Archive for April, 2008

Potential for Vitamin D synthesis

By Razib Khan | April 30, 2008 11:27 am

From The evolution of human skin coloration, page 12:

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CATEGORIZED UNDER: Genetics

Ben Stein is a barbarian?

By Razib Khan | April 29, 2008 1:36 pm

John Derbyshire has a long column excoriating Ben Stein and the Discovery Institute titled A Blood Libel on Our Civilization:

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CATEGORIZED UNDER: Creationism

Why it was best to be white

By Razib Khan | April 28, 2008 10:32 am

farmingflowsb.jpg

CATEGORIZED UNDER: Genetics

Margaret Sanger: anti-abortionist?

By Razib Khan | April 28, 2008 7:57 am

Over @ Stranger Fruit John Lynch points a section from a paper which recounts the Christian assocation with eugenics:

On the whole the evangelical mainstream in the decades following the turn of the century appeared apathetic, acquiescent, or at times downright supportive of the eugenics movement. In this article, I argue that the evangelicals often accepted eugenics as a part of a progressive, reformist vision that uncritically fused the Kingdom of God with modern civilization.

In Better for All the World: The Secret History of Forced Sterilization and America’s Quest for Racial Purity the author makes the case that to a large extent this was an issue of class; the higher orders, generally professing Christians of a sort, favored eugenics, while the lower class victims and their preachers naturally objected. The more progressive churches also often aggressively got behind race-betterment. This is not to deny that secularists such as H. L. Mencken were enthusiastic eugenicists on scientistic grounds; rather, it is to offer that the social realities of the day suggested that a eugenical inclination was the dominant position, one which many of the Christian churches acceded to reinforce their relevance to contemporary society and its ills (it is notable that the Roman Catholic church in Europe was more successful in blocking eugenics in the nations in which it was powerful than the Protestant churches of northern Europe were, assuming the latter were so inclined).1

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CATEGORIZED UNDER: Culture

Gene Genie #30

By Razib Khan | April 27, 2008 1:49 am

gene_genie_logo_400.jpgWelcome to the 30th Gene Genie!
Indulge in the fascinating world of Radiology and Nuclear Medicine has a “genetics lifestyle” post, Home Improvement For Geneticists. Not quite Tim Allen. Fellow ScienceBlogger Sandra illustrates Mapping polymorphisms in 16S ribosomal RNA. Definitely worth checking out, anyone interested in biology should be down with ribosomes, and rRNA has also been critical in taxonomy. Biotech Weblog notes that Gene Therapy May Treat Cocaine Addiction. ‘nuf said. Migraines affect about 1 out of 6 people in the world; so pay attention when Genetics and Health suggest the possibility for a Genetic breakthrough for migraine sufferers. KQED’s Quest offers a podcast which illuminates the light shed upon Human Genetics through Dogs. Have you read The History and Geography of Human Genes? Then you must read Yann Klimentidis, p-ter and G; beware of how PCA is displayed! We live in a world where hundreds of thousands of Americans are currently stationed in Iraq. So it is probably important to wonder about A Genetic Susceptibility to PTSD?, as Brain Blogger does. Think Gene engages in a little heresy from the Central Dogma, blogging the revolution as Scientists clarify a mechanism of epigenetic inheritance. Are you going to be well aged? Ouroboros asks Is there anything SIRT1 can’t do? It might be part of the answer, along with a helping hand from our friends at Big Pharma. You hear a lot about Hox genes, especially with the rise of evo-devo, DNA and You makes it a bit personal. A HOXA2 mutation is responsible for one type of autosomal recessive microtia (congenital deformity of the outer ear), a mouthful that remains relevant.
Speaking of which, let’s move specifically into the domain of Personalized Genetics:

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CATEGORIZED UNDER: Genetics

Talk Islam

By Razib Khan | April 26, 2008 3:56 am

Just a heads up, I’ve been posting now and then to the quasi-Twitteresque site Talk Islam run by my friend Aziz Poonawalla. I also have a sub-weblog where I’ll be posting some of my longer form ruminations…but it might be best to just sign up for the RSS so you’re notified when I start posting there regularly. I’ve been reading God’s Rule – Government and Islam: Six Centuries of Medieval Islamic Political Thought on & off for weeks now, and I think I’ll put up a review over there after I’m done….

