genetics
razib | September 29, 2006In the post below on skin color within a multiracial family I made the point that genetics is inherited in a discrete fashion. In the post-genomic era, or even the post-DNA era, this seems intuitively clear. Our genetic sequence, our genome, is a string of precisely four base pairs, A, G, T and C. The genome is digital, not analog. Case closed, right?
Not really. One of the main reasons I wrote the post below is the consistent misconception that genetics is blending, that children are a mix of the essences of their parents. This captures the expectation, but the variance. A natural…
pharyngula | September 28, 2006Carl Zimmer brings up another essential point about the HAR1F study: it was work that was guided by evolutionary theory. The sequence would not have been recognized in the billions of nucleotides in the genome if it hadn't been for an analysis directed by the principles of evolution.
Wells' diatribe was amazingly wrong. I looked at it again and there could be another half-dozen essays in just picking up apart the stupidity in it.
razib | September 28, 2006Check out this Mendelian Genetics reference site, which has an enormous catalogue of links. It doesn't just talk about Punnett Squares, there's also a link to a simple introduction to the chi square test.
clock | September 27, 2006A really cool new study:
DailyScience: How Butterflies Got Their Spots: A 'Supergene' Controls Wing Pattern Diversity:
To explore the genetic backgrounds of each of these species, the authors crossed different races of each species and genotyped the offspring in order to identify genes responsible for the color patterns. Thus, they were able to map the color pattern controlling loci in each species: N, Yb, and Sb for H. melpomene; Cr for H. erato; and P for H. numata. Using molecular markers within the pattern encoding genic regions, the authors then found that the loci controlling color…
razib | September 27, 2006Last winter a story surfaced about "black" and "white" twins. As you can see by the picture the main difference is in skin color, though genetically full sisters (fraternal twins), one twin has the complexion typical of a northern European, while the other is darker skinned. Contrary to the news reports the darker skinned twin does not seem to exhibit the modal complexion of sub-Saharan Africans, rather, she is several shades lighter. In fact, the photo suggests that she is about the same color as her parents, who are both genetically 1/2 European and 1/2 black.* Seeing as how adults are…
razib | September 26, 2006Sandy at Discovering Biology in a Digital World responded to my post about skin color with White People are Mutants. This is an interesting juxtposition with a observation that some might claim that this implies that one is saying white people are more evolved. But it's more complex than that, as I point out, it seems that before our species evolved dark skin, we were white skinned, underneath our fur, so white people are "back to the future." Does that mean they are primitive? Or evolved back to primitivity? Obviously not, these sort of categories, "more evolved," or "advanced," are really…
razib | September 25, 2006A year ago, Armand Leroi, the author of Mutants, wrote:
...We don't know what the differences are between white skin and black skin, European skin versus African skin. What I mean is we don't know what the genetic basis of that is. This is actually amazing. I mean, here's a trait, trivial as it may be, about which wars have been fought, which is one of the great fault lines in society, around which people construct their identities as nothing else. And yet we haven't the foggiest idea what the genetic basis of this is. It's amazing.
Wonder no more Armand! Some have said we are in the…
clock | September 25, 2006Fruit Fly Aggression Studies Have Relevance To Humans, Animals:
Researchers in the North Carolina Sate University genetics department have identified a suite of genes that affect aggression in the fruit fly Drosophila melanogaster, pointing to new mechanisms that could contribute to abnormal aggression in humans and other animals.
The study, led by doctoral student Alexis Edwards in the laboratory of Dr. Trudy Mackay, William Neal Reynolds Professor of Genetics, appears online in PloS Genetics.
Feisty flies themselves may not be very scary, but their genes and biochemistry have more in common…
razib | September 22, 2006Two articles are out, one by Stephen Oppenheimer, author of The Real Eve, and another profiling some of Bryan Sykes'1 new research. The headlines are eye-catching, "We're nearly all Celts under the skin!" The fine print:
Even in England, about 64 per cent of people are descended from these Celts, outnumbering the descendants of Anglo- Saxons by about three to one.
The proportion of Celts is only slightly higher in Scotland, at 73 per cent. Wales is the most Celtic part of mainland Britain, with 83 per cent.
Sykes and Oppenheimer tell the tale of the resettlement of northern Europe, and…
razib | September 21, 2006The first chapter of Evolutionary Genetics: Concepts & Case Studies gives a quick sketch of the arc of the field that the book covers via exposition of topical and current issues. Michael R. Dietrich focuses on the series of controversies which serve as "hinges of history." I have addressed the controversy between the biometricians & Mendelians before, below are the "highlights" over a longer period based on the outline constructed by Dietrich in his chapter, From Mendel to molecules: A brief history of evolutionary genetics.
