Did our ancestors nearly die out?

Abstract

• Genetic analyses suggest an ancient human population crash 900,000 years ago Earth’s climate system began to change during the Middle Pleistocene transition, which is associated with a severe cooling phase about 900,000 years ago. How this change might have affected human populations is difficult to determine, because the human fossil and archaeological records are relatively sparse for this period and lie beyond the reach of ancient DNA recovery. On page 979 of this issue, Hu ( ) use a new method of analysis called FitCoal to project current human genetic variation backward in time, to estimate the size of populations at specific points in the past. The results suggest that our ancestors suffered a severe population bottleneck that started around 930,000 years ago and lasted for almost 120,000 years. This is estimated to have reduced the number of breeding individuals to ∼1300, bringing our ancestors close to extinction.