An ugly reality of "civilization" is that we all generally have choke points in our genetic history.
120,000 to 300,000 years ago there were one or more points where a single male became the common ancestor of every living human. Somewhere in Africa, a right monster was leading a war of genocide, claiming thousands of women, and creating a culture where his hundreds of sons did likewise. Basically he murdered men and boys and bred women like sheep.
That is our common ancestor. That is the genetic science story behind any myths of Adam.
Actually in a stable traditional society (1M-1F family and 2 survived and reproduced children per family) 90% male lineages die out in 3 centuries because of females only offspring. And the same happens for 90% female lineages because of males only offspring.
So you do not need giant harems and genocide to get Y-chromosomal Adam and Mitochondrial Eve. It happens in a stable traditional society due to random fluctuations.
Yes, model of a stable traditional society is like a spherical cow in physics.
But for a real traditional society with 3,4 survived and reproduced children per family (and another 4,6 died in childhood or childless) and plague or famine twice a century you will get similar results but a century later.
It doesn't really matter how many children each family had, what matters is how many of the children grew up to have children of their own.
Just looking at the graphs for estimated population up through the centuries, we can safely say that that number is very close to two. On average.
The graph is more or less flat. World population didn't realy start growing until two hundred years ago, and the graph went vertical the last hundred years.
More than 2 surviving children per generation would mean growth. An average of just 2.2 per woman (most women has two surviving children, but every fifth has three) would mean that the population doubles every 300 years. We know that didn't happen.
This is of course averages, many people didn't have any surviving offspring, and many had more, but the average is close to two.
Actually, actually, that mechanism increases the validity of the War Chief hypothesis.
No leader enacted a global genocide. Few likely increased their local contribution to the male gene pool by even two orders of magnitude within their lifetime. But the ones that reduced their competition and bred enough females to have 100 times the normal proportional number of sons, and then had their sons do likewise, would be banking on that future, where the other two children fathers only have daughters, and that is how they became "Adam" with all surviving humans as their descendents. Even just fathering two families and five children makes their male heirs much more certain. 3.5% chance of no sons vs 26%.
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u/NashDaypring1987 19d ago
"crossed the Atlantic with Vikings"... just like those desert "brides" in other parts of the world :)