January 25, 2017

Race and Crime: the Causes of Black Crime Rates

First, let’s look at the basic statistics on race and crime in America. Some people like to point out that Whites commit more crimes each year than Blacks. This is true, but only because Whites make up a greater proportion of the population than Blacks.

The FBI’s Uniform Crime Reports show that, relative to their share of the population, African-Americans make up a disproportionately high share of criminals, especially violent criminals, and this means that they commit crime at a higher per capita rate than Whites do. Asian Americans, by contrast, commit crime at a lower rate than Whites do.

Basic Crime Data.png

Some people try to obfuscate this fact by pointing out that most crime is intra-racial. This is true, but the fact that most crimes with Black offenders also have Black victims does not change the fact that there are more Black crimes per capita than White crimes. Furthermore, when crime is inter-racial it is usually Black on White.

Interracial Crime.jpg

So far, I’ve been relying on arrest statistics as a proxy for crime. Some argue that this is invalid because the police are biased and Blacks are more likely to be arrested than Whites. This argument can easily be refuted using data from The National Crime Victimization Survey (NCVS). The NCVS is a survey carried out yearly in which the Department of Justice asks Americans about their experience with crime over the last year. The DOJ first asks participants if they have been the victim of a violent crime and, if they have, they are asked to answer various questions about the crime and the perpetrator of said crime.

Using this data, the proportion of violent criminals who are Black, according to the victims of violent crimes, can be calculated. We can then compare these figures to the offender rates by race in the FBI’s arrest data. Doing so reveals that there is essentially no racial bias in arrest data.

UCR vs NCVS.png

The National Crime Victimization Survey Validates the Uniform Crime Report’s Data on Black Crime

Of course, victimization surveys can’t tell us anything about victimless crimes, and many liberals point to self-report data suggesting that Blacks use drugs at the same or a lesser rate than Whites even though they are more likely than Whites to be arrested for drug use. This, they argue, is strong evidence of bias in the justice system.

The first problem with this argument is that African-Americans are more likely than Whites to lie about using drugs. How do we know this? Well, criminologists sometimes conduct studies in which they run biological tests on people’s hair, blood, urine, etc., to test what drugs they have recently taken and then compare the results of these biological tests to what drugs they claim they have recently taken. Such studies consistently find that Blacks are more likely than whites to lie and claim that they have not used a drug when they actually have (Page et al., 2009Falk et al., 1992Feucht, Stephens, and Walker, 1994, and Fedrich and Johnson, 2005).

This argument also ignores important differences between African American and White drug users. What kind of differences? Well, to quote one study comparing African American and White drug users:

“African Americans are nearly twice as likely to buy outdoors (0.31 versus 0.14), three times more likely to buy from a stranger (0.30 versus 0.09), and significantly more likely to buy away from their homes (0.61 versus 0.48).” – Ramchand , Pacula, and Iguchi MY, 2006.

Similarly, a  report issued by the Justice Department found that African American drug users use drugs more often than White drug users, use more dangerous drugs than White drug users, and are more likely to use drugs in areas with high crime rates (Lagan, 1995). All 6 of these differences will make African American drug users more likely get to arrested than White drug users.

Given all this, there is no good reason to suppose that African American drug arrest rates reflect racism. Combining this with NCVS data, we clearly see that African Americans are more likely than Whites Americans to commit crime.

The Police War on Blacks

Briefly, it is worth noting that police shootings also show no signs of racial bias. If we compare the proportion of people killed by police who are Black to the proportion of violent criminals who are Black we find that, if anything, we would expect more Blacks to be killed by police in a color blind society.

Police Brutality.png

Racial Crime Differences Across Time, Space, and Age

In the US, racial differences in misconduct are known to start early. Several reports, both by the department of education and civil rights groups, have shown that Blacks are far more likely than Whites to be suspended and expelled as early as preschool (Kamenetz, 2016; Lewin, 2012; Resmovits, 2016).

Some liberals argue that this, too, is just due to bias on the part of schools and teachers, but this is not what the empirical record shows. For instance, one study found that the black-white suspension gap was completely accounted for by controlling for past behavioral problems.

