Demographers, people who study population, have estimated that since 50,000 B.C., a total of 105 billion people have lived on Earth.
That means about 5.5 percent of everyone who has ever lived is alive today.
It was a popular belief in the 1970s that 75% of all the people who had ever lived were alive in the 1970s, which put the total number of people who ever lived as of the 1970s as less than the number of people alive today.
This theory was eventually disproved and debunked.
The number of humans who have ever lived in the world is difficult to estimate because solid statistical data only exists for the last two or three centuries, and the specific characteristics that define a human is still up for debate.
Many events in history make it even more difficult to make an estimate, for example:
The Black Death pandemic in the 14th century may have reduced the world’s population from an estimated 450 million to between 350 and 375 million in 1400, and it took about 200 years for Europe’s population to regain its 1340 population level.