genetics
razib | July 17, 2008I was curious why an old Genetics and Health post, Twins with Different Skin Color Genes, was sending me many referrals today. Now I know, Two in a Million: Twins Born - One Black, One White:
The twin boys, named Ryan and Leo, are the offspring of a mixed-race couple.
The mother, Florence, hails from Ghana in western Africa, and dad, Stephan, is from Potsdam in Germany.
"Ryan came first, and everything was as usual," said the hospital's doctor, Birgit Weber. "But when Leo was born, I couldn't believe my eyes."
"Both kids have definitely the same father," the doctor added.
These aren't the…
razib | July 17, 2008Brandom Keim at Wired says Genes Don't Explain African AIDS Epidemic:
Seen in the wrong light, the numbers could present Africa's AIDS tragedy as a biological inevitability. Several press accounts do exactly that. The New York Times credits the mutation for "explaining why the disease is more common there than expected." Reuters says it could "help explain why AIDS has hit Africa harder than all other parts of the world," as this can't be fully rooted in "sexual behavior and other social factors." The Guardian says it "may go some way" to explaining the African prevalence of AIDS. And the…
edyong | July 16, 2008
Many measures to curb the obesity epidemic are aimed at young children. It's a sensible strategy - we know that overweight children have a good chance of becoming overweight adults. Family homes and schools have accordingly become critical arenas where the battle against the nation's growing waistlines is fought. But there is another equally important environment that can severely affect a person's chances of becoming overweight, but is more often overlooked - the womb.
Overweight parents tend to raise overweight children but over the last few years, studies have confirmed that this…
clock | July 12, 2008Abbie and PZ chat about the recent discoveries in biology, how exciting those discoveries are, and how annoying it is when Creationists try to put a damper on such excitement:
clock | July 10, 2008This is very cool - African Bushmeat Expedition is a project which takes high school students to Africa where they both learn the techniques and at the same time do something very useful - track the appearance of wild animal meat in the market:
Although illegal wildlife poaching is conducted worldwide, the impact in Africa has been devastating. Unsustainable commercial hunting for bushmeat will inevitably lead to species extinction. In turn, localized species extinction impacts the health of native ecosystems. Marketing of illegal bushmeat can also have serious ramifications because pathogens…
clock | July 9, 2008Jim Evans, my friend here at UNC, says Yes, in an interview with NYTimes, and again on NPR's People's Pharmacy. He teaches a course on genetics to judges:
A lot of judges report that they did prelaw in college because it did not involve science. One of my favorite judges, a brilliant man, is fond of telling people he "flunked science in kindergarten." So in these workshops, I think of myself as a newfangled type of science teacher, instructing extremely smart and distinguished adults in science fundamentals.
razib | July 6, 2008I was looking at poll results for Genetically Modified Organisms (GMO). Internationally the results are all over the place, but within nations the data suggest a pretty strong notional resistance to "playing God," with a rank order of aversion spanning plants (least averse) to humans (most averse). There is some mild positive correlation between education and trust/acceptance of GMOs, and also some between irreligion and attitudes towards cloning and such for animals. The The Pew Initiative On Food And Biotechnology has some good data. For example:
Religious attendance also has a…
razib | July 3, 2008David continues his series on the thinking of the great evolutionary geneticist Sewall Wright. Today's post, Notes on Sewall Wright: Migration. First, the general:
Continuing my series of notes on Sewall Wright's population genetics, I come to the subject of migration. This is important in understanding the differences between Wright and R. A. Fisher on the role of genetic drift in evolution. Fisher and Wright both agreed that genetic drift would be too weak a process to be of evolutionary significance in large populations (above, say, 10,000 in effective size)...Equally, they agreed that it…
razib | June 30, 2008PZ Myers outlines synteny. RPM says he's kind of wrong. Check out the definition in Wikipedia. Since RPM came down on me for confusion on this term I knew he would bring this up. I don't really care much about which definition is "correct," but I thought I'd point interested readers to the debate.....
pharyngula | June 30, 2008RPM of Evolgen disagrees with my definition of synteny! This is terribly distressing. Especially since, strictly speaking, he is precisely correct. The word has evolved in its usage from the pure form that RPM is describing to a more colloquial, pragmatic, somewhat sloppier sense as used by people looking at comparative genomics rather than classical Drosophila genetics.
If you read contemporary evo-devo papers, my definition is more useful in comprehending what they're saying. If you want to read Drosophila genetics papers, you better know what RPM is talking about, or god help you (and…
razib | June 29, 2008Baby to be born free of breast cancer after embryo screening:
The couple produced 11 embryos, of which five were found to be free from the gene. Two of these were implanted in the woman's womb and she is now 14 weeks pregnant.
