What is your evidence to support that? there is no 1:1 comparison here. The groups that likely survived these collapses were largely nomadic or at the fringes of society, used to sustaining themselves without the support of the existing power structures.

At that time distance from now, we're essentially all related to anyone who reproduced back then.

http://www.stat.yale.edu/~jtc5/papers/CommonAncestors/Nature...