genetics
razib | May 16, 2006Don't have much time to comment, but I thought I'd point you to pending paper in PNAS (as usual, PNAS' webmaster is slow in getting this out though the press release says it is on their website) which suggests chimps have copy number variations similar to H. sapiens. The human genome is obviously interesting, but the recent focus on chimps too is obviously going to be important because to answer the question "what does it mean to be human?" it is good to have some perspective, and chimps are our nearest living relatives.
razib | May 15, 2006In an update to my previous post, I point you to David B's post at my other blog where he expresses skepticism about the recent study that applied Hamiltonian principles to royal fratricide.
razib | May 13, 2006Discovery News has a fascinating review of new research which suggests that royal fratricide tended to follow Hamiltonian principles, that is, cousins were killed so that nearer relations could prosper. Hamilton's Rule states that an "altruistic" behavior is genetically beneficial if Cost over two units. The logic is simple: imagine you carry a gene which states "be altruistic to your siblings!" To make this simple, assume that it was a de novo mutation in one of the parents. Well, there is a 50% chance that your sibling is carrying this gene (assume that the parent is heterozygous, so…
razib | May 12, 2006I'm reading Austin Burt & Robert Trivers' Genes in Conflict, and I'm in the chapter on genomic imprinting. They make a reference to a paper published a few years back which I vaguely remembered, by I decided to look it up again. Titled Paternally inherited HLA alleles are associated with women's choice of male odor, the authors found that women preferred the smell of men whose HLA alleles matched their paternally transmitted HLA alleles. Trivers & Burt point out that the actual HLA alleles the father actually had but did not transmit were not relevant, so that eliminates the…
razib | May 11, 2006...because they die!!!!. I got to thinking about this when I saw this article titled Leaving the Wild, and Rather Liking the Change, about the emergence of an isolated tribal population into the Columbian mainstream. This caught my eye:
Though it is unclear how big the Nukak population once was, anthropologists believe that what little contact the Nukak have had with outsiders has most likely left them reduced by Western diseases, including influenza and the common cold, to which they have no natural defenses.
Read 1491 by Charles C. Mann, and you'll see that unfortunately the decimation…
razib | May 10, 2006Evolgen points me to another paper about positive selection for an allele which doesn't always help us out. Intelligent Designer my ass, Mr. Omnipofuck-up needs to go back to bioengineering school!
razib | May 9, 2006I would like to give a heads up that the last volume of W.D. Hamilton's papers are out, Narrow Roads of Gene Land, The Collected Papers of W. D. Hamilton Volume 3: Last Words. Of course, you should check our volume 1, on social theory, and volume 2, the evolution of sex. If you don't know who Hamilton is, you should. Matt Ridley and Richard Dawkins as we know them are in large part due to Hamilton's body of work, from his gene-centered social models to exploration of the "Red Queen" theory of the origins of sex. Hamilton's hero early in life was the great evolutionary biologist R.A.…
razib | May 8, 2006Weird finding:
A mutation in a gene commonly associated with deafness can play an important part in improving wound healing, a scientist told the annual conference of the European Society of Human Genetics in Amsterdam, The Netherlands, today (Monday 8 May 2006). Dr. Stella Man, from the Institute of Cell and Molecular Sciences, Queen Mary's University, London, UK, said that the discovery may have implications for the treatment of a wide range of wounds, including post-surgery.
...
Professor Kelsell was the first to describe the link between Cx26 mutations and deafness in 1997. "Since many…
razib | May 6, 2006Over the past few years I have cast a skeptical eye at human phylogeography. Researchers like Spencer Wells have parlayed the study of uniparental lineages into books and television specials. Taking gene trees constructed from the Y chromosome Wells fashions the story of our species, in particular, of men. The problem of course is that Wells is looking at the lineage of the Y chromosome only! Humans are not neat little vacuum packages, nor are populations, rather, we are messy amalgamations of discrete genetic coalitions which are always in flux. Primed by our cultural mythologies and…
razib | May 3, 2006Pten Regulates Neuronal Arborization and Social Interaction in Mice:
...PTEN mutations in individuals with autism spectrum disorders (ASD) have also been reported, although a causal link between PTEN and ASD remains unclear. In the present study, we deleted Pten in limited differentiated neuronal populations in the cerebral cortex and hippocampus of mice. Resulting mutant mice showed abnormal social interaction and exaggerated responses to sensory stimuli...Thus, our data suggest that abnormal activation of the PI3K/AKT pathway in specific neuronal populations can underlie macrocephaly and…
razib | May 2, 2006Mike Lynch and Bruce Walsh are working on a "sequel" to Genetics and Analysis of Quantitative Traits. Thanks to the glory of the internet you can read draft chapters of Evolution and Selection of Quantitative Traits in PDF form.
