The human population might have been reduced to as few as 1000 individuals at one point:
[1]https://academic.oup.com/genetics/article-abstract/229/1/iya...
[2]https://academic.oup.com/mbe/article/42/2/msaf041/8005733
[3]https://www.biorxiv.org/content/10.1101/2024.03.25.586640v1