genetics
razib | January 7, 2009Language Log has a fascinating post up, The Linguistic Diversity of Aboriginal Europe. The distribution of language families, and their relationships, are not arbitrary. They tell us something about human history. Here is the interesting part for readers of this weblog:
It follows that the appearance of IE languages in much of Europe at an early date must reflect a considerable spread of IE languages from their point of origin. Many commentators, for a great variety of reasons, would like to believe that that spread occurred without any significant population movements; but that, too,…
sporte | January 7, 2009I don't know if any DIY biologists are looking for projects, but I think engineering yeast with a gene to detect heavy metals might be a good DIY biology project and I have some ideas for how to do this.
What are the advantages of using yeast and working on this kind of problem?
This could have a socially beneficial result. Contamination of soils, water, and even toys with heavy metals like lead, arsenic, and others, is a growing problem. If DIY biologists could make a cheap test, it could be helpful for a large number of people.
Yeast, at least the ones I'm thinking about, Saccharomyces…
sporte | January 6, 2009My garden at home is looking a bit bleak after all the snow, Mendel's Garden is blooming wonderfully at Jeremy Cherfas' blog Another Blasted Weblog.
Jeremy has prepared a nice collection of perennial favorites. I especially like the story about pea breeding and, if you view the post, there are several interesting pictures of peas. These peas are far more diverse than the kind you'd normally see in a genetics text. Not all peas are shrunken or waxy.
genetics, Mendel's garden, blog carnival
razib | January 4, 2009A commenter below sayeth:
I remember reading somewhere that a child can't be darker than the darker of his two parents and that in such instances the biological father is not the putative father. I have no idea if that's true or not.
This seems like a common sense assertion, but as I noted this is not really strictly correct in an apodictic sense. That is, just because you have a very dark skinned parent and a light skinned parent, it does not necessarily follow that the range of the offspring shall be bounded by the values of the parents. To some extent I can see how this makes sense; I…
evolgen | January 2, 2009
Mendel's Garden is the original genetics blog carnival. The next edition will be hosted by Jeremy at Another Blasted Weblog. If you would like to submit a blog post to be included in the carnival, send an email to Jeremy (jcherfas at mac dot com). The carnival should be posted within the next few days, so get your submissions in ASAP.
Also, hosts are needed for future editions of Mendel's Garden. If you would like to host, please send me an email (evolgen at yahoo dot com). A new edition is usually posted around the first Sunday of each month.
razib | January 1, 2009Every now and then British newspapers publish the story of twins born to an interracial couple who seem to resemble only one of the races of their parents. The irony being that siblings may appear to be of different populations. I've commented on several of these stories before. Now we have another one to ring in the new year, Mixed-race couple give birth to black and white twins - for the second time:
Seven years after having one black twin and one white twin, the 27-year-old mother has given birth to a second set of twins with different coloured skin at odds of one in 500,000.
When the…
razib | December 31, 2008ScienceBlogs has a new contributor, Rebecca Skloot of Culture Dish. The title is in part a reference to her new book, The Immortal Life of Henrietta Lacks. Looks interesting. If Henrietta Lacks doesn't ring a bell, look her up, it's rather freaky....
razib | December 28, 2008Dienekes points me to a new paper, Searching for the origin of Gagauzes: Inferences from Y-chromosome analysis:
The Gagauzes are a small Turkish-speaking ethnic group living mostly in southern Moldova and northeastern Bulgaria. The origin of the Gagauzes is obscure. They may be descendants of the Turkic nomadic tribes from the Eurasian steppes, as suggested by the "Steppe" hypothesis, or have a complex Anatolian-steppe origin, as postulated by the "Seljuk" or "Anatolian" hypothesis. To distinguish these hypotheses, a sample of 89 Y-chromosomes representing two Gagauz populations from the…
edyong | December 28, 2008Solar power is a relatively new development for humans but, of course, many living things have been exploiting the power of the sun for millions of years, through the process of photosynthesis. This ability is usually limited to plants, algae and bacteria, but one unique animal can do it too - the emerald green sea slug Elysia chlorotica. This remarkable creature steals the genes and photosynthetic factories of a type of algae that it eats (Vaucheria littorea), so that it can independently draw energy from the sun. Through genetic thievery, it has become a solar-powered animal and a…
razib | December 24, 2008PLOS has a think piece up, "It's Ok, We're Not Cousins by Blood": The Cousin Marriage Controversy in Historical Perspective, which comes out against the laws in the United States which ban the marriage of cousins:
It is obviously illogical to condemn eugenics and at the same time favor laws that prevent cousins from marrying. But we do not aim to indict these laws on the grounds that they constitute eugenics. That would assume what needs to be proved - that all forms of eugenics are necessarily bad. In our view, cousin marriage laws should be judged on their merits. But from that standpoint…
gregladen | December 23, 2008It has long been known that incest is not as bad as you think. Anti-cousin marriage laws are like prohibition laws and blue laws. They arise from a Christian conservative movement that swept Western Civilization from the late 18th century through the 19th century, up to about the time of the repeal of Prohibition.
