genetics
razib | July 15, 2006Strong words from a "progressive" site:
Because it further negates their discrimination-based "biblical worldview," the science of human genetics - which has again suggested homosexuality is genetic (determined before birth) and not simply "a lifestyle choice" - is the Christian Right's special target. Genetic mutations and evolution are not theories. They're facts the validity of which cannot be disputed scientifically. (Ask any bacterium or virus, or read the medical literature on pathogens evolving to become resistant to traditional drugs used against them.)
The more people…
razib | July 15, 2006In my post below on the phenotypic difference in sensitivity to PTC (and ergo, bitterness), I allude to the fact that until recently the inheritance mode of this simple mongenic Mendelian trait (that is, controlled from one locus in the genome) was assumed to express via a dominance-recessive relationship on the phenotypic level. In other words, if you were heterozygous, you were a taster, and only homozygous individuals for non-taster alleles (two copies with lack of function) would express the "recessive" phenotype. Well guess what? Turns out that there are three phenotypes, and they seem…
razib | July 13, 2006In modern philosophy of the mind an unresolved issue is the question of qualia [update: I might be wrong about this actually]. What is 'whiteness' or 'sweetness,' as such? Well, I'm not a philosopher, but one thing that has interested me over the past few years has been the genetics of taste. Not surprisingly there seems to be a strong genetic and biological component in regards to perception and preferences. For example, it has long been known that there is variation in the extent of sensitivity to "bitter," assayed via the famous PTC test. Of late it has been shown that not only are…
razib | July 12, 2006A few months ago I posted on a conundrum that faces liberal moderns when it comes to engaging "traditional" peoples. The short of it is that the typical Eurasian pathogen load is deadly over the life history of individuals from many smaller isolated populations. I posted after reading Land of the Naked People, an attempt by an Indian science journalist to assay the situation on the ground in the Andaman Inslands. Now, John Hawks points to an article in Science which moots many of the issues I brought up.
Fundamentally a liberal order assumes equality before the law, but, as realists who…
razib | July 10, 2006This is somewhat Onion worthy, but it happens to be true: identical twins now run Poland. Specifically, both the legislative (Prime Minister) and executive branches (President) are under the control of a of monozygotic twin (via ParaPundit).
pharyngula | July 10, 2006Carel Brest van Kempen has extracted a few fascinating quotes from an old book he has. It's titled Creative and Sexual Science, by a phrenologist and physiologist from 1870, and it contains some wonderful old examples of folk genetics.
President Bush would be pleased:
"Human and animal hybrids are denounced most terribly in the Bible; obviously because the mixing up of man with beast, or one beast species with another, deteriorates. Universal amalgamation would be disastrous."
Although, unfortunately, he then goes on to use this as an argument against miscegenation.
Another lesson is that…
razib | July 10, 2006Just a reiteration on prosopagnosia. Let's assume that the findings as to the extent of face blindness pan out (I am willing to grant they found something seeing as there was an autosomal dominant pattern of inheritance in the pedigree).
1) I am skeptical that the 2% frequency in the population is due to reduced selection pressure in some populations. This behooves us to believe that we are just "catching" the German population on its way toward fixation. Additionally, this is a dominanttrait, so it seems less likely to be a loss-of-function which emerges because of relaxed selection (loss-of…
razib | July 7, 2006Prosopagnosia is "An inability or difficulty in recognizing familiar faces; it may be congenital or result from injury or disease of the brain." I've talked about this before. Well, Jake "The Superficial" Young now has a follow up post on the paper which elicited my initial skepticism. Since you can read the abstract, here is the conclusion:
Congenital PA is the only known monogenic dysfunction of a higher cognitive visual skill. Among more than 90 different cognitive functions (e.g., musical mind, absolute pitch) and dysfunctions (e.g., agraphia, dyscalculia, dyslexia) related to…
purepedantry | July 7, 2006Prosopagnosia is a rare disorder that can result from strokes where the individual is unable to recognize faces but maintains the ability to recognize other non-face objects. Disorders like prosopagnosia suggest to neuroscientists that the machinery for processing faces in the brain is in part special and segregated from the machinery for processing other objects.
