effects cancel out, and the number of heartbeats per typical lifetime is roughly the same for all mammals—about 1.5 billion heartbeats.

A typical human heart beats between sixty and a hundred times a minute. In the modern world, where we are the beneficiaries of advanced medicine and nutrition, humans live on average for about twice as long as West’s scaling laws would predict. Call it 3 billion heartbeats.

Three billion isn’t such a big number. What are you going to do with your heartbeats?²

1. Bryson, B. (2004). A short history of nearly everything. Broadway.
2. Carroll, S. (2016). The big picture: On the origins of life, meaning, and the universe itself. New York: Dutton.