CATEGORIZED UNDER: Religion

The Inner Asian gap: the Afanasievo breakthrough

By Razib Khan | April 25, 2008 11:02 pm

If you read this weblog you are aware that I have a fascination with the intersection of human history and human evolutionary genetics. There are many questions I have about the finding from evolutionary genomic studies that light skin evolved at least twice independently in Eurasia within the last 20,000 years or so at the extremities. The selection coefficients are large, so I am confused as to why even minimal gene flow did not result in equilibration and homogenization of the allelic profiles of the populations. I have posited that the answer has to do with very low population densities verging upon nil in Central Asia. From The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World (a book I can not recommend enough!):

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CATEGORIZED UNDER: History

Katz

By Razib Khan | April 25, 2008 4:17 am

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CATEGORIZED UNDER: Blog

Behavior genetics + neuroscience + genomics = ?

By Razib Khan | April 25, 2008 3:36 am

Genetic variation in human NPY expression affects stress response and emotion:

Understanding inter-individual differences in stress response requires the explanation of genetic influences at multiple phenotypic levels, including complex behaviours and the metabolic responses of brain regions to emotional stimuli. Neuropeptide Y (NPY) is anxiolytic…and its release is induced by stress…NPY is abundantly expressed in regions of the limbic system that are implicated in arousal and in the assignment of emotional valences to stimuli and memories…Here we show that haplotype-driven NPY expression predicts brain responses to emotional and stress challenges and also inversely correlates with trait anxiety. NPY haplotypes predicted levels of NPY messenger RNA in post-mortem brain and lymphoblasts, and levels of plasma NPY. Lower haplotype-driven NPY expression predicted higher emotion-induced activation of the amygdala, as well as diminished resiliency as assessed by pain/stress-induced activations of endogenous opioid neurotransmission in various brain regions. A single nucleotide polymorphism (SNP rs16147) located in the promoter region alters NPY expression in vitro and seems to account for more than half of the variation in expression in vivo. These convergent findings are consistent with the function of NPY as an anxiolytic peptide and help to explain inter-individual variation in resiliency to stress, a risk factor for many diseases.

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CATEGORIZED UNDER: Genetics

No Anglo-Saxon Apartheid?

By Razib Khan | April 23, 2008 12:08 pm

Is it necessary to assume an apartheid-like social structure in Early Anglo-Saxon England? :

It has recently been argued that there was an apartheid-like social structure operating in Early Anglo-Saxon England. This was proposed in order to explain the relatively high degree of similarity between Germanic-speaking areas of northwest Europe and England. Opinions vary as to whether there was a substantial Germanic invasion or only a relatively small number arrived in Britain during this period. Contrary to the assumption of limited intermarriage made in the apartheid simulation, there is evidence that significant mixing of the British and Germanic peoples occurred, and that the early law codes, such as that of King Ine of Wessex, could have deliberately encouraged such mixing. More importantly, the simulation did not take into account any northwest European immigration that arrived both before and after the Early Anglo-Saxon period. In view of the uncertainty of the places of origin of the various Germanic peoples, and their numbers and dates of arrival, the present study adopts an alternative approach to estimate the percentage of indigenous Britons in the current British population. It was found unnecessary to introduce any special social structure among the diverse Anglo-Saxon people in order to account for the estimates of northwest European intrusion into the British population.

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CATEGORIZED UNDER: Genetics

Want sons? Eat well!

By Razib Khan | April 22, 2008 11:01 pm

Mother’s Diet Influences Infant Sex: High Energy Intake Linked To Conception Of Sons:

…The study shows a clear link between higher energy intake around the time of conception and the birth of sons. The findings may help explain the falling birth-rate of boys in industrialised countries, including the UK and US.
The study focused on 740 first-time pregnant mothers in the UK, who did not know the sex of their fetus. They were asked to provide records of their eating habits before and during the early stages of pregnancy. They were then split into three groups according to the number of calories consumed per day around the time they conceived. 56% of the women in the group with the highest energy intake at conception had sons, compared with 45% in the lowest group. As well as consuming more calories, women who had sons were more likely to have eaten a higher quantity and wider range of nutrients, including potassium, calcium and vitamins C, E and B12. There was also a strong correlation between women eating breakfast cereals and producing sons.

