Everyone Who Ever Lived

How many human beings have ever lived?

What a question! I wasn’t there to count them all a few hundred thousand years ago when anatomically modern humans first burst onto the scene, but is there a way to reasonably estimate the number of people who have been born?

This idea first cropped up in my mind a long time ago, but within the last decade or so, it has become easier to come up with some kind of a reasonable estimate. After all, answers to virtually everything are on the internet.

If this problem seems insurmountable, you’re not alone in thinking that, but there’s a way to simplify it. Today, the global population is just over 8 billion, an almost unfathomable amount. Our brains are wired to understand numbers in the dozens, not in the billions.

One thing we are capable of grasping is ratios. Just a century ago, the human population was a hair under 2 billion, or a quarter of what it is today. A hundred years before that, it was about a billion.

A thousand years ago, there were more like 300 million. Go back 5000 years, and it’s more like 14 million. 10,000 years ago and any time before this, it’s likely that there were a million or fewer humans around at any given time.

Here’s a chart of how many human beings were alive on the planet over time:

See how it sort of moves to the right for a while, kind of slowly sloping upward, and then it sort of takes off like a rocket ship, almost straight up?

It turns out that this exponential growth is our key to making a reasonable estimate in the total number of humans who have ever lived. If you add them all up, about half of the humans lived within the last 2000 years or so, and half lived during the 250,000 or so years of before that.

In just a hundredth of the time, we’ve lived as many lives as before the Roman Empire. Rome itself had reached a population of about a million people (and 150 public restrooms!), which may have been around the total population of the entire planet at the dawn of the so-called agricultural revolution 8,000 years earlier.

Demographers have used birth and death rates over time to come up with an estimate that somewhere around 117 billion humans have ever existed. That means that somewhere around 7% of everyone, ever is alive right now.

This hit me like a brick in the face when I realized what it implied: that just because other humans in the past have always done things a certain way, that is not a good enough reason for us to do those things. We don’t need to go quietly in the night as our ancestors did if there are other alternatives, and since the people alive today have access to far more ideas than at any previous time in our history, we don’t necessarily have to follow the rules of the past.

The common causes of death in the past need not be our causes, and we might be surprised at the new paradigms we can create. For the first several hundred thousand years of our existence, if we got an infection, we died. The last ten billion or so humans have been beneficiaries of antibiotics, extending human lifespans by years.

Besides life extension and quality of life improvements, we’ve got a chance now to do things differently. Ideas no longer exist in isolation; instead, they spread around the globe at the speed of light. This gives us access to more and more minds capable of solving some of our toughest problems, and innovating like never before.

For me, the most important takeaway is that we—the people alive today—make up a significant chunk of all humans who have ever lived, and our generations alive today are vastly better equipped to innovate than every group who has come before.

The future is unwritten, and it’s up to us to create the next pages in our journey. What are some of the things we might be able to do differently?