Resolved: Caucasians are not more intelligent than African Americans.

Heritability and AgeIn the last round, I presented evidence that heritability increases with age. My opponent has an odd and unconventional interpretation of this as somehow being an argument against genetic influences.In fact, this is generally seen as an argument for genetic influences. As I noted in the last round, humans, chickens, pigs, fish, and virtually all species are very similiar at very early stages of development. However, as these organisms develop, differences become apparent as genes express themselves more strongly. In fact, there was a recent 2009 study done on this from Molecular Psychiatry, a scientific journal, finding that heritability of cognitive ability (intelligence) does increase with age. They look at 11000 sets of twins from four different countries, a larger sample size than all previous studies combined. They found that heritability of intelligence was 41% at age 9, 55% at age 12, and 66% at age 17. This is consistent with the idea, found in all other studies, that intelligence is more heritable with age. The authors of this study say that the reason intelligence increases with age is that with age people increasingly select, create, and modify their own experiences, largely based on their genetic predisposition. This increased freedom and independance allows their genetic tendencies to express themselves more strongly [1].IQ and NutritionMy opponent's next claim is that malnutrition is the main cause of the black-white IQ gap. I explained in my last post that this is implausible for a number of reasons, namely the lack of malnutrition in America. My opponent responded by claiming that 30% of black children reside in a house without access to food. This is a sourceless claim. Therefore, I do not have to respond to it, and, even after looking for it, I could not find this statistic. However, I will respond to the point anyway. I did find a source that found 34.6% of black children lived in a "food insecure" home. 23.2% of children in the general population live in "food insecure" homes [2]. This, however, is not really a victory for my opponent's point.All my opponent has actually shown is that severe malnutrition can lower IQ scores. She has not shown that moderately low amounts of nutrients can lower IQ, probably because such evidence does not exist. "Food insecure" does not mean malnutrition. In fact, malnutrition is extremely rare in America. Even poor American children are very well nourished (source [4] in my last round). "Food insecure" simply means that a family had some difficulty with food expenses at some point during a given year. This means that a vast majority of "food insecure" households are actually quite well fed.The point of all this is that only severe malnourishment can substantially lower IQ scores, and such malnourishment does not exist in any significant way in America. There certainly is not enough to explain the black-white IQ gap.IQ and DrugsIn the last round, my opponent claimed that drug use was a major explanation of the black-white IQ gap. I pointed out, in response, that she only offered evidence that drugs can lower IQ scores. She did not offer evidence that it was in any way a cause of the black-white IQ gap. In fact, I showed in the last round that white teenagers actually use more drugs than black teenagers. My opponent, in response, offered a source showing that the black population as a whole, including adults, is more likely to have recently used drugs than the white population as a whole.This is true. However, my opponent claims that this difference in drug use is the explanation for the large, 15 point black-white IQ gap. This is highly unlikely, as my opponent's source shows that 9.7% of black people report having used a drug in the past month while 8.5% of white people have reported the same thing. This is a very small difference, and it is simply not feasible that this very insignificant difference in drug use explains the large and persistent 15 point black-white IQ gap. Especially given the fact that it is unclear how much drug use lowers IQ scores.Tizard StudyMy opponent, rather oddly, claims that I cannot refute the Tizard study in this round. This is flatly untrue, as my opponent mentioned it in the previous round as one of her major points, so I can absolutely refute it. The Tizard Study is obviously flawed in many ways. Namely, it tests children at ages 2 to 5. This is far too early, as it is before genes have expressed themselves in enough of a way for human differences to be evident. There is also something obviously wrong with the study, perhaps the sampling group, because the results finding that black children are much more intelligent than white children is completely at odds with the well known and well accepted phenomenon of the black-white IQ gap [3].Eyeferth StudyMy opponent also cites the Eyeferth Study to support the view that genetics do not play a role in the black-white IQ gap. This study has many well known flaws. Just for people that don't know, this study looked at children of German mothers that were raped, some by black men and some by white men. This study has numerous well known flaws. One major flaw is that 30% of the blacks in the US military dropped out, versus only 3% of the whites. This means that there was a much more selective group of blacks than whites in the military at this point, because the bottom 30% of blacks were gone while only the bottom 3% of whites were gone. Another flaw is that the IQ tests were done at too early an age to gauge any results, as differences in IQ are usually expressed later in life [4].Finally, the Eyeferth study finds that white boys have IQs of 101 while white girls have IQs of 93. This is an 8 point IQ gap between boys and girls found in this study. In the real world, boys are found to only have IQs that are about 3 points higher than girls [5]. This inconsistency with the real world makes this study highly questionable.Minnesota Transracial Adoption StudyMy opponent makes a lot of the fact that this study's authors are skeptical of its conclusions that support genetic basis for the IQ gap. In fact, there is a well known reason why the authors of this study are skeptical. It is that the authors, Sandra Scarr and Richard Weinberg, were actually hoping to show that genetics played no role in the black-white IQ gap. However, their results did not show what they were hoping to show, so they were more neutral on the results.This study is the only study that has tested adopted children at an old enough age to get an accurate picture of how much genetic differences matter. Not surprisingly, this study found that genetic differences play a large role in the black-white IQ gap [6].I have shown that heritability of intelligence rises substantially with age. I have also shown that things like malnutrition and drug use cannot account for the black-white IQ gap. Finally, I have shown that my opponent has cited flawed studies to support her conclusion, and I have also shown that the Minnesota Transracial Adoption Study was accurate and did show genetic differences playing a big role. My opponent, on the other hand, made numerous unsourced claims, most of which were claims that clearly needed sources, made numerous logical fallacies, and failed to affirm the resolution.I have successfully negated the resolution. Therefore, the only logical vote is to vote Con.Sources:[1] http://www.nature.com...[2] http://www.bread.org...[3] http://en.wikipedia.org...[4] http://en.wikipedia.org...[5] http://en.wikipedia.org...[6] http://en.wikipedia.org...