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View Full Version : How many humans were born in the last 50,000 years?


Humes fork
17th April 2013, 12:42 PM
In this debate (http://www.skeptic.com/reading_room/the-great-afterlife-debate/), Michael Shermer claims:

It has been estimated that in the last 50,000 years about 106 billion humans were born.

This looks like waaaay too much to me. Given that there was more than a billion humans alive just a few centuries ago, and that before that there weren't that many humans, certainly not before the spread of agriculture, the figure should be lower. Or am I wrong? Anyone knows?

Professor Yaffle
17th April 2013, 12:47 PM
In this debate (http://www.skeptic.com/reading_room/the-great-afterlife-debate/), Michael Shermer claims:



This looks like waaaay too much to me. Given that there was more than a billion humans alive just a few centuries ago, and that before that there weren't that many humans, certainly not before the spread of agriculture, the figure should be lower. Or am I wrong? Anyone knows?

http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx

Dinwar
17th April 2013, 01:44 PM
...and that before that there weren't that many humans, certainly not before the spread of agriculture, the figure should be lower. My initial thought is that you're underestimating the number of children born in the past. Infant mortality rates reached as high as 50% in some cases--meaning that the number of births per year in a stable population was double the number of deaths (on average). So until fairly recently as many people died as children as lived to adulthood in some areas. Certainly 1 in 4 mortality rates weren't uncommon.

Mojo
17th April 2013, 02:02 PM
Most of them, I would have thought.

Dinwar
17th April 2013, 02:04 PM
Minor correction: In a stable population, the birth rates roughly equal the death rates (and do equal them on average). Birth rates should be twice ADULT death rates in a population that's both stable and has an infant mortality of 50%. Obviously all the children who die should be included in the death rates.

Loss Leader
17th April 2013, 02:11 PM
The important thing is that you are the only one of you there is, and that makes you special.

bobwtfomg
18th April 2013, 05:14 AM
I think this may be where he got his estmate, with description of how estimate arrived at

http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx

ETA or guesstimate

Dessi
18th April 2013, 08:29 AM
http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx
Oh wow!

Percent of those ever born who are living in 2011: 6.5

. . .

Life expectancy at birth probably averaged only about 10 years for most of human history. Estimates of average life expectancy in Iron Age France have been put at only 10 or 12 years.

Dinwar
18th April 2013, 08:35 AM
Life expectancy at birth probably averaged only about 10 years for most of human history. Estimates of average life expectancy in Iron Age France have been put at only 10 or 12 years. These numbers always annoy me. Problem is, there weren't a bunch of 10 to 15 year olds running around in the past with no adults to control them. High infant mortality skews the data pretty far to the young side; that said, if you made it to your 10th birthday you were highly likely to make it to your 40th or even 50th or 60th birthday (not as likely as today, what with the spearing mammoths and all, but still, you had a pretty good shot).

If you want to get a better sense of when people died you'd have to separate infant mortality (say, deaths before the age of 5 or so) from the mortality of the rest of the population.

JoeTheJuggler
18th April 2013, 09:25 AM
My initial thought is that you're underestimating the number of children born in the past. Infant mortality rates reached as high as 50% in some cases--meaning that the number of births per year in a stable population was double the number of deaths (on average). So until fairly recently as many people died as children as lived to adulthood in some areas. Certainly 1 in 4 mortality rates weren't uncommon.

Also 50,000 years is a long time. Even though world population at any given moment wasn't very high until relatively recently, there were an awful lot of generations over 50,000 years.

Dinwar
18th April 2013, 09:35 AM
Also 50,000 years is a long time. Even though world population at any given moment wasn't very high until relatively recently, there were an awful lot of generations over 50,000 years.

Assuming a 20-year span per generation (not lifespan, but after 20 years your kids are now adults), it's 2,500 generations. To put that in perspective, Jesus was allegedly born 101 generations ago, and Ur was a cultural centerr 250 generations ago. So roughly ten times the length of time from the first major cities to today.

JoeTheJuggler
18th April 2013, 09:40 AM
Assuming a 20-year span per generation (not lifespan, but after 20 years your kids are now adults), it's 2,500 generations. To put that in perspective, Jesus was allegedly born 101 generations ago, and Ur was a cultural centerr 250 generations ago. So roughly ten times the length of time from the first major cities to today.

So even though we're closing in on a living population of 7 billion right now, a great majority of the people born over the past 50,000 years lived during prehistoric times (prior to something like 5500 years ago).

ETA: So, yeah, I have no problem with an estimate of about 106 billion.

Dinwar
18th April 2013, 09:54 AM
So even though we're closing in on a living population of 7 billion right now, a great majority of the people born over the past 50,000 years lived during prehistoric times (prior to something like 5500 years ago).

If we assume a relatively stable population of 500 million until, oh, let's call it 20 generations ago (400 years, or roughly the end of the Middle Ages), we get a total number of humans reaching adulthood of 1.23 trillion (I used a stable population because each generation would have the same number of people reaching adulthood, on average; obvoiusly this is merely a simplifying assumption). A stable population of 100 million gives us roughly 250 billion humans that reached adulthood before Rennaissance.

Bear in mind, those are the ones that lived. Double that to account for infant mortality. And these aren't wildly unrealistic numbers; 100 million is a hair under 1/3 the population of the United States of America. Spread over the entire globe.

I'm sure I'm screwing something up; this is a back-of-the-envelope calculation, after all, and I'm more ecology than population dynamics. But it shows that if anything, the author in the OP is underestimating the number of humans born.

aleCcowaN
18th April 2013, 11:23 AM
60 to 100 milliards (billions, for those who use them as milliard) is a good estimation, taking into account an average of 6.5 to 7 births per adult woman who lived beyond an age of 30, and that human populations have being extremely scarce, even during the twentieth century, wherever farming, cattle and all the needed technology were absent. The Earth has being estimated to be capable to sustain some 2 to 10 million humans of Neolithic culture.

You can count the number of Egyptians in the Nile, from the First Cataract to the Delta, to have been constant of some seven millions for any practical calculations from the times of the creation of lake Qarun to 1900, that is, during roughly 4,000 years. With natality rates of 4 to 4.5% a year, which was normal -I suppose it was just 3% in Egypt because of self-regulation, the most important is the age for women to marry, as regulating that from 13 to 21 has been used historically as a mean of population control-. But anyway, with a 4% it gives a bit above a milliard of human beings born in the historical Egypt. Remember that Egyptians were some 7 to 15% of all mankind three to five millennia ago, some 0.5-0.8% during the nineteenth century and some 1.2% now.

I bet the figure is closer to 60 milliards.

Loss Leader
18th April 2013, 01:43 PM
So even though we're closing in on a living population of 7 billion right now, a great majority of the people born over the past 50,000 years lived during prehistoric times (prior to something like 5500 years ago).


According to the article sourced above, Prehistoric births are not the great majority. Births before 1 A.D. account for about 45% of all people. Without a doubt, we've seen a population explosion; it's just not as explosive as is popularly believed.

Lorentz
21st April 2013, 08:22 AM
The important thing is that you are the only one of you there is, and that makes you special.

Sadly no.
All of you are unique.
I'm not.