It turns out that there is also a wildly underreported and surprisingly prevalent form of hereditary prosopagnosia (HPA), as shown in a new paper in American Journal of Medical Genetics. HPA has a prevalence of almost 2.5% and…
razib | July 6, 2006This entry is somewhat unconvential, but I will place in the "brain & behavior" category because I want comments on my own feelings & attitudes from those who know some psychology. I am an individual with opinions about the world. I suppose you could say that I'm your typical individual with a scientific & operationally materialistic worldview. I'm also mildly right-of-center, and tend to have as many issues with Post Modern "progressives" thought as I do with Religious Right reactionaries. Like the Religious Right I do believe there are truths in this world which are sacred…
razib | July 5, 2006A worthy (so I believe) repost from my other blog....
[begin repost]
Several years back David wrote about Sewall Wright's Shifting Balance Theory. If you know much about the history of mathematical genetics you know that R.A. Fisher and Wright's disputes over the importance of population substructure, genetic drift and the adaptive landscape was a simmering pot looming in the background of the emergence of the Modern Synthesis. One of the points that Fisher and Wright clashed over was the relative evolutionary importance of epistasis. I want to emphasize the evolutionary importance, because…
clock | July 4, 2006
I got several e-mails yesterday about a new study about the molecular mechanism underlying circadian rhythms in mammals ("You gotta blog about this!"), so, thanks to Abel, I got the paper (PDF), printed it out, and, after coming back from the pool, sat down on the porch to read it.
After reading the press releases, I was in a mind-frame of a movie reviewer, looking for holes and weaknesses so I could pounce on it and write a highly critical post, but, even after a whole hour of careful reading of seven pages, I did not find anything deeply disturbing about the paper. Actually, more I read…
razib | July 3, 2006The Guardian has a long piece up by a Muslim who has wrestled with the issue of reconciling his faith with evolutionary theory. The author is a secretary for The Muslim Council of Britain, an organization criticized for its illiberal tendencies (e.g., rejection of the participation of homosexual Muslim groups under their umbrella group). The interesting point, for me, is that the author alludes to the evolution of Muslims themselves, as they encounter evolutionary biology with their own pre-scientific models of the universe. The reaction of denial and incredulity seems akin to how some…
razib | July 3, 2006Evolgen has a nice little post up on the problems with mitochondrial DNA (mtDNA) in regards to using it to infer demographic history. This form of genomic information is useful in that it is relatively copious, being present in the hundreds of mitochondrion to be found within every cell. This is one reason that the early work on molecular clocks in the context of paleoanthropology used mtDNA, you needed a lot of raw material in the pre-PCR era. Remember mitochondrial Eve?
Now that neat story is fallling apart as the reality that mtDNA is subject to a great deal of selection seems to be…
pharyngula | July 2, 2006The science blogosphere must be getting big if it can support biology subspecialty carnivals: now you can read collections of posts about just bioinformatics or genetics. And here I thought a general science carnival might be too narrow to draw in a wide readership, way back in the dark ages!
razib | July 2, 2006A population bottleneck has a tendency of reducing the long term effective population size (harmonic mean) a great deal. I'm sure all of you knew that, and I'm sure you know that it also has a tendency of reducing variation. This is because low effective population sizes increase the power of genetic drift, which tends to expunge variation from a population.1
Great. The only thing though is that sometimes bottlenecks can "release" variation and make it available for selection. Additive genetic variance (heritability) increases as the genetic background is fixed on many loci, but not all,…
razib | July 1, 2006My focus on this weblog will tend to be a bit more theoretical and abstract when it comes to genetics. Specifically, as I've made clear before, I'm interested in how theoretical population genetics as conceived of during the Fisher-Wright-Haldane era can be applied and made relevant in the postgenomic epoch. That being said, obviously genetics/genomics plays an important role in the health & well being of individuals in the context of medicine and life choices, so I'll point you to DNA Direct Talk (via Genetics & Health, which also hits some of the same topics, though with a more…
razib | June 29, 2006It seems that others have a compulsion to control the means of my opinion production. 5 questions from Hsien Hsien Lei aimed at me. Lei runs a great weblog, Genetics and Health.