[lanstin]

That is one relatively isolated group. The existence of small isolated groups does not mean the whole species has a small number of distinct subgroups. The smallness here is intended to apply to the number of groups, with the size of the groups being correspondingly large.

[djrj477dhsnv]

The boundaries between groups may be blurred, but surely a person whose ancestors lived in location A for the last 10 thousand years will be genetically more similar om average to other people from that location than to people in location B on the other side of the planet.