The Misguided IQ Debate

Candice eetimesThere has been an uptick in the number of articles, podcasts, and online debates about IQ differences between groups, most especially regarding the so-called ‘races’ and of course between the sexes.  There are typically two sides, both equally right and at the very same time equally wrong.  One side cites IQ studies that show that there are differences between groups and thus conclude that there are genetic differences between them.  The other side says that is pure racism or sexism.  The first side then claims that the second side is anti-science and knee jerk “social justice warriors”.

In all of this debate, I have read only one man, who straddled both sides, who came closer to the right answer when he said that those talking about the IQ differences in the science literature is about two different phenomena.  One, is where we note that there are average differences between defined groups.  The other is where we research the genetics of IQ.  The two do NOT meet.  Sadly, he failed to go into enough detail to explain why.

First, lets talk about the genetics studies of IQ.  The first thing researchers wanted to know is what it the “heritability” of IQ.  To do this they used twin studies, noting the differences and similarities in IQ scores of  identical vs fraternal twins in situations where they are raised together vs apart.  This leads to four different cases.  In one case, it is assumed that both siblings share both genetic and environmental influences while in the other case, only 50% of the genes are shared while maintaining the same early environmental influences if they are raised together.  If raised apart… well, you get the idea.  From this, studies have led to estimates of 50% to 80% heritability.  That is to say, that genetic differences can account for half to 80% of the VARIABILITY of IQ scores.

Remember, so far, we’ve been looking at the variability of individuals within a population, not the differences between populations.

Here we need to understand why the studies show such widely different results.  It is caused by the very nature of environmental influences.  The closer to optimal environmental conditions, the greater the genetics will explain the variability and thus the presumed heritability.  If everyone in a study had absolutely perfectly optimal environmental conditions, or even just the same environmental conditions, ALL of the variability would have to be from the genetic differences and thus a study would show that IQ was 100% heritable.  But life is never the same for two individuals.  And they certainly aren’t the same, nor optimal, for all individuals everywhere for all time.

Thus, the differences in environmental conditions may (they don’t have to automatically be this way) lead to greater variability in a population and thus lower the estimates of heritability.  The question to be asked is how sensitive is IQ to differences in environmental conditions?  The answer is… an amazing amount !  How do we know this?  The Flynn Effect.

Please take a moment to read the Wikipedia entry on the Flynn Effect (so I don’t have to repeat what it says):

The Flynn effect describes the changes in average IQ scores in the same genetic population (gene pool) over a very short period of time.  We don’t have to know what causes the effect.  We need only note that the effect has caused a significantly larger change in average IQ within genetic populations over time than the putative differences found between populations (and in the difference in range of IQ between the sexes).  Is it too much of a stretch to conjecture that any putative differences found between populations is more likely to be attributable to environmental differences, that populations are distributed along different points of the Flynn Effect, than to any putative differences in genetics?

Thus, we see that one group has jumped to the wrong conclusion about the differences between populations because of ‘racial’ bias and another group is reacting in an anti-science manner out of fear that any conclusion will adversely effect disadvantaged populations. Both are wrong.

The number of genes and the number of environmental factors are both very large… too large to come to any conclusion regarding putative differences between populations at this time.

Besides, this argument is looking at the wrong thing.  We shouldn’t be looking at the genetics.  We should be looking at the data to find out what is the optimal environment and ensuring that each and every human being on the planet experiences it.

Further External Reading:

So is it nature not nurture after all?

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