How many people have lived on Earth?

This question is important to some Christian and pseudo Christian groups who believe that God will resurrect most of those who have died. Some groups believe that all the resurrected people will actually live on Earth, and others believe that the dead will return to Earth only briefly for judgement before being assigned to Heaven or Hell.

Whether there is going to be enough room for everyone, already troubled some people over a century ago. The following, for example, appeared in a Californian paper probably in the 1870s:
 
 

Estimates of the total number of people to have lived vary:

One extreme is Radford (1990) who wrote:

The opposite extreme might be represented by Rumble & Carty. (c.l948)  These two Catholic priests were criticising the Russellite belief that almost all the dead will live again on Earth. They argued:
 

Deevey (1960) estimated all humans to have totalled 110 billion. These include 36 billion paleolithic (about 1 million years ago to 25,000 years ago) hunters and gatherers; another 30 billion until the invention of agriculture; and the rest until 1960.

In his book GENETICS OF THE EVOLTIONARY PROCESS (1970) geneticist Theodore Dobzhansky gave total human numbers as:
600,000 B.C. to 6000 B.C.   12,000 million
6000 B.C. to 1650 A.D.       42,000 million
1650 A.D. to 1962 A.D.      23,000 million

The GUINNESS BOOK OF RECORDS for 1983 said:

The 1993 GUINNESS BOOK OF RECORDS said:
 

Whatever calculation we make will obviously be greatly influenced by how old we presume humankind to be and by whether we try to include every baby who died at birth or only persons who survived infancy.
 

One major sect teaches:
 

When this seemingly objective statement says "many students of the subject" it probably refers to sect members. This conclusion follows from the fact that the publications of the sect, but very few other sources, have estimates of total human numbers even as low as 20 billion. For example:
 
 

Let’s try to calculate approximately the number of people to have lived on this planet since 2,000 BC. I’ll start with the 20th century.

In the 1980s about 180 million were born each year.
In the 1970s about 150 million were born every year.
In the 1960s 120 million each year.
1950s —100 million yearly.
1940s — 90 million    "
1930s — 80 million    "
1920s — 70 million    "

And 1900 to 1920 about 50 million were born each year. These figures are all approximate but are accurate enough for our purpose.

Of course the world population did not increase by these amounts, because people were also dying.

By adding up these figures for each decade of the 20^th century the total for the 20^th century until 1990 is approximately 9,000 million.
 
 

I’m going to simplify the calculation for centuries prior to the 20^th century. I’ll do this by estimating the mid-century world population and multiplying by the number of generations in that century. In the 19^th century we can assume that the average life span was about 33 years. This amounts to 3 generations for the19th century. The mid-19^th-century world population was about 1,150 million. The estimate for the entire century therefore comes to 1,150 million x 3 = 3,450 million.

Assuming 4 generations in the18th century — that is average life spans of 25 years — and a mid century world population of 750 million we get a total for the 18^th century of 750 million x 4 = 3,000 million.

In the 17^th century medical technology was primitive and human life spans averaged perhaps 20 years. This was mainly due to high infant mortality. Therefore I’ll assume 5 "generations" per century and a mid century world population of 550 million. The total number of humans for the 17^th century is therefore 550 x 5 = 2,750 million.
 
 

I’m going to simplify things further now. The world population when Jesus lived was about 200 million. In 1000 A.D. humans numbered about 270 million and in 1600 A.D. about 500 million.

I’ll assume an average of 250 million for the whole 16-century period.

It’s been estimated that in the Roman Empire the average life was only 12-15 years long. Again this was because of the high mortality in childhood. This would amount to 7 or 8 "generations" per century. I’ll use the number 7.

The total humans for the first 16 centuries after the birth of Christ comes to 250 million x 7 x 16 = 28,000,000 million.
 
 

The book ATLAS OF WORLD POPULATION (1978) gives world populations of::
 

The total for this 2,000 year period comes to 80 million x 6 x 20 = 9,600 million.
 
 

I won’t go any further back than 2,000 B.C. The following table summarises the figures I’ve provided:

TIME PERIOD       TOTAL HUMANS BORN

2000 B.C. to 1 B.C.              9,600 million
1 A.D. to 1600 A.D.           28,000     "
1601 to 1700      "               2,750     "
1701 to 1800      "               3,000     "
1801 to 1900      "               3,450     "
1901 to 1990      "               9,000     "

The total number of humans to have lived since 2000 B.C. comes to 56 billion. This would include all those who died in infancy. This number is not exact because the subtotals it is based on included quite a few approximations and assumptions.
 
 

The sectarian figure of 20 billion is absurdly small. Notice that this sectarian estimate remained the same from 1924 to 1988. Apparently the sect is implying that nobody had any babies for 64 years — 1924 to 1988. In fact about 5,500 million babies were born during that period.

My total of 56 billion since 2000 B.C. could easily fit into a comparatively small area. They could all fit into the state of Texas and enjoy 123 square metres of space each. Or they could all fit into Australia’s smallest state with about 12 square metres of space per person.

Religions that believe in the resurrection of almost everyone back to this Earth are therefore not yet refuted if we base our arguments solely on population estimates and land areas.

However, many biologists and other experts believe that the present world population of 5,400 million is already too great for planet Earth to sustain indefinitely. This belief is based on statistics for deforestation, land desertification, soil erosion, environmental pollution, and the rates of exploitation of mineral resources.

Others, however, argue differently. For example:
 

Current discoveries in environmentally safe methods of pest-control and in genetic engineering of plants to make them disease-resistant and/or able to grow in marginal areas might make Deevey’s hypothetical 20-fold increase even more optimistic.

Nevertheless, religions that teach that everyone, or almost everyone, will be resurrected and then live permanently on planet Earth are on the borderline of refutation. This follows from comparing estimates of how many people planet Earth can sustain with calculations of how many people have been born.