Wednesday 2 January 2019

An Attempt to Reconcile the Group Differences in IQ - Part 2

Earlier in October 2017, I had made an attempt to reconcile the observed group differences in IQ scores. This article is a sequel, albeit a short one, that aims to propose a working mechanism for the biological marker k, that was proposed to be responsible for the differences. This article follows the critical reasoning and inductions of its prequel.

Everything is different, but the same

Another new paper finds that the GWAS hits for IQ – largely determined in Europeans – don’t work in people of African descent. That was always a possibility: I’ve talked about it. If you look at the frequencies of height alleles (determined from GWAS in Europeans) you would predict that Pygmies are pretty short – but they’re considerably shorter than that. They have their own private alleles influencing height, which make them even shorter than you would think. Or, if you tried to estimate skin color in Koreans by the frequencies of variants that cause light skin in Europeans, you would conclude that they were black as night – but they’re not. They’re pretty light-skinned, but that’s caused by light-skin alleles common in East Asia, almost completely disjoint from the common light-skin alleles in Europeans.

So you can’t use those GWAS hits to tell how smart sub-Saharan Africans are, at least not today. All you can use are IQ measurements and achievements. It is as if the only way we could determine your height was by using a ruler, instead of GWAS predictions.

- Gregory Cochran, on his blog post.

A light that is getting brighter?

The paper that was mentioned is titled, Heterogeneity in polygenic scores for common human traits. Appropriately titled, the paper suggests differences in trait architecture between groups. And we can reasonably expect architectures to have projections.

The paper had stated that "PGSs created using weights derived from GWAS performed in individuals with European Ancestry generally do not perform as well in individuals with African Ancestry". So different groups have different trait architectures.

We may safely assume that an IQ score is a projection of the intelligence trait. If we are correct, scores within a group may be projections of their trait architecture for intelligence. 

Why so? What really is intelligence? Commenting on this, Patrick Meredith, professor of psychophysics at Leeds University, England, said: "It might be held that Frenchmen are brighter than pygmies, but if you see pygmies in their natural environment making bridges out of fibre and living life successfully you might ask what you mean by intelligence. . .". It may be that a pygmy has a different intelligence trait architecture from a Frenchman's, hence his lower IQ score (suggesting a difference in projection, but not necessarily in intelligence).

This may equally explain the anomaly of the low-IQ-score Africans not showing intellectual disability.

But as I had stated earlier, in the first article, persons of different groups at equal percentiles of IQ within their respective groups may possess similar "intelligence" represented by capacity, c for academic achievement (as an alternative -- although a weak one today -- to g which is strongly tied to absolute IQ scores).

Egypt once used to run circles around the world. The Egyptian civilization was advanced and clearly beyond others. The other groups were there, and what had happened to their intelligence? Today, Egypt has an average IQ score of 81! Of course, the Europeans (and Americans of European descent) are the kings of today. But history tells us that some other civilizations had shown a form of world supremacy -- military or economic -- in the past. Babylon, Assyria, Medo-Persia.

It may appear as if we are beginning to descend into pseudoscience. But everything adds up. 

We cannot deny the fact that becoming and sustaining a world power correlates with some form of intelligence. So what is the point? Perhaps, intelligence is a complex trait that manifests itself in alternate ways beyond just absolute IQ scores (remember Flynn effect?). Or between-group differences in IQ scores are differences in trait architecture projections.

This takes us to the topic of projection transformation or what I would like to call projection normalization. To equate the intelligence of persons of different groups at equal percentiles of IQ within their respective groups, we would have to transform their architecture projections or normalize them. Within this, lies the constant k. k is dependent on the intelligence trait architecture for a group.

1 comment:

  1. Isn't it like pygmy range shrunk due to neighbors' pressure? Wouldnt it suggests thatothers are better adopted

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