1.2 mill years ago there were only 18.500 people ... (was: population size in the ancient ancestors of Homo sapiens)

population size in the ancient ancestors of Homo sapiens:

By comparing the likelihood of various demographic models, we estimate that the effective population size of human ancestors living before 1.2 million years ago was 18,500, and we can reject all models where the ancient effective population size was larger than 26,000. This result implies an unusually small population for a species spread across the entire Old World, particularly in light of the effective population sizes of chimpanzees (21,000) and gorillas (25,000), which each inhabit only one part of a single continent.

doi.org/dv75x8