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In which John gets curious about when the median human being lived, and along the way learns something surprising about the human story.
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Most of the population data in this video comes from the Population Reference Bureau, especially this excellent article: https://www.prb.org/articles/how-many-people-have-ever-lived-on-earth/ That's also where I learned that life expectancy in Iron Age France was 10-12.

The graphs and much of the information on life expectancy at various ages comes from Our World in Data, which is amazing. Here's their article on life expectancy over time and across communities: https://ourworldindata.org/life-expectancy

Their article on child survival and mortality statistics: https://ourworldindata.org/child-mortality

And their article examining mortality in the distant past: https://ourworldindata.org/child-mortality-in-the-past

I mostly relied on PRB info for global populations at various times, but this research summary from census.gov was also helpful: https://www.census.gov/data/tables/time-series/demo/international-programs/historical-est-worldpop.html

Here's my math for why most people have never been 20: Of the first 100 billion people who lived, at least half (the most prominent researchers in the field consider that estimate on the low end) of people died before 15. Counting the 3% or so who died between 15 and 20, that means that probably at least 53 billion of the first 100 billion people died before the age of 20. Of the most recent 10 billion who died (most of whom were born between 1800 and 1950), over 30% died before the age of 20. That takes us to a conservative estimate of 56 billion of the 110 billion people who've died so far. (2.6 billion people are CURRENTLY under the age of 20, so even if you look at the entire population of humans, it is probable that most people have never been 20--hence the title.)


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Good morning Hank it’s Tuesday I recently got to wondering when  the median human being was born and in researching that question  I learned something interesting and surprising.

But let’s start with that hypothetical median person. So obviously we don’t have like super firm statistics on how many people  have ever lived, or when they died, or any of that  but through a mix of population modeling and genetic research our best current guess  is that about 117 billion “modern humans,” as we are known, have ever lived.

So I was trying to figure out when did the person in the middle of  that 117 billion live The, uh, I’m bad at math,  58.5 billionth person? Now I probably would’ve guessed, like, 1900? 1750?  Something like that. Because there are way more  humans than there used to be.

I mean fewer humans  lived on Earth 6,000 years ago than currently live in Mexico City.  7% of the people who’ve ever lived are currently alive,  so the median human can’t be that far removed from us, right? Except, no. That’s wrong.

At least according to  the population reference bureau,  the 58.5 billionth person Probably was born sometime  between 10 and 100 CE, so about 2,000 years ago. That is to say,  of all the people who’ve been born, most were born and died before  the Roman Emperor Nero or the Malian Emperor Mansa Musa. They lived and died before the idea of minutes   and seconds, before guns,  before the emergence of Christianity and Islam as global forces,  And before potatoes or pineapples were in Afroeurasia.

This median person almost certainly could not read or write.  They probably did not believe in one God. And if they survived to adulthood–  Which they probably didn’t– they probably were farmers  And probably had many children, some of whom almost definitely died. Now, when I was young, I was taught that in the old days–  the old days were never quite defined– life expectancy was 30.  Which I took this to mean that the average adult  died at 30, and that's not the case.

At least in Sweden, where we have relatively  good data, if you lived to be 10 in the early 1800s,  Your life expectancy was around 46. And in 1841 England, if you lived to be 20,  your life expectancy was around 60. It’s just that overall life expectancy  was brought down to under 30 because child mortality was so high.

These days, one sometimes hears that the only reason life expectancy  has gone up is because child mortality has gone down, and that's also not the case. In 1865, Italy, even if you survived childbirth, your life expectancy was  under 50; today it’s well over 70. Like, it’s worth remembering, that two hundred years ago,  about a quarter of all humans died of tuberculosis, and most of them  died under 40.

Also, girls who survived childhood had a very high chance of dying in childbirth.  In some communities, over 10%. That said, child mortality was very, very high.  Like, in 1800, about 30% of people born in France died before  the age of 10, but it used to be even higher. Like in Iron Age France,  life expectancy wasn’t 28 or 30– it was 10 or 12.

Our best current guess is that when the median person was born  2,000 years ago,  half of all people died before the age of 10. Child mortality was so high that birth rates were five   times greater than they are now,  but the overall population of humans barely increased. And this is why the median human was born 2,000 years ago–  Not because there were so many people back then, but because there were so many  people who died young.

Early death wasn't common the way that dying, at say 65 is now,  it was the norm, the way dying at 80 is now. I mean, even last year,  more people died before the age of 5 than died between 65 and 69. So it’s likely that even today, Most of the 110 billion humans who’ve died,  never saw the age of 20.

We can’t do anything about historical rates of premature death, of course,  but we can choose to live in a world where fewer people die early.  I know we can make that choice because we have made it before.  That’s what we’re trying to do at PIH.org/hankandjohn  and through silly things like Pizzamas, which,  by the way, raised over $130,000 toward better maternal and child  health in impoverished communities. Thank you. Hank, I'll see you on Friday.