What’s going on? Probably the Trivers-Willard Hypothesis:

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CATEGORIZED UNDER: Genetics

Obama & McCain & Clinton on autism

By Razib Khan | April 22, 2008 2:27 pm

Seems like both the Republican nominee and the likely Democratic nominee entertain the autism and vaccination “hypothesis”. I don’t follow politics very closely, this sort of comment really disturbs me….
Via TNR.
Update: And Clinton too.
Update II: Insolence & Aetiology have more.

CATEGORIZED UNDER: Science

Drugs that make you smart?

By Razib Khan | April 22, 2008 3:21 am

A follow up to the scientists & drugs topic, Wired‘s current issue is devoted to cranking up your intelligence. Most of the advice is kind of kooky, but there is a neat chart of mind-amping drugs if you are so inclined.

CATEGORIZED UNDER: Biology

What L. L. Cavalli-Sforza got wrong?

By Razib Khan | April 21, 2008 11:39 pm

History and Geography of Human Genes is one of my favorite books; it might rank up there in my “top 10″ if I ever wished to enumerate one. But in both Human Evolutionary Genetics, a textbook, and A Genetic and Cultural Odyssey, a biography of L. L. Cavalli-Sforza, it was noted that the PCA maps pioneered in History and Geography of Human Genes have never really caught on. There might be a reason…Interpreting principal component analyses of spatial population genetic variation:

Nearly 30 years ago, Cavalli-Sforza et al. pioneered the use of principal component analysis (PCA) in population genetics and used PCA to produce maps summarizing human genetic variation across continental regions…They interpreted gradient and wave patterns in these maps as signatures of specific migration events…These interpretations have been controversial…but influential…and the use of PCA has become widespread in analysis of population genetics data…However, the behavior of PCA for genetic data showing continuous spatial variation, such as might exist within human continental groups, has been less well characterized. Here, we find that gradients and waves observed in Cavalli-Sforza et al.’s maps resemble sinusoidal mathematical artifacts that arise generally when PCA is applied to spatial data, implying that the patterns do not necessarily reflect specific migration events. Our findings aid interpretation of PCA results and suggest how PCA can help correct for continuous population structure in association studies.

If this critique holds up, it’s a step back for the synthesis of genetics & history. But so it goes. Science is fundamentally about proper method, not congenial outcome. G & p-ter comment futher. G’s point is important to keep in mind:

…These results do not to say that human populations did not expand out of particular regions, just that PCA maps are not the best tool to judge this. The authors also note that this does not invalidate the use of PCA to correct for structure in association studies, and in fact might aid in their interpretation in epidemiological models.

Related: My 10 questions for L. L. Cavalli-Sforza.

CATEGORIZED UNDER: Genetics

Vitamin D deficiency makes you dumb?

By Razib Khan | April 21, 2008 4:15 pm

Vitamin D Important In Brain Development And Function:

McCann & Ames point out that evidence for vitamin D’s involvement in brain function includes the wide distribution of vitamin D receptors throughout the brain. They also discuss vitamin D’s ability to affect proteins in the brain known to be directly involved in learning and memory, motor control, and possibly even maternal and social behavior. The review also discusses studies in both humans and animals that present suggestive though not definitive evidence of cognitive or behavioral consequences of vitamin D inadequacy. The authors discuss possible reasons for the apparent discrepancy between the biological and behavioral evidence, and suggest new, possibly clarifying avenues of research.

As you might know, it seems that most dark-skinned people at higher latitudes have a deficiency. Also, tests of natural selection seem to suggest that humans have become far lighter over the past 10-20,000 years. Why?
Here’s the citation:
McCann, JC, Ames BN (2008) Review Article: Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction” FASEB J. 22: 982-1001.
The paper is not online yet….
A word of caution: many nutrients are involved in thousands of biochemical pathways. The main reason I focus on Vitamin D is that the data for selection of lighter skin at northern latitudes is very powerful….

