The primary thing I have never heard addressed on the issue of nutrition.  According to Adelle Davis, nutritionist and author, the human brain is literally in gestation until age 4.  Nutritional deficiencies from conception to age 4 can impair brain development.  This is a very significant factor in evaluating intelligence by race.  It should be included in future studies.<br><br>I would also like to see if nutrition has anything to do with brain development regarding autism.  Doctors have been discouraging pregnant women from eating fat or gaining too much weight.  It is my understanding that the brain is almost 100% cholesterol.  What impact on brain volume alone, would a lowfat diet during gestation, ie mother's diet during pregnancy and the child's diet through age 4.  I understand that the brain continues to develop and mature until adulthood, but the period of gestation, conception through age 4, is very important.<br><br>Why is no one looking at this?,(reply>), They <b>did</b> look into it. Why do you think they add iodine to table salt in most of the developed world? And why on Earth would anybody postulate that malnutrition after the age of 4 won’t impair brain development!?<br><br>(And, no, that’s not why blacks score lower than whites… or why gentile whites score lower than East Asians and Ashkenazi Jews… or why Southern Europeans score lower than North and Central Europeans.)