Back in the 1970s, an unknown writer said that most of the people who had ever lived were alive then [1]. The idea persists, even though it’s not true.
From what I can find, estimates of the number of people ever born range from 50 to 120 billion, with 6 billion now living.
The number intrigues me on two fronts. First, if people are reincarnated, everyone now alive might have had somewhere between 9 and 20 past lives. That’s a useful number to throw out when gong the rounds with believers.
Second, and more interesting for me, this is a fundamental concept when trying to understand “pedigree collapse” — go back far enough and each of us has more theoretical ancestors than there were people living at the time. Therefore, we must, each of us, descend many thousands and millions of times from the same relatively small number of people. We are each our own cousin many times over.
I was pleased to find an article by Carl Haub at the Population Reference Bureau, How Many People Have Ever Lived on Earth? He thinks the number must be about 106 billion, with 6.2 billion living in 2002.
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1. Some reports say it was Annie Dillard. Some reports say the number was 50%, some say it was 75%.