How can you answer the question, “How many people have lived on this planet?” If you write this in Google or Chatbot AI, you will get an answer very quickly – usually 117 billion. This number, at least in my opinion, looks very small. After all, the world’s population currently It is estimated at 8.2 billion people. This means that we make up about 7 percent of all people who were born at all.
The number of 117 billion people includes everyone who saw Nour today-including those who died young. The average life expectancy increased in the world over time. As a result, there are other strange population questions that must be taken into account. For example, the 2014 article in the Economist It was mentioned that half of all people between the ages of 65 years or older are alive today. Could this be really true? How can you even calculate something like this?
Demographic asked such questions for decades. One of the biggest challenges they face is the data: you need to know the number of people who lived at different times, as well as average life or birth rate. These numbers are available today (although records are not always reliable) but less for centuries. Statistical analyzes and census were not carried out routinely everywhere and across all societies. Therefore, demographic should rely heavily on estimates.
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Then there are some basic questions that must be taken into account. What exactly is “human”? Do we mean all members of sex? Homo Those who walked our planet or only Hoomo, the sane particularly? Looking at the challenges, it is surprising that when all the people who lived at all, it is usually presented with only one, 117 billion, instead of a scale with low and high estimate. I claim that this is completely appropriate from a scientific point of view and indications that the result is round. The arrangement of the size may seem reasonable, but the question cannot be answered exactly.
Population growth modeling
To assess the estimation of 117 billion people realistically, you first need data. From the twentieth century to the present time, you can find many population characters, thanks to the regular census conducted in many countries since the 1950s.
When looking back in history, the number of people who live almost can be estimated based on the size of cities and population density. Even previous times, archaeological remains provide evidence.
however, Some sources Place the world’s population in the year 1 C at 170 million people and others at a price of 300 million, or nearly this number. There is also an issue to what extent we should even look. There are estimates in it Demographic returns to 4.5 million years To look at all sex members Homo. Others, however, focus on Hoomo, the sane And see back between 50,000 and 200,000 years.
Over the years, the number of living people has not only changed, but also the rate of population growth in return. The world’s population is very slowly increasing, but it seems that they have grown faster in recent centuries. This is because the birth rate has decreased while the death rate has decreased more – a mix that may be difficult to design.
However, it can be assumed that the growth rate is fixed for small periods of time. Demographic uses this assumption to estimate the number of all living people in a certain period of time. You must divide the period in view of different sections; For example, you can start 50,000 years before our time and end in 2025. The more sub -divisions you do, the more accurate the result.
If we now assume that the birth rate Z And death rate S Fixed within a section of this schedule, then the size of the population N Changes according to the following differential equation:
On the condition Z and S It is supposed to be fixed during a period of time, the size of the population in this area can be designed with a mital function: N((R.)) = N0EKtWhere the teachers your (The rate of pure growth) and N0 (The size of the population is time R. = 0) It is determined by data points.
To determine the number of people who lived at all, you must add the number of all living people at each point in time R.. This can be done by calculating the integration of the specific job respectively R. In the concerned section:
This approach exaggerates the actual answer, though. Think about it this way: If you are reading this article, you are currently alive; I was already already alive 10 years ago, as I contributed in the world at the time. Consequently, the integrated result should be divided into the average life expectancy of people who lived during the period in question. In the end, you can add results for all time periods and-BaThe result should be compatible with the total number of people who lived at all.
Technical Prejudiced With the school project. His students put the same task: They were estimating the number of all the people who lived at all. But these students have not yet known how to calculate the integration of the assignment.
A group of students simply decided to calculate the medium value for specific time periods. For example, if there are about 1.6 billion people in 1900 and 2.5 billion in 1945, students assumed that on average 2.05 billion people lived during these 45 years. Then they struck these medium values in the relevant time period (45 years, in this case) and divided them into the average life expectancy that people had at that time (by taking the average age in 1900 and 1945). This method gave the group an approximate appreciation to the inhabitants of the whole world without the need to resort to complex calculation methods such as integration.
Two ways with amazing similar results
To compare these techniques, you can calculate the population with an example. I chose to use data Which was previously used by the demographic Karl Hop in the article of the Resvenual Reference Office published in 2011. He assumed that humanity originated 50,000 years ago with two people. The average life expectancy was estimated for each time separation.
I added a final data point with the estimated population and the expected age in 2025.
In total, there are 10 points available in this example specifying nine sections. Within these, the proper luxury functions of the growth of the growth concerned can be defined. By dividing it on the average life expectancy in this period, you can get the number of people alive at the time.
This leads to the conclusion that more than 93 billion people have been born. The number is based on 117 billion That appeared in 2022 with updated population data. (Researchers assumed, among other things, that the human race had arisen 200,000 years ago.)
If you apply the simplest calculation method used by Scheja students to data from the table above, the end result is more than 140 billion – more than the result that the other way got. This difference may seem great, but it is actually impressive that it ends with the same arrangement.
What about people between the ages of 65 years and above?
Al -Nahjan provides the assessment of the number of people who were born at all. But what about the statement of the journalist Farid Pears In his book 2010 Next population crashes Of all the people who have reached the age of 65, half of them are alive today? In 2017, a team of demographic led by Miguel Sanchez Romero of the Wittgenstein Center for Demographic Crawl and Global Human Capital Check this statement After it appeared in a 2014 Economist condition. The researchers developed two different demographic models for the investigation: one in which the population growth was fixed and the second in which they looked at excessive population growth.
They also used various data sets to slander them to provide realistic estimates of error. Their conclusion: Farid Pierce was incorrect. “In fact, this number will never be achieved, theoretically (in a stable group), nor experimental according to the current data,” they wrote in their paper.
According to their accounts, the percentage of people who reached the age of 65 or older and the ionic day ranges between 5.5 and 9.5 per cent. This means that even in the most extreme cases, less than 10 percent of all 65 -year -old or older people today. Even if this greatly relieves Pierce’s original statement, I still find the result very amazing. Imagine that there is a kind of lottery that has decided at any point in the history of mankind, you are alive based on your life. If you are 65 years old, you will have a possibility of about one in 10 of survival today – even if you take into account the past 200,000 years.
This article was originally appeared in Spectrum of science It was cloned with permission.