Odds and Ends
Be careful what you say
18 7, 9:00pm
[ Race, as a social construct, ...]
No need to read any further, because I am not that much interested in social constructs in this case.
Race, as a biological and mathematical construct, is another matter entirely. And if you were to read that wiki article more thoroughly, then you would have to agree that "race as a social construct" is dead while the "race as a biological construct and mathematical model" is very much alive, more so than it ever has been in the past.
[ Polar bear and brown bear are completely different species, not "races". ]
They are intermingling species, which makes them subspecies and the phenotypes within them can be called races. And those races (well, phenotypes, actually, or genetic principal components) are more older than the species.
[ As for hominids, only one subspecies remains, all others having been either destroyed or absorbed by the Homo Sapiens. ]
Your logic is flawed.
If you assume that all others have been absorbed by the homo sapiens, then you would have to assume that all subgroups of homo sapiens are homogenous (and thus the assimilation has ended). They are not. The genetic components of dissimilarity among living humans goes back hundreds of thousands of years, back to homo erectus at the very least.
I have no clue what publications you have read, but scientific studies are clearly not among them. You have so far even managed to misrepresent the scientific method, itself, let alone genetic research.
[ All humans share identical biological reproductive behaviour. ]
I am not sure in which sense do you use the phrase "reproductive behaviour".
But I do know that diseases (including genetical diseases) vary among within-group offspring and between-groups offspring.
And that in scientific speak is statistically significant difference.
[ Trying to explain away cultural differences with biological factors became scientifically obsolete some 60 years ago. ]
Perhaps you should reread the wiki article you yourself referred to.