IQ is genetic, and the genes for it have been identified...
- Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence
- Childhood intelligence is heritable, highly polygenic and associated with FNBP1L
...And the frequency of IQ genes varies among the human races:
Larger brains are smarter...
...And the size of the brain varies among the races:
- Brain Structure in Young and Old East Asians and Westerners
- Variability in Frontotemporal Brain Structure
- Probabilistic MRI Brain Anatomical Atlases Based on 1000 Chinese Subjects
- The Construction of a Chinese MRI Brain Atlas
- Brain size, cranial morphology, climate, and time machines.pdf
IQ test results:
- Ethnic Group Differences in Cognitive Ability in Employment and Educational Settings: A Meta-Analysis
- Patterns of Mental Abilities: Ethnic, Socioeconomic, and Sex Differences
...And historical studies:
- The Testing of Negro Intelligence
- Analysis of brain weight. I. Adult brain weight in relation to sex, race, and age
- Brain-weight and size in relation to relative capacity of races
- A quantitative study of Australian Aboriginal and Caucasian brains
- Cerebral Convolutions of the Negro Brain.pdf
- A Racial Peculiarity in the Pole of the Temporal Lobe of the Negro Brain
- Some Racial Peculiarities of the Negro Brain
- The Australian Aboriginal Brain
- The Bushman Brain
- The Brain of the Kenya Native