razib | September 11, 2007A comment on another weblog asked why the United States might have a confrontation with China at some point in the future. They pointed out, correctly, that Chinese imperialism has been weak tea in comparison to the world-striding European form. That is, the Middle Kingdom asserted a pretense of being the universal empire, but engaged in little projection of imperialism outside of its traditional sphere of influence (e.g., Korea, Vietnam and the Tarim Basin). That is the past, and it should inform our perception of the course of the future. But prior information needs to be updated with…
razib | September 11, 2007Foetal testosterone linked to autistic traits:
This latest update on their progress, presented by Simon Baron-Cohen and Bonnie Auyeung at the British Association's Festival of Science in York today, shows that the correlation between foetal hormone levels and autistic-trait behaviour continues as the children grow up.
...Baby boys produce more testosterone in the womb, which means they can also expose a non-identical female twin to higher levels of the hormone. But other genetic and environmental factors are thought to also play a role.
This is of course part of Simon Baron-Cohen's research…
razib | September 10, 2007I'm sure you know about Alex passing, well, I noticed he made the front page of The New York Times website! Here's the obit & profile.
razib | September 10, 2007Loss of ACTN3 gene function alters mouse muscle metabolism and shows evidence of positive selection in humans:
More than a billion humans worldwide are predicted to be completely deficient in the fast skeletal muscle fiber protein α-actinin-3 owing to homozygosity for a premature stop codon polymorphism, R577X, in the ACTN3 gene. The R577X polymorphism is associated with elite athlete status and human muscle performance, suggesting that α-actinin-3 deficiency influences the function of fast muscle fibers. Here we show that loss of α-actinin-3 expression in a knockout mouse model results in a…
razib | September 10, 2007The Austrian Economists and Dani Rodrik have been talking about the use of mathematical formalism in their field. I think Rodrik gets it right:
In other words, we use math not because we are smart, but because we are not smart enough.
The low level of mathematics that I am familiar with, calculus, linear algebra, statistics and probability, is an aid to clear thinking, not an enabler of scientific obscurantism. Most people of some intelligence can understand the logic behind calculus and linear algebra, and one doesn't need to derive proofs from first principles to obtain greater insight…
razib | September 10, 2007I've been bandying a particular hypothesis about lately in terms of human evolution: strong recent selection for adaptive alleles will result in a fitness drag due to pleiotropic effects. In short, I'm working with the assumption that a new mutant which has significant positive benefits because of a phenotypic change is also liable to foul up other functional pathways. Sickle cell as an adaptation to malaria is a classic case of this; the fitness benefits of heterozygosity are great enough to outweigh the drag of a proportion of anemic homozygotes (this is a case of balancing selection via…
razib | September 9, 2007Over at 2 Blowhards there's an interview with Greg Cochran. Greg is of course a "friend of the blog," and you mostly know him because of his work in the area of evolution. But he does have strong opinions on other topics, as you might have noticed if you subscribe to The American Conservative. Part II is coming up tomorrow.
razib | September 9, 2007Recently I've been reading a fair amount of material in economics. In addition to popular books on specific economic topics aimed such as Farewell to Alms and Knowledge and Wealth of Nations, I've been hitting texts such as Hal Varian's Intermediate Microeconomics.
As I told a friend of mine who is an economist the learning curve is definitely a bit gentler because the formalism in much of low level economics isn't that different from evolutionary biology, as attested by the parallel developments of game theory within the two fields in the mid-20th century. Mathematical tools from…
razib | September 9, 2007Diet and the evolution of human amylase gene copy number variation:
...We found that copy number of the salivary amylase gene (AMY1) is correlated positively with salivary amylase protein level and that individuals from populations with high-starch diets have, on average, more AMY1 copies than those with traditionally low-starch diets. Comparisons with other loci in a subset of these populations suggest that the extent of AMY1 copy number differentiation is highly unusual. This example of positive selection on a copy number-variable gene is, to our knowledge, one of the first discovered in…
razib | September 7, 2007Over at my other blog I reaffirm Richard Dawkins' criticism of Freeman Dyson's off the cuff opinions about evolutionary genetics. Dyson is basically asserting that the rate of evolution is inversely proportional to the square root of population size. In short, small populations evolve fast in his mind because of stochastic fluctuations, clearly drift. I've posted a fair amount about stochastic dynamics...and it's complicated. Science is complicated. That's just life.
Now, Dyson is pretty much wrong. But his intuition is conventional; I've met many people who believe that somehow…
razib | September 7, 2007Over at my other blog I have an exposition of a set of ideas which have crystallized in my mind in regards to the patterns of human physical variation that we see around us in the world today. A reconsideration of some concepts was triggered in large part by the material I covered in the post about South Asian skin color. Over the next few months I hope to flesh out a precise and clear verbal outline of what I believe to be the general trends in human evolution over the past 50,000 years. In terms of formal/mathematical representations I know of what I speak, but translating the ideas into…
razib | September 7, 2007Last year Shelley Batts of Retrospectacle was the winner of a blog scholarship. This year they've increased the top award to $10,000. Check if you qualify (hint: don't click if you don't blog or aren't enrolled as a student at a college or university).
razib | September 7, 2007David at my other blog is putting up some posts on statistics as a primer for a series on Sewall Wright's population genetic work. Check out correlation: part 1. Should be interesting nerd candy....
razib | September 6, 2007Why are brown people so many shades of brown? If you were raised in a South Asian family I'm sure that you've had to deal with the "color" issue somehow. This isn't a cultural blog, so I'm not going to go there, but I do think that the salience of complexion in South Asian culture makes this new paper, A genome-wide association study of skin pigmentation in a South Asian population (PDF), of more than passing interest. If you plotted a frequency distribution of skin reflectances of South Asians within 2 standard deviations from the median you would see a range from brunette white from…
razib | September 6, 2007A few days ago I posted on a gene, HMGA2, which seems to be implicated in a small proportion of the normal human variation in height. There seems to be an SNP which comes in two flavors which results in a different in height in an additive & independent manner. A friend of mine pointed out that this SNP exhibits different frequencies in different populations. The "short" allele, which tends to have an average effect of decreasing the expectation in height, is the derived form. That is, it is a newer mutant in relation to the ancestral "tall" allele. Second, it seems that it is extant…
razib | September 5, 2007As my friend Chet Snicker would say to Larry Craig, you sir are no gentleman! Some of you know that I have recently trekked across this great nation of ours. One of the main differences between the most recent of my travels and previous peregrinations has been my relative trepidation and discomfort in public restrooms. Every time I was in a stall and a fellow citizen in distress entered to relieve themselves adjacent I could not help myself from wondering about the appearance of the infamous "wide stance." Gladly I was not faced with such a disquieting circumstance, but it is striking…
razib | September 5, 2007Proceedings of the Royal Society B has a paper out which reports evidence of positive selection on genes which seem to have some relationship to the heritability of schizophrenia (Nature has a good summary). The authors imply that the genes in question were likely selected for reasons totally unrelated to schizophrenia, but that the new variants increase susceptibility toward the disease. This is understandable, rapid selective bursts can result in the increase in frequency of alleles which might have negative side effects that are on the balance erased by the benefits which they confer (a…