Basically I hear this number being thrown around alot that throughout human history approximately 110 Billion individuals have lived. And I was, in all honesty, too lazy to do a proper background check on it so it may just be a piece of misinformation that spread, similar to the "~50% of all humans ever died of Malaria" nonsense. So if that’s the case feel free to enlighten me :) However if’s infact true, I just wonder how the math works out? I know that the Black Plague killed like a third of all humanity with "just" 25 million deaths. That was around 1350 so the population back then is rather negligible in the bigger picture of 110B and since I don’t think before there had been any really significant decreases in human population (in absolute numbers) all the generations having lived before are rather negligible as well. As far as I know human popoluation only ever began rapidly increasing in the 20th century. Considering that my personal, unscientific estimates would’ve put the number at maybe 15-20 Billion instead of 110. so, incase I‘m wrong, can you explain to me why? What did I not take into account
For a crude back-of-the-envelope estimate, we can assume that the average world population for the last 2,000 years has been about 500 million. For most of this time, life expectancy has been about 30 years. Therefore, about 0.52000/30 = 33 billion. This doesn't adequately take into account the very high populations of recent times. Therefore, we can add to that, to account for the last century, an average population of 3 billion, and a life expectancy of 50, adding 5100/50 = 10 billion for a 2000 year total of 43 billion.
Of course, we can do better than such a crude estimate - our estimates of world population for the last 2,000 years are accurate enough. From better estimate of world population and its growth than my averages above: about 60 billion. See https://www.prb.org/articles/how-many-people-have-ever-lived-on-earth/ for this estimate.
Going back further in time, our estimates of world population become less accurate, but adding earlier populations to the total is going to increase it to even more than 60 billion. Going back from AD1 to 8,000BC adds another 45 billion people, and takes us to the dawn of civilisation, when the world population was much smaller than today's. Going earlier than that only adds about another 10 billion. Due to the very small populations in that time, this estimate of about 10 million isn't very sensitive to when we start counting (i.e., when people become "people", or if we prefer, when "people" become people).
Therefore, we reach a total of about 115 billion people who have ever lived.
This past question about whether the living outnumber the dead:
might be of interest.
Black Plague killed like a third of all humanity with "just" 25 million deaths.
This is the usual estimate for the minimum number of deaths in Europe during that particular pandemic. Europe, with about 75 million people, only had about 17% of the world's total population. If one was to (incorrectly) assume that this 25 million deaths was for the whole world, you'd get an estimate of the number of people who had ever lived that's only 17% of the real figure. Adjusting your 15-20 billion for this 17% gives a revised estimate of 88-118 billion, agreeing with our best current estimates.