Genetic evidence suggests the ancestors of Native Americans split from Siberians and East Asians about 25,000 years ago, perhaps when entering the now mostly drowned landmass of Beringia, which bridged North America and the Russian Far East. Thus any cognitive differences between Native Americans and East Asians may tell us a great deal about the very final stages of human evolution.

161 Native Americans (mean age about 57) were administered a battery of cognitive tests including the verbal abstract reasoning and spatial analytical reasoning subtests of the WAIS-R on which they averaged raw scores of about 9.5 and 25.3 respectively. For their age group, this equates to IQ equivalents of 85 and 105 respectively (U.S. norms) or about 82 and 103 (white norms). However correcting for the Flynn Effect (the study is from 1992 and the WAIS-R was normed in 1978) reduces the verbal IQ to 79 and their spatial IQ to 100. Given the 0.56 correlation between these two subtests in the 55-64 year-old age group, this works out to a composite IQ of 88. The participants were from the Cheyenne River Sioux Reservation in South Dakota. About 52% had completed high school compared to 65.5% of Native Americans adults in general in 1990.

To put this in perspective, on the same subtests, black Americans would average a verbal IQ of 89, a spatial IQ of 83 and a composite IQ of 84 (white norms). But considering that black Americans are about 25% white on the genetic level, correcting for white admixture gives verbal IQ 85, spatial IQ 77, and composite IQ 79.

On the same two subtests, Japanese 16-year-olds average a verbal IQ of 102 , a spatial IQ of 116 and a composite IQ of 110.

It makes sense that Native Americans would have a higher spatial IQ than unmixed black Americans (100 vs 77) given the extreme selection pressure of the Last Glacial Maximum and the visual-motor skills needed to sew clothing, build fire, make shelter, hunt mega fauna etc. But it’s curious that Native Americans should have a lower verbal IQ than unmixed black Americans (85 vs 79) and much lower than East Asians (102 vs 79).

Given that East Asians and Native Americans are both mongoloid, it’s interesting that they should both show such a huge verbal < spatial IQ gap. As Richard Lynn speculated, the extreme cold of Northern Siberia likely caused evolution to select enhanced spatial ability at the expense of verbal skills, with the left hemisphere of the brain (normally reserved for language) forced to take on more spatial processing.

But what explains the huge East Asian > Native American IQ gap? What happened in the last 25,000 years to drive these two cousins apart? Perhaps the common ancestor of East Asians and Native Americans would have scored like Native Americans today (verbal IQ 79, spatial IQ 100) but civilization in East Asia raised their verbal IQ 23 points, and since the verbal and spatial subtests correlate 0.56, a verbal increase of 1.5 SD would cause a spatial increase of about 1 SD.

Similarly, the fact that blacks have higher verbal IQ than Native Americans might also be explained by black Africa (located near the Middle East) having more exposure to civilization than the Northern Americas.

[UPDATE MAY 11, 2023, a previous version of this article contained a mathematical typo that was corrected after exposed in the comment section]