By screening out embryos carrying the gene, called BRCA-1, the couple, from London, will eliminate the hereditary disease from their lineage.
Obviously the headline is hyperbolic in this specific case. Changing probabilities is not necessarily a guarantee. But I think the bigger picture here warrants serious notice. Armand Leroi has outlined the major issues, so I…
razib | June 27, 2008I just read an interesting new paper, Genetic Variation in Political Participation:
The decision to vote has puzzled scholars for decades...The results show that a significant proportion of the variation in voting turnout can be accounted for by genes. We also replicate these results with data from the National Longitudinal Study of Adolescent Health and show that they extend to a broad class of acts of political participation. These are the first findings to suggest that humans exhibit genetic variation in their tendency to participate in political activities.
Here's a figure which really…
evolgen | June 27, 2008PLoS Genetics has published an interview with Jenny Graves. Graves is one of the leaders in monotreme and marsupial genetics, and has been involved in some of the recent mammalian genome projects, including the platypus genome project (doi:10.1038/nature06936). She is also an expert in the evolution of mammalian sex chromosomes and sex determining genes. However, I'd like to point to a quote in PLoS Genetics' interview of Graves that deals with science education:
So I'm becoming very interested in education, particularly of young children, which is where I think the rot sets in. Science is…
gregladen | June 26, 2008... is certainly still in the future. But we have seen a step in that direction in a new paper, coming out this week in Science. This research applies intensive and extensive genomic analysis to the avian phylogenetic tree. The results are interesting.
This paper is summarized in a number of locations, most notably here on Living the Scientific Life. Here, I will summarize it only very briefly. However, there are two observations I would like to make about this paper and its apparent meaning. One has to do with the nature of science, and the other has to do with the nature of…
pharyngula | June 26, 2008
This is an amphioxus, a cephalochordate or lancelet. It's been stained to increase contrast; in life, they are pale, almost transparent.
It looks rather fish-like, or rather, much like a larval fish, with it's repeated blocks of muscle arranged along a stream-lined form, and a notochord, or elastic rod that forms a central axis for efficient lateral motion of the tail…and it has a true tail that extends beyond the anus. Look closely at the front end, though: this is no vertebrate.
It's not much of a head. The notochord extends all the way to the front of the animal (in us vertebrates, it…
razib | June 26, 2008Sandy pointed me to letter to Nature by a group which has done some earlier pigmentation work, Two newly identified genetic determinants of pigmentation in Europeans:
We present results from a genome-wide association study for variants associated with human pigmentation characteristics among 5,130 Icelanders, with follow-up analyses in 2,116 Icelanders and 1,214 Dutch individuals. Two coding variants in TPCN2 are associated with hair color, and a variant at the ASIP locus shows strong association with skin sensitivity to sun, freckling and red hair, phenotypic characteristics similar to those…
pharyngula | June 25, 2008Let's play the most boring card game in the universe!
Here are the rules. We start with a fully sorted deck of 52 cards, and we deal out four hands. We don't deal in the ordinary way, either: we give the top 13 cards to the first player, then the next 13 to the second, and so forth. (We could also do the usual deal, but it makes the illustration and logic a little more difficult to see. We'll keep it simple for now.)
This is what the table will look like.
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Hand 3
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Hand 4
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razib | June 24, 2008Humans, being who we are, are really interested in how our external phenotype is shaped. Since the year 2000 many of the genetic underpinnings of the gross physical features which we use to categorize people, the sort of thing that might show up in a people description, have been elucidated. We know, for example, the genes which control variation in skin color to a first approximation at this point. It also seems that we've zeroed in on the primary gene responsible for eye color variation. Additionally, recently there's been the discovery of the gene which seems to control East Asian hair…
razib | June 24, 2008One of the great things about evolutionary genetics is that it is such a diverse field in terms of the cognitive toolkit which one must access as a matter of course. Since R. A. Fisher's The Genetical Theory of Natural Selection (along with the contemporaneous work of Sewall Wright and J. B. S. Haldane) we've been habituated toward thinking of evolutionary processes on an abstract level which might allow us to make general deductive inferences from first principles. Genetic drift, selection, migration, etc., are parameters which are used to construct models that allow us to generate…
razib | June 23, 2008Another story about recent human evolution, this time, really recent. The paper in PLOS is A Drastic Reduction in the Life Span of Cystatin C L68Q Carriers Due to Life-Style Changes during the Last Two Centuries. A mouthful, but the authors are really good at explaining what they're finding and why it's important:
....The detrimental phenotypic impact of the L68Q mutation appears to have emerged in reaction to common life-style changes almost three centuries after the mutation occurred. We believe that this is the first report of phenotypic flexibility of a monogenic disease in reaction to…