Of course there is a biological claim. Intelligence is hereditary, so certain populations may have higher average IQs than the others. Also we can see that in nature - every dog owner will tell you that certain races of dogs are of higher average intelligence than the others.

We also know that many - if not most - character traits are also genetic. There has been a ton of twin studies and adoption studies proving that. A book "Blank Slate" has multiple examples.

Having said that, I agree with keeping the research on race and intelligence/character a taboo. We know where such research leads to, and if there is a part of science better left unexplored, it would be this one.

Dog intelligence is not measure by a single number on a test designed with factor analysis. Dog intelligence is basically a vague scent people give to them loosely based on how obedient they are. And dogs have also been explicitly breed by this vague scent. Humans have never been breed to score differently on an IQ test (although some eugenicist really wanted to).

As for the twin studies, they have been largely debunked at this point. There is an inherit bias (pun not intended) where twins are much more likely to be adopted into a specific socio-economic group—confirming the fact that IQ measures social status more then intelligence (for some arbitrary definition of intelligence). But on top of that, it turned out that twin-studies were reeked bad science, everything from forged data to biased sampling.

Like I said, this isn’t science, it is pseudo-science, there is nothing to explore except for historians showing how easily scientific racism was endorsed by academia for well over a century.

Huh? Twin studies and adoption studies are two different things, and you are talking about twins being adopted?

Also - are claiming that intelligence is a purely social construct? I would need a citation on that, because as far as I know it was always considered to be inherited.

As far as I’m aware the gold standard for estimating the heritability of intelligence are twins that have been adopted into different families. You compare the variance of monozygotic twins adopted into separate families to the variance of dizygotic. If there is greater variance between dizygotic twins you can conclude, since the monozygotic twins share close to 100% of their genes, that the diminished variability can be explained with their shared genes.

However, like I said, there are problems with this assumption, mostly from sampling bias. But you can also argue that the twins share environment while in the womb, the bacterial environment actually interacts with your genome so the shared genome is not actually 50% vs. 100% but somewhat lower. But my problem is actually related to the definition of intelligence. There is no consensus that IQ is an accurate estimate of intelligence, far from it.

Between-breed variation is an order of magnitude higher than human genetic variation.

No it isn't, the human breeds are very different and africans have been separated from other humans for >50k years in very different environments. Even Darwin recognized the differences are massive and some populations seem like different species.

The human genome wasn’t recognized in Darwin’s time so there is no surprise that he would underestimate how much of our genome is actually shared.

> africans have been separated from other humans for >50k years

This is flat out not true. People have always traveled and intermarried between Europe, Africa and Asia. Even the Roman Empire included parts of all three continents. There are only a few populations that have historically been separated for 50k years (which is not a long time in genetic terms) and it is only if you define intelligence in really euro-centric terms where you could claim that natural selection has resulted in those populations being less intelligence then the afro-eurasian population. In other words, this is a racist talking point.

It doesn't matter how much of the genome is shared, what matters is how large the phenotypic differences are. Same with dog breeds who share a large portion of their genome but are very different. This is classic Lewontin's fallacy.

And no, there wasn't much gene flow at all between africans and non-africans, and selection operated strongly during that timeframe due to things like different degrees of civilization between populations creating massively different selective pressures.

If the definition of intelligence corresponds strongly to thriving in complex large-scale civilizations, some populations are far less adapted. It's not like calling it "ability to thrive in current society" is going to please the science-denialist crowd.

If that is true, then you have to find the phenotypes that matter. So far, after a century of trying, they only exist after an extensive factor analysis in intelligence testing, a statistical method known for giving biased results if you feed it with biased data.

No, if anything there would be a natural selection against intelligence. As society grows more complex there is less and less need for any individual to be smarter as humans operate better collectively. However for such a minor trait in the overall scheme of survival, I doubt there has been any time in the past 50k years to select for or against it.

As for continental differences in humans. Humans are a remarkably homogeneous species. Isolated populations are far less common among humans then among other mammals. Any difference between population is bound to be insignificant next to the difference between individuals. I am aware Lewontin’s fallacy (it is weird, that Lewontin’s “fallacy” is always brought up at this point; as if the goalpost keeps shifting. See https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...)

> use a single metric to assess something as broad and vague as intelligence.

That's not what IQ is trying to do. It's just trying to create a score that represents how well you do on IQ tests, and that score happens to be correlated with some outcomes after correcting for confounders.

I have not seen any evidence that shows IQ isn't heritable, so I'm left to believe that, like many other traits, it is. At least to an extent.

Modern IQ tests are based on factor analysis. The theory goes something along the line that different segments with in the test (e.g. spatial reasoning, basic logic, etc.) correlate with each other and form a single intelligence factor called g. There might be some tests out there that only claim to measure a made up metric called IQ (similar to the SAT) however most modern IQ tests are designed to estimate this g-factor. This is off course pseudo-science as the only evidence that this g-factor exists is from these tests.

Now does this score correlate with some behavior, off course it does. Do groups vary on IQ-scores, off course they do. However, the behavior you can explain with IQ is nothing you couldn’t explain with astrology (outside of very low IQ-scores, which mostly correlate with mental disabilities). They do predict education prospects, but not much better then you parent’s wealth does, and certainly no better then SAT scores. IQ is not a trait, it is a metric, just like SAT scores.

As for group difference, it has been shown over and over again that this group difference can be explained with other more useful metrics like access to education, or your diet. Is it heritable? No. The research accumulated to demonstrate that (mostly done in the latter half of the last century) is reeked with bad science, including forged data, statistical manipulation, false assumptions, etc. The burden of proof is actually on the IQ people. They’ve spent more then a century trying to prove a racial difference, and they have so far utterly failed. Because there isn’t any, and their whole endeavor is pseudo-science.

This is almost all wrong and no actual intelligence researcher agrees with any of it. IQ is substantially heritable and the group difference has persisted for a very long time, and even survives admixture based studies where mixed individuals place as expected regardless of skin color or other factors. The gap is largely genetic.