Mixedrace children suffer from more health problems
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448064/
A massively well-funded study of over 100,000 schoolchildren found that “Adolescents who identify themselves as mixed race are at higher health and behavior risk than those of 1 race.” Indeed, even when controlling for education, socioeconomic status, and other factors, there is an across-the board higher rate of health risks amongst mixed race adolescents than mono-racial adolescents.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1448064/
One study found that White-Asian mixes had a 2x higher rate of being “diagnosed with a psychological disorder, such as anxiety, depression or substance abuse.”
http://www.eurekalert.org/pub_releases/2008-08/uoc--baa081108.php
A study on Black-White mixes in agreement found that ”When it comes to engaging in risky/anti-social adolescent behavior, however, mixed race adolescents are stark outliers compared to both blacks and whites.” This holds true despite being raised in similar environments to mono-racial children.
http://www.msu.edu/~renn/RHE-_mixed_race.pdf
Often race-deniers and cultural Marxists will bring up Haldane’s rule, arguing that since races can mix and create fertile offspring, the genetic distance is not too great. Haldane’s rule is “when in the offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterogametic [XY] sex.”
http://www.nature.com/scitable/topicpage/haldane-s-rule-the-heterogametic-sex-1144
Black Americans are a hybrid race of around 22% White ancestry
http://genomebiology.com/content/10/12/r141
LTA4H, or “leukotriene A4 hydrolase” is found on chromosome 17. An allele of this gene increases the risk of heart attack (the #1 cause of death in America) in Blacks by more than 250%, but only 16% in Whites. The 30% of Whites with this allele have counteracting genes, while the 6% of Black Americans who obtained it through race mixing do not.
http://www.ncbi.nlm.nih.gov/pubmed/16282974
The average rate of success for mixed race couples is around half that of same race couples, 0.127 compared to 0.213.
http://www.jstor.org/stable/4145377
One study showed that people tend to find their own face when morphed into the opposite sex most attractive, even when he/she doesn't know it's his own face, strongly suggesting that people typically prefer those who look like themselves, in other words their own racial/ethnic group.
http://www.psyc.nott.ac.uk/research/vision/jwp/papers/pentonvoak1999.pdf
Hybrid vigor (heterosis) does not seem to apply to humans as we are already very heterozygous, at 0.776
http://mbe.oxfordjournals.org/content/14/7/707.full.pdf
The neurotransmitter oxytocin "makes people more co-operative, benevolent, loyal, generous and trusting of others. It is involved in the parent-child bond - new mothers and fathers have raised levels of oxytocin. Production also increases when people hug and when they have sex and, recent research suggests, when they receive psychological warmth." However, oxytocin has been alleged to "foster racism."
http://www.guardian.co.uk/technology/2011/jan/30/bright-ideas-oxytocin-hormone-racism
The study found that "intergroup bias that fuels prejudice, xenophobia, and intergroup violence… Which maybe modulated by brain oxytocin." This suggests that the instinctual desire to pursue the interests of one's own ethnic group to further ensure the existence of one's people is linked to racial bias, coinciding with the observation that diversity is a weakness, not a strength.
http://www.pnas.org/content/early/2011/01/06/1015316108
Although egalitarians suggest that only a racist would consider race when it comes to reproduction and mate choice, this study observed a general, innate tendency to prefer one's own race especially when most likely to be impregnated.
http://www.cdnresearch.net/pubs/private/racebias.pdf
The more people of different backgrounds who produce offspring = the more types that are harder to match. Multiracial patients have uncommon profiles and since there can be many possible racial and ethnic combinations in multiracial societies, finding a match can still be extremely difficult.
http://m.phys.org/_news162659550.html
One obstacle to finding a matching donor was her mixed ethnic background. Her father is black, with West Indian and Panamanian roots. Her mother is white, with Russian-Jewish roots. In addition, only 5 percent of registered donors are black.
http://www.nytimes.com/1996/04/18/sports/baseball-rod-carew-s-daughter-dies.html
If you become ill with a blood cancer or other disease that requires a stem cell transplant, here's an uncomfortable fact: Your race matters. Diversity is a strength in much of life, [citation needed!] but it's a curse when finding a stem cell donor match.
http://articles.washingtonpost.com/2013-08-05/national/41085742_1_stem-jeffrey-chell-ancestors
The FDA have approved a heart failure drug called Bidil, but only for blacks, as blacks do not benefit from conventional heart failure drugs.
http://online.wsj.com/article/SB116096445875393515.html?mg=com-wsj
Sickle cell anaemia is a condition found almost exclusively in blacks, about 1 in 4 west Africans carry the gene for it, almost no whites do. Any whites who carry the gene most likely have a black ancestor.
As a result of population growth in African-Caribbean regions of overseas France and immigration from North and sub-Saharan Africa to mainland France, sickle cell disease has become a major health problem in France. SCD has become the most common genetic disease in this country.
https://en.wikipedia.org/wiki/Sickle_cell_anemia
Nonindigenous species can bring about a form of extinction of native flora and fauna by hybridization and introgression either through purposeful introduction by humans or through habitat modification, bringing previously isolated species into contact. These phenomena can be especially problematic for rare species coming into contact with more abundant ones. Increased use of molecular techniques focuses attention on the extent of this underappreciated problem that is not always apparent from morphological observations alone. Some degree of gene flow is a normal, evolutionarily constructive process, and all constellations of genes and genotypes cannot be preserved. However, hybridization with or without introgression may, nevertheless, threaten a rare species' existence.
http://www.annualreviews.org/doi/abs/10.1146/annurev.ecolsys.27.1.83
"Human races are evolving away from each other," Harpending says. "Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity." He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, "and there has not been much flow of genes between the regions since then."