genetics
grrlscientist | February 19, 2007Swedish researchers claim that it may be possible to read a person's personality by analyzing their irises. They studied 428 people and correlated iris patterns with warm-heartedness and trust or neuroticism and impulsiveness. The researchers looked at crypts (pits) and contraction furrows (lines curving around the outer edge of the iris), which are formed when pupils dilate.
It was found that those with more crypts were likely to be tender, warm and trusting, while those with more furrows were more likely to be neurotic, impulsive and give in to cravings.
The researchers suggest that a…
razib | February 17, 2007Success begets succes, Dienekes was looking closely at genetic data due to the publication two papers which suggest an Anatolian origin for Etruscans (there has been previous mtDNA going back at least 5 years as well). He finds that central Italy exhibits a relatively high frequency of a variant of Haplogroup J, famously connected to the spread of farmers from Anatolia into Europe during the Neolithic revolution. Not that we're on the trail of the definitive answer I suspect that things will "fit into place" far more easily. Scholarship is informed by scholarship, knowing that the Etruscans…
razib | February 15, 2007Yesterday I posted about the mtDNA results which suggest that Etruscans were Anatolian emigres to Italy. More data just came to light:
In the region corresponding to ancient Etruria (Tuscany, Central Italy), several Bos taurus breeds have been reared since historical times. These breeds have a strikingly high level of mtDNA variation, which is found neither in the rest of Italy nor in Europe. The Tuscan bovines are genetically closer to Near Eastern than to European gene pools and this Eastern genetic signature is paralleled in modern human populations from Tuscany, which are genetically…
razib | February 14, 2007Most of you know that I believe there are serious problems with much of contemporary historical population genetics. Grand unfounded narratives, and scientists who lack requisite historical knowledge, litter the field. But, narrow, precise and crystal clear studies do emerge now and then. This is a case in point, Mitochondrial DNA Variation of Modern Tuscans Supports the Near Eastern Origin of Etruscans:
Interpopulation comparisons reveal that the modern population of Murlo, a small town of Etruscan origin, is characterized by an unusually high frequency (17.5%) of Near Eastern mtDNA…
razib | February 13, 2007Had to link to a paper with such a title. Relative Impact of Nucleotide and Copy Number Variation on Gene Expression Phenotypes:
...SNPs and CNVs captured 83.6% and 17.7% of the total detected genetic variation in gene expression, respectively, but the signals from the two types of variation had little overlap....
Here's a quote from a popular press article:
"We've been able to look back into our history and find changes that are older and likely to be shared among populations," explained Dr Manolis Dermitzakis, senior author and Project Leader at the Wellcome Trust Sanger Institute. "But we…
razib | February 11, 2007Update: Greg Laden has a post worth reading on tis topic.
Sexual selection is an expansive topic. It is also one with a complicated history and fits messily into a rigorous empirical research program. I will base this post predominantly on the verbal exposition in R.A. Fisher's The Genetical Theory of Natural Selection. My reason is simple: though progress in formalization of sexual selection theory has been significant within the past 25 years, the major issues and concepts were sketched out by Fisher.
Prior to Fisher sexual selection was discussed quite extensively by Charles Darwin, but…
razib | February 10, 2007Many months ago I was reviewing R.A. Fisher's The Genetical Theory of Natural Selection when I touched upon his view of the nature of adaptation, precisely, that it occurs though the substitution of mutations of small effect. This dovetails with the "gradualism" which Charles Darwin promoted, and is also the thinking that drive's Richard Dawkins conception of evolution promoted in his popular books. In contrast, in the contemporary age S.J. Gould was most closely associated with the position that mutations and evolutionary changes of a larger scale, macromutations, may play a role in…
razib | February 9, 2007The "domestic" cat, Felis silvestris catus, has been with us for nearly 10,000 years. Recently, a 9,500 year old burial of a human and their companion cat was discovered on Cyprus. Cats are not indigenous to the island, so it seems that the presence of this cat must be owed to human intervention in some manner. Though we are used to thinking about how humans shaped cats through selective breeding the recent data on Toxoplasma gondii suggests that cats might have an impact on human behavior that could explain cultural differences! Some intellectuals have posited that the selection of…
grrlscientist | February 9, 2007The 11th edition of Mendel's Garden is now available. This blog carnival celebrates the best of genetics writing in the blogosphere.
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tags: blog carnival, genetics
evolgen | February 9, 2007Hsien at Genetics & Health has posted the newest edition of my favorite (just) science blog carnival: Mendel's Garden. There are oodles of reasons why you should love genetics (and only a couple why you should not).
