I'm late to this thread, and sadly read through all of this crap to catch up. That said, there was a prevailing argument perpetuated awhile back that there might be genetic significance which supports some racial beliefs. The idea that black people have a higher amount of testosterone, are more susceptible to sickle-cell, etc... The genetic argument for racism comes up pretty often, and it seems most people here genuinely are trying to form rational opinions, not justify racism. There's some arguments which need to be made here...
Genetics for racism are, indeed, bullshit. Dave at one point said "Black people have darker skin than white people." As if this, at a base level, distinctly sets up an argument for some level of racism. (This isn't an attack on Dave, just clarifying an argument). The problem exists inherently in the argument, it's a logical fallacy. Darker skin is a genetic trait just like blond hair or brown eyes. Darker shades of skin tend to be a dominant genetic trait, which means if two light skinned people have a child, it will definitively be a light skinned child. (They both MUST be lacking a dominant gene, or else they'd be dark skinned). Meanwhile, two dark skinned people may have a light skinned child if both were carrying a light skinned gene. This is basic biology which I'm sure most people have some understanding of. But the point is, skin color is a single genetic trait, such as hair color or eye color, and has no bearing on other genetic traits a person carries.
To expand a bit, the sickle cell argument came up. The origin of sickle cell anemia comes from a genetic evolution locals had to combat malaria. Because malaria is less effective against sickle-shaped blood cells, people who had sickle cell were far more likely to survive in areas where malaria was rampant. Since malaria is spread primarily by mosquitoes, this tended to be in areas with a lot of moisture and heat (along the Equator). So, while Northern Europeans aren't likely to have sickle cell unless they have Asian, South American or African ancestors, this hardly means it is a genetic trait shared by black people. It's also worth noting that sickle cell is common among people with Greek, Sicilian or Turkish ancestry, which most might call "dark skinned white people." Or something. At the same time, natives to, say, the fire island, who are dark skinned, aren't likely to develop sickle cell, because malaria isn't a significant issue in the fire islands.
I've honestly never heard much about the testosterone argument before, but that sounds a great deal like the fast twitch muscle argument. Because of how evolution works, it's highly unlikely to be a study which could actually hold up to peer review. The fact is, people don't evolve based on wide-ranging or world-ranging concepts. There weren't multiple populations of humans (blacks, whites, and asians) who all evolved on similar tracks in separate locations. Instead, people evolve regionally. And many of these regional evolutionary traits tend to be highly localized. The genetics for someone whose primary roots lie in the Congo would likely vary as much from someone from Niger as they would England. The only difference is our easy ability to distinguish the difference, because skin color is such an obvious way to tell two people apart.
The point is, as Gour hinted at and as 216 poorly attempted to argue, skin color is a single genetic trait, but it has zero bearing on other genetic traits. And simply because some regional genetic histories might mean some part of the black population bears a difference from some part of the white population (such as sickle cell) is not indicative of multiple, easily categorical differences. Racism is a convenient way society categorizes people, but scientifically it holds zero weight.
What does play a much larger role in terms of crime rate, incarceration rate and employment rate are things like income level, stability of a child's household, education, and, yes, racism. The problem with our society right now is we tend to focus all of our problems on one issue in a vacuum. In the case of the Zimmerman trial, it's really hard to argue George did everything "right" that night. I'd also say it's nigh impossible to definitively say he acted without a modicum of racism. No one besides George knows exactly why he picked out Trayvon and decided to follow him. However, our legal system dictates someone is innocent so long as there is reasonable doubt, and the Zimmerman case was nothing if not filled with reasonable doubt. The most upsetting part of this case is the focus on George, and racism, and not the fact that, at the end of the day, a 17 year old kid is dead.