The study found that, around 98.7% of human ancestors were lost,
This plunge in human population, which correlates with the sparse fossil record, also reshaped present-day human genetic diversity, driving the evolution of brain size.
Our ancestors survived with small numbers for an estimated 120,000 years, until climatic and other conditions improved for human habitation.
Scientists believe that extreme climatic cooling could have led to the population crash, by reducing available food and the ability to simply survive the cold.
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