Debunking Denialism

Defending science against the forces of irrationality.

Tag Archives: human genetic variation

Genetic Clusters, Racial Medicine and Fishes

Neurologica Blog

Humans are pattern-seeking animals are are thus prone to detect patterns where none exists. We are also very interested in categorizing things, presumably because it is easier to handle cognitively. Imagine the difficulty we would have if we had to mentally treat each leaf as a separate entity and could not consider them “just a bunch of leaves”! But there is a downside to this as well, because we can be mislead and neglect complicated patterns because our categories are easy and psychological influential. These issues and questions often appear in discussions about human genetic diversity. This is enhanced by the fact that complicated genetic and computational analyses feeds us with visually striking graphs that tickle our imagination, while we do not pay equal attention to the underlying methodology.

However, reality is more complicated. Genetic clusters overemphasize differences, largely ignore similarities and is confounded by low sampling density and geographic distance. Thus, a modern analysis of human genetic variation reveals that it is, with a few exceptions, mostly clinal in nature and that notions of discrete genetic races is not an accurate description.

It is often said that ethnicity is useful in medicine, but this is also more complicated due to confounders such as health disparities, bias, discrimination, healthcare seeking behavior and compliance, as well as socioeconomic status. It turns out that ethnic status is at best a crude proxy for the alleles of a person and sequencing individuals will be much more useful. Finally, a focus on racial medicine has led to misdiagnosis of some diseases, such as sickle-cell anemia, thalassemia and cystic fibrosis.

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Mailbag: Modern High-Throughput Genomics Versus Race Realism

mailbag letter

It is time for another entry in the mailbag series where I answer feedback email from readers and others. If you want to send me a question, comment or any other kind of feedback, please do so using the contact info on the about page.

With access to constant media reporting from around the world, it is hard to ignore stories about economy, elections, crimes and war. A lot of this news reporting involve coverage that is in some way related to differences within and between countries in terms of poverty and richness, ethnic tensions, scientific progress and lack of basic resources for life. It is understandable that we often ask ourselves about the nature of such differences, how they came about, what they mean, and how we can approach them.

However, dark clouds often appear on the horizon. Political and religious groups claim to have the truth on these matters and that their particular narrative of the nature and causes of, and solutions to, world problems should be preferred over others. These are often based on ideology and beliefs, rather than the result of scientific research and rational thinking. Typically, these narratives have a substantial flaw: they are simplistic and only include a single factor or perhaps a few, while and ignore the multifactorial nature of complex problems. It is tempting to be lured into simplistic explanations for a complex world, because they are cognitively easy and allows us to put blame on one group or a few groups of people. However, they are often as false as they are naive. Instead, we should banish proposed “explanations” that try to explain a complex societal processes with simplistic causes.

After reading some of the articles on Debunking Denialism about the scientific problems with race realism, RH decided to send me an email about some of the issues he was thinking about. The topics involve genetics, heritability, inventions, poverty, national economy, crime, history, and politics.

High-throughput modern genetic studies finds very low between-group genetic variation

RH writes:

I mean how can you argue against racialism/race realism and say humanity is one race when the world just seems to contradict that?

The general answer to this question is that we must not be misled by how the world seems. Instead, we must boldly explore beyond the limited scope of our own personal beliefs and biases by testing them against broad scientific data without being selective and seeing what we want to see.

When scientists carry out high-throughput genomics research and look at 650 000 single nucleotide polymorphisms (SNPs) and close to 400 microsatellites, they find that the vast majority of human genetic variation, ranging from 84.7%-95% depending on the study and genetic elements, occurs within populations (Li et al., 2008; Rosenberg et al., 2002). Only a tiny minority of genetic variation occurs between continental groups. Thus, the available scientific evidence strongly disagree with the race realist position. Instead, human genetic diversity is better described as mostly continuous clines, with a few rare exceptions (Serre and Pääbo, 2004). Certainly, there is still a scientific debate about details as in many other areas, but this is the mainstream scientific position with regards to human genetic diversity.