CATEGORIZED UNDER: Biology

Racial differences & heart attacks

By Razib Khan | April 21, 2008 4:10 am

If you don’t like the word “racial,” just substitute “population.” In any case, Many African-Americans Have A Gene That Prolongs Life After Heart Failure:

About 40 percent of African-Americans have a genetic variant that can protect them after heart failure and prolong their lives, according to research conducted at Washington University School of Medicine in St. Louis and collaborating institutions.

“By mimicking the effect of beta blockers, the genetic variant makes it appear as if beta blockers aren’t effective in these patients,” he explains. “But although beta blockers have no additional benefit in heart failure patients with the variant, they are equally effective in Caucasian and African-American patients without the variant.”

The researchers…found that 41 percent of African-Americans have a variant GRK5 gene that more effectively suppresses the action of adrenaline than the more common version of the gene. People with the variant gene could be said to have a natural beta blocker, Dorn says. The variant is extremely rare in Caucasians, accounting for its predominant effects in African-Americans.

Here’s the original paper, A GRK5 polymorphism that inhibits bold β-adrenergic receptor signaling is protective in heart failure:

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CATEGORIZED UNDER: Genetics

Expelled, success or not?

By Razib Khan | April 20, 2008 11:55 pm

Chris Mooney is claiming Expelled is a box office success. Documentaries don’t make a very big splash typically, but whatever you think about the impact of Expelled, the fact that Fahrenheit 9/11 will go down as a much bigger success illustrates the contrast between depth and breadth of feeling from their respective audiences. Michael Moore’s politics have a smaller potential audience than the half of Americans who are Creationist, and the 3/4 of Americans who are open to the idea of “equal time,” but the devotees of Moore’s brand of Leftism are far more intense in their sentiment. I am not totally ignorant of the dynamics of Creationist politics in the United States, the history seems to be one where every time the movement manages to exceed a particular threshold of success a counter-reaction quickly dampens its damage. Despite the broad sympathy from the masses for the Creationist cause the intensity of elite feeling on this topic means that a position held by half of Americans remains marginal in the commanding heights of the culture.
Here’s the assessment from Weekend Box Office:

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CATEGORIZED UNDER: Creationism

Massimo Pigliucci gets married?

By Razib Khan | April 20, 2008 1:32 am

Massimo Pigliucci‘s wedding profiled in The New York Times… (did a double-take when I saw that on the front page…but it’s for real)

CATEGORIZED UNDER: Uncategorized

Expelled was OK…

By Razib Khan | April 19, 2008 7:33 pm

…as a piece of propaganda. I noticed that the local “art house” theater was screening Expelled, so I decided to check it out. There weren’t many people there. It started off very heavy-handed, a montage of archetypical scenes from the Communist and Nazi regimes, but the production values & execution of the first half of the documentary wasn’t half bad. I assume the producers were pitching this to a sympathetic autidence, so the intent was glamorize and present the argument effectively, not convert anyone to the message. The interviews with the eminences of the Intelligent Design movement were presented in very tight “sound bite” formats, in appealing settings with natural light. In contrast, the anti-Creationists were depicted in a far less flattering fashion; the lighting often artificial and harsh, the angles strange, and the cutting often was choppy. There wasn’t really that much data or new evidence in the film, and the arguments for and against Intelligent Design weren’t really explored with any depth. It was a superficial exposition of the issures, but Expelled does a good job of being less embarrassing than the ameteurish films that Creationists have been peddling for years (this is a low bar, I know).

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CATEGORIZED UNDER: Creationism

Americans are good at murder?

By Razib Khan | April 18, 2008 1:36 pm

Some debate below about the various parameters which shape social pathologies. One of facts which we are well aware of is that the United States has a lot of homicide compared to other developed countries. But another fact which is also well known is that a disproportionate number of these murders are committed by racial & ethnic minorities, as well as by particular subcultures (e.g., Southerners vs. New Englanders). So I took the state-by-state homicide rate and compared them to the international data for selection nations. Results below the fold….

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CATEGORIZED UNDER: Culture
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