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Gene variant linked to language learning

8 Jul

Unfortunately this paper is behind a paywall, so it is hard to evaluate it. The claim is that a variant of the FOXP2 gene is associated with superior ability to learn a second language. Here is the abstract:

“A mutation of the forkhead box protein P2 (FOXP2) gene is associated with severe deficits in human speech and language acquisition. In rodents, the humanized form of FOXP2 promotes faster switching from declarative to procedural learning strategies when the two learning systems compete. Here, we examined a polymorphism of FOXP2 (rs6980093) in humans (214 adults; 111 females) for associations with non-native speech category learning success. Neurocomputational modeling results showed that individuals with the GG genotype shifted faster to procedural learning strategies, which are optimal for the task. These findings support an adaptive role for the FOXP2 gene in modulating the function of neural learning systems that have a direct bearing on human speech category learning.”


Domestication and brain size in trout

20 Mar

I have to confess, I didn’t even know that there was such a thing as domesticated trout before I read this paper, “Aggressive Behavior, Brain Size and Domestication in Clonal Rainbow Trout Lines,” in the journal Behavior Genetics. But they do exist.

In the process of domestication, animals undergo intense artificial selection that make them different from their wild cousins. There is a line of speculation that human beings are, in effect, self domesticated. Thus, a better understanding of domestication might lead to a better understanding of ourselves.

Here is the abstract from the paper:

“Domestication causes behavior and brain size changes in many species. We addressed three questions using clonal rainbow trout lines: What are the mirror-elicited aggressive tendencies in lines with varying degrees of domestication? How does brain size relate to genotype and domestication level? Finally, is there a relationship between aggressive behavior and brain size? Clonal lines, although sampling a limited subset of the species variation, provide us with a reproducible experimental system with which we can develop hypotheses for further research. We performed principal component analyses on 12 continuous behavior and brain/body size variables and one discrete behavioral variable (“yawn”) and detected several aggression syndromes. Two behaviors, “freeze” and “escape”, associated with high domestication; “display” and “yawn” behavior associated with wild lines and “swim against the mirror” behavior associated with semi-wild and domestic lines. Two brain size traits, total brain and olfactory volume, were significantly related to domestication level when taking total body size into account, with domesticated lines having larger total brain volume and olfactory regions. The aggression syndromes identified indicate that future QTL mapping studies on domestication-related traits would likely be fruitful.”


Gene linked to longevity and brain volume

6 Feb

The enzyme Klotho affects the sensitivity of cells to the hormone insulin. The amount and type of Klotho in cell membranes seem to affect how long an animal will live. These factors are under genetic control.

Research published in The Annals of Clinical and Translational Neurology suggests that these genes may also play a role in brain volume. From the paper’s conclusion:

“Our data reveal that carrying a longevity-promoting variant of KL is associated with greater frontal brain volume and executive function. In two independent cohorts of healthy, cognitively normal older adults, carrying one copy of the KL-VS haplotype was strongly associated with greater volume of rDLPFC, a region vulnerable to structural and functional decline with aging.[8, 43-46] This advantage was limited to heterozygotes, as homozygotes tended to show reduced volume and function. The results of this study suggest that genetic influences on longevity, such as KL variants, may also promote structural and functional integrity of the brain.”


The genetics of coffee consumption

13 Oct

A paper in the journal Molecular Psychiatry reports on six genetic loci linked to coffee consumption. You can find the abstract here. PBS has a good summary.

“Findings published today in Molecular Psychiatry confirm the long suspected belief that genetics determine coffee drinking behavior. Scientists have now pinpointed six new gene variations that are more common in those who gulp down the caffeinated beverage frequently.

That’s in addition to two previously identified genetic variants that each code for biological traits. We now have eight loci on record that account for an underlying propensity to drink coffee.

The large-scale study of 120,000 regular consumers provided researchers at the Harvard School of Public Health and Brigham Women’s hospital with ample data. In analyzing the subjects’ genetic makeup via DNA sequencing and comparing it to self-reported coffee drinking figures, the scientists were able to determine why some people need more of the stimulant than others for optimal caffeine effect.”

Is coffee good for us? Dr. Greger weighs in:

Genetics of math and reading

30 Sep

Yesterday, I blogged about the misuse of the word “proof” by science journalists. Wouldn’t you know it, later, I came across this blog post, which tells us:

“Now, a new study proves that people who are good at reading are also quite naturally talented at math.”

Actually, not really. The study, in and of itself, is quite interesting, but this blogger, apparently relying on an LA Times piece rather than the original paper, gets a number of the details wrong.

You can read the original paper here. The abstract reads:

“Dissecting how genetic and environmental influences impact on learning is helpful for maximizing numeracy and literacy. Here we show, using twin and genome-wide analysis, that there is a substantial genetic component to children’s ability in reading and mathematics, and estimate that around one half of the observed correlation in these traits is due to shared genetic effects (so-called Generalist Genes). Thus, our results highlight the potential role of the learning environment in contributing to differences in a child’s cognitive abilities at age twelve.”

One of the big confusions that accompanies a study like this is the misunderstanding of the concept of heritability. Heritability is not a measure of the percentage of a trait is caused by genes. It is not even an individual level measure of a trait, it is a measure of how much of the variance in a population is genetic.

One of the consequences of this is that heritablity is not fixed, it will be affected by the level of environmental variance. We can see this by a simple thought experiment. Imagine a society with total absolute equality between individuals. In that circumstance, since there would be no difference in environment, heritablity would be one hundred percent. This conclusion, strikes many as counterintuitive but if you contemplate it for a while you will see that this must be true.


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