We don’t know exactly how narrow are the bottlenecks we’ve survived already.
We can estimate this for a lot of the major bottlenecks. For example, we can look at how likely other intelligent species are to survive and in what contexts. We have a fair bit of data for that. We also now have detailed genetic data so we can look at historical genetic bottlenecks in the technical sense for humans and for other species.
We can estimate this for a lot of the major bottlenecks. For example, we can look at how likely other intelligent species are to survive and in what contexts. We have a fair bit of data for that. We also now have detailed genetic data so we can look at historical genetic bottlenecks in the technical sense for humans and for other species.
http://en.wikipedia.org/wiki/Population_bottleneck#Humans