If You have 2 parents, 4 grandparents, 8 great parents, so if you go back 40 generations you’d have a supposed 1 Trillion ancestors, But only 100B humans have ever existed. Explain.
In: Biology
at certain points in the far history it is suspected (backed by genetic diversity) that the human population went through bottlenecks.
its suggested the pre-1942 Americas population is derived from 70 individuals who crossed the land bridge from asia. Also the sub-sarahan population was as low as 2000 individuals for many thousands of years before spreading out of africa.
https://en.wikipedia.org/wiki/Population_bottleneck
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