genetics
gregladen | December 12, 2007Some of the base pairs in a given genome are strung together into templates that code for proteins or RNA molecules. These are the classic "genes." Other base pairs probably have little or no function. Among the DNA that is not in classic gene-templates, however, there is a lot of important information, including "control regions."
How much of each "type" of DNA exists in a particular genome varies. A recent study suggests that the currently used methods for scanning DNA for regulatory sequences may systematically m miss more than half of that information.
Looking specifically at the DNA…
razib | December 11, 2007In light of the recent work on the acceleration of human evolution due to increased population size, this paper in Genetics, Inferring Human Population Sizes, Divergence Times and Rates of Gene Flow From Mitochondrial, X and Y Chromosome Resequencing Data:
We estimate parameters of a general isolation-with-migration model using resequence data from mitochondrial DNA (mtDNA), the Y chromosome, and two loci on the X chromosome in samples of 25-50 individuals from each of 10 human populations. Application of a coalescent-based Markov chain Monte Carlo technique allows simultaneous inference of…
gregladen | December 11, 2007There seems to be some interesting things going on with the recently reported study of rates of evolution in humans. We are getting reports of a wide range of rather startling conclusions being touted by the researchers who wrote this paper. These conclusions typically come from press releases, and then are regurgitated by press outlets, then read and reported by bloggers, and so on. Here is, in toto, the press release from the University of Wisconsin, where John Hawks, one of the authors of the study, works. I reproduce the press release here without further comment.
Genome study…
grrlscientist | December 10, 2007tags: James Watson, racism, African ancestry, genetics, genome, deCODE Genetics
James Watson, 1962 Nobel Prize winner
for co-discovering the structure of DNA along with
Francis Crick and Maurice Wilkins.
This is one of the funnier things I've read recently. It turns out that 1962 Nobel laureate, James Watson, who recently made some disparaging comments about the intelligence of Africans, probably is of African descent himself.
Watson, whose genome was completely sequenced, is the second person whose entire genome was published on the internet. As a result, it is freely accessible to the…
gregladen | December 10, 2007There is a new paper, just coming out in Proceedings of the National Academy of Sciences, that explores the idea that humans have undergone an increased rate of evolution over the last several tens of thousands of years.
By an increased rate of evolution, the authors mean an increased rate of adaptive change in the genome. By recent times, the authors mean various things, depending on which part of the analysis you examine, and depending on what is meant by "increased." ... In other words, the timing of an event that is not really an event (but rather a change in rate of something) is hard…
pharyngula | December 9, 2007It would seem like sweet poetic justice if James Watson were found to be 1/8th African, but I'm afraid I don't quite believe it. This is news coming from a company called deCODE genetics, an Icelandic outfit that analyzes an individual's racial background on the basis of various genetic markers. While I can buy the claim that they can assess the distribution of various alleles in populations, I really dislike the game of trying to work in reverse and assign the fraction of a race to an individual.
I don't think Larry is much impressed with them, either. Here's another article that brings up…
razib | December 7, 2007Thought I'd pass on two links. Greg Laden has posted a video of Robert Wright's interview with the late John Maynard Smith. I've watched it before, it's a great interview (or, at least Smith's responses are really interesting & meaty quite often). Also, this week's In Our Time covers Genetic Mutation. If names like Hugo de Vries are unfamiliar to you, probably worth listening to.
razib | December 7, 2007Check out Popgen Ramblings. There isn't really much up yet, but it looks like it's going to be good. Something new for the RSS!
razib | December 6, 2007Most ancient case of tuberculosis found in 500,000-year-old human; points to modern health issues:
Although most scientists believe tuberculosis emerged only several thousand years ago, new research from The University of Texas at Austin reveals the most ancient evidence of the disease has been found in a 500,000-year-old human fossil from Turkey.
...
The research team identified two shared characteristics in the communities: a path of migration from low, tropical latitudes to northern temperate regions and darker skin color.
People with dark skin produce less vitamin D because the skin…
grrlscientist | December 6, 2007tags: researchblogging.org, evolutionary behavior, sociobiology, ornithology, birds, avian, evolution, William Dilger, Agapornis roseicollis, Agapornis fischeri, lovebirds
Peach-faced lovebirds, Agapornis roseicollis (left)
and Fischer's lovebirds, Agapornis fischeri (right),
can interbreed to produce sterile offspring.
Images: LoveBirds New Zealand.