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Abusing Heritability: “Libertarian Realist” Edition (Part II)

Libertarian Realist and misuse of heritabilityh

In online exchanges with proponents of pseudoscience, they often tend to derail the conversation by bringing up a large number of peripheral objections not related to the main issues. The reason behind this particular technique is a bit unclear. It could be a method used to hide the fact that substantive arguments are missing or maybe is an act of desperately finding something to object in order to attempt to cast a shadow of doubt over the arguments pertaining to the central issues. Typically, the assertions deployed by proponents of pseudoscience are merely regurgitated and counterarguments are rarely addressed. At this point, further response from scientific skeptics are by no means productive as there are far more deployed distractions than substantive arguments. On the other hand, if you do not respond right away, some may view it like you conceded the argument.

Recently, one of the most active race realists on Youtube (called Libertarian Realist) tweeted me a link to one of his videos. We had a short exchange on Twitter and I wrote a post that exposed his misunderstandings of heritability. First, by the use of deceptive wording, he made it appear as if heritability (the proportion of phenotypic variation in a population and environment that can be attributed to genetic variation) was related to the degree to which genes mattered for a given phenotype. Second, he gave the appearance that heritability estimates were informative about between-group differences (they are not). Finally, he did not seem to understand that heritability estimates depend on the population being studied and what environment they are being studied in. Because a singular, context-free estimate for a given population (especially for composite population) is misleading, this effectively undermined his excessive focus on a particular heritability estimate.

After some time, Libertarian Realist made a video response to my criticisms. However, his response largely lacked substantive content, put an excessive focus on a large number of peripheral objections unrelated to the main issues and he declined to engage with any of my six evidence-based challenges to race realism. This post will examine his response in detail. It is split up into two major sections.

Substantive issues

This first section deals with responses made by Libertarian Realist to the substantive issues I raised in my previous post. This includes topics such as the population and environment dependence of heritability estimates, the non-relevance of with-in group heritability estimates for the causes of between-group differences and the scientific case against race realism.

The bait-and-switch / false dichotomy / straw man combo: Libertarian Realist states that his position is that “genetic differences between Africans and Europeans in the United States account for a significant proportion of the observed differences in IQ distributions between the two groups”. However, he then uses a bait-and-switch tactic when he rhetorically asks viewers “So what is the alternative to the thesis that genetic differences between African-Americans and European-Americans account for a proportion of the observed IQ differences between the two ethnic groups?” Notice how Libertarian Realist has now switched between “significant proportion” and “a proportion”. Although he does not state what he considers this “significant proportion” to be, I suspect that his estimate is more than 0.5 and probably anchored around the within-group heritability estimate for IQ that he holds to (~0.75). Clearly, there are other options besides “significant” (i.e. considerable) and none. For instance, “moderate”, “minor” or “unknown”. Libertarian Realist continues with “the alternative would be that genetic differences play zero role”. In other words, Libertarian Realist tries to portray those who disagree with his position as proponents of an extreme environmental hypothesis.

Indeed, this kind of flawed approach is also taken by people in the comment section of the video.

Youtube comment by White Man

Another case of black-and-white thinking. They apparently reason that either any observed differences is mostly due to genetics, or you have to believe in the blank slate. This is a clear example of false dichotomy. Read more of this post

Mailbag: The Absurdity of Race Realism

I am always happy to answer reader emails set to me via the contact form at the About page of this blog. This email comes from “Nigel”. Nigel writes that:

Speaking about denialism, what about politically correct race-deniers? These people are so wrapped up on some ideology of Boasian Cultural Marxism that they regularly try to subvert the truth.

In just this short message, consisting of nothing more than two sentences, Nigel has managed to set off my baloney detector several times. This is because phrases such as “politically correct” and “cultural Marxism” are buzzwords frequently used by extremist right-wing…thinkers, who are often anti-immigration. “Politically correct” designates their belief that they are being suppressed by the establishment and “cultural Marxism” signifies the related idea that the establishment was been taken over by leftists who ignore the truth that race realists think is plain as day. Thus, Nigel has carried out two very common denialist tactics that I described in the article Common Denialist Tactics Defined and Destroyed, namely playing the martyr card and conspiratorial thinking: Read more of this post


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