The evidence and data on racial differences of IQ are pretty well established. In the scientific community, there is virtually no question that there are major differences in IQ between races, with Orientals and Caucasians at the high end and Negros, Mesoamericans, etc at the lower end. There are massive differences in biochemistry, physiology and neurology in almost every area between racial groups, including brain size, skeletal structure, biochemistry, genetics, eye color, skin color, and so on, for instance Caucasians are the only racial group where most adults can digest Lactose, and this is clearly due to tens of thousands of years of divergent evolution that caused some races in cold climates to develop higher IQ and larger brain capacity. A strong and compelling scientific argument has been made by many, such as J.P. Rushton, et al that racial genetics is the cause, for instance, the fact that IQ differences show up by age 3 before education has had a large effect, the MRI studies that have shown that Caucasians have a larger brain that the Negro, and as well the strong predictor that IQs are of SAT scores. Studies of black children living with adoptive white parents show that blacks still have the same IQ as black children living with black parents. The study found that even that where white children and black children were living with the same adoptive parents, the white children still scored 20% higher despite growing up with the same parents. The higher IQ of caucasians likely developed due to the cold, temperate climate of Northern Europe which required more long term planning and skilled crafts to develop technologies to survive the cold winters. The cold winters heavily selected for higher IQ, whilst the tropical environment, where the fruit hangs on the true all year, does not. SAT scores and IQ scores are accurate predictors of life outcomes a well, showing that IQs are a very accurate measurement of a persons intelligence occupational capabilities. As in the book, IQ and the Wealth of Nations, the success of countries is tightly coupled to the average IQ levels, and since IQ levels is the result of the racial makeup of the population, it reflects the racial groups. This is why you can very easily predict GDP of different countries with the racial demographics of the countries, as well a predict a vast number of other things from test scores to rates of homicides. Some have also looked at the fact that Caucasians have a larger frontal lobe than even orientals, where impulse control and creativity is based, which could explain why Caucasian majority countries have had longer lived, healthier democracies, especially the US. Orientals have excellent math skills, but seem to have a totalitarian streak. Caucasians and Orientals have been shown easily beat the average Negro in mathematical tests.
It is pretty clear that entire civilizations are nothing more than the reflection of microscopic DNA that constructs the neurological system and constructs human behaviour. Cultural interactions can share information and influences, but the more of the high IQ racial groups you have, the most of such sharing and origination occurs. The population tends to take on the characteristics of the average individual rather than the outlier. For Einstein to do his work required a country that had a well established industrial base, faciliitated by a high IQ, highly capable population that could provide the environment stable enough that things could move a bit past basic sustenance level of existance, that there was enough industrial base to provide for labatory equipment for instance. Einstien was building on previous work, of others as well, so these things do not come about as a result of the lone genius but require a country that is well populated with High IQ genetics. If Einstien had been born in Nigeria, no matter how intelligent or smart he was, he wouldnt have gotten very far for the lack of everything that he would have needed. Indeed, there is a feedback effect, the high IQ population caucasian and oriental countries are most fertile for science because of the general nature of the population being favorable, and the larger number of contributions by many.
IQ differences most visibly show up when doing math studies, and math tests and such intellectual work that requires high level computation and processing. The effects that become blatantly visible in a regular or mundane conversational interaction below an IQ of 80 or so.
Even when the IQs are corrected for the Flynn effect, large IQ gaps remain. Negros seem to have a pre-flynn IQ level of about 70 in subsaharan Africa, with an 85 post flynn IQ in the USA. Causasians seem to have an 85 pre-flynn iQ and a 105 post flynn IQ in the USA. It seems as though higher level brain functions need a little training to be used. It is quite possible that lower IQ groups have a less variable and less moveable IQ. For instance, a racial group that has a maximum potential IQ of 105, can score anywhere from 0 to 105 on an IQ test, if they wished, but, a population that has a maximum potential average IQ of 85 could score less only a very short distance before reaching a level of profound mental retardation, that is, with a maximum IQ level of 85 you have much of a shorter distance downward before reaching a level of mental retardation than the 105 maximum IQ races. An IQ of 85 is marginal intellectual functioning while 70 is the line of mental retardation. The Subsaharan African groups do score borderline metal retardation, and the general negro population in the USA scores marginal, mediocre functioning. It may be that for a racial group that has a 105 maximum IQ average, that it takes a little effort to reach that, while reaching an 85 IQ level for those races is effortless. For a negro to try to reach higher IQ levels would take vastly more effort, dozens of times more effort, if they can reach it at all. So for a Caucasian or Oriental, with a little work they an get to 105, with a Negro, it can be dozens of times more difficult or impossible.
