In part 1 of this series I described an extremely important study where 35 children of varying degrees of Australoid ancestry, adopted into ordinary white homes in Adelaide, South Australia, were intelligence tested. One of the tests used was called “Conservation of Quantity” and is based on Jean Piaget’s theory that the human mind develops through stages. For example, very young children and very retarded adults, think that if you dump a cup of tea into a tall and skinny glass, causing the water to stretch out, you suddenly have more tea. They may also think that if you take some cookie dough and flatten into a really big circle, you suddenly have more cookie. Or they may think that if you take 4 pennies, and spread them apart on the table so they take up more space, you suddenly have more pennies.

However as the mind matures, we suddenly understand this is nonsense. Substances conserve their amount regardless of the form they take. What makes this a great intelligence test is that very few of us are ever taught conservation, but at a certain age we just get it, like the kid in this quick video.

An interesting question is do we get it because life experience teaches us, or do we get it because of the physical maturation of the brain? I suspect a toddler could play with water everyday for a year and never grasp conservation, but an adult, who was raised with no exposure to liquid (he drank only from a straw from a lidded cup and thus never saw it) or any other malleable substance, would immediately grasp it, simply because his brain was neurologically developed.

I don’t know the exact questions the kids in the study were asked but the results can be crudely inferred from the below graph. I may have to revise some of these numbers since reading from a graph is not an exact science, but it seems that at age eight, 87% of white kids tested in Canberra, Australia in 1969, grasped quantity conservation but only about 18% of Australian aboriginals tested the same year at Hermannsburg mission did. Assuming both groups formed a bell curve with similar variance, that suggests the Australoid bell curve is 2.07 standard deviations to the left of the white one.

At age nine, it seems 97% of white kids grasp quantity conservation, but only 38% of Australoids do, however among the Adelaide sample (largely hybridized Australoids adopted by whites), about 72% do. From these data, it seems the white > Australoid gap is 2.2 SD, while the white > mixed Australoids raised by whites gap is 1.3 SD. At age 10, there’s no data for the mixed race adopted Australoids, but only 27% of the traditional Australoids do while 97% of whites do, suggesting a gap of 2.47 SD.

At age seven, 67% of the whites grasped quantity conservation while 50% of the part-white Australoids adopted by whites did, suggesting a gap of 0.47 SD. The percentage of traditional Australoids who grasped it this young is too small to measure.

Source: Dasen, P. R., de Lacey, P. R., & Seagrim, G. N. (1973). Reasoning ability in adopted and fostered Aboriginal children. In G. E. Kearney, P. R. de Lacey, & G. R. Davidson (Eds.), The psychology of Aboriginal Australians, (pp. 97-104). Sydney: Wiley.

Averaging the data, the whites scored 2.25 SD higher than traditional Australoids, and 0.89 SD above the part-white Australoids raised by whites.

However the paper notes, “Canberra children, forming the comparison group for conservation of quantity, tend to come from relatively high-socioeconomic levels of the population”. By contrast the paper noted that the adopted part-white Australoids were raised by typical whites and I assume, the traditional Australoids were raised by typical Australoids.

In 2016, about 36% of the Canberra population (age 15+) had a Bachelor Degree level education or higher, compared to 22% for Australia as a whole. While I don’t have stats from circa 1970, assuming its education rank has been stable, the average Canberra adult was about 0.47 SD above the average Australian, and given about a 0.7 correlation between IQ and education, about 0.47(0.7) = 0.33 SD smarter than the average Australian, and given the 0.5 correlation between the IQs of parents and their kids, the children were likely 0.33(0.5) = 0.16 SD smarter than the average Australian (white kid).

So because Canberra kids were used as the white sample, we need to reduce their scores by 0.16 SD to adjust for their above average IQs. Thus the true white > traditional Australoid IQ gap becomes 2.09 SD (31 IQ points) and the true white > part-white & raised white Australoid gap becomes 0.73 SD (11 IQ points).

The IQ of Australoids raised by whites is an estimate of the genetic IQ of Australian aboriginals, and as mentioned, they score 11 points below whites. However because these had only 58% Australoid ancestry (on average) the expected IQ of an unmixed Australoid raised by whites would be 11/0.58 = 19 points below the white mean, or IQ 81.


On a scale where white Australians average IQ 100 (SD = 15) on a test of quantity conservation, the average unmixed Australian aboriginal likely scored about IQ 69 (1.9 percentile of the white distribution). However if raised in the same environment as whites, their IQ increases to 81, suggesting about 61% of the white > Australoid IQ gap is genetic. The effect of adoption at near infancy from a traditional fringe dwelling Australoid family into an average white family is to raise IQ by 12 points which is actually a lot considering how culture-fair conservation tests are thought to be (by some).

But perhaps not this one. The paper states: “the subject has to be able to justify his conclusions with fairly sophisticated explanations. Those children demonstrating conservation but unable to justify it receive a lower classification than those who can justify it”

Still, the effect of adoption is much less on this test than it was on the Picture Vocabulary test discussed in part one, so it’s a relatively culture fair test.