A race is simply a sub-species defined by common parentage. Borders are, at best, gently defined by geography. But two people can have common parentage spanning thousands of miles.
Various sub-populations exist with various different characteristics, but there is no discrete border where one stops or the other begins.
Because all humans (and prior to us, quite a few branches of proto-human) can and do fuck and procreate with abandon, the concept of race isn't discrete. You can have both African and American Native parents while living in Australia. Your race (s) have been functionally defined by parents, not geography.
The entire world is just a smeared gradient of genotypes, all from the same species without significant variations.
The advent of mass travel and migration over the last three centuries has made it one. But we also had people who were geographically isolated for dozens - even hundreds - of generations. The phenotypical markers are just the surface. There is significant familial variation thanks to both mutation and adaptation.
The current global blending is the exception, not the rule.
A race is simply a sub-species defined by common parentage. Borders are, at best, gently defined by geography. But two people can have common parentage spanning thousands of miles.
Because all humans (and prior to us, quite a few branches of proto-human) can and do fuck and procreate with abandon, the concept of race isn't discrete. You can have both African and American Native parents while living in Australia. Your race (s) have been functionally defined by parents, not geography.
The advent of mass travel and migration over the last three centuries has made it one. But we also had people who were geographically isolated for dozens - even hundreds - of generations. The phenotypical markers are just the surface. There is significant familial variation thanks to both mutation and adaptation.
The current global blending is the exception, not the rule.