Here is a synopsis of some evidence from the Rushton study:
"Race differences show up by 3 years of age, even after matching on maternal education and other variables," said Rushton. "Therefore they cannot be due to poor education since this has not yet begun to exert an effect. That's why Jensen and I looked at the genetic hypothesis in detail. We examined 10 categories of evidence."
The Worldwide Pattern of IQ Scores. East Asians average higher on IQ tests than Whites, both in the U. S. and in Asia, even though IQ tests were developed for use in the Euro-American culture. Around the world, the average IQ for East Asians centers around 106; for Whites, about 100; and for Blacks about 85 in the U.S. and 70 in sub-Saharan Africa.
Race Differences are Most Pronounced on Tests that Best Measure the General Intelligence Factor (g). Black-White differences, for example, are larger on the Backward Digit Span test than on the less g loaded Forward Digit Span test.
The Gene-Environment Architecture of IQ is the Same in all Races, and Race Differences are Most Pronounced on More Heritable Abilities. Studies of Black, White, and East Asian twins, for example, show the heritability of IQ is 50% or higher in all races.
Brain Size Differences. Studies using magnetic resonance imaging (MRI) find a correlation of brain size with IQ of about 0.40. Larger brains contain more neurons and synapses and process information faster. Race differences in brain size are present at birth. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.
Trans-Racial Adoption Studies. Race differences in IQ remain following adoption by White middle class parents. East Asians grow to average higher IQs than Whites while Blacks score lower. The Minnesota Trans-Racial Adoption Study followed children to age 17 and found race differences were even greater than at age 7: White children, 106; Mixed-Race children, 99; and Black children, 89.
Racial Admixture Studies. Black children with lighter skin, for example, average higher IQ scores. In South Africa, the IQ of the mixed-race "Colored" population averages 85, intermediate to the African 70 and White 100.
IQ Scores of Blacks and Whites Regress toward the Averages of Their Race. Parents pass on only some exceptional genes to offspring so parents with very high IQs tend to have more average children. Black and White children with parents of IQ 115 move to different averages--Blacks toward 85 and Whites to 100.
Race Differences in Other "Life-History" Traits. East Asians and Blacks consistently fall at two ends of a continuum with Whites intermediate on 60 measures of maturation, personality, reproduction, and social organization. For example, Black children sit, crawl, walk, and put on their clothes earlier than Whites or East Asians.
Race Differences and the Out-of-Africa theory of Human Origins. East Asian-White-Black differences fit the theory that modern humans arose in Africa about 100,000 years ago and expanded northward. During prolonged winters there was evolutionary selection for higher IQ created by problems of raising children, gathering and storing food, gaining shelter, and making clothes.
Do Culture-Only Theories Explain the Data? Culture-only theories do not explain the highly consistent pattern of race differences in IQ, especially the East Asian data. No interventions such as ending segregation, introducing school busing, or "Head Start" programs have reduced the gaps as culture-only theory would predict.
In the comments section, there are examples of south american indigenous people with outstanding intellectual achievements, despite extreme poverty in childhood (the excuse used with blacks), Julio Granda and Jorge Cori can be used as axamples.
There is also something you can verufy easily. Non-black athletes, no matter how top-notch is their training, would never compete against Usain Bolt, Asafah Powell or other elite black athletes. And the opposite happens in the Nobel laureates, fields medalists or Chess super-GM arena.
If it's accepted that race can determine biological differences (lactose intolerance, hair and skin color, etc), I don't understand why they insist so strongly that race can't determine intelligence average difference.