Another study looked at middle school suspensions and found that the racial gap in suspension rates persisted after socioeconomic status was controlled for, but that whites and blacks had the same chance of being suspended once they were sent to the principal’s office. This too suggests that these disparities are not due to bias.

Racial crime disparities in the United States have also been around for a long time. Though the size of the gap has changed over the decades, DOJ records show that Blacks were far more likely than non-Blacks to be incarcerated as early as the 1920s.


Other research has found that this was the true in the 19th century as well.

The Black-White crime gap is not unique to the United States, either. Government data show the same thing happening in Canada, Isael, England, and Japan. Furthermore, Africa, Latin America, and the Caribbean, the places on earth with the most Blacks, have the highest crime rates in the world.


These basic trends make two explanations for the Black-White crime gap unlikely. First, African American ghetto culture did not exist in the 1920s, does not exist in Japan or Africa, and probably isn’t very strongly internalized by 3-year-old preschoolers. Yet, the Black-White crime gap persist in all these circumstances. Given this, ghetto culture probably isn’t a root cause of racial crime disparities.

Secondly, racism in America has declined dramatically since 1920, but the crime gap has increased, and there is no “White privilege” in Japan or Africa. Given this, racism doesn’t seem like a plausible root cause either.

Further still, the proportion of a city’s population which is Black continues to correlate with its crime rate even after controlling for variables like povertysingle parent homes, education, and lead exposure. In fact, upper-class Blacks have higher crime rates than do poor Whites.

Rich vs Poor.png

Chart from Ehrenfreund (2016) data from Zaw and Darity (2016)

Given this, none of these variables can explain the Black-White crime gap either. With these common myths debunked, let’s take a look at factors which actually do play a role in racial crime differences.


IQ negatively correlates with crime across nations, US states, and counties (Lynn and Vanhanen, 2012; Bartels et al., 2010; Beaver and Wright, 2011). Moreover, the relationship among counties was shown to persist after controlling for county differences in socio-economic status.

Ellis and Walsh (2003) meta-analyzed over 70 studies done on the relationship between individual IQ and crime, delinquency, and related variables, and the overwhelming majority of studies were found to support a link between crime and IQ.

Some might think that this is just because low IQ tends to go hand and hand with poverty and other home environment variables. This hypothesis was falsified by Frisell et al. (2012) who looked at the association between IQ and crime in a total male birth cohort sample from Sweden (n=700,514). IQ was negatively associated with crime and not only did this relationship persist after adjusting for differences in single motherhood and income, it was also true within families such that the lower IQ individuals within pairs of siblings were more likely to be a criminal. Given that this relationship exists within families, differences between families cannot possibly explain it.

Further still, IQ predicts crime from a very early age. Farrington (1989) found that IQ at age 8 was a significant predictor of being convicted of a violent crime as an adult. Stattin et al. (1993) found that future criminals scored lower than future non-criminals on measures of intelligence as early as age 3.

Lastly, it is important to note that controlling for IQ accounts for the majority of raical crime differences:


(Murray and Herrnstein, 1994)

Finally, as reviewed in this article, Blacks probably have lower IQs than Whites for genetic reasons.

Self Control

Another trait relevant to racial crime disparities is self control. Studies have shown that low self control predicts criminality even after controlling for IQ and parental socio-economic status (Moffitt et al., 2010).

Racial differences in self control have been shown to exist across many studies. Said differences exist around the world, in children and adults, and cannot be explained by racial differences in socio-economic status (Last, 2016A).

Further more, a handful of gene variants have been shown to predict impulsive behavior and they are all more common in Blacks than in Whites (Minkov and Bond, 2015; Last, 2016B)


Testosterone activity has been linked many times to aggression and crime. Meta-analyses show that testosterone is correlated with aggression among humans and non human animals (Book, Starzyk, and Quinsey, 2001). Moreover, artificially increasing the amount of testosterone in a person’s blood has been shown to lead to increases in their level of aggression (Burnham 2007Kouri et al. 1995). In fact, a study of Rhesus monkeys found that injecting female fetuses with testosterone caused them to behave just as aggressively as young males (Book, Starzyk, and Quinsey, 2001). Finally, people in prison have higher than average rates of testosterone (Dabbs et al., 2005). Thus, testosterone seems to cause both aggression and crime.