1860s
Genesis
Charles Darwin brings forth an evolutionary…
razib | September 20, 2006A report in The University of Chicago Magazine details the problems that interracial children have in relation to monoracial children, specifically, violence, drug abuse and disciplinary problems. Ah, but note this:
Choi has yet to decipher all the factors that exacerbate multiracial youths' "bad outcomes," but racial discrimination is part of the equation. Kids act out in response to ridicule or ostracism. In junior high and high school, "some [racial] groups are very exclusive. Other children will push you out if you're a racial combination." In similar surveys in Hawaii, she notes,…
evolgen | September 20, 2006Over a year and half ago (~1 eon in internet time) I wrote this blog entry in which I turned around the title of Dobzhansky's famous essay "Nothing in Biology Makes Sense Except in the Light of Evolution". I didn't think I was being all that clever when I came up with the following:
NOTHING IN EVOLUTION MAKES SENSE EXCEPT IN THE LIGHT OF GENETICS
I pointed out that evolution requires heritable variation first and foremost, hence genetics lies at the center of all of evolution. I then took the opportunity to explain why Hardy and Weinberg's derivation that random mating does not change allele…
razib | September 19, 2006A few weeks ago I posted my fixations which put the spotlight on some elementary population genetics formalisms. I thought I'd put my elementary Illustrator skills to use and throw up the canonical diagram use to elucidate basic population genetics in many classrooms. Here you see two demes, two breeding populations, and the arrows show the factors which increase and decrease genetic diversity. While mutation increases genetic variation, genetic drift tends to remove variants. Similarly, while balancing selection, whether it be frequency dependent or heterozygote advantage, tends to…
evolgen | September 19, 2006I'm slowly working my way1 through my complementary copy of What We Believe but Cannot Prove. I'm almost done -- at page 214 out of 252 -- and I can say that it is very diverse. The essays range from very thoughtful and interesting to way too specific to a particular discipline . . . to off the mark. Thankfully essays in the last category are few and far between. But when someone gets it so very wrong (or not even wrong), and they're writing about something you know about . . . well, it warrants a blog entry. This is that blog entry (with a maximal number of ellipses).
The someone in this…
razib | September 18, 2006Not much on evolution and genetics of late...well, sometimes life goes in other directions. But, I though I'd point you to JP over at my other blog commenting on a paper where the author dismisses the rate of human genomic evolution next to his vaunted Drosophila (the full paper can be found in the links over there). RPM responds over at his blog. The comment boards on my other blog have been hoppin', with RPM being the Drosophile, and JP making the case that H. sapiens is the next big model organism. Scroll down and you'll see the Allen Iverson.'
I just got Evolutionary Genetics:…
pharyngula | September 16, 2006An old pal of mine, the splendiferously morphogenetical Don Kane, has brought to my attention a curious juxtaposition. It's two articles from the old, old days, both published in Nature in 1981, both relevant to my current interests, but each reflecting different outcomes. One is on zebrafish, the other on creationism.
1981 was a breakthrough year for zebrafish; I think it's safe to say that if one paper put them on the map, it was Streisinger et al.'s "Production of clones of homozygous diploid zebra fish (Brachydanio rerio)"1. George Streisinger was the father of zebrafish as a model system…
pharyngula | September 15, 2006
I mentioned before that IDEA clubs insist that expertise is optional; well, it's clear that that is definitely true. Casey Luskin, the IDEA club coordinator and president, has written an utterly awful article "rebutting" part of Ken Miller's testimony in the Dover trial. It is embarrassingly bad, a piece of dreck written by a lawyer that demonstrates that he knows nothing at all about genetics, evolution, biology, or basic logic. I'll explain a few of his misconceptions about genetics, errors in the reproductive consequences of individuals with Robertsonian fusions, and how he has completely…
pharyngula | September 15, 2006We just had one of these!
Mendel's Garden #6
Friday Ark #104
Well, just to flesh it out a little more with some random links, here are some photos. I was told the second one made someone think of me (warning: body modification!). And, jebus help me, for some reason I thought this photo was very sexy. Or appetizing. I don't know, something in the midbrain flickered.
Oh, and several of us sciencebloggers were interviewed for an article by Eva Amsen on "Who benefits from science blogging?" It doesn't mention the benefit of people sending you pictures that tickle the cingulate.
evolgen | September 15, 2006The sixth edition of Mendel's Garden has been posted at The Voltage Gate. Like Ice Cube, MC Ren, and Eazy-E, this one's straight outta Compton. Go check it out to see what NWA gots to do with genetics blogging. I know I'm pimpin' my Raiders hat over a Jheri curl right now.