alt Hacker NewsFWIW the populations weren't actually as small as a lot of these articles (including about human bottlenecks) allege in the popular press. This comes from a knowledge gap in the public compared to a biologists understanding here. The biologists are talking about effective population size (1) in most all these cases. This is an idealized sort of population size based on the idea of using the smallest possible population size that can fully capture the observed genetic diversity. It makes sense to use this measure, considering you are never fully sure how large a real population can be beyond its effective population size. So you just use the effective population size and implicitly acknowledge its assumptions.
This is well past HS biology though so popular press just skips that nuance and equates it to true population size.