Sure, marrying, or just plain having sex with, your sibling is disgusting. I mean, think about it. No, wait, don't even think about it. But cousin marriage? That depends. Your cousin may be kinda cute, you never know.
But seriously, anthropologists have long known of ... and…
razib | December 22, 2008Say you have a abstruse paper such as, Accelerated genetic drift on chromosome X during the human dispersal out of Africa:
Comparisons of chromosome X and the autosomes can illuminate differences in the histories of males and females as well as shed light on the forces of natural selection. We compared the patterns of variation in these parts of the genome using two datasets that we assembled for this study that are both genomic in scale. Three independent analyses show that around the time of the dispersal of modern humans out of Africa, chromosome X experienced much more genetic drift than…
razib | December 18, 2008Mike White finally left a comment on my post Complex traits & evolution:
I'm trying to make a distinction between what geneticists call complex or quantitative traits (traits affected by different alleles of many different genes, with a quantitative range of phenotypes), and something I would call a physiologically complex (or complicated) trait.
Complex or quantitative traits include both height and intelligence. But I'm arguing that something like height is not physiologically complex the way intelligence is.
...
So, for example, in the case of height, you can imagine that it is easy…
purepedantry | December 17, 2008I have been meaning to talk about this story, but I have been busy.
A study in Nature looked for genes linked with "common" obesity (more on that in a moment), and it was one of the first to link genes to the disease. Turns out several are genes expressed in the brain:
A genetic study of more than 90,000 people has identified six new genetic variants that are associated with increased Body Mass Index (BMI), the most commonly used measure of obesity. Five of the genes are known to be active in the brain, suggesting that many genetic variants implicated in obesity might affect behaviour,…
sb admin | December 17, 2008Larry Moran points to a couple of posts critical of microarrays (The Problem with Microarrays):
Why microarray study conclusions are so often wrong
Three reasons to distrust microarray results
Microarrays are small chips that are covered with short stretches of single stranded DNA. People hybridize DNA from some source to the microarray, which lights up if the DNA hybridizes to the probes on the array.
Most biologists are familiar with microarrays being used to measure gene expression. In this case, transcribed DNA is hybridized to the array, and the intensity of the signal is used as a…
razib | December 15, 2008Over at Genetic Future. Dan "the Man" MacArthur has been quite prolific recently. You should add Genetic Future to your RSS, or at least bookmark it if you are old school.
razib | December 15, 2008Six new loci associated with body mass index highlight a neuronal influence on body weight regulation:
Common variants at only two loci, FTO and MC4R, have been reproducibly associated with body mass index (BMI) in humans. To identify additional loci, we conducted meta-analysis of 15 genome-wide association studies for BMI (n > 32,000) and followed up top signals in 14 additional cohorts (n > 59,000). We strongly confirm FTO and MC4R and identify six additional loci (P < 5 10-8): TMEM18, KCTD15, GNPDA2, SH2B1, MTCH2 and NEGR1 (where a 45-kb deletion polymorphism is a candidate…
razib | December 15, 2008One of the major reasons that so much human genetic work is fixated on ascertaining the nature of population substructure is that different populations may respond differently to particular drugs. Of course population identification is only a rough proxy, but in many cases it is a good one. Years ago, Neil Risch reported the utility of genetic markers in differentiating individuals into distinct groups, and the high fidelity of these identifications with self-report. But this sort of generalization is contingent on particular conditions. In Brazil centuries of admixture have resulted in a…
razib | December 12, 2008Genetic variation in South Indian castes: evidence from Y-chromosome, mitochondrial, and autosomal polymorphisms:
We report new data on 155 individuals from four Tamil caste populations of South India and perform comparative analyses with caste populations from the neighboring state of Andhra Pradesh. Genetic differentiation among Tamil castes is low...reflecting a largely common origin. Nonetheless, caste- and continent-specific patterns are evident. For 32 lineage-defining Y-chromosome SNPs, Tamil castes show higher affinity to Europeans than to eastern Asians, and genetic distance…