Richard et al. (2014) meta-analyzed data from 14 separate studies and found that Blacks had higher levels of free floating testosterone in their blood than Whites suggesting that testosterone levels may predispose Blacks towards higher rates of crime.

Exacerbating this problem even further is the fact that Blacks are more likely than Whites to have low repeat versions of the androgen receptor gene. The androgen reception (AR) gene codes for a cell receptor by the same name which reacts to hormones like testosterone. This receptor is a key part of the mechanism by which testosterone has its effects throughout the body and brain.

All versions of this gene have several repeats of a particular kind of strand of DNA called a “CAG” nucleotide sequence. AR gene variants differ in the number of these repeats. Versions of this gene with fewer than average numbers of repeats lead to increased testosterone activity and has been associated many times with crime and aggression (Last, 2016C).

Four separate studies have shown that low repeat alleles of the AR gene are more common among Blacks than among Whites (Irvine et al 1995Wang et al. 2013, Bennet et al. 2002, and Shibalev et al. 2013). Given this, it is highly likely that low repeat AR alleles increase Black crime rates by enhancing Black people’s reactivity to testosterone.

The MAO-A Gene

Different versions of the MAO-A gene have also been linked to crime. Many studies have found that “low repeat” versions of this gene (repeats of a different kind of DNA strand than the repeats in the AR gene) predict aggression and crime in humans, and genetic engineering studies on mice have definitively shown that these gene variants causes aggression (Bryd and Manuch, 2013; Ficks and Waldman, 2014; Roux 2014Vaughn et al., 2009Beaver et al., 2009Beaver et al., 2013; Cases et al., 1995; Scott et al., 2008Vishnivetskaya et al., 2007; Mejia, 2002).

These versions of the gene have also been linked to high levels of credit card debt and obesity (Camarena et al. 2004Neve and Flower 2009Need et al. 2005, and Feummeler 2008). Given this, it seems plausible that low activity versions of the MAO-A gene leads to increased impulsivity which in turn leads to an elevated risk for criminal activity, aggression, obesity, and credit card debt.

Racial differences in MAO-A genotypes are well established. Blacks are far more likely than Whites to carry these low repeat crime associated variants of the gene (Last, 2016C).  Thus, the MAO-A gene is a well-established genetic (partial) explanation for the Black-White crime gap.


Finally, let’s look at the relationship between skin color and crime. Variation in the color of people’s skin is largely due to variation in the concentration of melanin in their skin. The more melanin a person has the darker their skin will tend to be. The amount of melanin a person produces is significantly controlled by their levels of a hormone called melanotropin (Emerson). There is some evidence that melanotropin causes aggression (Reviewed in Rushton and Templer 2012).

First, there are studies of skin color variation in humans. Studies which utilize estimates of the average skin color of over 100 countries find that darker skin predicts higher crime rates. A similar correlation has been found in non-human animals. In fact, Animal research has shown that dark skin predicts more aggression in over 200 species.

The evidence that melanotropin causes aggression is not limited to correlations, either. Experiments which breed animals to become less aggressive, from mice to fox, tend to end up with lighter skinned animals. Even more impressively, injecting animals with melanotropin has been shown to cause them to become more aggressive.

This data strongly suggests that there is some relationship between skin color and aggression. However, it does not tell us whether melanin itself or the hormone melanotropin is what causes aggression. Either is possible. Melanotropin is a complex hormone that could have unknown effects on many biological systems. Melanin also has surprising effects. For instance, dark skin is a leading cause of vitamin D deficiency, and recent evidence has linked vitamin D deficiencies to differences in cognition, suggesting that it could have many unknown effects on the mind.


Hopefully, this has demonstrated that it is at least plausible that biology and genetics play a role in racial crime differences. This is not to say that the environment has no effect. It obviously does. However, we should stop ignoring the role of genetics in societal problems and, more importantly, stop blaming other people for acts of nature.

Facebook Comments
  • John Henry Eden

    The cause of “black” crime?…Negroes.

  • Roof Top Voter

    Pull the hispanics out of some the white categories and it changes even more.