How Many People Have Lived?

How Many People Have Lived? My wife was speaking about her Uncle a Doctor who lives in Southeast United States. He used to like to say half jokingly that "He had a 50% chance of living forever, because half the people who have ever lived are alive now."

Knowing that knowledge and estimates of how many humans have lived have changed a lot since microcomputers were invented and put into use in the 1980s I decided to go online and try to get a good estimate of how many humans have lived in total on earth so far.

Here is one source:

http://www.straightdope.com/classics/a2_085.html

begin quote:
"Estimates of the total roster of humankind rely heavily on guesswork, a state of affairs not entirely unknown to us here at the Straight Dope, and accordingly the numbers vary widely. Demographers have come up with estimates ranging between 69 billion and 110 billion humans. That gives us a spread of 41 billion, a pretty formidable margin of error.

Still, these numbers should put to rest the line of baloney put out years ago by the zero-population-growth alarmists, namely that the majority of humans who have ever lived is alive today. That's flat wrong no matter what your assumptions.

For example, creationists, who believe it all started with Adam and Eve around 6,000 years ago and that a flood in 2700 B.C. killed off everybody except Noah and his relatives, say the world population to date is 51 billion. Some may feel the creationist figure is entirely too close to the "real" figures for comfort. Maybe, you're thinking, we should abandon the pretense of science and address future demographic inquiries directly to God.

Well, I told you this involved a lot of guesswork. The main problem is that we have only a vague idea of the birth rate and average lifespan in ages past. Another complication, among scientists at least, is that it's impossible to say precisely when our primate ancestors became human. Many researchers have arbitrarily settled on one million years ago, even though our own subset of the genus Homo, H. sapiens sapiens, didn't emerge until around 40,000 years ago. If the paleolithic crowd (1 million years to 25,000 years ago) strikes you as too crude for admission to the communion of saints, subtract 36 billion or so from the figures above." endquote.

You might find other or better sources than I but I think an estimate of 51 billion (creationist estimate) and 110 billion might be the best guess for now. However, this could all change if, for example, evidence of space faring cultures like atlantis, Lemuria and Mu become available which would greatly predate all the other estimates and tie us to other worlds that we might be related to as humans.