The reason is the phenomenon of “Y-chromosome bottleneck”. This phenomenon occurred at a time in the Stone Age when genetic diversity abruptly stopped, at least among male genes. After about 2000 years of continuous decline, there is only one man left for every 17 women.
In the past, scholars have suggested that this may have to do with our ancestors’ discovery and settlement of new lands. They call it the “founding effect,” when small groups of individuals are constantly moving to discover new lands.
However, a new study published in the scientific journal Nature uncovers a much more devastating truth. Men at that time killed each other.
The number of men in Europe, Asia, Africa and the Middle East dropped dramatically due to this phenomenon about 5000 to 7000 years ago. The father’s Y chromosome will be passed on to his sons, which is why nearly entire families have been wiped out on a large scale. At one time, the world’s population was estimated at between 5 and 20 million, with more than 9.5 million men killed.
The Stanford team suggested that the reason was “competition between blood groups”. The team created 18 computer simulations that included different scenarios to explain the decline in the number of males, including factors such as Y-chromosome mutations, competition between males and females. ethnicity and mortality.
The results showed that war between patriarchal clans caused many men to die before they could have sex to have children, thereby reducing chromosome diversity. And since the patriarchal clans have the same Y chromosome, if one clan destroys another, it also means that the Y chromosome is unlikely to be passed on to the next generation.
And yet, after those wars, the number of women is often higher than that of men. Marcus Feldman, study author at Stanford University, said: “In the same patriarchal clan, women can come from anywhere. They can come from another clan that has lost the war or be women who have lived in the area before.”
Essentially, the winning clans will exterminate the opponent’s men to ensure continued dominance and eliminate potential competition. They will then capture the surviving women. “If you look at the history of the colonies, you will see that people used to kill all the men and keep the women for themselves.”
Chris Tyler Smith – evolutionary geneticist at the Sanger Institute (UK) – said: “Researchers at Stanford University conducted careful computer simulations before coming to a conclusion. The hypothesis is that, Ancient warfare is a very plausible cause of the Y-chromosome cork, especially during the Neolithic.”
Humans still lived in small farming clans from 5,000 to 7,000 years ago. Then they moved on to larger social groups and built big cities. During this period, the male population gradually recovered. “It’s the conversion of farming that uses stone tools to metal tools,” says Tyler-Smith.
“Our results are supported by archaeological discoveries and anthropological theories,” said the Stanford team.
Evidence of Neolithic wars can be found in fossil skeletons throughout Europe, including England. Many of the skeletons showed signs of being attacked by bows and arrows, maces and stone axes – weapons of the people of the time.
Marta Mirazón Lahr, an anthropologist at the University of Cambridge (UK), said: “The fossils show that these people – who lived by hunting and gathering – were massacred in a deliberate attack. of raiders from other regions.”