If you would like to host a future edition of Mendel's Garden, visit the carnival's blog and leave a comment or email Paul.
razib | February 8, 2007I've always had an interest in human origins, and have been an avid consumer of books and papers relating to the emergence of our own species through an evolutionary lens. Though I am interested in paleontology, my own bias has been to look toward the genetic evidence because it is more accessible (that is, paleontology focused on morphological characters presupposes a knowledge of anatomy and general familiarity with osteology which I lack). Because of my age some of the works which I stumbled upon were from the 1970s, during which a debate had erupted between Allen Wilson, who argued for a…
razib | February 7, 2007Why do humans cooperate? Why do we behave "altruistically"? These are the sort of "big" questions which the human sciences explore. From the vantage point of evolutionary biology there has been a long history of exploring, and attempting to explain, altruistic behavior. And yet such questions weren't always considered of great value, the great W.D. Hamilton was discouraged from his exploration of this topic by his department head. At one point he took up carpentry to furnish for himself an income while he pursued his science in his spare time, so pessimistic was he about receiving academic…
clock | February 7, 2007Just got this exciting news by e-mail:
Data on Equine Genome Freely Available to Researchers Worldwide
BETHESDA, Md., Wed., Feb. 7, 2007 - The first draft of the horse genome sequence has been deposited in public databases and is freely available for use by biomedical and veterinary researchers around the globe, leaders of the international Horse Genome Sequencing Project announced today.
The $15 million effort to sequence the approximately 2.7 billion DNA base pairs in the genome of the horse (Equus caballus) was funded by the National Human Genome Research Institute (NHGRI), one…
evolgen | February 6, 2007Where the variation comes from.
Evolution proceeds by the action of many different evolutionary forces on heritable variation. Natural selection leads to the increase in frequency of variation that allows individuals to produce more offspring who, themselves, produce offspring. Genetic drift changes the frequency of variation through random sampling of individuals from one generation to the next. Population subdivision divides the variation into isolated groups where other forces (selection, drift, etc) act upon it. But where does all this variation come from?
Given the title of the post, the…
razib | February 6, 2007The idea of stochastic training wheels sounds a bit scary, but I am alluding to the series of posts on stochastic dynamics adapted from chapter 5 of Evolutionary Genetics: Concepts & Case Studies by John Gillespie. Using Gillespie's terminology the posts were:
Boundary Process
Origination Process
Genetic Drift
Genetic Draft
Random Environment
There was also another factor which Gillespie points to, which didn't have a particular section and rather loomed over all the other parameters, and that was Deterministic Selection.
Of Gillespie's parameters only one is highly dependent on the…
evolgen | February 5, 2007I've been chatting up Wilkins about the role of natural selection in speciation (and when I say "speciation" I mean "reproductive isolation"). Wilkins listed a few cases where speciation would occur independently of natural selection. Amongst the mechanisms in Wilkins's list was speciation via karyotypic changes (polyploidy, inversions, fusions or fissions). I cried shenanigans, and this is why.
The karyotype refers to the organization of an organism's genome -- chromosome number, fusions/fissions of chromosomes, and gene order within chromosomes. One way to change the karyotype is to…
clock | February 5, 2007Just quickly for now without commentary:
Totally cool paper in the last Science:
S. Libert, J. Zwiener, X. Chu, W. VanVoorhies, G. Roman, and S.D.Pletcher
Regulation of Drosophila lifespan by olfaction and food-derived odors:
Smell is an ancient sensory system present in organisms from bacteria to humans. In the nematode Caeonorhabditis elegans, gustatory and olfactory neurons regulate aging and longevity. Using the fruit fly, Drosophila melanogaster, we show that exposure to nutrient-derived odorants can modulate lifespan and partially reverse the longevity-extending effects of dietary…
razib | February 5, 2007The conventional Mendelian
model for diploid organisms assumes that the expression of an autosomal
allele within an individual should be invariant of its sex of origin,
that is, whether it is inherited from the father or the mother.
This model is incorrect for a subset of alleles across many taxa, in
particular mammals. In 1989 David Haig and Mark Westoby outlined
the evolutionary rationale for parent specific gene expression.1
In 1992 paternal and maternal specific imprinting of the insulin growth
factor 2 and insulin growth factor 2 repressor loci (Igf2,
Igf2r) in mice confirmed their…
grrlscientist | January 30, 2007
tags: transgenic chickens, genetic engineering, chickens, birds
Like bacteria, various farm animals have been cloned to produce a variety of protein drugs that benefit humans. These protein drugs can counteract medical conditions such as anemia and diabetes and even some cancers. However, these cloned animals are expensive, large, and most take years before they can produce these desired protein drugs in sufficient commercially-viable quantities.
However, some researchers have decided that chickens can be desirable protein drug factories because they are small, inexpensive and have rapid…