These questions are not answerable from the current data.

What is answerable — at a rough level — is the approximate time of the divergence (around 20,000 years ago) and the approximate genetic distance between the two branches at the time of divergence.

These parameters constrain the demographic models that researchers use to understand the founding of the Americas, and they contribute to the growing picture of a founding process that was more extended in time and more complex in its population structure than simple models suggest.

The demographic modeling associated with the 2018 paper estimated the effective population size of the founding population — the number of individuals contributing to the genetic diversity of the population — in a range consistent with a relatively small but not tiny group.