Friday, November 13, 2020

How Many Humans Have Ever Lived?

I can't know how many humans have ever lived, but I can make some reasonable estimates. Humans were around for a very long time before writing was invented, so unless prior generations kept journals and diaries that somehow survived to the present day then we will never really know exactly how many humans there were in total throughout history. We are not even sure how many people lived during the Stone Age period which lasted from roughly 3 million years ago until about 12-30000 years ago when organised agriculture first began to be developed (which of course depended on previous inventions like stone tools). That being said it is likely to be in the low millions as this figure includes all human species existing at that time including Homo erectus and Homo habilis who had already evolved into modern humans by 1.8 million years ago.

The first written records are in Mesopotamia and date from around 3200 BC. According to the most recent estimates there is a 95% probability that between 1,000 and 10,000 million people lived before this time.

There are also the estimates of how many people have been born in total, which I will now explain.

If you look at the estimated number of births since 1900 (which is about 2.5 billion people) and go back a hundred years from that point, to 1900 minus 100 which gives you an estimate of 25 million people born around that time. This is because it typically takes about 20-30 years for a person to be born after their parents have had them as children tend to start having families when they are in their late teens or early twenties.

So, there is a 95% probability that between 1,000 and 10,000 million people have ever lived. The number of births since 1900 is about 2.5 billion multiplied by 25 million which gives an estimate of 62.5 billion births occurring since the year 1900 alone.


I find myself thinking about the number of humans that have ever lived. I am not sure how many there are right now, but it is probably at least 7 billion, and perhaps as much as around 10 billion or more.

As I think about it, there are many more humans who have ever lived than the current number of humans alive. It is like asking how many leaves there have been on a tree, or how many blades of grass in a field.

There have been a lot of humans in the past, many more than are alive right now. I wonder what would be an estimate that is roughly accurate?

Humans live longer than leaves on a tree or blades of grass in a field, but humans die at different times. It is likely that not every human has died yet.

Also, humans are constantly being born. I wonder if the human race is increasing or decreasing in size?

When I think about it, the human race is probably increasing in size. There are a lot of humans now. I bet that there have been even more humans in the past than right now.


If you're asking how many humans have ever been born, that's an impossible question to answer. Births and deaths are events on the individual level, but they don't really mean much in a world where people live in families of varying sizes. You could ask about the number of people who have lived at some time during history, or even just this century. Or you could ask about all the humans who will be alive until 2050. It depends on what you want to know.

Now, if you're asking how many humans have ever existed, that's a much easier question to answer. At any given time in history there were roughly 100 million people alive on Earth. Of course, the population has been growing over time.

So, if you're asking how many humans have ever existed, the answer is roughly 100 million.

If you're asking how many humans have ever lived, that's a much harder question to answer. If we're talking about the number of people who had a mother and father (and didn't die before becoming an adult), then it was roughly 100 billion.

But what about people who didn't have a mother and father? What about clones, or babies made from test tube embryos? It could be 100 billion, or it could be as much as 1012. Hard to say for sure.

Also, there's the question of what you mean by 'ever lived'. If we're talking about all the humans who were ever born before today, and assuming that they will die at some point in the future (as opposed to going off into space or something), then you could say it's roughly 1012. But if we're only counting people who have actually been alive for a substantial amount of time, then it might be as much as 1016.


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