pharyngula | April 30, 2006
In previous articles about fly development, I'd gone from the maternal gradient to genes that are expressed in alternating stripes (pair-rule genes), and mentioned some genes (the segment polarity genes) that are expressed in every segment. The end result is the development of a segmented animal: one made up of a repeated series of morphological modules, all the same.
Building an animal with repeated elements like that is a wonderfully versatile strategy for making an organism larger without making it too much more complicated, but it's not the whole story. Just repeating the same bits over…
razib | April 27, 2006Over at John Hawks, Has the dam broken on mtDNA selection?. I don't know if this matters that much scientifically since non-human phylogeography tends to be more cautious than the field of historical human population genetics, but it matters a lot for the public which has been habituated to a steady stream of mitochondrial data being interpreted by popularizers and the press since African Eve.
razib | April 26, 2006There is a preprint in the website of The American Journal of Human Genetics titled "Genetic variation in the CCL18 - CCL3 - CCL4 chemokine gene cluster influences HIV-1 transmission and AIDS disease progression." The title is a mouthful, but the short of it is what we've known for a long time, that human genetic variatian responds differently to HIV infection (or the risk of infection). This is surely going to be important, not because the science is a priori killer, but because AIDS is a big public policy issue. Back in the 1990s some people were talking about HIV resulting in the…
razib | April 26, 2006Greg Cochran's comment below is worth turning into a post:
There's more to it than that. Tribes often have extremely limited HLA variation, contain only a small subset of the variation that you see in a wider set of Amerindians. Whereas in the old world, even little tiny groups with very low gene flow have lots of different HLA alleles. [Cavalli-Sforza 1994] You'd think that they'd lose those rare alleles by drift, but they don't - has to be frequency-dependent selection, the same force that has kept alleles around for tens of millions of years. But in the Americas, it appears that those…
pharyngula | April 25, 2006This really is an excellent review of three books in the field of evo-devo—
From DNA to Diversity: Molecular Genetics and the Evolution of Animal Design (amzn/b&n/abe/pwll),
Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom (amzn/b&n/abe/pwll), and
The Plausibility of Life:Resolving Darwin's Dilemma (amzn/b&n/abe/pwll)—all highly recommended by me and the NY Times. The nice thing about this review, too, is that it gives a short summary of the field and its growing importance.
razib | April 24, 2006Earlier this week I hinted that I had a priori genetic reasons for being skeptical of a "two wave" theory for the peopling of the New World. Well, I was going to do some literature searches and slap something together that was meaty, but I don't have time, so I'll just offer up an attenuated but sufficient outline of what my issue is.
First, look at this map and note the "Amerindians" and other populations. Now, look at this table and note the level of heterozygosity of Amerindians vs. other populations. In short, Amerindians are notoriously genetically homogenous on the MHC loci compared…
razib | April 24, 2006John put up his last thoughts on race, and Evolgen chimed in with his ruminations.
First, nice exchange. Quick points....
1) I'm not hung up on a word. If you want to agree on another word that captures what I'm trying to say, I'm willing to go along with it.
2) One key point I want to make is that we should be cautious about relying on Lewontin's 85% intragroup vs. 15% intergroup data. Evolution and genetics are sciences of some subtly, and one can not draw a straight line between statistical data and pithy verbal conclusions. Context and framing matters a lot. What exactly does "…
razib | April 23, 2006John responds to the "race" response from Matt & I. I'm not interested in making a point-by-point response to the response because I don't think the "objective" difference in opinion is that great, rather, it seems to be that we are clashing in the turbulent waters of nominalism.
First, I will respond to what I believe is the perception by John that I am conceiving of race as an essential and fundamental taxonomical unit. I don't hold to that. I've rejected the Platonic conception of race before. The problem that "race based public policy" often has is that the legal system is…