How Many People Ever Lived?

By George Johnson | August 11, 2013 7:58 pm

Vintage postcard of Cuban cemetery. Flickr

While I was writing The Cancer Chronicles, I came to a point, early on, where I wondered how many people had ever been alive in the world. The best answer I could find came from a study by an organization called the Population Reference Bureau: 108 billion.

I was stunned by the magnitude of the number. It is still common to hear that more people are alive today than have ever lived. Or an even more extreme claim: that 75 percent of everyone who ever walked the earth is living today. But that is not even close to being correct. By the Population Reference Bureau’s reckoning, the proportion of living to dead is only about 6 percent.

The author of the study, Carl Haub, describes the assumptions that went into his calculations. Modern homo sapiens is widely believed to have made its appearance around 50,000 B.C., so that was year zero for his count.

As more people began to move from a nomadic existence as hunter-gatherers to a more sedentary life as farmers, the world population grew at an increasing pace. There is actually a specialty called paleodemography, and Haub drew on various estimates to come up with a population of around 5 million in 8,000 B.C.

World Population Growth. Wikimedia Commons

By 1 A.D. experts estimate that there were at least 45 million people in the Roman Empire. Extrapolating upward, Haub put the world population back then at roughly 300 million. Based on various assumptions about birth rate and the impact of infant mortality, infanticide, and the Black Death, it took until 1650 for the number to reach half a billion, surpassing 1 billion only in the 19th century. Today the population is 7.1 billion and rising, but the total accumulation of people, living and dead, has reached 108 billion.

That was interesting enough. My primary interest, however, was to compare the number with how many human remains have actually been found. All of our theories on what life was like in prehistoric times — including the prevalence of cancer and other diseases — can only be derived from the evidence at hand. So how big is the sample size? Getting that second number was a little tricker and will be the subject of my next post.

Related story: The Long Shadow: Cancer Has Afflicted People Since Prehistoric Times

@byGeorgeJohnson

For a preview of The Cancer Chronicles, including the table of contents and index, please see the book’s website.

  • highly_adequate

    How is 7.1/(108-7.1) only 3%?

    • http://talaya.net/ George Johnson

      Thank you for catching that. I made the fix.

  • ryanwc

    A related question – if you average out the birth dates and death dates, using actuarially expected death dates for those now living, you’ll find that on average we’ll all been dead for about 375 years.

    • Mark McAndrew

      That’s not a question…

      • SixSixSix

        Is about the reliability of the numbers and statistical methodology.

  • Sinibaldi

    Transient memory.

    If
    a fine

    leaf
    appears

    in
    the heart

    of
    the country

    I
    can see, near

    a
    glimmer, a

    delicate
    white

    dream.

    Francesco
    Sinibaldi

  • Kirk Holden

    According to our wiki, Genus Homo, Species Sapiens is ~200K years old. Our fair sub-species is on the order of 50K. The long tail of early man adds only round off error but the distinction seems important.

  • viadd

    From the data, life is only fatal 94% of the time.

    The null hypothesis of immortality is NOT rejected at the P<0.05 level and death is statistically insignificant.

    I'm gonna live forever!!!

    Thank you Ronald Fisher.

    • Cranthom Roberts

      The many worlds theory says we will all live forever.
      The versions of us that die don’t make any timeline, but the ever increasingly unlikely versions of us that do survive, will always do so in some timeline.
      Only those versions will be alive, but they will live forever too.

      • David M. Brown

        Any “theory” or hypothesis with zero evidence has no relevance to our understanding of the world and provides no basis for any investigation of the world.

        • Nicholas Reynolds

          The theory of many worlds or multi-dimensional realism provides an interesting prospect for many, and hope as well. If a theory intrigues or provides a benefit other than its own aspired result, knowledge is bound to come of it, and therefore has much relevance. Until it can be disproved, the scientific community at large and I will stay open to this theory.

  • tob

    Thanks, I’ve been looking for that number. 7 yrs ago I guessed ’100 bil’. Women hated when I guessed their age, now I guess 5 yrs short. Works excellent.

  • bob

    The fossil record does not agree. So where are all the required fossils?

    • http://blogs.discovermagazine.com C Giroux

      Living things today are where to find the “required fossils.” The material has mostly been recycled. The next article is sure to be interesting, and even more controversial than this.

  • Carl_s_Jones

    Interesting. I once read an article that claimed everyone alive had atoms from Nepoleon in them. Going on the 108 billion, we all must have a lot of our ancestors in us. Even though there are 7.1 billion alive to day, there are over 10 dead for every living person.

  • http://blogs.discovermagazine.com C Giroux

    73% of all statistics are made up on the spot. ;)

    • Bobareeno

      100% of made up statistics are quoted by “them” and “they”.

      • fungus_Amongus

        0% of statistics change 100% of peoples opinions.

        • Bobareeno

          Yes..we LOVE statistics when they favor our biases, but grit our teeth and shake our fists when they go against them!

  • jjdickson

    I thought the perceived wisdom was that there are more people alive today than have ever died, not lived?

    • Matthew Slyfield

      How many immortals are among us?

      Long term, # births = # deaths.

    • Foo Bar

      Umm… unless there are billions of methuselahs secretly hiding somewhere, the counts of people who ever lived vs who ever died differ by a very small fraction.

  • Gary Huddleston

    The way I have heard the statistic in general states: the are more humans alive today than at any other one point in history.
    This was to quantify population explosion in just the last 100 years of the industrial and now technological revolutions.

  • bobgeezer

    100+ Billion?
    You are kidding, no?
    You do know the difference between Billion and Million, ,no?
    (Apparently not!)

  • Virtuous2012

    You used the Christian time terminology BC (Before Christ) and AD (Anno Domini = Year of our Lord) [whose "lord"].

    The world is full of people who are not Christian, as is the U.S.

    So I’m suggesting that you respect those who belong to different belief systems (religions), or none, and use the neutral terms CE (Common Era) and BCE (Before the Common Era).

    These terms have long ago migrated from the academy to popular writing, so let’s all be on the same page.

  • Bobby Leo

    There was a show on the history chan …group of doctors trying to see if we can live forever…everytime the drug that did help cells to live longer… it eventually caused cancer…so if you try to live forever the only cells that do that are cancer…your doomed to your 70 + years…then kiss your ass goodbye…

  • Matt Sowersbry

    It’s a weird and compelling question. Being talentless, I like to set myself a more impossible task.

    I’m trying to find out how many ‘selves’ have existed since the beginning of life; not just humans, but mammals, dinosaurs, insects, plants and micro-organisms – everything and anything in the history of life on our planet that we as humans can classify as a ‘living self’.
    I’m not very good at math though so I always end up with philosophy.

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Whether a subtle new pattern shows up in an experiment on the Higgs boson, an epidemiological report about a suspected cancer cluster, or a double-blind trial purporting to demonstrate ESP, it can be maddeningly difficult to distinguish between what we see and what we think we see. "Fire in the Mind" takes a look at the big questions behind today’s science news.

About George Johnson

George Johnson writes about science for the New York Times, National Geographic Magazine, Slate, and other publications. His nine books include The Cancer Chronicles: Unlocking Medicine's Deepest Mystery (August 2013), The Ten Most Beautiful Experiments, A Shortcut Through Time, and Fire in the Mind. He is a winner of the AAAS Science Journalism Award and has twice been a finalist for the Royal Society science book prize. Co-founder and director of the Santa Fe Science Writing Workshop, he can be found on the Web at talaya.net. Twitter @byGeorgeJohnson.

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