Do all people on earth have the same ancestor?

The scientific community has generally proved that human beings have a common ancestor, and people on the earth now all bleed the same blood. But how far away is this different ancestor from us? Scientists recently gave the answer through mathematical calculations.

American scientists said in the recently published "Nature" magazine that although there are currently up to 6.5 billion people living on the earth, and people around the world are very different in skin color, language and religion, the number of people on the earth is now 6.5 billion people all have the same ancestor, and this person is not far away from us, perhaps living 5,000 to 7,000 years ago.

This means that as long as we go back to the Golden Age of ancient Greece or the Three Sovereigns and Five Emperors era of China, we can find a person who is related by blood to everyone in the world today.

The computer calculated "the same ancestor"

American scientist Steve Olson said: "Through mathematical methods, we can be sure that this person exists." Olson has been studying the development of the human family tree. In 2002, he published the popular science book "Exploring Human History", which elaborated on the footprints of human development in Africa since 100,000 years ago.

Recently, there has been a trend of "searching for one's roots" in Western countries. People consult family trees, collect antiques and inspect historical relics, hoping to find clues to understand where they come from.

With the help of statisticians, computer scientists and a supercomputer, Olson has built an extremely complex model of the family tree. This family tree shows that if you go back 2000 to 5000 years ago, you may encounter such a person, and everyone living today can be regarded as a descendant of this person.

If we use Olson's model and continue to extrapolate to about 5,000 to 7,000 years ago, then the ancestors of everyone today at that time will completely overlap. In other words, everyone who lived at that time was either an ancestor of all 6.5 billion people today, or his lineage has been discontinued and there are no descendants that continue to this day.

Yordon Hein, a statistician at the University of Oxford, wrote in a commentary that the research results are "very surprising. If you go back to the earth in 3000 BC and walk into any In a village, the first person you meet may be your ancestor."

How did you come to the conclusion?

"This is the result of mathematical derivation," Olson said. Everyone has two parents, four grandparents, and eight great-grandparents. If calculated from generation to generation, the subsequent numbers will be 16, 32, 64, 128 and so on. You don’t have to go back a few centuries and you already have thousands of ancestors. Push forward to the 15th century and you already have 1 million ancestors. Push forward to the 13th century and you have 1 billion ancestors. And around the 9th century, 40 generations ago, you had 1 trillion ancestors.

However, there could not have been so many people in the world in the 9th century AD.

So you need to imagine it again. For example, there is a man who lived 1,200 years ago. His daughter is your mother's 36th great-grandmother, and his son is your father's 36th great-grandfather. This man will therefore appear in two of your family trees. On the branches, one is on the mother's branch and one is on the father's branch. The fact is that people who lived 1,200 years ago appear not just twice on our family trees, but thousands of times, because there were only 200 million people at that time. Divide 1 trillion by 200 million and you get that each person will appear 5,000 times in all our family trees.

But things can never be explained simply by averages. Many people who lived in AD 800 had no descendants, and these discontinued people would not appear on our family trees. Therefore, others appear more than 5,000 times. If this projection continues, fewer and fewer people will appear in the genealogical tree of 6.5 billion people. Mathematically, at some point it is inevitable that an ancestor will appear in everyone's family tree at least once. If we continue to extrapolate, there will always be a point in time when everyone on the earth is one of our ancestors, unless that person has no descendants and the branch ends abruptly when it reaches him.

Immigration is the key to the unity of mankind

Seven years ago, one of Olson’s colleagues, Joseph, a statistician from Yale University, began to think about how to calculate the emergence of The same ancestors of 6.5 billion people in the world today, and a simple mathematical model was established.

A few years later, Joseph and Olson began to take into account influences such as geography. The human family tree they depict also tends to be more scientific. With the help of computer scientists, they decided to use supercomputers to reconstruct a complex model to restore the historical process of human birth, migration, reproduction and death.

They set the time when the first common ancestor of modern humans appeared between 7,000 and 20,000 years ago, and entered different immigration rates. The results showed that when the immigration rate was extremely low, modern humans The earliest ancestor of the Chinese people appeared around 5000 BC.

People often feel that in pre-industrial societies, people had few connections with the outside world. But history is not like this. Alexander the Great conquered a large area from Greece to northern India, and his descendants were scattered everywhere.

After being defeated by the Han Dynasty in Asia, the Xiongnu moved westward, and the Mongols swept across Eurasia. These wars led to the Great Migration.

Even if it is an inconspicuous immigrant in peacetime, even if it is a sailor left behind in a foreign country, a young man going to other places to pan for gold, or a woman following a foreign businessman, as long as they have children, they will be together. Weaving a web of kinship around the world, connecting different groups of people.

Olson and his colleagues believe that immigration is the key to bringing humanity together. If a new resident moves to a village, once the new resident marries the locals, a huge number of his or her ancestors will be connected with the ancestors of the original residents of the village.

"When a lineage spreads, it has the ability to go absolutely anywhere," Olson said.

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