In any case, life was short. Life expectancy at birth probably averaged only about 10 years for most of human history. Average life expectancy in Iron Age France (from 800 B.C.E. to about 100 C.E.) has been estimated at only 10 or 12 years. Under these conditions, the birth rate would have to be about 80 live births per 1,000 people just for the species to survive. To put that in perspective, a high birth rate today is about 35 to 45 live births per 1,000 population, and it is observed in only some sub-Saharan African countries.
These short life expectancies mean that the human population had a hard time increasing. One estimate of the population of the Roman Empire, spanning Spain to Asia Minor, in 14 C.E. is 45 million. Other historians, however, set the figure twice as high, suggesting how imprecise population estimates of early historical periods can be.
By 1650, the world’s population rose to about 500 million—not a large increase from the estimate of 300 million in 1 C.E. The average annual rate of growth was actually lower in this period than the rate suggested for 8000 B.C.E. to 1 C.E. One reason for the unusually slower growth was the Black Death. This dreaded plague was not limited to 14th-century Europe but may have begun in western Asia in about 542 C.E. and spread from there. Experts believe that half the Byzantine Empire was destroyed by plague in the sixth century, a total of 100 million deaths. Such large fluctuations in population size over long periods greatly compound the difficulty of estimating the number of people who have ever lived.
By 1800, however, the world population passed the 1 billion mark and has since continued to grow to its current 8 billion (our most recent estimate as of 2022). This growth is driven in large part by advances in public health, medicine, and nutrition that have lowered death rates, allowing more people to live far into their reproductive years.
Assumptions Help Us Estimate Human Population History
Guesstimating the number of people ever born requires determining population sizes for different points in human prehistory and history and applying assumed birth rates to each period. We start at the very, very beginning—with just two people (a minimalist approach!). Although it is unlikely that humans descended from two people, this approach simplifies our estimation.
One complicating factor is the pattern of population growth. Did it rise to some level and then fluctuate wildly in response to famines and changes in climate? Or did it grow at a constant rate? We cannot know the answers to these questions, although paleontologists have produced a variety of theories. For the purposes of this exercise, we assumed a constant growth rate applied to each period up to modern times. Birth rates were set at 80 per 1,000 population annually through 1 C.E. and at 60 per 1,000 from 2 C.E. to 1750. Rates then declined to below the 20s by the modern period (see Table 1).
This semi-scientific approach yields an estimate of about 117 billion births since the dawn of modern humankind. Clearly, the period 190,000 B.C.E. to 1 C.E. is key to our estimate but, unfortunately, little is known about that era’s population size. If we were to challenge our conclusion at all, it might be that our method underestimates the number of births to some degree. The assumption of constant rather than highly fluctuating population growth in the earlier period may underestimate the average population size at the time.
We Account for a Large Percentage of People Who Have Ever Lived
Given a current global population of about 8 billion, the estimated 117 billion total births means that those alive in 2022 represent nearly 7% of the total number of people who have ever lived (see Table 2). Because we have existed on Earth for approximately 200,000 years, that’s actually a fairly large percentage.
TABLE 2. Snapshot of Population History
| Estimated number of people ever born | 117,020,448,575 |
| World population in mid-2022 | 7,963,000,000 |
| Percentage of those ever born who are living in 2022 | 6.8 |
As new archaeological discoveries are made and analyzed using increasingly innovative methods, our understanding of human population history will likely expand further, allowing us to improve on this ever-intriguing proposition!
Featured Resources
FAQs
Approximately 108 billion humans have lived on earth ever since hom*o sapiens first came into existence, about 52,000 years ago.
How many people have lived on Earth ever? ›
No demographic data exist for more than 99% of the span of human existence. Still, with some assumptions about population size throughout human history, we can get a rough idea of this number: About 117 billion members of our species have ever been born on Earth.
What is the percentage of time humans have lived on Earth? ›
A long time ago… To put it into perspective, the origin of our species, hom*o sapiens, dates back approximately 300 thousand years ago, which also seems a long time ago, but represents only 0.007% of the entire history of the planet (4.5 billion years)!
How many living things have ever lived on Earth? ›
We can (extremely roughly) estimate that, including other arthropods, invertebrates and vertebrates, there have been approximately 4.5 x 10^27 animals ever on Earth.
How many people were alive 10,000 years ago? ›
By 10,000 B.C., the world's population was around 1 million. 2,000 years later there were about 5 million people on Earth—the same number that live in Finland today.
How many humans have already existed? ›
Discoveries now suggest modern hom*o sapiens existed much earlier, around 200,000 B.C.E. This major change in our understanding of human existence spurred new calculations and consultations with experts, resulting in an estimate that about 117 billion members of our species have ever been born on Earth.
When was the first human born? ›
The first humans emerged in Africa around two million years ago, long before the modern humans known as hom*o sapiens appeared on the same continent. There's a lot anthropologists still don't know about how different groups of humans interacted and mated with each other over this long stretch of prehistory.
How many humans can live on Earth at once? ›
Van den Bergh and Rietveld (2004) reviewed 94 “limits to world population”: “When taking all studies into account, the best point estimate is [the median estimate,] 7.7 billion people; the lower and upper bounds, given current technology, are 0.65 billion and 98 billion people, respectively.” “Given current technology, ...
What is the oldest life on earth? ›
The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.
How much longer can life exist on Earth? ›
Four billion years from now, the increase in Earth's surface temperature will cause a runaway greenhouse effect, creating conditions more extreme than present-day Venus and heating Earth's surface enough to melt it. By that point, all life on Earth will be extinct.
Around 600,000 years ago, humanity split in two. One group stayed in Africa, evolving into us.
What was the lowest human population ever? ›
The team estimated that the population bottleneck — which reached an estimated minimum of some 1,280 breeding individuals — occurred roughly 813,000 to 930,000 years ago at around the same time as climate changes that marked the mid-Pleistocene transition, wiping out nearly 99 percent of the human ancestors that ...
Did humans exist 9000 years ago? ›
9000 to c. 8000 BC. The people were hunter-gatherers who hunted the now-extinct Bison antiquus. In Patagonia, the Fell's Tradition prevailed through the millennium at Cueva Fell.
How many humans existed 100,000 years ago? ›
[A horizontal line is drawn on the graph, showing population levels hovering around 1 million from 100,000 BC to 10,000 BC, when it suddenly slopes upward.] [TEXT: With the advent of farming, growth picked up. By AD 1, world population reached approximately 170 million people.]
How many people lived to be 100 years old? ›
USA number of centenarians.
Out of a US population of approximately 336,997,624, in 2021, there were 89,739 centenarians (age 100+) or a prevalence of 0.027%.
What is the lowest number of humans in history? ›
Estimates of the size of these populations are a topic of paleoanthropology. A late human population bottleneck is postulated by some scholars at approximately 70,000 years ago, during the Toba catastrophe, when hom*o sapiens population may have dropped to as low as between 1,000 and 10,000 individuals.
