"N.B. states that because ‘mixed-race’ offspring are viable in our present time nature must have intended it;"

-I never said nature must have intended it, I am hypothesizing that since it does occur, often times through laws of attraction, that it isn't an unnatural occurrence. As nature has a way of weeding out what is detrimental to it, I don't see a natural phenomena taking place that is inhibiting caucasians and non-caucasians from reproducing.

As far as autism goes, I typed autism and race and biracial and so on into the search engine, and came up short, except for the wikipedia entry that states. "Most professionals believe that race, ethnicity, and socioeconomic background do not affect the occurrence of autism." That's not to say I'm not listening, please provide the information though. Same results with trisome 21, please provide the information, and the Rhesus factor, well...

"Differences in the prevalence of Toxoplasma infection between geographical regions (0-95%) could also explain the striking variation in the frequency of RhD-negative alleles between populations. It is possible that the better psychomotor performance of RhD-negative subjects in the Toxoplasma-free population could be the reason for spreading of the “d allele” (deletion) in the European population. In contrast to the situation in Africa and certain (but not all) regions of Asia, the abundance of wild cats (definitive hosts of Toxoplasma gondii) in the European territory was very low before the advent of domestic cat."

Apparently the caucasian population where the Rhesus factor occurs most is amongst Basque Europeans, which, after looking them up, seem to represent a fairly small portion of caucasians, hopefully they've all got a house cat now?!

I can't figure how the development of 20th century science accounts for the survival of people living with the Rhesus factor, as they've managed to make it up until this point, again, they probably got house cats before the 20th century.

I apologize for the sarcasm, but I just didn't find these points to be a very substantial argument.

"The reintegration and its consequences was and is clearly a choice of ‘man.’"

-Perhaps, but the human and its actions aren't totally apart from nature either. Can we prove that natural law stands against reintegration and its consequences?

Selam