Is behavior genetically "programmed" or is it the result of learning? Or is it instead a little bit of both? This is the old "nature versus nurture" argument that has occupied behavioral and evolutionary scientists, psychologists and even…
razib | December 6, 2007Individual differences in allocation of funds in the dictator game associated with length of the arginine vasopressin 1a receptor RS3 promoter region and correlation between RS3 length and hippocampal mRNA:
Since variation in the length of a repetitive element in the vole AVPR1a promoter region is associated with differences in social behavior we examined the relationship between RS1 and RS3 repeat length (base pairs) and allocation sums. Participants with short versions...of the AVPR1a RS3 repeat allocated significantly...fewer shekels to the 'other' than participants with long versions....…
evolgen | December 5, 2007There are two recent genetics related posts on other blogs that evolgen readers might find interesting:
First, check out Query Gene (via ScienceRoll). This web-ap allows you to couple a nucleotide blast search with a Google search for a term related to your blast query. Here is how the creators describe it:
Query Gene is a web-based program that searches for information about genetic sequences on the web. It is distinctive because it is not limited to a single database, but instead captures genetic information on the entire Internet using Google. Query Gene works by taking a gene sequence in…
evolgen | December 3, 2007
Not all animals must have sex with another individual to produce perfectly viable offspring. And neither do humans, thanks to technological breakthroughs in artificial insemination. But what about those critters that do not require masturbation and meat basters to produce babies sans contact with another individual? Remarkably, this is quite common in the animal kingdom, although different animals go about doing it in different ways.
Caenorhabditis elegans, the roundworm that has become a popular model in developmental biology, lives in populations made up almost entirely of hermaphrodites.…
evolgen | November 29, 2007PLoS ONE has recently published a paper entitled "Beyond the Gene" by Evelyn Fox Keller and David Harel, in which the authors take a stab at the long standing question: What is a Gene? Because this is such a big picture question, the appropriate discussion of the paper would involve a synthesis of what they authors wrote, what has previously been written, and what I think about all of that. I'm not going to do that. I'm too lazy and too stupid to do that. Instead, I'm going to read the paper and live-blog it. This one's for you, Bora.
Quick tip: If you're planning to read an entire paper,…
clock | November 28, 2007
When Wilhelm Johannsen coined the word "gene" back in 1909 (hmmm, less than two years until the Centennial), the word was quite unambiguous - it meant "a unit of heredity". Its material basis, while widely speculated on, was immaterial for its usefulness as a concept. It could have been tiny little Martians inside the cells, it would have been OK, as they could have been plugged into the growing body of mathematics describing the changes and properties of genes in populations. In other words, gene referred to a concept that can be mathematically and experimentally studied without a…
gregladen | November 28, 2007The origin and early history of Native American people has always been an issue of debate and contention. There has never been a moment when all, or even most, interested parties agreed on anything close to a single story. New research published in the Open-Access journal PLoS Genetics tends to support a very traditional (among archaeologists) view of a single relatively simple migration from Siberia across the New World, more or less from north to south.
Studies of genetic variation have the potential to provide information about the initial peopling of the Americas and the more recent…
purepedantry | November 28, 2007Wang et al., publishing in PLoS Genetics, looked at the genetic diversity in Native American populations from Canada all the way down into South America. They wanted to see whether the genetic diversity observed in Native peoples correlated in any way with geography.
If the genetic diversity did not correlate with geography this would suggest that Native people colonized the New world from the Old world at different times in different waves of expansion. If, on the other hand, the genetic diversity correlated well with geography (on a North to South axis of decreasing diversity) this would…
katie glasrud | November 27, 2007I spent a summer working on an Arabian horse ranch when i was 17. I loved that place and am crazy about Arabians but... let's face it. We've severely inbred horses for show. Exhibit A:
It's not uncommon for an Arabian pedigree to boast seven lines of relation to one horse. Bask, for instance, was a famous Arabian stallion and today a large percentage of Arabs are his decendents including my horse, Rebel, of whom I'm foolishly fond:
Well, I learned some interesting news at today's Senior Seminar. Why inbreed when you can clone! It…
harderkid13 | November 27, 2007While reading Jonathan Weiner's book - Time, Love, Memory, I ran across several topics that are quite controversial. I thought that the book did an excellent job of presenting the science of these subjects while remaining neutral. One such topic is the genetic component of homosexuality. Studies have shown a tenative link between certain genes and homosexuality. Other studies have shown no such link. The thing about genetics is that genes interact with one another in very complex ways. It has taken decades to work out the mechanism of genes involved in circadian rhythm, and new discoveries…